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joicegiz
2012-Dec-15, 07:54 AM
Hi,

I have read some studies that aliens are true and they do exists. What are your perspective on this?

Colin Robinson
2012-Dec-15, 11:06 PM
Hi,

I have read some studies that aliens are true and they do exists. What are your perspective on this?

Please tell us a bit more about the studies you've read... That would make it easier to give a perspective.

ASTRO BOY
2012-Dec-16, 04:47 AM
We have no solid observational or experimental evidence that life exists other then on Earth.
In saying that and in my opinion it would be the height of arrogance to think we are it.
We have 100's of billions of stars in this galaxy alone, and billions of galaxies with more or less the same amount of stars...We have the stuff of life everywhere we look, and extra solar planets have now been shown to be common place along with water in one form or another....As Elly said in the movie "Contact", "If we are it, it seems like an awful lot of wasted space"
[or at least words to that effect]

Also worth noting that as measurements and observations of extra solar planets become more precise, the discovery of an Earth like planet draws gets closer all the time.

And all this just in our "Observable Universe"...no doubt a very small fraction of the whole Universe.

Paul Beardsley
2012-Dec-16, 12:30 PM
I have read some studies that aliens are true and they do exists. What are your perspective on this?

There have been no credible accounts of aliens visiting Earth.

It seems very likely that life arose elsewhere in the universe but so far we have no evidence that confirms this.

It seems unlikely to an extreme that Earth is the only planet in the universe where life arose, but reality has a habit of surprising us. See my sig line!


We have no solid observational or experimental evidence that life exists other then on Earth.
In saying that and in my opinion it would be the height of arrogance to think we are it.

Please let as have an end to this cliche. Arrogance is when you think you are superior to or more important than others. Having doubts that life arose elsewhere has nothing to do with arrogance.

Selfsim
2012-Dec-16, 08:06 PM
We have no solid observational or experimental evidence that life exists other then on Earth.
In saying that and in my opinion it would be the height of arrogance to think we are it.
We have 100's of billions of stars in this galaxy alone, and billions of galaxies with more or less the same amount of stars...We have the stuff of life everywhere we look, and extra solar planets have now been shown to be common place along with water in one form or another….What we think, and what exists, are two completely distinct realms.

Most of science is counterintuitive. That's where science comes from.

Thinking something is arrogance, says nothing about the physical universe.


As Elly said in the movie "Contact", "If we are it, it seems like an awful lot of wasted space"
[or at least words to that effect]A fictional character in a movie, (created by a romanticist), can say anything.

How does that influence what exists?


Also worth noting that as measurements and observations of extra solar planets become more precise, the discovery of an Earth like planet draws gets closer all the time.

And all this just in our "Observable Universe"...no doubt a very small fraction of the whole Universe.Opinion is used to rule out doubt, eh?

What did you say arrogance was? … Oh … you didn't say …

Cheers

ASTRO BOY
2012-Dec-17, 12:58 AM
Please let as have an end to this cliche. Arrogance is when you think you are superior to or more important than others. Having doubts that life arose elsewhere has nothing to do with arrogance.



The church was renowned in their arrogance in maintaining a geocentric Universe even in the face of overwhelming evidence...........
I'm sure Galileo would agree with me.
I see no reason to believe we are alone in the Universe...other then arrogance of sorts.

ASTRO BOY
2012-Dec-17, 01:10 AM
What we think, and what exists, are two completely distinct realms.

Most of science is counterintuitive. That's where science comes from.

Thinking something is arrogance, says nothing about the physical universe.



Most of science is common sense in hindsight.






Opinion is used to rule out doubt, eh?



Cheers


We all have opinions...I just think mine is supported by the numbers on this issue.





What did you say arrogance was? … Oh … you didn't say …

I'm sure my signature illustrates what arrogance of sorts is.

Again, in my opinion to say life does not exist elsewhere in light of the numbers is arrogant...

ASTRO BOY
2012-Dec-17, 01:14 AM
A fictional character in a movie, (created by a romanticist), can say anything.



What did you say arrogance was? … Oh … you didn't say …

Cheers

Pedant....
It's a quote from a movie, no more, no less, and used to illustrate a valid point......
cheers.

Paul Beardsley
2012-Dec-17, 07:39 AM
Again, in my opinion to say life does not exist elsewhere in light of the numbers is arrogant...

Numbers? So, given a situation where the elements necessary for life are present, tell us what the probability is that life will arise.

If you cannot answer that, take it as your cue to think again about what arrogant really means.

ASTRO BOY
2012-Dec-17, 08:04 AM
Numbers? So, given a situation where the elements necessary for life are present, tell us what the probability is that life will arise.

If you cannot answer that, take it as your cue to think again about what arrogant really means.



I've got a better idea.......You tell me how many stars, galaxies, planets we have in the observable Universe, then given the observation that the stuff of life is everywhere, what is the likelyhood of it arising again.
Quite good most Astrophysicists seem to think.

Selfsim
2012-Dec-17, 08:21 AM
Most of science is common sense in hindsight.Really?
What exactly is common sense, in hindsight, about wave particle duality or quantum entanglement? Or maybe, that 0.999 (recurring) equals 1? Or, maybe that mathematics is a completely solid basis for producing reliable deductions? The list of counterintuitive science done in the past, is extensive ... and its still counterintuitive today.

We all have opinions...I just think mine is supported by the numbers on this issue.And you're welcome to think whatever you like. Same for other folk, but I personally request that you refrain from then using your opinions as the basis for accusing others' of 'arrogance', simply because theirs don't line up with yours.

The 'numbers' say nothing, because there are no 'numbers'.

If you have no instances of exo-life to extrapolate from, your claim of: 'is supported by the numbers' is meaningless. It doesn't matter how many exo-planets exist in the universe .. its mathematically irrelevant.
Go ahead .. give it a try … try calculating the numbers of planets with exo-life, without making any assumptions about what you 'think' might be the 'likelihood' of exo-life. One simply can't do it. I really think this the only way you'll realise that your view is not supported by any 'numbers' at all. Neither is the opposite view of: 'no exo-life'.


I'm sure my signature illustrates what arrogance of sorts is.

Again, in my opinion to say life does not exist elsewhere in light of the numbers is arrogant...And you can have your opinion .. everyone has one … and they make absolutely no difference to physical reality.
It also makes absolutely no difference how many quotes, (of historical curiosity), about technology predictions you have in your signature line, either. What relevance does a wayward 19th Century technology prediction have to do with the topic we're discussing?

ASTRO BOY
2012-Dec-17, 08:53 AM
Really?
What exactly is common sense, in hindsight, about wave particle duality or quantum entanglement? Or maybe, that 0.999 (recurring) equals 1? Or, maybe that mathematics is a completely solid basis for producing reliable deductions? The list of counterintuitive science done in the past, is extensive ... and its still counterintuitive today.



Yep we have some exceptions....But we can also now describe from a tiny fraction of a second after the BB, how our Universe/space/time expanded evolved and developed.




And you're welcome to think whatever you like. Same for other folk, but I personally request that you refrain from then using your opinions as the basis for accusing others' of 'arrogance', simply because theirs don't line up with yours.

The 'numbers' say nothing, because there are no 'numbers'.




I used the term arrogance as that seemed to sum up mankind in many instances as is obvious with the church in past eras. Also the term was used collectively not personally.
And I couldn't disagree with you any more re the numbers...They mean everything and we do have at least 1 example of life arising.




[/QUOTE]
If you have no instances of exo-life to extrapolate from, your claim of: 'is supported by the numbers' is meaningless. It doesn't matter how many exo-planets exist in the universe .. its mathematically irrelevant.
Go ahead .. give it a try … try calculating the numbers of planets with exo-life, without making any assumptions about what you 'think' might be the 'likelihood' of exo-life. One simply can't do it. I really think this the only way you'll realise that your view is not supported by any 'numbers' at all. Neither is the opposite view of: 'no exo-life'.[/QUOTE]


With the example of life arising at least once, my view is in my opinion supported by the near infinite numbers invlolved.







And you can have your opinion .. everyone has one … and they make absolutely no difference to physical reality.
It also makes absolutely no difference how many quotes, (of historical curiosity), about technology predictions you have in your signature line, either. What relevance does a wayward 19th Century technology prediction have to do with the topic we're discussing?



Again the "physical reality" is that we have an unncountable number of stars, galaxies and planets and the example of life arising on at least one .
In my opinion those numbers and other physical realities of the Universe [like the stuff of life being everywhere we look] give good reason to believe that it has/will happen again, sometime somewhere........

Selfsim
2012-Dec-17, 08:59 AM
We have 100's of billions of stars in this galaxy alone, and billions of galaxies with more or less the same amount of stars...We have the stuff of life everywhere we look, and extra solar planets have now been shown to be common place along with water in one form or another....As Elly said in the movie "Contact", "If we are it, it seems like an awful lot of wasted space"
[or at least words to that effect]A fictional character in a movie, (created by a romanticist), can say anything.

Pedant....
It's a quote from a movie, no more, no less, and used to illustrate a valid point......
cheers.No ... its been used to illustrate your point ... ie: that: "100's of billions of stars in this galaxy alone, and billions of galaxies with more or less the same amount of stars...We have the stuff of life everywhere we look, and extra solar planets have now been shown to be common place along with water in one form or another" and furthermore: "to say life does not exist elsewhere in light of the numbers is arrogant"

To which I'll say: a string of random data, never having been demonstrated in theory or otherwise, to be anywhere near remotely sufficient, for producing life anywhere.

Selfsim
2012-Dec-17, 09:09 AM
Again the "physical reality" is that we have an unncountable number of stars, galaxies and planets and the example of life arising on at least one .Uncountable????
I thought your very argument relied directly upon the countability of exo-planets, etc?
Are you now saying that 'the numbers' cannot be quantified because they're uncountable?

In my opinion those numbers and other physical realities of the Universe [like the stuff of life being everywhere we look] give good reason to believe that it has/will happen again, sometime somewhere........Well, it seems you are more easily convinced than me.
Now what does any of this have to do with arrogance?

ASTRO BOY
2012-Dec-17, 09:10 AM
It also makes absolutely no difference how many quotes, (of historical curiosity), about technology predictions you have in your signature line, either. What relevance does a wayward 19th Century technology prediction have to do with the topic we're discussing?



I see many examples of signatures taking the form of historical quotes on many forums, and most of those express the overall outllok and opinion of the person using it...Mine is no different.

It also illustrates how even great men in the past [and probably present] are contained in a windowless square, accepting present technologies and achievements but unable to be imaginative enough to be open to future change and development........Lord Ernest Rutherford was another when he slammed the idea raised by Leo Szillard re an atomic "Chain reaction.....and of course even the greatest...Albert Einstein was so restrained by the beliefs of his day that he added a Cosmological Constant to maintain a static Universe.

ASTRO BOY
2012-Dec-17, 09:20 AM
Uncountable????
I thought your very argument relied directly upon the countability of exo-planets, etc?
Are you now saying that 'the numbers' cannot be quantified because they're uncountable?
Well, it seems you are more easily convinced than me.
Now what does any of this have to do with arrogance?

My argument relies on the enormity and extent of the Universe both in size and number.
Funnily enough latest evidence which points to a flat Universe [with the possibility of slight errors] which means an infinite or at least near infinite Universe in numbers and extent....Now if it were infinite there would be 100% certainty of life elsewhere just like us.

Not to sure about being more easily convinced but if I were to buy a ticket in a lottery selling only 10 tickets, my chances of winning the big one would be far greater then if they were selling 100,000 tickets

Paul Beardsley
2012-Dec-17, 09:32 AM
I've got a better idea.......You tell me how many stars, galaxies, planets we have in the observable Universe, then given the observation that the stuff of life is everywhere, what is the likelyhood of it arising again.
Quite good most Astrophysicists seem to think.

No you haven't got a better idea. You are simply persisting in missing the point.

Colin Robinson
2012-Dec-17, 10:08 AM
I've got a better idea.......You tell me how many stars, galaxies, planets we have in the observable Universe, then given the observation that the stuff of life is everywhere, what is the likelyhood of it arising again.
Quite good most Astrophysicists seem to think.

Yes. Most scientists (astronomers and biologists) who have recently expressed views about life beyond Earth seem to think there is likely to be lots of it. Though some expect multicelled life to be rare in comparison to microbial life.


It seems very likely that life arose elsewhere in the universe but so far we have no evidence that confirms this.

Yes — it is true that we don't have conclusive evidence yet. As Selfsim keeps reminding us, we don't know. And I don't think any reputable scientist claims to know.

Selfsim
2012-Dec-17, 10:22 AM
... It also illustrates how even great men in the past [and probably present] are contained in a windowless square, accepting present technologies and achievements but unable to be imaginative enough to be open to future change and developmentRather than generalise about particular views some scientific figureheads may have expressed, (under cirumstances long forgotten), one should consider their net contributions alongside their particular 'styles'.

David Hilbert, a highly prominent German mathematician (around 1900), challenged his peers by publically listing what may be arguably, the 23 greatest unsolved mathematical problems of the 20th Century. The motivation behind one of the key problems was presented from the perspective of attempting to fully support axiomatized mathematics with definitive principles, which could banish all theoretical uncertainties. It ended in failure almost immediately, with Godel's demonstration of the Incompleteness Theorem. Many key advances happened following that particular development, in spite of the seeming negativity Godel's proof represented. Hilbert's historical reputation was in no way tarnished by the failure. He is still viewed as one of the true 'giants' of mathematics, and so is Godel.

One might also see Hilbert's approach, (in retrospect), as one of 'arrogance', but tremendous progress ensued in spite of the general belief of the day, that mathematics was believed to be 'virtually infallible'. Hilbert's approach in no way held any research at bay, and without his 'challenge', one could argue that many advances in 20th Century Science and Mathematics, might not have happened.

Einstein had issues with quantum mechanics ... but did the development of QM suffer, or did it benefit from this?

I'm sure there are many other such examples.

I guess it all comes down to the significance one attaches to the subjective interpretation of 'arrogance'(??)

Strange
2012-Dec-17, 12:03 PM
It also illustrates how even great men in the past [and probably present] are contained in a windowless square, accepting present technologies and achievements but unable to be imaginative enough to be open to future change and development

It doesn't require much imagination and is very easy, with hindsight, to criticize those in the past for not being able to predict the future with 100% accuracy. For every one of those "hilarious" blind spots (many of which are apocryphal, anyway) there will be a large number of moments of genius and foresight.

The reason those people are considered "great" in the first place is because they did have the imagination and brilliance to challenge the status quo and produced the changes and developments that some people seem to take for granted.

Strange
2012-Dec-17, 12:06 PM
Einstein had issues with quantum mechanics ... but did the development of QM suffer, or did it benefit from this?

It benefited enormously from having someone of his genius and imagination asking awkward questions, which encouraged others to develop theoretical and experimental test that only further strengthened the theory.

Paul Beardsley
2012-Dec-17, 05:36 PM
No you haven't got a better idea. You are simply persisting in missing the point.

While I was walking into work today, it occurred to me that my point could be better illustrated using figures plucked from the air.

Let's suppose that the number of locations, N, where all the requirements for life can be found is 10^60. That's a nice colossal number, assuming a nearly flat universe.

Now let's suppose the propability, P, of life actually arising when the requirements are all present is 1 in 10^40. That's long odds but when you have 10^60 goes, you're going to have a lot of wins - it means about 100,000,000,000,000,000,000 life-bearing planets.

On the other hand, what if P is 1 in 10^80? Well, in that case, the chances of there being any life-bearing worlds is 1 in 100,000,000,000,000,000,000. So by rights we'd expect there to be no life in the universe at all. Obviously that is not correct because there is of course one life-bearing world, which with these figures would mean we are lucky beyond imagining - there is certainly no need to suppose it happened twice.

Until we know the real values of both N and P, or encounter an actual alien life form, we cannot have a meaningful discussion about how often life has arisen in the universe. Our being alone is nothing to do with arrogance, it is simply one possible scenario.

ASTRO BOY
2012-Dec-17, 07:03 PM
It doesn't require much imagination and is very easy, with hindsight, to criticize those in the past for not being able to predict the future with 100% accuracy. For every one of those "hilarious" blind spots (many of which are apocryphal, anyway) there will be a large number of moments of genius and foresight.

The reason those people are considered "great" in the first place is because they did have the imagination and brilliance to challenge the status quo and produced the changes and developments that some people seem to take for granted.


I'm in no way challenging the greatness and achievements of those scientists that I have mentioned...just that some were still in certain respects curtailed by the "thoughts and technology of the day"...an obvious human fraility throughout history....and they were still human.

ASTRO BOY
2012-Dec-17, 07:05 PM
No you haven't got a better idea. You are simply persisting in missing the point.

No, I just interprete that point different to you.

ASTRO BOY
2012-Dec-17, 07:07 PM
I guess it all comes down to the significance one attaches to the subjective interpretation of 'arrogance'(??)


In retrospect I may have used the wrong word.......Let's just say that some are more optimistic and/or pessimistic then others.
I remain optimistic.

TooMany
2012-Dec-17, 07:20 PM
In retrospect I may have used the wrong word.......Let's just say that some are more optimistic and/or pessimistic then others.
I remain optimistic.

Arrogance is usually defined as having a boastful sense of superiority. However, it does makes sense in this context. Declaring that there is something very special about us than cannot occur elsewhere in spite of similar conditions and billions of opportunities, is boasting that we are superior to any other creation in the Universe - i.e. arrogant.

ASTRO BOY
2012-Dec-17, 07:43 PM
Arrogance is usually defined as having a boastful sense of superiority. However, it does makes sense in this context. Declaring that there is something very special about us than cannot occur elsewhere in spite of similar conditions and billions of opportunities, is boasting that we are superior to any other creation in the Universe - i.e. arrogant.

The point I was making and which was highlighted by the actions and beliefs of the church at that time.

Selfsim
2012-Dec-17, 07:54 PM
Its easy to get overwhelmed by 'the numbers'.

Just for fun, I had a go at trying to compare 'the chances' of a single organism emerging from a DNA molecule, and compared it with an estimate of the numbers of planets in the observable universe. (Ignoring that the organism didn't evolve by pure chance .. just to make the calculation easier). The post is here. (http://cosmoquest.org/forum/showthread.php/129932-It-s-full-of-not-enough-galaxies?p=2002681&highlight=bases#post2002681)

The result was:


Whilst there is no physical significance in making this comparison, it could be said that:
- on one planet out of ~1032 planets, we know the sequence for 'Hepatitis B' presently exists;
- of all the 1.075x101924 possible base pair sequences for this chunk of DNA, one results in what we call 'Heptatitis B', a marginal life-form.

So, as big as the observable universe is, there is an even bigger space of possible DNA sequences right under our noses

This might go some way to explaining my lack of excitement with 'the numbers' argument. Its kind of one way of getting a feel for the probability of uniqueness within a big sample space, which is kind of the other side of the coin, when it comes to the chance of another life instance elsewhere in the universe.

(There are many shades of grey missing in my calculation .. but hey .. at least its a start).

TooMany
2012-Dec-17, 08:05 PM
Its easy to get overwhelmed by 'the numbers'.

Just for fun, I had a go at trying to compare 'the chances' of a single organism emerging from a DNA molecule, and compared it with an estimate of the numbers of planets in the observable universe. (Ignoring that the organism didn't evolve by pure chance .. just to make the calculation easier). The post is here. (http://cosmoquest.org/forum/showthread.php/129932-It-s-full-of-not-enough-galaxies?p=2002681&highlight=bases#post2002681)

The result was:



This might go some way to explaining my lack of excitement with 'the numbers' argument. Its kind of one way of getting a feel for the probability of uniqueness within a big sample space, which is kind of the other side of the coin, when it comes to the chance of another life instance elsewhere in the universe.

(There are many shades of grey missing in my calculation .. but hey .. at least its a start).

Flip a coin 2000 times and the number of possible outcomes is - well large. The chances of getting the exact same pattern twice is equally miniscule. So? How does this affect the chances for alien life?

ASTRO BOY
2012-Dec-17, 08:10 PM
This might go some way to explaining my lack of excitement with 'the numbers' argument. Its kind of one way of getting a feel for the probability of uniqueness within a big sample space, which is kind of the other side of the coin, when it comes to the chance of another life instance elsewhere in the universe.

(There are many shades of grey missing in my calculation .. but hey .. at least its a start).

And when you take those numbers over billions of years and look at the concept of an infinite Universe beyond the Observable, I would start thinking that the chances of life arising of life elsewhere is inevitable.

R.A.F.
2012-Dec-17, 08:16 PM
... the concept of an infinite Universe beyond the Observable...

Infinite?

ASTRO BOY
2012-Dec-17, 08:23 PM
Infinite?


The latest data from WMAP points to a Universe that is flat [within tiny error bars] and a flat Universe denotes an Infinite Universe according to the Cosmologists, or at least "near infinite" taking into account the error bars.


http://www.universetoday.com/38269/infinite-universe/

ASTRO BOY
2012-Dec-17, 08:24 PM
By combining the General Theory of Relativity and the Cosmological Principle, we are able to arrive at three possible space-time curvatures or geometries of the Universe: closed like a sphere, open like a saddle, and flat like a sheet of paper. The first geometry is equivalent to a finite universe while the other two are different versions of an infinite one.

Read more: http://www.universetoday.com/38269/infinite-universe/#ixzz2FLJmMLPP

Selfsim
2012-Dec-17, 08:38 PM
Flip a coin 2000 times and the number of possible outcomes is - well large. The chances of getting the exact same pattern twice is equally miniscule. So? How does this affect the chances for alien life?It doesn't directly influence the 'chances of alien life' at all. Nor was my post intended for this purpose. As I said, its a way of getting a feel for what uniqueness might mean within systems in nature .. that's all.

Having said that, it is reasonably 'accurate', (to orders of magnitude, and mutations aside), to say only one sequence results in what we choose to call Hep B. That isn't intended to mean much, (although, many will try to make it so .. and there is no real defence for that interpretation, so don't expect me to take it on).

Many sequences may not result in viable life, also.
Some might result in more viruses, others in viable life. Some might even end up being Eukaryotes. Interestingly, another 'number': there are ~8.74 million (estimated) Eukaryote species on Earth. (Only ~14% have been described and catalogued). We're just one of 'em. None of these figures need to mean anything in the context of the 'alien life' discussion but they do help to position 'uniqueness' within some context of comparable magnitude.

I can't see much difference in meaning between these 'figures' and ASTROBOY's 'numbers' argument.

Selfsim
2012-Dec-17, 08:39 PM
And when you take those numbers over billions of years and look at the concept of an infinite Universe beyond the Observable, I would start thinking that the chances of life arising of life elsewhere is inevitable.And that would only be your opinion .. nothing more.

Selfsim
2012-Dec-17, 08:44 PM
My argument relies on the enormity and extent of the Universe both in size and number.
Funnily enough latest evidence which points to a flat Universe [with the possibility of slight errors] which means an infinite or at least near infinite Universe in numbers and extent....Now if it were infinite there would be 100% certainty of life elsewhere just like us.The concept of 'The Infinite Universe', is a theoretical concept .. and is a moot point in a discussion about physical reality.

ASTRO BOY
2012-Dec-17, 08:50 PM
The concept of 'The Infinite Universe', is a theoretical concept .. and is a moot point in a discussion about physical reality.

The concept of an Infinite Universe is based on scientific data and experimental results like most science.

Selfsim
2012-Dec-17, 09:05 PM
The concept of an Infinite Universe is based on scientific data and experimental results like most science.The concept of 'The Infinite Universe' was around long before the COBE and WMAP data … it was derived from a long history of pondering the mathematical concept of infinity. That the WMAP data shows within its bounds of measurable uncertainties, that the observable universe appears flat, does not say anything about what lies beyond its abilities to measure.

Your generalisations about science, are not supportable at greater depths than superficial.

R.A.F.
2012-Dec-17, 09:15 PM
The concept of an Infinite Universe is based on scientific data and experimental results like most science.

Infinite based on data??...then the data is in error...


STRIKE that... i believe (as Selfsim hinted at} that you are misinterpreting the data.

ASTRO BOY
2012-Dec-17, 09:22 PM
The concept of 'The Infinite Universe' was around long before the COBE and WMAP data … it was derived from a long history of pondering the mathematical concept of infinity. That the WMAP data shows within its bounds of measurable uncertainties, that the observable universe appears flat, does not say anything about what lies beyond its abilities to measure.

Your generalisations about science, are not supportable at greater depths than superficial.

COBE and WMAP reinforced that concept and the error bars from memory are less then 2%
And of course we have no reason at all to believe that what lies beyond the observable Universe is any different then what we can see.....The homogeneous and Isotropic nature of the Universe is a cosmological accepted part of that.

We all appear to generalise [as you put it] when it supports our interpretation of things.

ASTRO BOY
2012-Dec-17, 09:51 PM
Infinite based on data??...then the data is in error...


STRIKE that... i believe (as Selfsim hinted at} that you are misinterpreting the data.



I don't think so....

By combining the General Theory of Relativity and the Cosmological Principle, we are able to arrive at three possible space-time curvatures or geometries of the Universe: closed like a sphere, open like a saddle, and flat like a sheet of paper. The first geometry is equivalent to a finite universe while the other two are different versions of an infinite one.

Read more: http://www.universetoday.com/38269/i...#ixzz2FLJmMLPP


and this.....

The WMAP spacecraft can measure the basic parameters of the Big Bang theory including the geometry of the universe. If the universe were flat, the brightest microwave background fluctuations (or "spots") would be about one degree across. If the universe were open, the spots would be less than one degree across. If the universe were closed, the brightest spots would be greater than one degree across.

Recent measurements (c. 2001) by a number of ground-based and balloon-based experiments, including MAT/TOCO, Boomerang, Maxima, and DASI, have shown that the brightest spots are about 1 degree across. Thus the universe was known to be flat to within about 15% accuracy prior to the WMAP results. WMAP has confirmed this result with very high accuracy and precision. We now know that the universe is flat with only a 0.5% margin of error. This suggests that the Universe is infinite in extent; however, since the Universe has a finite age, we can only observe a finite volume of the Universe. All we can truly conclude is that the Universe is much larger than the volume we can directly observe.

from....

http://map.gsfc.nasa.gov/universe/uni_shape.html


It appears my claim that the WMAP error bar being 2% is incorrect...It is 0.5%

Paul Beardsley
2012-Dec-17, 10:04 PM
Arrogance is usually defined as having a boastful sense of superiority. However, it does makes sense in this context. Declaring that there is something very special about us than cannot occur elsewhere in spite of similar conditions and billions of opportunities, is boasting that we are superior to any other creation in the Universe - i.e. arrogant.

1. It's a strawman argument because I don't think any informed person does this. It's something people like to imagine other people doing because then they can say, "It's arrogant to think we're the only life in the universe," and they do that because they can then conclude that there is definitely life elsewhere in the universe, which is what they want to believe.

2. If I walk into an empty room and declare, "I'm the best chess player in this entire room!" does that make me arrogant?

3. How can you feel superior towards others when the whole point is that you don't think there are any others?

Again, please stop using or promoting this word in this context because it's silly, and not in a good way.

IsaacKuo
2012-Dec-17, 11:06 PM
While I was walking into work today, it occurred to me that my point could be better illustrated using figures plucked from the air.

Let's suppose that the number of locations, N, where all the requirements for life can be found is 10^60. That's a nice colossal number, assuming a nearly flat universe.

Now let's suppose the propability, P, of life actually arising when the requirements are all present is 1 in 10^40. That's long odds but when you have 10^60 goes, you're going to have a lot of wins - it means about 100,000,000,000,000,000,000 life-bearing planets.

On the other hand, what if P is 1 in 10^80? Well, in that case, the chances of there being any life-bearing worlds is 1 in 100,000,000,000,000,000,000. So by rights we'd expect there to be no life in the universe at all. Obviously that is not correct because there is of course one life-bearing world, which with these figures would mean we are lucky beyond imagining - there is certainly no need to suppose it happened twice.

Until we know the real values of both N and P, or encounter an actual alien life form, we cannot have a meaningful discussion about how often life has arisen in the universe. Our being alone is nothing to do with arrogance, it is simply one possible scenario.
Ah, but the fact that we exist, and the fact that life seems to have arisen on Earth pretty quickly, are more than a little suggestive. It's complicated by the anthropic principle, but let's look at how it works when it isn't complicated by the anthropic principle:

Suppose someone rolls a die, and it comes up with the letter "Q". You haven't examined this die. You don't know whether it's weighted fairly. You don't even know what's on the other sides. Maybe the chances of it coming up "Q" are 1 in 1. Maybe the chances of it coming up "Q" are 1 in 10^80. You don't know. But do you really think that it's likely to be 1 in 10^80?

According to strict frequentist probability theory, you may be right in thinking that you lack sufficient information to figure out the probability. But Bayesian probability theory gives you a valid framework to at least get started, and to reject the theory that the probability is 1 in 10^80 as implausibly unlikely.

Personally, I find Bayes probability theory weird and...well, I don't know exactly what it is I don't like about it, but it rubs me the wrong way. But it's part of mainstream scientific thought whether I like it or not.

IsaacKuo
2012-Dec-17, 11:13 PM
Infinite based on data??...then the data is in error...


STRIKE that... i believe (as Selfsim hinted at} that you are misinterpreting the data.
Why do you dismiss the possibility that the Universe is infinite? It's one mainstream theory of the extent of the universe, which is consistent with the data and enjoys the benefit of Occam's razor compared to some other alternatives (such as a Universe which is flat but bounded, or flat but wraps around onto itself via a hypertoroidal geometry).

TooMany
2012-Dec-17, 11:27 PM
1. It's a strawman argument because I don't think any informed person does this. It's something people like to imagine other people doing because then they can say, "It's arrogant to think we're the only life in the universe," and they do that because they can then conclude that there is definitely life elsewhere in the universe, which is what they want to believe.

2. If I walk into an empty room and declare, "I'm the best chess player in this entire room!" does that make me arrogant?

3. How can you feel superior towards others when the whole point is that you don't think there are any others?

Again, please stop using or promoting this word in this context because it's silly, and not in a good way.

Obviously you don't like that word applied to this idea. You are not walking into an empty room. The room as 100 billion stars systems. You are declaring that your planet is the only planet that has life. You are arguing for some uniqueness of earth without any foundation for how it could possibly be so unique. You are saying my planet is the only one with life. It just like claiming you are the only good chess player in a large city.

This is not a 50/50 question. The idea that we are the only life, really makes little sense as a hypothesis at all. I mean what is so magical about Earth that a similar thing cannot happen under similar conditions elsewhere? Arguing the uniqueness of life on earth supposes that the development of life is a very rare event and only happens through some very strange and unlikely accident which has only happened once in the galaxy. No we don't really know, but that does not give equal weight to that conclusion. That conclusion just does not have any sensible motivation. Why in heck should we think that it's an unbelievably rare accident? Is there anything else in nature that you would care to speculate might happen only extremely rarely given the same conditions as on Earth?

Selfsim
2012-Dec-18, 01:03 AM
Obviously you don't like that word applied to this idea. You are not walking into an empty room. The room as 100 billion stars systems. You are declaring that your planet is the only planet that has life.I certainly haven't declared this … has anyone else on this thread declared that? Where did your statement come from?

You are arguing for some uniqueness of earth without any foundation for how it could possibly be so unique.'Uniqueness' is as prevalent in the universe as 'sameness'. Denial of uniqueness is what I see going on here.

You are saying my planet is the only one with life.Who said that?


This is not a 50/50 question. The idea that we are the only life, really makes little sense as a hypothesis at all. I mean what is so magical about Earth that a similar thing cannot happen under similar conditions elsewhere? Arguing the uniqueness of life on earth supposes that the development of life is a very rare event and only happens through some very strange and unlikely accident which has only happened once in the galaxy.This 'strangeness' and 'magic' you speak of … where did that come from?
It seems you continually infer this from everything written on this subject. You could learn a lot more about self-similarity and uniqueness. I think mathematics gives one this dimension … this aspect appears to be missing from your recognition filters. Is the basis of your judgement of others, built around what you know, as opposed to what you don't know?

'No we don't really know, but that does not give equal weight to that conclusion.How do you know that .. if 'we really don't know'?
That conclusion just does not have any sensible motivation. Why in heck should we think that it's an unbelievably rare accident? Is there anything else in nature that you would care to speculate might happen only extremely rarely given the same conditions as on Earth?Sure are .. is there another precise copy of 'TooMany' on Earth?

Selfsim
2012-Dec-18, 01:23 AM
Ah, but the fact that we exist, and the fact that life seems to have arisen on Earth pretty quickly, are more than a little suggestive. It's complicated by the anthropic principle, but let's look at how it works when it isn't complicated by the anthropic principle:

Suppose someone rolls a die, and it comes up with the letter "Q". You haven't examined this die. You don't know whether it's weighted fairly. You don't even know what's on the other sides. Maybe the chances of it coming up "Q" are 1 in 1. Maybe the chances of it coming up "Q" are 1 in 10^80. You don't know. But do you really think that it's likely to be 1 in 10^80?

According to strict frequentist probability theory, you may be right in thinking that you lack sufficient information to figure out the probability. But Bayesian probability theory gives you a valid framework to at least get started, and to reject the theory that the probability is 1 in 10^80 as implausibly unlikely.

Personally, I find Bayes probability theory weird and...well, I don't know exactly what it is I don't like about it, but it rubs me the wrong way. But it's part of mainstream scientific thought whether I like it or not.Actually, Spiegel and Turner (Princeton) used Bayesian reasoning (http://phys.org/news/2011-07-astrophysicists-logic-downplay-probability-extraterrestrial.html) to show that:
… just because we evolved in such conditions, doesn’t mean that the same occurrence would necessarily happen elsewhere; using evidence of our own existence doesn’t show anything they argue, other than that we are here.
..
As Spiegel and Turner point out, basing our expectations of life existing on other planets, for no better reason that it exists here, is really only proof that were are more than capable of deceiving ourselves into thinking that things are much more likely than they really are.
...

The two argue that just because intelligent life occurred rather quickly here on Earth, once conditions were ripe, giving rise to the people we are today, that doesn’t mean it naturally would on another planet just like ours in another place in the universe.I don't believe we can dismiss the anthropic influence … even for a hypothetical intended to show anything new(??) (It seems its just not that simple, I'm afraid). Their paper is here. (http://arxiv.org/abs/1107.3835)

R.A.F.
2012-Dec-18, 01:25 AM
Why do you dismiss the possibility that the Universe is infinite?

Define infinite.

R.A.F.
2012-Dec-18, 01:32 AM
1. It's a strawman argument because I don't think any informed person does this. It's something people like to imagine other people doing because then they can say, "It's arrogant to think we're the only life in the universe," and they do that because they can then conclude that there is definitely life elsewhere in the universe, which is what they want to believe.

Yep....that about covers it.

IsaacKuo
2012-Dec-18, 01:37 AM
Actually, Spiegel and Turner (Princeton) used Bayesian reasoning (http://phys.org/news/2011-07-astrophysicists-logic-downplay-probability-extraterrestrial.html) to show that:
...
I don't believe we can dismiss the anthropic influence … even for a hypothetical intended to show anything new(??) (It seems its just not that simple, I'm afraid). Their paper is here. (http://arxiv.org/abs/1107.3835)
I'm actually already familiar with that paper, and it demonstrates one of the things that bugs me about Bayesian probability reasoning--that it produces different answers depending on what arbitrary assumptions you decide to start with. They simply assume an a priori logarithmic probability distribution base because...well, basically just because. It's an assumption not based on any physical observations or theoretical model at all. But it does lead to their particular conclusion, so...

I wouldn't start with that a priori assumption at all. I'd think that a physical process would have a different sort of probability profile. But it's still largely guesswork.

IsaacKuo
2012-Dec-18, 01:52 AM
Define infinite.
In this context, infinite means that the volume of the universe at any particular comoving time is infinite. Assuming cosmologically flat space everywhere, the theory is that the universe at any particular comoving time is approximately E3 (Euclidean 3 space) at large scales.

Selfsim
2012-Dec-18, 02:24 AM
I'm actually already familiar with that paper, and it demonstrates one of the things that bugs me about Bayesian probability reasoning--that it produces different answers depending on what arbitrary assumptions you decide to start with. They simply assume an a priori logarithmic probability distribution base because...well, basically just because. It's an assumption not based on any physical observations or theoretical model at all. But it does lead to their particular conclusion, so...

I wouldn't start with that a priori assumption at all. I'd think that a physical process would have a different sort of probability profile. But it's still largely guesswork.Hmm … I'll have to have another read (its been a while), but I'm not sure that it matters what kind of distribution one assumes. Having just been involved in a thread which dealt with the Central Limit Theorem, according to that, it all evens out in the limit to being a normal distribution anyway.
(I'll have to read it again .. I might be off beam with this comment??).

R.A.F.
2012-Dec-18, 02:48 AM
In this context...

Oh i see...you require the definition be put into some predetermined context before it actually applies....


Never mind then......

ASTRO BOY
2012-Dec-18, 05:24 AM
I think Too Many has summed it up admirably..
We all know the proper scientific answer re life elsewhere in the Universe is "we don't know"
But when all other facts are taken into account, like numbers involved, the stuff of life being everywhere we look, the billions of years for evolution to take hold and possibly go extinct, the possible infinite nature of the Universe, I find it quite surprising that a person could argue that we on this little blue orb, in the outer suburbs of an ordinary spiral galaxy, orbiting an average red dwarf star, are it.

I'm rather surprised that some seem to find the term "infinite" when applied to the Universe as unacceptable.
Admittedly for this average Joe Blow, "Infinite" in any context is hard to fathom and to get ones laughing gear around, but then again to apply "finite" to the Universe also raises some awkward questions and situations for cosmologists.

At this stage I accept "infinite" or at least immeasurably large when applied to the Universe due to the scientific data.

Not sure if this would be going off track but could someone explain to me why a finite Universe is easier to accept then an Infinite Universe.

ASTRO BOY
2012-Dec-18, 05:28 AM
Oh i see...you require the definition be put into some predetermined context before it actually applies....


Never mind then......

We are debating the term "Infinite" when applied to the Universe...IsaacKuo has answered that quite admirably.

Selfsim
2012-Dec-18, 05:31 AM
Frankly, what may may not exist beyond our Particle Horizon, is really quite irrelevant for us. Why would it matter when its beyond causal range?

One may as well ponder the significance of one's navel, as worry about things at such distances.

ASTRO BOY
2012-Dec-18, 08:14 AM
Frankly, what may may not exist beyond our Particle Horizon, is really quite irrelevant for us. Why would it matter when its beyond causal range?

One may as well ponder the significance of one's navel, as worry about things at such distances.



Religion has survived on irrelevancies such as unseen omnipotent deities for many thousands of years.
I'm sure for most of us knowing that intelligent beings inhabited the Universe even if beyond our particle horizon, would always be a cause for wonder and questions.
I'm sure most would not trivialise such knowledge.

But we have numbers vast enough within our observable Universe to be confident of such existance.

Paul Beardsley
2012-Dec-18, 09:01 AM
Obviously you don't like that word applied to this idea. You are not walking into an empty room. The room as 100 billion stars systems. You are declaring that your planet is the only planet that has life. You are arguing for some uniqueness of earth without any foundation for how it could possibly be so unique. You are saying my planet is the only one with life. It just like claiming you are the only good chess player in a large city.

My point was that if we are alone, there is nobody for us to be superior to, and so (once again) the word "arrogant" cannot be used.

You know, I happen to think that life is unique to Earth when the discussion is limited to the inner solar system. So, no life on Mercury, Venus, the Moon, Mars, Phobos or Deimos, and hey, let's include the asteroids as well.

Does this make me arrogant? Do I feel superior to those non-existent life forms on Mercury? Of course I don't!

The only way the word "arrogant" could be used correctly is if we said or thought something like, "Oh I expect there are other life forms on other planets but we're bound to be better than them." If you really want to use emotive language, use "lonely" because it at least makes sense.


This is not a 50/50 question. The idea that we are the only life, really makes little sense as a hypothesis at all. I mean what is so magical about Earth that a similar thing cannot happen under similar conditions elsewhere?

It's nothing to do with "cannot happen", it's to do with whether it did.

Let's suppose life is commonplace throughout the universe. Given that, there is nothing magical about the English language. So what's to stop aliens speaking English? Perhaps somewhere in the Virgo cluster somebody is complaining about the way greengrocers misuse apostrophes. After all, there's only a finite (albeit large) number of arrangements of spoken sounds and written symbols, and the universe is possibly infinite. Are you so arrogant that you think English is only spoken here?


Arguing the uniqueness of life on earth supposes that the development of life is a very rare event and only happens through some very strange and unlikely accident which has only happened once in the galaxy.

It might be so. We don't know.


No we don't really know, but that does not give equal weight to that conclusion. That conclusion just does not have any sensible motivation.

Who do you think is giving equal weight to that conclusion? For my own part I simply consider it a possibility. And what do you mean by "motivation"? In science, the only motivation is to get at the truth.


Why in heck should we think that it's an unbelievably rare accident?

Because we don't know that it's not.


Is there anything else in nature that you would care to speculate might happen only extremely rarely given the same conditions as on Earth?

Ooh, good question. Let me see.

Ah, here's one. Volcanoes! I think volcanoes are probably unique to Earth.

Excuse me... What's that, Sooty? You say there are volcanoes on the Moon? On Mars too? On Io? On Venus? Goodness me! You know what that means? It means we can have an informed opinion about them!

IsaacKuo
2012-Dec-18, 10:18 AM
Oh i see...you require the definition be put into some predetermined context before it actually applies....


Never mind then......
I don't understand what point you're trying to make. Mathematically, there are many different infinities. There isn't just one definition that applies everywhere.

And even the term "infinite universe" can apply to several different concepts. In particular, it can refer to the temporal extent of the universe. This includes a once mainstream theory which has lost favor--the steady state theory that the universe's past and future extend indefinitely--as well as a current mainstream theory that the universe's future extends indefinitely (as opposed to ending in a finite time due to the big crunch or big rip).

The relevant definition of "infinite universe" in the context of this discussion is one about the spatial extent of the universe, which is the definition I described. It is a mainstream theory which implies there would be an infinite number of star systems in the universe, and an infinite number of Earth-like planets with Earth-like life. While these might be far outside our current light horizon, that's no guarantee that they'll forever be outside our (ever expanding) horizon, and even if so, the existence of this vast infinite universe beyond our horizon can be relevant to the implications of the anthropic principle.

Paul Wally
2012-Dec-18, 02:42 PM
I don't see what the actual size of the universe has to do with anything. Whether the universe is just inconceivably huge or really infinite is just an academic question as far as the existence of life is concerned. For what we are really interested in is for instance whether there is other life in our solar system and in our galaxy. But if it turns out that one in every million galaxies has one planet with life on it, for all practical purposes, that would be the same as if we were alone in the universe, for in that case we will never establish any kind of contact, physical or otherwise.

IsaacKuo
2012-Dec-18, 03:14 PM
I don't see what the actual size of the universe has to do with anything. Whether the universe is just inconceivably huge or really infinite is just an academic question as far as the existence of life is concerned. For what we are really interested in is for instance whether there is other life in our solar system and in our galaxy. But if it turns out that one in every million galaxies has one planet with life on it, for all practical purposes, that would be the same as if we were alone in the universe, for in that case we will never establish any kind of contact, physical or otherwise.
I wouldn't bet against it, at least not until the big crunch is ruled out. If the big crunch is true, we may get a chance to establish contact with aliens that are currently really far away.

If life evolves on roughly one planet in every million galaxies, the nearest planet other than Earth with life on it may be only a hundred million light years away. That's actually not too far away for us to expand to, given our understanding of the expansion of the universe, unless one of the extremely pessimistic big rip scenarios turns out to be true.

It's certainly close enough for us to potentially detect and study with telescopes. For example, if these life forms evolved, say, half a billion years earlier than us, expanded, and converted the stars of the local galaxies into Dyson spheres, then we'd notice that patch of galaxies as very different than most galaxies. Over time, we might even notice their expansion in all directions (including ours), and decide to do something about our own expansion before they get to us.

In contrast, if the nearest exoplanet with evolved life is trillions of light years away, then there's a good chance that there really is no chance for us to ever see them, depending on how the expansion of the universe is going to go. Typical inflation theories lead to expansion acceleration so fast that it will eventually outstrip even light speed starships, at least on cosmological scales. If so, then there's a certain comoving distance beyond which it's too late for us to ever reach and vice versa. Twice this comoving distance is the limit to how far we can have meaningful interaction.

Still, the existence or non-existence of life beyond this distance limit is significant with respect to the anthropic principle.

R.A.F.
2012-Dec-18, 04:27 PM
I don't understand what point you're trying to make.

You are defining infinite differently than I am...that's all.

I just don't see anything further to discuss.

Strange
2012-Dec-18, 05:47 PM
You are defining infinite differently than I am...that's all.

I'm curious what you mean by infinity, then? (And why you think the universe can't be infinite)

R.A.F.
2012-Dec-18, 06:02 PM
I'm curious what you mean by infinity, then? (And why you think the universe can't be infinite)

Please beg my pardon...I see nothing but major disagreements ahead, and to avoid those I simply have nothing further to say.

Call it my xmas "gift" to Swift. :D

Selfsim
2012-Dec-18, 07:36 PM
I wouldn't bet against it, at least not until the big crunch is ruled out. If the big crunch is true, we may get a chance to establish contact with aliens that are currently really far away.

If life evolves on roughly one planet in every million galaxies, the nearest planet other than Earth with life on it may be only a hundred million light years away. That's actually not too far away for us to expand to, given our understanding of the expansion of the universe, unless one of the extremely pessimistic big rip scenarios turns out to be true.

It's certainly close enough for us to potentially detect and study with telescopes. For example, if these life forms evolved, say, half a billion years earlier than us, expanded, and converted the stars of the local galaxies into Dyson spheres, then we'd notice that patch of galaxies as very different than most galaxies. Over time, we might even notice their expansion in all directions (including ours), and decide to do something about our own expansion before they get to us.

In contrast, if the nearest exoplanet with evolved life is trillions of light years away, then there's a good chance that there really is no chance for us to ever see them, depending on how the expansion of the universe is going to go. Typical inflation theories lead to expansion acceleration so fast that it will eventually outstrip even light speed starships, at least on cosmological scales. If so, then there's a certain comoving distance beyond which it's too late for us to ever reach and vice versa. Twice this comoving distance is the limit to how far we can have meaningful interaction.

Still, the existence or non-existence of life beyond this distance limit is significant with respect to the anthropic principle.A pile of speculative gobbledygook, which rules itself out completely on the basis of impracticality … and all to justify what?

Answer: (originally) to justify labelling others as 'arrogant'.

Great stuff.

TooMany
2012-Dec-18, 08:07 PM
TooMany: Why in heck should we think that it's an unbelievably rare accident?
Paul Beardsley: Because we don't know that it's not.

There is the theoretical possibility that there is no other planet with a waterfall, but would you place bets on that idea? (Note that we have never found one.) Why is it that we would assume that this particular natural event of life is extremely rare. What basis is there for suspecting such a thing? You have to make some argument about the nature of life that makes it an extreme rarity. On Mars there were oceans and rivers, there is sedimentary rock and lava flows like on Earth. The conditions are just not as hospitable to life as on Earth because Mars was too small and perhaps too far from the Sun. That's your answer to why there aren't Martians, not some imagined difficulty in life starting. Perhaps if we do find life on Mars, your attitude will be tempered and you will have to admit that it's just another natural process and that nothing miraculous is required.

We do know that once life starts, an incredible variety of forms emerge through evolution and it adapts to all sorts of environments, as if it's easy. People use the complexity argument to deny evolution: "How can random chance produce a human eye?" Not all that different from the argument: "Life is so complex that the chances of it ever developing are negligible."

IsaacKuo
2012-Dec-18, 08:12 PM
A pile of speculative gobbledygook, which rules itself out completely on the basis of impracticality … and all to justify what?
Nothing I described is impractical.

If the big crunch is true, then we don't need advanced space propulsion technology to contact aliens that are currently extremely far away. They'll get a heck of a lot closer in the future whether we like it or not.

Given the expected future expansion of the universe over the next billion years under most models, there really aren't any problems with interstellar expansion to a mere hundred million light years away.

And if alien life forms have converted galaxies into Dyson spheres, that's something we could detect with current technology telescopes.

Exactly what, if any of the above do you think qualifies as gobbledygook?


Answer: (originally) to justify labelling others as 'arrogant'.

Great stuff.
I never labelled others as "arrogant".

TooMany
2012-Dec-18, 08:16 PM
Exactly what, if any of the above do you think qualifies as gobbledygook?


Apparently anything that is not proven fact is "gobbledygook".

Paul Beardsley
2012-Dec-18, 08:17 PM
A pile of speculative gobbledygook, which rules itself out completely on the basis of impracticality … and all to justify what?

Answer: (originally) to justify labelling others as 'arrogant'.

Great stuff.

Are you sure you're replying to the right post?

Paul Beardsley
2012-Dec-18, 08:58 PM
There is the theoretical possibility that there is no other planet with a waterfall, but would you place bets on that idea? (Note that we have never found one.) Why is it that we would assume that this particular natural event of life is extremely rare.

I'm starting to lose patience here... I have never once said that I assume the emergence of life is extremely rare. I said we do not know the probability of life emerging, and so we have to accept that it could be extremely high or extremely low or anywhere in between. Attempts to create life in the laboratory have not been successful so we can rule out the more extreme end of the extremely high.


What basis is there for suspecting such a thing? You have to make some argument about the nature of life that makes it an extreme rarity. On Mars there were oceans and rivers, there is sedimentary rock and lava flows like on Earth. The conditions are just not as hospitable to life as on Earth because Mars was too small and perhaps too far from the Sun. That's your answer to why there aren't Martians, not some imagined difficulty in life starting.

And as I remind you in my sig, a hundred years ago one of the leading figures of the equivalent of astrobiology was certain that there was an advanced civilisation on Mars. As recently as July 1976, on the eve of the Viking 1 landing, it was possible to watch serious speculative documentary films that showed the life forms we might expect to find on Mars. This wasn't stupidity, it was simply a case of projecting our desires onto insufficient data.


Perhaps if we do find life on Mars, your attitude will be tempered and you will have to admit that it's just another natural process and that nothing miraculous is required.

I'm guessing you wrote this while tired.

If we do find life on Mars, then we'll have data, we'll have more than one reference point, we will no longer be trying to extrapolate from a sample of one (which, BTW, is what you appear to be doing).

And I have never suggested the emergence of life was miraculous. I have argued that we don't know how many factors have to be exactly right. I suspect the recipe of life is probably like the recipe for a souffle - too much of one ingredient, too little of another, a third one too hot, a fourth not hot enough, any of these might be the equivalent of opening the oven door. From what we do know, creating life is not just a case of throwing some ingredients together and zapping the mix with lightning.

TooMany
2012-Dec-18, 10:15 PM
From what we do know, creating life is not just a case of throwing some ingredients together and zapping the mix with lightning.

You mean in one flask for a few months? I'll give you that one, but it's hardly comparable to the experiment of Earth cooling having water and organic chemicals providing billions of micro-environments with a large variety of conditions evolving over millions of years. How many zero's does that add to the chances? Isn't using that as evidence of a fundamental difficulty sort of like saying "I grew a dish of bacterial for a month, but they didn't evolve into another kind"?

I don't think life is probably common on earth-like planets because I desire it to be so, I think that because it's a more sensible hypothesis than "it can only happen under perfect conditions (whatever that means)".

P.S. The bottom line of course is that we don't know for sure. So we must wait and see, but if I have to make a bet...

Selfsim
2012-Dec-19, 02:06 AM
I wouldn't bet against it, at least not until the big crunch is ruled out. If the big crunch is true, we may get a chance to establish contact with aliens that are currently really far away.

If life evolves on roughly one planet in every million galaxies, the nearest planet other than Earth with life on it may be only a hundred million light years away. That's actually not too far away for us to expand to, given our understanding of the expansion of the universe, unless one of the extremely pessimistic big rip scenarios turns out to be true.

It's certainly close enough for us to potentially detect and study with telescopes. For example, if these life forms evolved, say, half a billion years earlier than us, expanded, and converted the stars of the local galaxies into Dyson spheres, then we'd notice that patch of galaxies as very different than most galaxies. Over time, we might even notice their expansion in all directions (including ours), and decide to do something about our own expansion before they get to us.

In contrast, if the nearest exoplanet with evolved life is trillions of light years away, then there's a good chance that there really is no chance for us to ever see them, depending on how the expansion of the universe is going to go. Typical inflation theories lead to expansion acceleration so fast that it will eventually outstrip even light speed starships, at least on cosmological scales. If so, then there's a certain comoving distance beyond which it's too late for us to ever reach and vice versa. Twice this comoving distance is the limit to how far we can have meaningful interaction.

Still, the existence or non-existence of life beyond this distance limit is significant with respect to the anthropic principle.A pile of speculative gobbledygook, which rules itself out completely on the basis of impracticality … and all to justify what?

Answer: (originally) to justify labelling others as 'arrogant'.

Great stuff.
Nothing I described is impractical.

If the big crunch is true, then we don't need advanced space propulsion technology to contact aliens that are currently extremely far away. They'll get a heck of a lot closer in the future whether we like it or not.

Given the expected future expansion of the universe over the next billion years under most models, there really aren't any problems with interstellar expansion to a mere hundred million light years away.

And if alien life forms have converted galaxies into Dyson spheres, that's something we could detect with current technology telescopes.

Exactly what, if any of the above do you think qualifies as gobbledygook?All of it … with the exception of: 'given our understanding of the expansion of the universe'.

Ie:
i) 'Alien lifeforms' are purely speculative. Testable in theory, but those tests are unable to be applied across the sample space, and over the distance ranges of which you speak.
ii) 'Dyson Spheres' are purely speculative… an engineering 'thought experiment'. The concept has never been shown to be practically producible or sustainable.
iii) 'The Big Crunch' requires a finite universe, (and yet you seem to argue for an infinite one). It also requires the cosmological principle not apply. The present Cosmology 'leaning', is towards a 'heat death', specifically because there is hard, measured CMBR data which shows that the expansion is accelerating.
iv) 'advanced space propulsion technology to contact aliens' … what constrains this technology, if we don't have a clue as to the existence of, or location of 'aliens'. If this is not physically constrained, it is not practically feasible.


I never labelled others as "arrogant".Agreed .. but look back, and you'll see that this is the argument you are indirectly defending.


Nothing I described is impractical.Isaac, I have no issues with you personally. I find you views very forward-looking .. please don't take this personally, (it is not intended to be so), but if you cannot see the impracticality of what you suggest, then all I can conclude is that you've lost sight of the physical constraints, which also apply to the technologies we create, (and will continue to do so).

Gomar
2012-Dec-19, 02:08 AM
if I were to buy a ticket in a lottery selling only 10 tickets, my chances of winning the big one would be far greater then if they were selling 100,000 tickets

So buy 10,000 tickets, and you have 1:10 odds.
I bought $10 of NY Take5 and won $24+QP. My uncle bought $10 scratch Win for Life, won
$5000/month for life.

Gomar
2012-Dec-19, 02:15 AM
Given 500Billion planets in the galaxy, 1/10 capable of supporting life = 50B;
1/2 that has life = 25B; 1/5 has fish, birds, animals, mammals = 5B;
1/5 has hominids = 1B; 1/10 hominids(or other species) evolved intelligence = 100m

1/4 die out due to wars, disease, etc. 1/4 natural or other catastrophe such as meteors,
left = 50m.
1/10 sends ships, probes, signals, lazers, etc. = 5m.

So, we have 5million alien species in the galaxy that could or might or has or will contact
Earth. Is 5m spread out in the entire galaxy enough to have a dialogue or contact or visitations
or invasions? No. Not enough spread or odds.
Ifcourse, if a certain species numbers in 100B, and has lasted 10m years, and has spread all
over, well...

eburacum45
2012-Dec-19, 03:18 AM
1/2 that has life = 25B; 1/5 has fish, birds, animals, mammals = 5B;
1/5 has hominids = 1B; 1/10 hominids(or other species) evolved intelligence = 100m


I'm glad that you mentioned other species, since the chance that there are hominids per se on other worlds is zero, unless they have made their way there from Earth somehow.

There are no hominids on other worlds; there may be organisms that resemble hominids, but unless they have come from Earth somehow, they have evolved separately so should be given some other taxonomic label.
There are no mammals on other worlds; there may be organisms that resemble mammals, but unless they have come from Earth somehow, they have evolved separately so should be given some other taxonomic label.
There are no fish on other worlds; there may be organisms that resemble fish, but unless they have come from Earth somehow, they have evolved separately so should be given some other taxonomic label.

Selfsim
2012-Dec-19, 03:34 AM
Given 500Billion planets in the galaxy, 1/10 capable of supporting life = 50B;
1/2 that has life = 25B; 1/5 has fish, birds, animals, mammals = 5B;
1/5 has hominids = 1B; 1/10 hominids(or other species) evolved intelligence = 100m

1/4 die out due to wars, disease, etc. 1/4 natural or other catastrophe such as meteors,
left = 50m.
1/10 sends ships, probes, signals, lazers, etc. = 5m.

So, we have 5million alien species in the galaxy that could or might or has or will contact
Earth. Is 5m spread out in the entire galaxy enough to have a dialogue or contact or visitations
or invasions? No. Not enough spread or odds.
Ifcourse, if a certain species numbers in 100B, and has lasted 10m years, and has spread all
over, well...
Hi Gomar;
Thanks for at least having a go at some kind of calculation …
However, I really don't see any difference between this calculation, and making a wild, outright unsupported assertion: 'that that there are 5 million aliens 'potentially' capable of making contact throughout the galaxy'.

What difference has the calculation made to the assertion?

My point is, that if initial assumptions are complete guesses, the answer will also be a complete guess. There is no empirical basis whatsoever, for any of the initial quantities assumed … so what is being demonstrated by performing calculation at all, (in terms of 'progress')?

'The numbers' mean 'zip' unless they have an empirical basis and there is none … 'zip' .. meaning no data whatsoever, when it comes to anything about imagined exo-life.

The prior probability calculation started by ASTROBOY, is also majorly flawed. It already assumes there to be a 'winning ticket'. In the analogous exo-life lottery selection, (from the 'Universe' sample space), the existence of exo-life only be theoretically supportable if, and only if, the universe is infinite both spatially and temporally. Max Tegmark's estimated calculation (http://cosmoquest.org/forum/showthread.php/125623-Man-s-Radio-Sphere?p=1972304#post1972304), (based on 'The Infinite Universe' concepts), places our nearest intelligent 'doppelganger' (ie: purely theoretically supportable 'intelligent Earth-like' lifeform), at as much as http://www.codecogs.com/eq.latex?{10^{10}}^{29}m distant, which would put these folk well beyond causal contact range of 62 Glyrs.

Regards

ASTRO BOY
2012-Dec-19, 03:35 AM
I find it rather strange that some have taken such exception to the use of the word arrogant....
So to get back on track I withdraw the comment
Even though It was used in a collective sense and I gave an example of man's collective arrogance in the past. It was not personal.
Again my view is that extreme numbers and the extent of space/time, plus the plentiful nature of the stuff of life, supports the view that ET life should exist elsewhere.
I remain optimistic of that fact and the day when we will have hard evidence to support it..

ASTRO BOY
2012-Dec-19, 03:46 AM
Hi Gomar;


My point is, that if initial assumptions are complete guesses, the answer will also be a complete guess. There is no empirical basis whatsoever, for any of the initial quantities assumed … so what is being demonstrated by performing calculation at all, (in terms of 'progress')?

Regards

I disagree......
The only assumption made is that the chances of life arising elsewhere has a high probability due to the reasons already stated many times.

Science has made many assumptions on similar data in the past...eg: the assumption that the Universe is homeginious and Isotropic.
I see these assumptions as logical based on the current data even if less then 100% certain.

Selfsim
2012-Dec-19, 04:09 AM
I'm glad that you mentioned other species, since the chance that there are hominids per se on other worlds is zero, unless they have made their way there from Earth somehow.

There are no hominids on other worlds; there may be organisms that resemble hominids, but unless they have come from Earth somehow, they have evolved separately so should be given some other taxonomic label.
There are no mammals on other worlds; there may be organisms that resemble mammals, but unless they have come from Earth somehow, they have evolved separately so should be given some other taxonomic label.
There are no fish on other worlds; there may be organisms that resemble fish, but unless they have come from Earth somehow, they have evolved separately so should be given some other taxonomic label.So if you are able to make the assertive claim of:
There are no …. unless they have come from Earth somehow … because they have evolved separately … {etc}... then why can't you also make the same assertive claim:
"that there is no exo-'life' … unless it has somehow come from Earth … because it evolved differently"?

Ie: if you are able to rule out such 'possibilities', using: the origin not being from Earth and evolutionary differences, (presumably including natural selection), then why can't you also rule out the existence of any exo-'life' whatsoever, using the same rationale, given that 'life' has only ever been defined, based on Earth-life?

IsaacKuo
2012-Dec-19, 03:41 PM
All of it … with the exception of: 'given our understanding of the expansion of the universe'.
I don't think your sense of science and reality is similar enough to that of scientific mainstream for us to conduct a meaningful discussion, then. You seem to consider practically all theories to be gobbledygook, regardless of whether or not they are scientific.

Ie:
i) 'Alien lifeforms' are purely speculative. Testable in theory, but those tests are unable to be applied across the sample space, and over the distance ranges of which you speak.
Nonsense. I gave a specific example of a test which we could apply using today's technology, over the distance range I described.

ii) 'Dyson Spheres' are purely speculative… an engineering 'thought experiment'. The concept has never been shown to be practically producible or sustainable.
Incorrect. A dyson sphere is simply a collection of enough solar powered satellites in solar orbit to capture sunlight in all directions. We have demonstrated and flown solar powered satellites into solar orbit. A dyson sphere is simply a matter of upscaling this with sufficient numbers of them. The engineering calculations for the resources required are straightforward enough, and Earth has sufficient resources to do so.

But this misses a really important point that it is not necessary for us to be able to create a Dyson sphere in order to test to see if we can see a Dyson sphere out there somewhere. For example, we can test to see if there's a Dyson sphere around our Vega. This is a scientific question with a scientific answer which can be answered using scientific observations. It's not gobbledygook simply because it would be extremely expensive for us to create a Dyson sphere using current technology.

iii) 'The Big Crunch' requires a finite universe, (and yet you seem to argue for an infinite one).
Wrong. The big crunch does not require a spatially finite universe. Even if the universe is infinite in spatial extent, the big crunch is a mainstream possible scenario. The big crunch is a mainstream theory by which the expansion of the universe eventually goes negative, and gravity produces negative expansion until space compresses to a singularity--like the big bang but time reversed. Just as the big bang theory does not require a spatially finite universe, neither does the big crunch theory.

It also requires the cosmological principle not apply.
Huh? Why not? The big crunch assumes the cosmological principle.

The present Cosmology 'leaning', is towards a 'heat death', specifically because there is hard, measured CMBR data which shows that the expansion is accelerating.
You are correct that mainstream cosmological is currently "leaning" toward heat death. But this is only a slight leaning, given our limited understanding of cosmological expansion and our uncertainty. The fact is, the big crunch is still a mainstream cosmological theory that mainstream cosmologists take seriously as still a plausible scenario. In contrast, the steady state theory has lost favor, being all but completely ruled out by various evidence lines in favor of the big bang theory.

You seem to have a fundamental misunderstanding of the CMBR data and its relevance to inflation theory. The CMBR data relates to theories of early universe inflation during the first fraction of a second of the universe. This is distinct from and different from cosmological accelerated expansion, which relates to the metric expansion of space in the billions of years since then.

iv) 'advanced space propulsion technology to contact aliens' … what constrains this technology, if we don't have a clue as to the existence of, or location of 'aliens'. If this is not physically constrained, it is not practically feasible.
I noted that advanced space propulsion technology is not required in the case of the big crunch theory.

Agreed .. but look back, and you'll see that this is the argument you are indirectly defending.
So what?

Isaac, I have no issues with you personally. I find you views very forward-looking .. please don't take this personally, (it is not intended to be so), but if you cannot see the impracticality of what you suggest, then all I can conclude is that you've lost sight of the physical constraints, which also apply to the technologies we create, (and will continue to do so).
Impracticality is not a limitation on what science may study.

Science studies many things beyond what we can physically touch and control. For example, science studies the big bang theory. According to mainstream theories, it is impossible to go back in time to the big bang. But we can scientifically study it anyway. Plausibly, we can never go back to the Big Bang, and we can never create our own Big Bangs. This does not make the big bang theory gobbledygook. This does not make the big bang theory pure speculation.

primummobile
2012-Dec-19, 03:47 PM
I have always heard a collection of satellites arranged spherically around a star referred to as a "Dyson Swarm". If I am not mistaken, Dyson's original thought experiment called for dismantling Jupiter to get the materials for a Dyson "Sphere", which was a solid shell around a star.

Paul Wally
2012-Dec-19, 04:37 PM
The prior probability calculation started by ASTROBOY, is also majorly flawed. It already assumes there to be a 'winning ticket'. In the analogous exo-life lottery selection, (from the 'Universe' sample space), the existence of exo-life only be theoretically supportable if, and only if, the universe is infinite both spatially and temporally. Max Tegmark's estimated calculation (http://cosmoquest.org/forum/showthread.php/125623-Man-s-Radio-Sphere?p=1972304#post1972304), (based on 'The Infinite Universe' concepts), places our nearest intelligent 'doppelganger' (ie: purely theoretically supportable 'intelligent Earth-like' lifeform), at as much as http://www.codecogs.com/eq.latex?{10^{10}}^{29}m distant, which would put these folk well beyond causal contact range of 62 Glyrs.

Regards

I'm certain that's not what Tegmark has in mind. The implication of the infinite universe concept is that if the universe is infinite in spatial extent then there must be some distance where an exact replica of Earth exists. Obviously that is going to yield a ridiculously large number. This infinite universe hypothesis could be considered an alternative to the Parallel universes (multiverse) idea.

Gomar
2012-Dec-19, 06:18 PM
Ifcourse, if a certain species numbers in 100B, and has lasted 10m years, and has spread all
over, well...

Let me edit that, of those if some species (say 1/100) has a population of 100B, and has
lasted 10m years, and has spread all over the galaxy, thus... there are 50,000 super
intelligent alien species in the galaxy.

Thus, 5m intelligent species which use radio, and send ships or probes; and 50,000 super-intelligent species
that have colonized/invaded other worlds, and might as well be considered God-like.

ASTRO BOY
2012-Dec-19, 08:06 PM
Did I see someone earlier in this thread that those that believe ET Intelligence exists, do so because they want it that way?
Besides being silly the reverse is probably closer to the truth.
That is those that hold firm beliefs that ET Intelligence does not exist do so because of religious connotations or other more sinister beliefs....Also the "fear of the unknown" can have a negative effect on some people.

I'm sure we all realise that no conclusive evidence exists either way for the existence of ET life.
But being human we make assumptions on that likelyhood, and from what I have read and seen most scientists assume [partly due to the numbers arguement I have put] that ET life does exist at many levels.
And with the evolution and existence of life, it has been shown that positive assumptions are far more likely then negative assumptions.

We once assumed that there was no life at the bottom of the ocean because of the lack of sunlight.
Other examples of life existing where we would assume it couldn't also exist.
We spend money on the research and searching for ET life and Intelligence...Even allowing for the long odds of finding anything due to time and distance.
I'm sure that would not be the case if the odds were in favor of Earth life being alone.

As Seth Shostak once said..."If we were the only "Intelligent life form" in the Universe, it would truly be a miracle"

Selfsim
2012-Dec-19, 10:30 PM
I disagree......
The only assumption made is that the chances of life arising elsewhere has a high probability due to the reasons already stated many times... And that 'only assumption' happens to be the key assumption which drives the outcome.

The 'reasons' mean what we want them to mean … the 'probability' of anything, is based on knowing, (from past knowledge/experiment), the possible outcomes of a given event. (Ie: we know, in advance there are only two sides of a coin and whether it is fairly weighted .. or; six faces with a different number of dots on them,and whether it is fairly weighted .. or; the number of tickets in a lottery and that one will be the winning ticket, etc, etc) ... (and we know that the next draw will be 'fairly close' to random). We don't need any 'reasons' why a coin has a 'head or a tail', or why a die has six sides, or unique dot patterns per face, etc

We have zero knowledge of the possible outcomes of that event, outside of Earth. If we have no data applicable outside of Earth, then we cannot make any legitimate predictive statements by using the pure concept of 'probability'. Life is defined by life on Earth. The scientific search for exo-life, is the experiment/test for the hypothesis that that Earth-like life may exist outside of Earth. This test, is the way to generate the missing data, which may then be eligible to be manipulated using statistical methods.

Even citing conditional probabilities doesn't work, because there are no known established direct causal relationships, between our own environment, (at the time of hypothesised emergence), and the emergence itself. (Ie: "given so many 'pre-biotic Earths', the probability of life emerging out there will be", for eg).

Even forgetting about emergence for a minute, there are also no known, (presently), remotely detectable factors which mutally exclude other natural non-life phenomena from generating similar bio-signs, with the exception of some very specific compounds which so far, are not known to occur naturally. If these were detected in 'sufficient' quantities, then the 'no-exo-life' hypothesis may ultimately be falsified, but our best life diagnostic tests would still need to be applied to a suspected 'exo-life' sample, in order to establish the mutually exclusive causal relationship beyond specifically Earth-life, (which may not be practically feasible).

Even the sensitivities known life has to certain environmental deviations from the 'norms', are only partially understood. Our own tests for our own 'life', make assumptions about environmental factors which have been sourced from our particular environment .. how can we assume them to be capable of ruling out other possibilities in other exo-environments, when no empirical data exists to give such an assumption any weight, whatsoever?


Science has made many assumptions on similar data in the past...eg: the assumption that the Universe is homeginious and Isotropic.
I see these assumptions as logical based on the current data even if less then 100% certain.Such principles are a guide to future research. They are continually put to the test in other parts of the universe. We cannot say that the analgous principles can be applied for a generalised definition of 'life', whilst eliminating uncertainties leading to definitive conclusions ... the practical application of the tests needed to do this, is simply not feasible, in the majority of the universe, which exists outside of Earth.

There are no tested 'theories of exo-life' (or models), which can be used to eliminate the uncertainties involved.
By way of the comparison you draw, there are however, such models in AstroPhysically based Cosmologies, for distinguishing astrophysical phenomena.

'Life' stands distinct from Astrophysical phenomena, because of its extreme complexity. Empicial test data is the only source we have for distinguishing exo-life in such a complex model ... and there is none to draw from. This is the way Biological Science works and consideration of it is essential, given that it is the strand of science, solely applicable for ultimately distinguishing 'exo-life'.

Selfsim
2012-Dec-19, 10:43 PM
The prior probability calculation started by ASTROBOY, is also majorly flawed. It already assumes there to be a 'winning ticket'. In the analogous exo-life lottery selection, (from the 'Universe' sample space), the existence of exo-life only be theoretically supportable if, and only if, the universe is infinite both spatially and temporally. Max Tegmark's estimated calculation, (based on 'The Infinite Universe' concepts), places our nearest intelligent 'doppelganger' (ie: purely theoretically supportable 'intelligent Earth-like' lifeform), at as much as m distant, which would put these folk well beyond causal contact range of 62 Glyrs.I'm certain that's not what Tegmark has in mind. The implication of the infinite universe concept is that if the universe is infinite in spatial extent then there must be some distance where an exact replica of Earth exists. Obviously that is going to yield a ridiculously large number. This infinite universe hypothesis could be considered an alternative to the Parallel universes (multiverse) idea.And there is nothing to suggest that any other permutations of molecules/atoms (considered by Tegmark in his theoretical study), would result in 'intelligent life forms' capable of communicating over less than such distances. (Ie there is no 'theory of intelligence' which explains the development of interstellar comms).

Empirically speaking however, of the ~8.7 million euraryote lifeforms presently estimated to exist, only one is capable of communicating over spatial distances. The 'weight' of known empirical 'evidence' gives no hints about a repetition of such capabilities, so why would one assume a repetition of this capability inside this radial distance?

IsaacKuo
2012-Dec-19, 10:52 PM
So if you are able to make the assertive claim of:... then why can't you also make the same assertive claim:
"that there is no exo-'life' … unless it has somehow come from Earth … because it evolved differently"?

Ie: if you are able to rule out such 'possibilities', using: the origin not being from Earth and evolutionary differences, (presumably including natural selection), then why can't you also rule out the existence of any exo-'life' whatsoever, using the same rationale, given that 'life' has only ever been defined, based on Earth-life?
Because the definition of hominid includes a requirement of shared ancestry with other hominids. If we see a mammal which looks like a hominid, but which is genetically distinct from them and, say, evolved from a marsupial, then it is not a hominid! We may call it a marsupial, and maybe depending on how different it is from other marsupials, we may invent a new taxonomic category for it. But it is not a hominid, because of the definition of hominid.

In contrast, there is no such requirement of shared ancestry on the definition of life in general. If we discover a new life form, such as an edicaran, we do not need to assume shared ancestry with a known taxonomic category in order to declare it a life form. To the contrary, the possiblity that it does not fit into an already known taxonomic category is exciting to scientists.

If scientists discover a life form which they find difficult or impossible to fit into an existing category, they don't dismiss it as not life.

Selfsim
2012-Dec-19, 11:22 PM
...In contrast, there is no such requirement of shared ancestry on the definition of life in general.Huh? See RNA and the Standard Genetic Code (http://en.wikipedia.org/wiki/Genetic_code#RNA_codon_table)... the 'shared ancestry' is encoded directly into all known DNA/RNA, and is the cornerstone for the theory which defines of the commonality of all 'life'.
(Excuse the short reply .. (no time for more words)).


If we discover a new life form, such as an edicaran, we do not need to assume shared ancestry with a known taxonomic category in order to declare it a life form. To the contrary, the possiblity that it does not fit into an already known taxonomic category is exciting to scientists.Assuming (in advance) is not the issue.
Empirical evidence, (including the common genetic code), is used as a template for testing anything new. And its derived entirely from all known Earth-life, and that code gives rise to metabolism, replication, etc. This would seem to be the very basis for defining defining 'life', no matter where it comes from.??.


If scientists discover a life form which they find difficult or impossible to fit into an existing category, they don't dismiss it as not life.That's not what Raoult/Drancourt say (http://cosmoquest.org/forum/showthread.php/140063-How-Small-Can-Life-Be?p=2086479#post2086479) about nanobacteria!

Van Rijn
2012-Dec-19, 11:37 PM
Huh? See RNA and the Standard Genetic Code (http://en.wikipedia.org/wiki/Genetic_code#RNA_codon_table)... the 'shared ancestry' is encoded directly into all known DNA/RNA, and is the cornerstone for the theory which defines of the commonality of all 'life'.
(Excuse the short reply .. (no time for more words)).

Assuming (in advance) is not the issue.
Empirical evidence, (including the common genetic code), is used as a template for testing anything new. And its derived entirely from all known Earth-life, and that code gives rise to metabolism, replication, etc. This would seem to be the very basis for defining defining 'life', no matter where it comes from.??.


So . . . if I'm understanding your argument, if we detected Dyson spheres, and found the builders, despite having metabolism, replication, etc., used something significantly different from Earth biology, you'd insist it was NOT life? If so, what term, other than "life," would you use to describe it?

Paul Wally
2012-Dec-19, 11:52 PM
And there is nothing to suggest that any other permutations of molecules/atoms (considered by Tegmark in his theoretical study), would result in 'intelligent life forms' capable of communicating over less than such distances. (Ie there is no 'theory of intelligence' which explains the development of interstellar comms).

There is nothing to suggest anything of relevance because Tegmark is not addressing the question of intelligent life elsewhere in the universe, at least not in his paper The Multiverse Hierarchy (2009). He is however considering the question of parallel universes, and how in an infinite universe we can expect to find another Selfsim exactly like you 101029m away. Other intelligent life different from us , should be considerably closer.


Empirically speaking however, of the ~8.7 million euraryote lifeforms presently estimated to exist, only one is capable of communicating over spatial distances.

Is that supposed to mean something?


The 'weight' of known empirical 'evidence' gives no hints about a repetition of such capabilities, so why would one assume a repetition of this capability inside this radial distance?

If there is a certain number of possible unlikely combinations then other combinations (including other life) are much more likely than an exact replica of us. So alien life different from us is much more likely than alien life exactly like us. So we can safely assume the existence of alien life-forms within the ridiculously large radius of 101029m. We can even expect other humans not identical to us to exist well within that radius.

Selfsim
2012-Dec-20, 12:18 AM
So . . . if I'm understanding your argument, if we detected Dyson spheres, and found the builders, despite having metabolism, replication, etc., used something significantly different from Earth biology, you'd insist it was NOT life? If so, what term, other than "life," would you use to describe it?Ok ... (I should clarify) ... the question I'm asking is why can't we dismiss our definition of 'Life' on the same basis as eburacum's dismissal of homids, mammals and fish (hs,ms,fs)? Ie:
There are no, {whatever species .. hs, ms, fs ..}, unless they have come from Earth somehow … because they have evolved separately …... after all, our definition of 'Life' is presently, (by necessity), is purely derived from an evolved Earth-life, which has also evolved separately from your speculated Dyson-sphere mass-producers.

Somewhere, in a vast number of posts in this forum, I have put my position as being that, when and if, some (exo)-lifeform, is fortuitously stumbled upon, (by virtue of the act of pure exploration), tests originally based on our own carbon-based lifeform tests, will be used in combination with the observed properties of whatever is discovered, to develop tests which will produce results, which can be catalogued into 'like and unlike' properties, relative to our own 'Earth-life' definitions. Just exactly how that will be done, is as much a function of the discovery itself, as it is a function of our present biology definitions/functions. We cannot say at present what that test, or its findings might look like to any degree of certainty, at present, so I can't see why we couldn't regard our present definition of 'life' as being potentially a completely 'disposable one', right now. (There seems to be some hesitancy about doing this, however. I'm prepared to accept there may be things I have not recognised, but I haven't seen them yet).

Our present definition of 'Life' is singularly derived from Earth-based life. An hypothesis is being tested, by looking for exo-life. That hypothesis is that our present universal definition of life, applies to a broader scope of instances, which may/may not exist beyond (near) Earth. The starting case is, broadly, carbon-based life.

Selfsim
2012-Dec-20, 12:39 AM
There is nothing to suggest anything of relevance because Tegmark is not addressing the question of intelligent life elsewhere in the universe, at least not in his paper The Multiverse Hierarchy (2009). He is however considering the question of parallel universes, and how in an infinite universe we can expect to find another Selfsim exactly like you 101029m away. Other intelligent life different from us, should be considerably closer. (My underline). Assumption based speculation. .. not coming from the mathematical basis underpinning the 'Infinite Universe' ...


Is that supposed to mean something? It should .. its the current state of empirically based knowledge on the subject.


If there is a certain number of possible unlikely combinations then other combinations (including other life) are much more likely than an exact replica of us. So alien life different from us is much more likely than alien life exactly like us. So we can safely assume the existence of alien life-forms within the ridiculously large radius of 101029m. We can even expect other humans not identical to us to exist well within that radius.You can 'expect', from opinion, all you like.
There is no evidence that any combinations of molecules outside of our 'common' genetic code, (at that scale), which is known to result in any functions which we'd categorise as 'life'! If there are, then you've falsified a major pillar of Science!

Man, I just can't get over how addicted some folk are to realising something which is not yet known .... (not singling out just you)!!!!

R.A.F.
2012-Dec-20, 12:52 AM
...I just can't get over how addicted some folk are to realising something which is not yet known ....

I think of it as an intellectual impatience. Why can't people simply await the evidence, rather than speculate about unknowns.

In other words, what's the "rush"??...if life exists elsewhere, then evidence will demonstrate that in time.

Selfsim
2012-Dec-20, 12:59 AM
I think of it as an intellectual impatience. Why can't people simply await the evidence, rather than speculate about unknowns.

In other words, what's the "rush"??...if life exists elsewhere, then evidence will demonstrate that in time.They're all just stories!

More sophisticated perhaps than a casual ATMer ... bit stories none-the-less.

What happens to the tools developed for specifically distinguishing reality, amidst all this stuff, I ask?
I think they're disappearing in a plume of smoke and sci-fi!

R.A.F.
2012-Dec-20, 02:43 AM
Did I see someone earlier in this thread that those that believe ET Intelligence exists, do so because they want it that way?

I would say, yes, there is a certain amount of "wish fulfillment" involved...otherwise known as bias.



those that hold firm beliefs that ET Intelligence does not exist do so because of religious connotations or other more sinister beliefs....Also the "fear of the unknown" can have a negative effect on some people.

So anyone who doesn't agree with your evidence free speculations are either...

A. Basing their opinion on a "religious" belief of some sort, or

B. Up to something "sinister", or

C. Afraid of "the unknown"?


Do you really expect us to accept these mischaracterizations of other posters?....because I, personally fail to fit any of those "examples", and am a bit perturbed that you thought it appropriate to post such "stuff" here...

It just makes it very difficult to take your opinions seriously, knowing this is how you think.

ASTRO BOY
2012-Dec-20, 04:24 AM
I would say, yes, there is a certain amount of "wish fulfillment" involved...otherwise known as bias.




So anyone who doesn't agree with your evidence free speculations are either...

A. Basing their opinion on a "religious" belief of some sort, or

B. Up to something "sinister", or

C. Afraid of "the unknown"?


.

Obviously not, just as those that believe ET life and Intelligence exists elsewhere cannot all be of that view because they wish it to be...It goes both ways.
There are many reasons for the positive and negative view on this matter, and I have mentioned some reasons for those that may be negatively inclined, just as the "wishful thinking" could in some circumstances be applied to those that are more positive.

ASTRO BOY
2012-Dec-20, 04:27 AM
I think of it as an intellectual impatience. Why can't people simply await the evidence, rather than speculate about unknowns.

In other words, what's the "rush"??...if life exists elsewhere, then evidence will demonstrate that in time.



Science is born of speculation and Imagination...sheesh!

Selfsim
2012-Dec-20, 05:23 AM
There are many reasons for the positive and negative view on this matter, and I have mentioned some reasons for those that may be negatively inclined, just as the "wishful thinking" could in some circumstances be applied to those that are more positive.What does this 'positive' and 'negative' emotionalism have to do with anything? That would seem to be some kind of purely superficial inference of what is going on here.

I see no value in adopting a provocative, opinionated judgement relating to emotional states, then conferring this upon the various views being presented.

I personally don't care whether exo-life exists or not ... how is that, in any way, a 'negative' or a 'positive' view?

Why?

The two hypotheses (loosely) of: 'exo-life' or 'no exo-life' are not the exclusive domain of the discussion at all, anyway.

'Not known' is the reality, and the scientific mainstream view.

ASTRO BOY
2012-Dec-20, 08:13 AM
'Not known' is the reality, and the scientific mainstream view.



Yep I've said that a few times...Still doesn't stop renowned experts and lay people like myself believing ET life probably does exist for the same reasons that I have stated.

Colin Robinson
2012-Dec-20, 08:16 AM
What does this 'positive' and 'negative' emotionalism have to do with anything? That would seem to be some kind of purely superficial inference of what is going on here.

I see no value in adopting a provocative, opinionated judgement relating to emotional states, then conferring this upon the various views being presented.

That is the sort of thing Mr Spock would say! You're not a Vulcan by any chance?:)


The two hypotheses (loosely) of: 'exo-life' or 'no exo-life' are not the exclusive domain of the discussion at all, anyway.

'Not known' is the reality, and the scientific mainstream view.

It's true that mainstream scientists don't know, and don't claim to know, whether there is life beyond Earth.

But do they regard "not known" as a reason to stop formulating hypotheses and testing them? Is there any mainstream scientist who regards "not known" as a substitute for a hypothesis?

I hope not. (Yes, an expression of emotion!)

Because if scientists did regard "not known" as a reason to stop formulating hypotheses, then scientific research could hardly continue...

ASTRO BOY
2012-Dec-20, 08:28 AM
What does this 'positive' and 'negative' emotionalism have to do with anything? That would seem to be some kind of purely superficial inference of what is going on here.

I see no value in adopting a provocative, opinionated judgement relating to emotional states, then conferring this upon the various views being presented.

I personally don't care whether exo-life exists or not ... how is that, in any way, a 'negative' or a 'positive' view?

Why?



The discovery of ET life existing would be an exciting awe inspiring and world changing event.
It would also probably be a great kick-a-long for space exploration world wide.
I find it surprising that you find it as lack-lustre as you see the need to portray.
The positive and negative "emotionalism" as you put it naturally applies to those with firm views on the subject in the positive or negative aspect of the question.
Again my view on the subject remains positive and unchanged for the reasons I have given.

IsaacKuo
2012-Dec-20, 08:37 AM
I think of it as an intellectual impatience. Why can't people simply await the evidence, rather than speculate about unknowns.

In other words, what's the "rush"??...if life exists elsewhere, then evidence will demonstrate that in time.
This evidence will be found by scientists looking for evidence, and scientific evidence requires formulating testable scientific hypotheses.

So, for example, SETI is a serious scientific study using serious scientific hypotheses and testing them by looking for evidence. It's not gobbledygook, and it's not just nonsensical speculation. It is science. It's the same scientific principle and process which has led us to discover planets outside our solar system. It wasn't a matter of scientists irrationally dismissing speculation about exoplanets as foolish "intellectual impatience". It was a matter of scientists taking the study of exoplanets as a serious endeavor even if evidence was not yet available, and using that study to determine how to look for that evidence!

SETI involves various hypotheses of what sort of radio signals aliens might have sent in our direction, and what sort of radio signals could be identified and distinguished from natural sources. This line of study and devoting radio telescope time to SETI is not just some fanciful imaginative exercise in "intellectual impatience". It's a serious scientific study that is doing something to gather evidence based on actual existing observational capabilities.

Selfsim
2012-Dec-20, 08:49 AM
That is the sort of thing Mr Spock would say! You're not a Vulcan by any chance?:)
Live long and prosper, Earthling. :p :)


It's true that mainstream scientists don't know, and don't claim to know, whether there is life beyond Earth.

But do they regard "not known" as a reason to stop formulating hypotheses and testing them? Is there any mainstream scientist who regards "not known" as a substitute for a hypothesis?

I hope not. (Yes, an expression of emotion!)

Because if scientists did regard "not known" as a reason to stop formulating hypotheses, then scientific research could hardly continue...There's a big difference between a professional formulating a scientific hypothesis for review by his/her peers, with the intention of bidding for funding, and idle speculation posted on a public forum.

We shouldn't kid ourselves that the speculation going on here, is in any way related to professional science speculation.

Selfsim
2012-Dec-20, 09:03 AM
... lay people like myself believing ET life probably does exist for the same reasons that I have stated.
...
Again my view on the subject remains positive and unchanged for the reasons I have given.It doesn't really concern me if you choose to maintain your opinion, or not.

I make no attempts to pursuade you, nor do I have any interest in doing so.

ASTRO BOY
2012-Dec-20, 09:15 AM
We shouldn't kid ourselves that the speculation going on here, is in any way related to professional science speculation.


But it is...and in many quarters.

IsaacKuo
2012-Dec-20, 09:17 AM
Huh? See RNA and the Standard Genetic Code (http://en.wikipedia.org/wiki/Genetic_code#RNA_codon_table)... the 'shared ancestry' is encoded directly into all known DNA/RNA, and is the cornerstone for the theory which defines of the commonality of all 'life'.
This is nonsense. Your link is simply to a reference on RNA and genetic code. There is nothing there which says that the definition of life requires that RNA/DNA must be part of it.

In fact, there are many fossil life forms for which we haven't got the slightest trace of RNA or genetic code. I gave the example of edicarans. We're rather sure that they were RNA/DNA based, but we don't have the slightest shred of direct evidence. But here's the important point--if we did get our hands on a living edicaran, we could conduct scientific tests to determine whether they had RNA/DNA, and this is something which could come up negative. If it did come up negative, would any scientists declare them to not be life? No. This blows a hole in your non-scientific line of thinking.

Empirical evidence, (including the common genetic code), is used as a template for testing anything new. And its derived entirely from all known Earth-life, and that code gives rise to metabolism, replication, etc. This would seem to be the very basis for defining defining 'life', no matter where it comes from.??.
Nonsense. Metabolism, replication, etc were all observed and defined as scientific tests for life before the discovery of DNA. The scientific study of fossil life forms predates the discovery of DNA, and continued uninterrupted during and after the discovery of DNA. The fact that DNA breaks down and does not survive as long as fossils do severely limits the utility of DNA evidence in studying fossil life forms.

There isn't the slightest traces of DNA available for edicaran fossils, anywhere. This does not mean that scientists throw their arms up in the air and say, "Oh well...we have no idea whether these were life forms, and it's just too bad we'll never know!" Of course not.
That's not what Raoult/Drancourt say (http://cosmoquest.org/forum/showthread.php/140063-How-Small-Can-Life-Be?p=2086479#post2086479) about nanobacteria![/QUOTE]
So what? Nanobacteria fail to satisfy some traditional characteristics of life, which make them borderline cases at best.

You don't seem to "get" that there is a scientific debate about whether or not nanobacteria should be considered life forms. It's not like the steady state theory of the universe where the scientific mainstream has all but rejected the theory entirely. In this case, there is a scientific debate because the evidence is not obvious and because nanobacteria lies on a borderline where one or two characteristics are satisfied but most others are not.

Because there is a scientific debate about the answer, you can't just cherry pick one opinion and declare that this is the only scientific answer. That's not how it works in science. The way it works in science is that scientists live and breath on the fuzzy edge of knowledge, where multiple theories are plausible and there aren't definitive answers are not set in stone.

Selfsim
2012-Dec-20, 09:23 AM
This evidence will be found by scientists looking for evidence, and scientific evidence requires formulating testable scientific hypotheses.Where does this 'evidence' term come from?

A hypothesis is formulated (and in professional science circles, its not just from pure wild imaginings). The hypothesis is tested. The data is evaluated. It either 'fits' the hypothesis, it doesn't, or its inconclusive. Science doesn't seek 'evidence'. People trying to prove something might. Courts of Law attempting to find the truth might too, but science isn't about looking for 'evidence' or trying to prove a hypothesis (or some truth).


So, for example, SETI is a serious scientific study using serious scientific hypotheses and testing them by looking for evidence. It's not gobbledygook, No, but what you just said is.


... and it's not just nonsensical speculation. It is science. It's the same scientific principle and process which has led us to discover planets outside our solar system. It wasn't a matter of scientists irrationally dismissing speculation about exoplanets as foolish "intellectual impatience". It was a matter of scientists taking the study of exoplanets as a serious endeavor even if evidence was not yet available, and using that study to determine how to look for that evidence!Science is about building knowledge in the form of testable explanations and predictions about the universe.

This is fundamentally different from looking for 'evidence' to justify some idea.

Can you see the difference?


SETI involves various hypotheses of what sort of radio signals aliens might have sent in our direction, and what sort of radio signals could be identified and distinguished from natural sources. This line of study and devoting radio telescope time to SETI is not just some fanciful imaginative exercise in "intellectual impatience". It's a serious scientific study that is doing something to gather evidence based on actual existing observational capabilities.I might agree with you in that you might see that SETI, (and maybe even some Astrobiologists), attempt to justify the existence of their subject matter .. but that is not what science does, and I don't agree that's what SETI (or proper Astrobiology) is about.

IsaacKuo
2012-Dec-20, 09:54 AM
Where does this 'evidence' term come from?

A hypothesis is formulated (and in professional science circles, its not just from pure wild imaginings). The hypothesis is tested. The data is evaluated. It either 'fits' the hypothesis, it doesn't, or its inconclusive. Science doesn't seek 'evidence'. People trying to prove something might. Courts of Law attempting to find the truth might too, but science isn't about looking for 'evidence' or trying to prove a hypothesis (or some truth).
Seriously? You seriously think science doesn't seek evidence? What in the world do you think scientists do? Where do you think "the data" comes from?

Scientists spend time and effort gathering that data, and analyzing it. That data, along with the analysis, is evidence.

Science is about building knowledge in the form of testable explanations and predictions about the universe.
This is fundamentally different from looking for 'evidence' to justify some idea.
You have a fundamental misunderstanding of the definition of "evidence", and you have been intellectually dishonest about your accusations of "gobbledygook", then.

For example, I proposed a scientific test for looking for evidence of alien life by looking for a Dyson sphere around Vega. Is this because I have some idea that this will justify some idea? What idea? The idea that there are aliens out there? How could this test promote that idea? I already know that Vega's spectrum is inconsistent with a Dyson sphere. Or the idea that there aren't aliens out there? How could this test promote that idea? It only suggests very slightly that there aren't aliens in the Vega system.

IsaacKuo
2012-Dec-20, 10:02 AM
Selfsim, you also seem to have a mistaken idea of my opinion on the likelyhood of alien life forms. I am uneasy with Bayesian probability theory, so I tend to gravitate toward a frequentist view where we currently lack sufficient evidence to form an estimate on the probability of alien life. I wouldn't be surprised at all if there are no life forms in the universe outside of Earth, and many of my speculations on what humanity might accomplish in the future assume no one else is out there.

Paul Wally
2012-Dec-20, 02:40 PM
Other intelligent life different from us , should be considerably closer.

(My underline). Assumption based speculation. .. not coming from the mathematical basis underpinning the 'Infinite Universe' ...


I'm not even speculating. I'm just stating what follows by implication from Tegmark's infinite universe idea. Or do you think that an exact replica of yourself elsewhere is more likely than life not identical to yourself?


We can even expect other humans not identical to us to exist well within that radius.

You can 'expect', from opinion, all you like.


I expect from pure logical reasoning. Why is that? Because the existence of humans is more likely elsewhere than the existence of you or me elsewhere.



There is no evidence that any combinations of molecules outside of our 'common' genetic code, (at that scale), which is known to result in any functions which we'd categorise as 'life'! If there are, then you've falsified a major pillar of Science!

If there are lifeforms based on a different genetic code then nothing is going to be falsified because there is no theory that says alien lifeforms should necessarily share the same genetic code with us.

R.A.F.
2012-Dec-20, 02:45 PM
Obviously not, just as those that believe ET life and Intelligence exists elsewhere cannot all be of that view because they wish it to be...It goes both ways.

How is it "obvious"? We're you just "kidding" with all the "If you don't think there is ET life you must be..." and then went on to be very insulting?

Does this "going both ways" entitle you to make such gross characterizations about those who don't share your opinion?



...I have mentioned some reasons for those that may be negatively inclined...

No, those were excuses that you brought to this board...there was no reasoning involved.



...just as the "wishful thinking" could in some circumstances be applied to those that are more positive.

So you deny that you "want" ET to be real?....it's called bais, and we all have it...it's just that some of us can never admit it



....and when did reserving judgement until conformational evidence is available become a "negative"?

See, that's the thing....you have arbitrary decided that those who believe without evidence are being "positive" and those who reserve judgement until evidence becomes available are being "negative", and I refuse to accept such irrelevant characterizations.

R.A.F.
2012-Dec-20, 02:52 PM
This evidence will be found by scientists looking for evidence, and scientific evidence requires formulating testable scientific hypotheses.

Sure... it certainly won't be found by "impatient" posters to an internet forum...ie., this is all just "coffee table specualtion" having zero effect on actual scientific discovery.

Thanks for that "set up". :)

R.A.F.
2012-Dec-20, 02:57 PM
Science is born of speculation and Imagination...sheesh!

If you are going to respond to my post, please have the courtesy to answer my question...what's the "rush"?

IsaacKuo
2012-Dec-20, 04:20 PM
Sure... it certainly won't be found by "impatient" posters to an internet forum...ie., this is all just "coffee table specualtion" having zero effect on actual scientific discovery.

Thanks for that "set up". :)
You don't know that. Oh, maybe you claim to know it with an absolute 100% certainty that no one on BAUT will ever come up with any idea that works, but in that case you're just wrong in your mistaken certainty.

You don't know where successful ideas will come from, so really, the joke's on you.

R.A.F.
2012-Dec-20, 04:33 PM
You don't know that. Oh, maybe you claim to know it with an absolute 100% certainty that no one on BAUT will ever come up with any idea that works, but in that case you're just wrong in your mistaken certainty.

You don't know where successful ideas will come from, so really, the joke's on you.

....and you will always be "right" because you never have to prove anything...


....and I was just disagreeing with Moose about the need for a major overhaul of this section of the board...my opinion has now changed.

IsaacKuo
2012-Dec-20, 04:35 PM
I have always heard a collection of satellites arranged spherically around a star referred to as a "Dyson Swarm". If I am not mistaken, Dyson's original thought experiment called for dismantling Jupiter to get the materials for a Dyson "Sphere", which was a solid shell around a star.
Actually, Dyson's original thought experiment was a collection of satellites. He didn't have any specific arrangement in mind, he just pondered that sufficient numbers of them could eventually block out and exploit sunlight in all or most directions. His original thought experiment was about searching for ET life in other star systems, so it wasn't tied to the resources of Jupiter or any other planet in our own solar system.

The "shell" like Dyson sphere concept is a later idea, made popular by science fiction depictions.

There are several different possible ways a Dyson sphere could be implemented. The most straightforward using known technology is a collection of satellites, but it involves a lot of overlaps and is relatively heavy compared to some alternatives. A more lightweight alternative is a thin shell of statites. Another alternative is a (hydrogen) gas supported bubble. These different possibilities could have significantly different spectral signatures, but they are broadly similar to each other--lots of IR and a lack of the sort of spectral lines typical of natural stars (due to non-hydrogen "contaminants"). Also, there are various things to hopefully distinguish them from protoplanetary dust clouds...but a Dyson sphere made of tiny dust-like satellites might indeed look a lot like a protoplanetary dust cloud.

IsaacKuo
2012-Dec-20, 04:54 PM
....and you will always be "right" because you never have to prove anything...
Huh? What are you even trying to get at?

....and I was just disagreeing with Moose about the need for a major overhaul of this section of the board...my opinion has now changed.
Please do make suggestions about what sort of changes you think are needed on the feedback forum. I think the moderators will side with mainstream scientific thought. I hope that you also think the moderators will side with mainstream scientific thought. We have a disagreement about what constitutes valid mainstream scientific thought.

R.A.F.
2012-Dec-20, 05:23 PM
Huh? What are you even trying to get at?

That portions of the board have become "havens" for anyone to make practically any claim without having the "burden" of proving themselves correct.

That was fine when it was an occasional thread, but lately, it has gotten way "out of hand"...and not just here, but on the Space Exploration, and Q and A parts of the board, too.

primummobile
2012-Dec-20, 05:26 PM
Actually, Dyson's original thought experiment was a collection of satellites. He didn't have any specific arrangement in mind, he just pondered that sufficient numbers of them could eventually block out and exploit sunlight in all or most directions. His original thought experiment was about searching for ET life in other star systems, so it wasn't tied to the resources of Jupiter or any other planet in our own solar system.

The "shell" like Dyson sphere concept is a later idea, made popular by science fiction depictions.



I did not know that.

Gomar
2012-Dec-20, 05:54 PM
and 50,000 super-intelligent species
that have colonized/invaded other worlds, and might as well be considered God-like.

It is possible that atleast 1/100 of the above have evolved beyond their physical form and exist
as pure energy. Or say they have genetically engineered a form of life that is capable of living 1000 years, or be able to hibernate in space, then 500 species in the galaxy are capable of inter-stellar space flight in their life span. Thus, they live forever, and travel all across the universe no matter how long it takes.
It's just a question if such God-like aliens already do exist, and have existed for millions of years, or if
humans are the most advanced species in the galaxy.

primummobile
2012-Dec-20, 06:19 PM
It is possible that atleast 1/100 of the above have evolved beyond their physical form and exist
as pure energy. Or say they have genetically engineered a form of life that is capable of living 1000 years, or be able to hibernate in space, then 500 species in the galaxy are capable of inter-stellar space flight in their life span. Thus, they live forever, and travel all across the universe no matter how long it takes.
It's just a question if such God-like aliens already do exist, and have existed for millions of years, or if
humans are the most advanced species in the galaxy.

Where are you getting these numbers? What is a "pure energy" being? How does any of that translate into living forever?

MaDeR
2012-Dec-20, 07:02 PM
I'm certain that's not what Tegmark has in mind. The implication of the infinite universe concept is that if the universe is infinite in spatial extent then there must be some distance where an exact replica of Earth exists.
Wrong. "Infinite" is not excuse for "anything goes".


What is a "pure energy" being?
I always loved this kind of nonsense. This is like spekaing about "pure kilogram" beings. :D

IsaacKuo
2012-Dec-20, 08:09 PM
If you are going to respond to my post, please have the courtesy to answer my question...what's the "rush"?
What rush? Why should there be any waiting period before scientific speculation on hypothetical alien life forms? Scientists aren't waiting for your permission. Why should we?

You seem to want everyone to shut up about the possibility of alien life forms until after hard evidence of alien life forms appears before us. Is that right? Because that's blatantly unscientific, and not what scientists are doing.

To the contrary, there are many scientific papers and scientific discussions about what alien life forms may be like and how to go about looking for evidence of alien life based on those scientific possibilities.

IsaacKuo
2012-Dec-20, 08:17 PM
Wrong. "Infinite" is not excuse for "anything goes".
Tegmark's analysis of implications of a spatially infinite universe is based on probability, not "anything goes". It's simply an analysis of how many particle configurations of our Hubble volume are possible (within the resolution limits of Heisenberg's uncertainty principle), and calculating the spherical volume required to contain all of those possible configurations. Beyond that radius, duplicated configurations are inevitable.

R.A.F.
2012-Dec-20, 08:20 PM
You seem to want everyone to shut up about the possibility of alien life forms until after hard evidence of alien life forms appears before us.

Not even close...

I'm going to stop posting to this section of the board, at least until Admin./mods figure out what changes are to be made...if any. It just ain't worth the "trouble" it would bring upon me.

ASTRO BOY
2012-Dec-20, 08:20 PM
How is it "obvious"? We're you just "kidding" with all the "If you don't think there is ET life you must be..." and then went on to be very insulting?

Does this "going both ways" entitle you to make such gross characterizations about those who don't share your opinion?


You seem to be taking a dishonest approach to what I said. If you refer to my use of the word "arrogant" then I suggest you read my posts again. [1] I did explain that it was a collective term and not personal and gave the arrogance of the church as an example. [2] I also gave other reasons why I think some people think we have no ET life, such as religious views again [the Earth being the center of the Universe and the be all and end all of God's creation and [3] the use of the word "arrogance" did not apply to the actual scientific valid answer of "we don't know"....It was directed at those that say, "we are it" and orginisations like the church.
We do have a saying though which goes something like this..."If the cap fits, wear it"







No, those were excuses that you brought to this board...there was no reasoning involved.


Your interpretation of what I said is wrong.....the points I raised are accepted reasons and why many cosmologists believe ET does exist even without hard evidence.






So you deny that you "want" ET to be real?....it's called bais, and we all have it...it's just that some of us can never admit it




Putting words into other people's mouth isn't very scientific.......I listen look and learn and make as unbiased opinion as is possible.
And with current data available, [ie the Infinite or at least "near infinite" extent of the Universe] the numbers involved and the stuff of life being everywhere we look, I take a positive approach to the question in hand.





....and when did [i]reserving judgement until conformational evidence is available become a "negative"?

Again stop putting words in my mouth, I didn't say that.






See, that's the thing....you have arbitrary decided that those who believe without evidence are being "positive" and those who reserve judgement until evidence becomes available are being "negative", and I refuse to accept such irrelevant characterizations.


I'm sure most people even in light of the "no evidence available either way" fact would have an opinion one way or the other. Fence sitting does not appeal to me and apparently it doesn't appeal to most astronomers either, since if most were asked to give an opinion one way or the other, most go with the positive scenario because of the reasons I have given.

ASTRO BOY
2012-Dec-20, 08:32 PM
If you are going to respond to my post, please have the courtesy to answer my question...what's the "rush"?

What rush?...What are you talking about?
Again, science is born of speculation and Imagination.

“Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand.”
Albert Einstein.

Selfsim
2012-Dec-20, 09:32 PM
I think this thread should be closed.

(I'm certainly done with it).

PetersCreek
2012-Dec-20, 09:41 PM
Okay...five pages and we're still arguing over "arrogance"? Everyone tone it down. If it doesn't improve then this is likely to be closed.

Now about that "arrogance" ASTRO BOY...yes, the question of ET life is bound to generate hypotheses if favor of the proposition. However, in the absense of evidence there are bound to be those who hold the null hypothesis until such evidence is to be had. Classifying such a position as arrogance was needlessly inflammatory. Please choose your words with greater care.

To others: do try to be a little less sensitive to such language framed in the general case. If you really do find it insulting, report it.

ASTRO BOY
2012-Dec-20, 10:22 PM
Okay...five pages and we're still arguing over "arrogance"? Everyone tone it down. If it doesn't improve then this is likely to be closed.

Now about that "arrogance" ASTRO BOY...yes, the question of ET life is bound to generate hypotheses if favor of the proposition. However, in the absense of evidence there are bound to be those who hold the null hypothesis until such evidence is to be had. Classifying such a position as arrogance was needlessly inflammatory. Please choose your words with greater care.

To others: do try to be a little less sensitive to such language framed in the general case. If you really do find it insulting, report it.



Gotcha...It certainly wasn't meant as inflammatory but I will chose my words more carefully next time.
Thanks.

MarianoRF
2012-Dec-21, 12:13 PM
We have no solid observational or experimental evidence that life exists other then on Earth.
In saying that and in my opinion it would be the height of arrogance to think we are it.
We have 100's of billions of stars in this galaxy alone, and billions of galaxies with more or less the same amount of stars...We have the stuff of life everywhere we look, and extra solar planets have now been shown to be common place along with water in one form or another....As Elly said in the movie "Contact", "If we are it, it seems like an awful lot of wasted space"
[or at least words to that effect]

Also worth noting that as measurements and observations of extra solar planets become more precise, the discovery of an Earth like planet draws gets closer all the time.

And all this just in our "Observable Universe"...no doubt a very small fraction of the whole Universe.

Yeah, I agree with you. To a certain extent, it feels like we couldn't be the only ones, doesn't it? I mean, in a sensorial and intuitive way, we "feel" that Universe is full of life. But, reality has shown to us, that we are still isolated and alone, in this planet.

And let's think of this: if there's life (simple or complex) in a planet too far away from us, let's say in Andromeda galaxy for example, given the EXTREME vast distances, how could we possible detect it? it's impossible! we can't observe or measure a planet 2.5 millons of light-years away... it's simply too far. So maybe other galaxies are full of life, full of civilizations, but we are unable to detect/contact/hear them given the fact that the distance among each other is simply too vast.

IsaacKuo
2012-Dec-21, 04:10 PM
Yeah, I agree with you. To a certain extent, it feels like we couldn't be the only ones, doesn't it? I mean, in a sensorial and intuitive way, we "feel" that Universe is full of life. But, reality has shown to us, that we are still isolated and alone, in this planet.
Unfortunately, we don't have much data on whether or not we are isolated and alone, in reality. The chemical properties of water suggest that naturally evolved life may require liquid water conditions. There are actually numerous places in our own solar system with liquid water conditions, but other than here on Earth these places require digging underneath the surface to examine. None of our probes so far have had this capability.

So, there's a real plausible chance that life is quite commonplace here in the Solar System, we just haven't yet sent any missions capable of accessing their environments. The expense and difficulty of an interplanetary digging probe is such that we've been trying to pursue methods of investigation that don't require them--such as investigating volatile gas indirect evidence of life, or a proposed Enceladus sample return mission that takes advantage of its geyers.

And let's think of this: if there's life (simple or complex) in a planet too far away from us, let's say in Andromeda galaxy for example, given the EXTREME vast distances, how could we possible detect it? it's impossible! we can't observe or measure a planet 2.5 millons of light-years away... it's simply too far. So maybe other galaxies are full of life, full of civilizations, but we are unable to detect/contact/hear them given the fact that the distance among each other is simply too vast.
There are possible ways to detect such life. The most famous possibility is SETI, which searches for radio signals purposefully sent by technological aliens.

Another possibility is trying to detect evidence of alien industrial activity, such as Dyson spheres, or trying to detect alien military activity, such as nuclear bombs (or other, more destructive weapons). Some odd phenomena might be evidence of alien activity; we don't start with that assumption but it's something we at least consider. Pulsars look a bit like navigation beacons. Gamma ray bursts look a bit like military weapons. Some brown dwarfs look a bit like Dyson spheres. These all have natural explanations, at least so far, but they were all candidates for evidence of alien life.

So, in fact, the Andromeda galaxy is not too far away for us to try and look for alien life. Here's an article about searching for "Dyson bubbles" in the Andromeda galaxy:

http://io9.com/5930827/why-we-should-look-for-extraterrestrial-bubbles-in-neighboring-galaxies

The basic idea is that if an alien civilization converted a region of space into Dyson spheres, it could show up as an unusual dark void in a galaxy. I'm a bit skeptical of this concept, since stars move around and you'd end up with the source stars spread out all over the place within mere millions of years. But it's at least something we can try to look for using already existing data. And it has a big advantage over traditional Dyson sphere searches in that traditional Dyson sphere searches require detailed spectral information to distinguish Dyson spheres from brown dwarfs and other natural stars. This concept works with plain old visible light photos.

ASTRO BOY
2012-Dec-21, 08:01 PM
Yeah, I agree with you. To a certain extent, it feels like we couldn't be the only ones, doesn't it? I mean, in a sensorial and intuitive way, we "feel" that Universe is full of life. But, reality has shown to us, that we are still isolated and alone, in this planet.

And let's think of this: if there's life (simple or complex) in a planet too far away from us, let's say in Andromeda galaxy for example, given the EXTREME vast distances, how could we possible detect it? it's impossible! we can't observe or measure a planet 2.5 millons of light-years away... it's simply too far. So maybe other galaxies are full of life, full of civilizations, but we are unable to detect/contact/hear them given the fact that the distance among each other is simply too vast.


Hi MarianoRF ......
It's obvious time and distance are the two great barriers to overcome before we get to meet any ET cousins.
Many species may have evolved and then gone extinct........
Distances is a little bit easier to overcome....with time and technological advancement we will be able to go further faster and more often...Given time, we maybe able one day to sample/visit some distant ET lifeform.

TooMany
2012-Dec-21, 08:37 PM
It could also be that very advanced beings aren't so interested in seeing how many trillions of individuals they can host around their star. It could be that a Dyson sphere is just an idea that intrigues us now due to our perception that ever increasing population growth is some ultimate goal.

IsaacKuo
2012-Dec-21, 09:18 PM
It could also be that very advanced beings aren't so interested in seeing how many trillions of individuals they can host around their star. It could be that a Dyson sphere is just an idea that intrigues us now due to our perception that ever increasing population growth is some ultimate goal.
There are plenty of other purposes for a Dyson sphere, but in any case it's certainly possible that advanced aliens do not generally create such things. I have a few speculations on possible reasons, but this all somewhat misses the original point of the Dyson sphere concept.

The original idea wasn't so much a bold prediction of alien behavior, but rather a thought experiment about a possible way for us to detect aliens. It's like SETI. Just because there's no guarantee that advanced aliens would send radio signals our way, doesn't mean we can't try to listen for them. It might not be a guaranteed way of detecting aliens, but at least it's a method we have the technological capability to detect.

Same thing with Dyson spheres. It's a method by which we could detect aliens, if they created such things. Obviously, a non-detection is not definitive, but the point is that it's something we can try to detect using existing technology.

That said, my speculative reasons for aliens not developing Dyson spheres only work to a certain extent...I can think of lots of plausible reasons why aliens here in the Milky Way galaxy or nearby galaxies haven't developed them. I can think of plausible reasons why the great majority of galaxies wouldn't be converted into "Dyson sphere galaxies". But there are so many visible galaxies that it seems to stretch credulity that there aren't any Dyson sphere galaxies, if life were common. That's one line of thinking which tends to make me skeptical of the idea that life is common.

My "Dyson sphere galaxy" argument goes something like this:

1) Assume that life is common, and that a decent fraction of galaxies develop advanced technological life within 10 billion years (say, somewhere between 0.01% and 100%).

2) At some radius, between 3 billion years away to 13 billion years away, we will see a large number of advanced life bearing galaxies, at an age before there has been enough time for intergalactic "mixing" between them. This lack of "mixing" means that it's impossible for some virulent expansionist alien faction to dominate more than a tiny portion of the galaxies we see at this radius.

3) These galaxies will develop independently, and it seems like at least some of them would decide to convert their galaxies into "Dyson sphere galaxies" or some other such megastructure dominated galaxies.

4) We don't see Dyson sphere galaxies.

5) Therefore, one or more of the argument links above must be broken. Perhaps advanced alien life is not common. Or perhaps there is some universal reason against Dyson sphere development. Or perhaps Dyson sphere galaxies are out there, but we just haven't recognized them as such.

I'm certainly game to the explanation that advanced alien life just isn't that common.

TooMany
2012-Dec-22, 12:51 AM
The original idea wasn't so much a bold prediction of alien behavior, but rather a thought experiment about a possible way for us to detect aliens. It's like SETI. Just because there's no guarantee that advanced aliens would send radio signals our way, doesn't mean we can't try to listen for them. It might not be a guaranteed way of detecting aliens, but at least it's a method we have the technological capability to detect.

Same thing with Dyson spheres. It's a method by which we could detect aliens, if they created such things. Obviously, a non-detection is not definitive, but the point is that it's something we can try to detect using existing technology.

That said, my speculative reasons for aliens not developing Dyson spheres only work to a certain extent...I can think of lots of plausible reasons why aliens here in the Milky Way galaxy or nearby galaxies haven't developed them. I can think of plausible reasons why the great majority of galaxies wouldn't be converted into "Dyson sphere galaxies". But there are so many visible galaxies that it seems to stretch credulity that there aren't any Dyson sphere galaxies, if life were common. That's one line of thinking which tends to make me skeptical of the idea that life is common.

My "Dyson sphere galaxy" argument goes something like this:

1) Assume that life is common, and that a decent fraction of galaxies develop advanced technological life within 10 billion years (say, somewhere between 0.01% and 100%).

2) At some radius, between 3 billion years away to 13 billion years away, we will see a large number of advanced life bearing galaxies, at an age before there has been enough time for intergalactic "mixing" between them. This lack of "mixing" means that it's impossible for some virulent expansionist alien faction to dominate more than a tiny portion of the galaxies we see at this radius.

3) These galaxies will develop independently, and it seems like at least some of them would decide to convert their galaxies into "Dyson sphere galaxies" or some other such megastructure dominated galaxies.

4) We don't see Dyson sphere galaxies.

5) Therefore, one or more of the argument links above must be broken. Perhaps advanced alien life is not common. Or perhaps there is some universal reason against Dyson sphere development. Or perhaps Dyson sphere galaxies are out there, but we just haven't recognized them as such.

I'm certainly game to the explanation that advanced alien life just isn't that common.

The really big assumption (3) is that there is reason to build a Dyson sphere. Suppose you had one, I guess it's supposed to surround a star at some habitable distance and might have a surface area 1 billion times the surface area of the Earth. So at Earth density you could fit 7 billion, billion beings. What's the point? It takes 30 minutes for a being on one side to ask a question of a being on the opposite side and get an answer. I don't see the purpose. Besides which, I think the transition to non-biological form will occur long before such a project is possible, so "be fruitful and multiply" to fill all available living space may cease to be a motive. We seem to assume that the goal would be to support as large a population as possible. So one problem is that we really have no idea what the goals of a vastly superior civilization would be. I'm not arguing that we should not look for Dyson spheres, we certainly should.

The Fermi paradox needs an answer. An obvious possible answer is that yes other civilizations arise, but by the time they are able to travel among the stars, they have no wish to conquer or spread their kind to every possible planet or to create something like a Dyson sphere. I don't consider the non-existence of other advanced civilizations as a likely explanation for the paradox, or even the difficulty of traveling among the stars. If some civilization in the galaxy reached interstellar capabilities even just a few million years ago (a drop in the bucket of time), they could have explored the entire galaxy by now.

Also consider this, if even only one civilization arises in the galaxy that is capable of interstellar travel, being the first such civilization it could "dominate" the galaxy before another such civilization has a chance to arise. It is quite possible that that particular "founding" civilization knows about everything going on in the galaxy, but chooses not to interfere. It could be that they monitor us either from afar or with local probes and may decide to contact us when we have progressed quite a bit more. But my main point is that it only takes one success to fill a galaxy. The founding civilization has a huge advantage over any that subsequently arises and could actually police the galaxy. We could be the very first, but how likely is that? Our system is relatively new in the history of the galaxy.

headrush
2012-Dec-23, 11:30 AM
The really big assumption (3) is that there is reason to build a Dyson sphere. Suppose you had one, I guess it's supposed to surround a star at some habitable distance and might have a surface area 1 billion times the surface area of the Earth. So at Earth density you could fit 7 billion, billion beings. What's the point? It takes 30 minutes for a being on one side to ask a question of a being on the opposite side and get an answer. I don't see the purpose. Besides which, I think the transition to non-biological form will occur long before such a project is possible, so "be fruitful and multiply" to fill all available living space may cease to be a motive. We seem to assume that the goal would be to support as large a population as possible. So one problem is that we really have no idea what the goals of a vastly superior civilization would be. I'm not arguing that we should not look for Dyson spheres, we certainly should.
The main purpose of a Dyson sphere IIRC is not to populate it maximally. It is to capture the most energy from the enclosed star. Energy allows us to do things. A sufficiently advanced civilisation will have energy needs and being sufficiently advanced, they might build such a system. The thought experiment gives a possible tell tale sign which we are capable of looking for now. It is not presumed they exist but that they might. How can we tell without looking or having a direction (concept) to look in ?


The Fermi paradox needs an answer. An obvious possible answer is that yes other civilizations arise, but by the time they are able to travel among the stars, they have no wish to conquer or spread their kind to every possible planet or to create something like a Dyson sphere. I don't consider the non-existence of other advanced civilizations as a likely explanation for the paradox, or even the difficulty of traveling among the stars. If some civilization in the galaxy reached interstellar capabilities even just a few million years ago (a drop in the bucket of time), they could have explored the entire galaxy by now. Could have is not the same as should have. And maybe they have, but before humans even evolved.


Also consider this, if even only one civilization arises in the galaxy that is capable of interstellar travel, being the first such civilization it could "dominate" the galaxy before another such civilization has a chance to arise. It is quite possible that that particular "founding" civilization knows about everything going on in the galaxy, but chooses not to interfere. It could be that they monitor us either from afar or with local probes and may decide to contact us when we have progressed quite a bit more. But my main point is that it only takes one success to fill a galaxy. The founding civilization has a huge advantage over any that subsequently arises and could actually police the galaxy. We could be the very first, but how likely is that? Our system is relatively new in the history of the galaxy.
Again, could have is not should have. One could argue that a civilisation with inter-stellar capabilities would necessarily have escaped self destruction, and further, have no reason to inflict it on others.

I think a lot of this is intellectual navel gazing, apart from the formulation of testable hypotheses.
And it appears that the scientific method works best when we have a subject to work on and the questions become how, why, etc. Any idea can be thought possible, but without something to test the idea is useless. Even blue sky thinking requires a problem to be solved, one that is usually based in some real world situation.

eburacum45
2012-Dec-23, 02:14 PM
The really big assumption (3) is that there is reason to build a Dyson sphere. Suppose you had one, I guess it's supposed to surround a star at some habitable distance and might have a surface area 1 billion times the surface area of the Earth. So at Earth density you could fit 7 billion, billion beings.

That's probably not what a Dyson sphere would be like in practice. It couldn't have a surface that faces inwards and is populated by humans looking upwards at the star; that would require fantasy technology (including gravity generators). If they existed in the real world, a Dyson sphere would either be a swarm of orbiting power collection devices or a thin, lightweight statite bubble supporting power collection devices.

The power collectors could supply power to a very large number of habitats, but the main point of the swarm would be to collect power for information processing, industry or possibly for spacecraft propulsion.

mutleyeng
2012-Dec-23, 02:17 PM
I was watching a google hangout the other day on the drake equation.
In this hangout was sara seager.
The idea was they would use recent observational data to better fill out the parameters where there was such data.
Started off just fine...numbers of stars...ok fine, reasonable guestimate.....
numbers of stars with planets...ok fine, we have some data indicating it high...
number which could facilitate life...bit more of a stretch, but ok you can extrapolate and thats fair enough.


number of habitable worlds where life evolves....sara seager says it likely 100% but they go with 1 in 5
number of world where evolves intelligence...sara says 1 in 5

To be fair to Sara, she does freely admit that it is her general belief that life is probably ubiquitous that motivates her in her work.
THATS why I couldnt give a monkeys what any astrophysicists gut instinct is about life in the universe. It would have been good to have had a biologist on for the second half of the equation. There is a void in our understanding of first life and of the jump to complex life. The error bars on any probability are gigantic.
(Just to be clear, Sara was very clear that she was using pure speculation .. i am not saying she shouldnt have done so... I am just saying a scientists gut instinct has no more value than anyone elses, especially when they are guessing on something that isnt their field of study)

this is the hangout for anyone curious
https://www.youtube.com/watch?v=GP-n9b_-n5E

MarianoRF
2012-Dec-27, 10:46 AM
The Fermi paradox needs an answer.

For a second, consider this: given the present facts, that we have simply no solid evidence of life beyond Earth... what if we are completely alone? what if we are the only "intelligent" civilization? What's the point then? so many many planets, galaxies, stars... just for ONE civilization: Earth. Does it make sense?

Frank Merton
2012-Dec-27, 11:34 AM
For a second, consider this: given the present facts, that we have simply no solid evidence of life beyond Earth...I would say we have no solid evidence of live beyond Earth but we also have no solid evidence of no-life beyond Earth.


what if we are completely alone? what if we are the only "intelligent" civilization? What's the point then? so many many planets, galaxies, stars... just for ONE civilization: Earth. Does it make sense?Well, yes, it means that we have an entire universe waiting for us.

primummobile
2012-Dec-27, 12:48 PM
For a second, consider this: given the present facts, that we have simply no solid evidence of life beyond Earth... what if we are completely alone? what if we are the only "intelligent" civilization? What's the point then? so many many planets, galaxies, stars... just for ONE civilization: Earth. Does it make sense?

It does seem, to us, that having a large, empty universe would be an awful waste of space. But that thinking is narrow-minded. There is no reason to think that the universe came into being just to allow intelligence to develop. Intelligence is just something that happened, at least one time, because our natural laws permitted it to happen.

A question I find more profound is why there is anything, rather than there being nothing. Planets, stars, and galaxies are enough of a "reason" for me for the universe to exist. There is no need for any more reason than that.

Frank Merton
2012-Dec-27, 12:59 PM
It does seem, to us, that having a large, empty universe would be an awful waste of space. The universe is good at wasting space. Consider the space between the stars or between the galaxies; for that matter, consider the space wasted in an atom.

primummobile
2012-Dec-27, 01:05 PM
The universe is good at wasting space. Consider the space between the stars or between the galaxies; for that matter, consider the space wasted in an atom.

Yes. Read further down my post. Where I said that we look at the universe through the very narrow vision of humans.

IsaacKuo
2012-Dec-27, 05:03 PM
For a second, consider this: given the present facts, that we have simply no solid evidence of life beyond Earth... what if we are completely alone? what if we are the only "intelligent" civilization? What's the point then? so many many planets, galaxies, stars... just for ONE civilization: Earth. Does it make sense?
What you see as a waste of space, I see as an opportunity.

We humans were not given a manual telling us what "the point" is. Even if we were given such a manual, it would be in our nature to question it anyway and form our own ideas about what "the point" is.

So, what's wrong with defining "the point" as seeing what humanity can really do, given plenty of elbow room?

Personally, I have a lot of ideas about how we could directly and/or indirectly expand into the universe, for various reasons (including "just because we can"). These ideas usually assume no one else is out there, for simplicity's sake. I do devote some speculation toward how we might skirt around others if they exist, but it's a lot harder to form plans due to the extremely varied possibilities.

ASTRO BOY
2012-Dec-27, 08:38 PM
What you see as a waste of space, I see as an opportunity.

We humans were not given a manual telling us what "the point" is. Even if we were given such a manual, it would be in our nature to question it anyway and form our own ideas about what "the point" is.

So, what's wrong with defining "the point" as seeing what humanity can really do, given plenty of elbow room?

Personally, I have a lot of ideas about how we could directly and/or indirectly expand into the universe, for various reasons (including "just because we can"). These ideas usually assume no one else is out there, for simplicity's sake. I do devote some speculation toward how we might skirt around others if they exist, but it's a lot harder to form plans due to the extremely varied possibilities.




Admirably put!
Particularly the last paragraph re expanding into the Universe.
I have often expressed the same view with the addition, as long as we overcome our own follies here on this little blue Orb and can avoid any Astronomical Catastrophe.
We have around a couple of billion years before the Sun goes into Red Giant phase and makes our planet inhabitable, and I'm pretty sure by then we will probably have advanced our technological abilities to encompass nearly all that is allowed by the laws of physics and GR. As long as we have Imaginative and Innovative characters around like yourself, [you can throw me in there too if you like :-) ] and those at the cutting edge of NASA and other space agencies, I see a great future.

MarianoRF
2012-Dec-28, 12:19 AM
We have around a couple of billion years before the Sun goes into Red Giant phase and makes our planet inhabitable

This planet will become inhabitable much much sooner than that. Global warming will probably kill us in 5000 or 10000 years from now, so really we don't have much time here. And the only responsible for that is human being.

Luckmeister
2012-Dec-28, 02:31 AM
This planet will become inhabitable much much sooner than that. Global warming will probably kill us in 5000 or 10000 years from now, so really we don't have much time here. And the only responsible for that is human being.

I think you and ASTRO BOY mean uninhabitable, don't you?

ETA: or unhabitable.

ASTRO BOY
2012-Dec-28, 08:44 AM
I think you and ASTRO BOY mean uninhabitable, don't you?

ETA: or unhabitable.

Yes on my part...Off goes my head and on goes a pumpkin! :-)

Frank Merton
2012-Dec-28, 08:54 AM
I doubt things are all that grim on the planet warming front. If nothing else, human caused planet warming will become self-limiting as the increasing problems diminish economic activity. More likely, self-sustaining technologies will take over. After all, even if society does nothing about it, in a few hundred years the available fossil fuels will be pretty much consumed anyway, ending the CO2 emissions.

As I understand it, the planet is becoming dessicated from the slow disassociation of water molecules in the upper atmosphere, with the hydrogen being lost to space. In a few hundred million years that should do us in, but that's the nearest real crisis I'm aware of.

IsaacKuo
2012-Dec-28, 10:44 AM
As I understand it, the planet is becoming dessicated from the slow disassociation of water molecules in the upper atmosphere, with the hydrogen being lost to space. In a few hundred million years that should do us in, but that's the nearest real crisis I'm aware of.
This not a problem. Our atmosphere has a cold trap which prevents water vapor from reaching the upper atmosphere.

Frank Merton
2012-Dec-28, 10:55 AM
This not a problem. Our atmosphere has a cold trap which prevents water vapor from reaching the upper atmosphere.
That's indeed good news, but how does such a cold trap prevent ordinary diffusion? If so, then I take it the next big threat is the gradual warming of the sun, which should do us in in roughly the same time frame (well before the sun enters red giant stage).

IsaacKuo
2012-Dec-28, 11:42 AM
That's indeed good news, but how does such a cold trap prevent ordinary diffusion?
I don't entirely understand your question. A cold trap prevents water vapor from reaching the upper atmosphere regardless of mechanism. The cold temperature causes a phase change to liquid or solid form. Gravity does the rest.

Frank Merton
2012-Dec-28, 11:49 AM
I would say you answered my question even if you didn't understand it. I'm not sure it works with complete efficiency though, and that water is not lost, but I could not defend such an assertion.

whimsyfree
2013-Jan-02, 03:39 AM
I would say you answered my question even if you didn't understand it. I'm not sure it works with complete efficiency though, and that water is not lost, but I could not defend such an assertion.

Of course it does not work with complete efficiency and Earth is losing water all the time. The rate at which it is losing it is insignificant compared with the volume of water here. When the Sun gets a bit warmer (≲ 10%) the cold trap will stop working, according to climatologists.

MarianoRF
2013-Jan-02, 11:33 AM
There have been no credible accounts of aliens visiting Earth.

It seems very likely that life arose elsewhere in the universe but so far we have no evidence that confirms this.

It seems unlikely to an extreme that Earth is the only planet in the universe where life arose, but reality has a habit of surprising us.

I agree. Because with so many stars, planets and galaxies, one would think that life is really common out there... but... reality has shown to us that simply, WE are the only ones. So, what if this is true? maybe Earth is the special planet. Maybe we are UNIQUE.

Paul Beardsley
2013-Jan-02, 11:39 AM
I agree. Because with so many stars, planets and galaxies, one would think that life is really common out there... but... reality has shown to us that simply, WE are the only ones. So, what if this is true? maybe Earth is the special planet. Maybe we are UNIQUE.

Er, I'm not sure you do agree. When I said "reality has a habit of surprising us" I wasn't saying Earth is the only planet where life arose. Merely that it's a possibility that we can't dismiss.

Reality certainly hasn't shown us that we are the only ones. It hasn't shown us anything yet.

neilzero
2013-Jan-02, 11:59 AM
The last I heard hydrogen ions in the solar wind and ice comets were captured by Earth's atmosphere at about the same rate that hydrogen is lost. If we lose 5% of our water in the next billion years this may prevent the oceans from rising, as the ice caps melt and the water expands due to increased average temperature. Is the 80 calories per cubic centimeter cooling from the melting ice significant to Earth's overall temperature = probably not as the Arctic seems to be warming faster than the rest of Earth. If the cold trap fails, will our atmosphere hold an additional one part per thousand of our total water of Earth? Will the deep in Earth water increase by 1 part per thousand if Earth's core temperature decreases by 5 degrees c = 9 degrees f?
The absence of aliens is far from confirmed. Possibly they are numerous even in our solar system and there is at least a slight possibility of their covert presence here on Earth. Neil

MarianoRF
2013-Jan-02, 12:12 PM
Er, I'm not sure you do agree. When I said "reality has a habit of surprising us" I wasn't saying Earth is the only planet where life arose. Merely that it's a possibility that we can't dismiss.

Reality certainly hasn't shown us that we are the only ones. It hasn't shown us anything yet.

Yes and No. We have two possibilities:

1) We are the only ones. Earth is unique. No other life form is present in the Universe
2) Universe is full of life (simple and complex, from simple bacteria to complex organisms/creatures). The number of life forms is really huge.

At present, we are in number 1. Possibility number 2 is hypothetical, and all discussions, opinions and speculations about it, take the conditional form: would, could, may, might... because we have no evidence.

Paul Beardsley
2013-Jan-02, 12:34 PM
Yes and No. We have two possibilities:

1) We are the only ones. Earth is unique. No other life form is present in the Universe
2) Universe is full of life (simple and complex, from simple bacteria to complex organisms/creatures). The number of life forms is really huge.

At present, we are in number 1. Possibility number 2 is hypothetical, and all discussions, opinions and speculations about it, take the conditional form: would, could, may, might... because we have no evidence.

We have two possibilities

No, not really.

3) There are precisely 12 life-bearing worlds in the universe, 7 of which have given rise to intelligence.

4) There are on average 7,489 civilisations in every galaxy.

And so on.

At present, we are in number 1. Possibility number 2 is hypothetical

Both are hypothetical. We are not in either of them (nor any of the in-between possibilities) because we do not have any data that supports one and rules out the other. I see you are another person who has trouble with the "we don't know" position.

MarianoRF
2013-Jan-03, 12:32 PM
It would be interesting to make a poll, and see how many of us actually believe in life beyond Earth (simple and/or complex).

Paul Beardsley
2013-Jan-03, 12:40 PM
It would be interesting to make a poll, and see how many of us actually believe in life beyond Earth (simple and/or complex).

Interesting, possibly, but belief is not science. And if you did make such a poll, I'd like to see an option for, "I neither believe nor disbelieve; I await evidence."

Paul Wally
2013-Jan-03, 01:04 PM
Interesting, possibly, but belief is not science. And if you did make such a poll, I'd like to see an option for, "I neither believe nor disbelieve; I await evidence."

That is not the option exercised by scientists active in their field. Scientists don't await evidence. They do the work necessary to acquire evidence, which includes thinking about the possibilities. Even if such thinking eventually turns out to be completely wrong, it is a useful contribution nonetheless, even if it's just based on some intuition or belief. That is because if we can show that a belief is wrong, empirically or logically, then we've learned something new.

MarianoRF
2013-Jan-03, 02:06 PM
Let's try it!

http://cosmoquest.org/forum/showthread.php/140769-POLL-Is-there-life-beyond-Earth

I know we have no evidence supporting life beyond our planet, but what do you really feel about it? What do you think?