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Diamond
2003-Dec-18, 08:04 PM
I think I have to explain why I have taken such a seemingly bizarre stand to such an innocent looking equation. (http://www.crichton-official.com/speeches/speeches_quote04.html)

Any questions?

TriangleMan
2003-Dec-18, 08:23 PM
Any questions?
Yes. How many people actually thought the Drake Equation was scientific? When I became familiar with it in university it was more like a philosophical exercise, no one used it to support testable theories.

informant
2003-Dec-18, 08:30 PM
N=N*fp ne fl fi fc fL
The equation is not correct in the article. It should be NL=N*fp ne fl fi fc fL, where NL is the number of stars with planets inhabited by civilizations that communicate.

Drake's equation is trivially correct, but it's expressed in terms of quantities which are for the most part unknown. You can fiddle with the unknowns to see what happens, but it doesn't tell you anything about reality.

However, I don't think that Drake's equation is the cornerstone of SETI. This part of the article seems a bit fallacious to me:

As a result, the Drake equation can have any value from "billions and billions" to zero. An expression that can mean anything means nothing. [...] The Drake equation cannot be tested and therefore SETI is not science. SETI is unquestionably a religion.

Added: Actually, we could use the Drake equation to estimate the number of stars with planets inhabited by civilizations that communicate in the galaxy, if we had a reliable sample of the planets in the galaxy - but we don't.

Spaceman Spiff
2003-Dec-18, 08:39 PM
I think I have to explain why I have taken such a seemingly bizarre stand to such an innocent looking equation. (http://www.crichton-official.com/speeches/speeches_quote04.html)

Any questions?

I agree with the above. Nobody sold SETI with the Drake equation. The latter was simply was an exercise in thought. Every book I've ever come across that mentioned the Drake equation presented both "answers" (i.e., from >100s of civilizations in the Milky Way to ~ zip).

Nevertheless he does make some interesting points; not that I agree with many of them.

But let's also keep this in mind...Michael Crichton's (a medschool graduate) credentials in physical sciences research are??

John Kierein
2003-Dec-18, 08:42 PM
http://www.geocities.com/CapeCanaveral/Galaxy/7827/

Another reason the Drake equation is wrong.

informant
2003-Dec-18, 08:50 PM
A lower bound estimate of the probability of finding extraterrestrial life, and intelligent communicating life in particular, has previously generally followed the Drake equation. This equation assumes that such life is only on other planets.
Interesting objection. It seems like a reasonable assumption in our current state of ignorance, though.


This premise of the Drake equation is wrong.
That, of course, remains to be seen. :)

Swift
2003-Dec-18, 09:06 PM
I've noticed a couple of these forums bashing the Drake equation recently. I am not a professional astonomer or SETI researcher, but my impression is as others have stated, that its more a starting point for thought experiments, not a hard and fast equation. And the funny thing is we are starting to very slowly fill in the numbers. Not that long ago the number of planets known outside of our own solar system was zero; I have not checked lately, but I think that number is now in the hundreds. Maybe in my lifetime we will also find evidence in our solar system of life outside of Earth's biosphere.

As far as the rest of Michael Crichton's talk, I was not impressed and it was as wordy as most of his books. I don't have the strength or interest to go over it point-by-point, but a couple of thoughts.

I would love that all science questions, particularly the ones that relate to public policy could be decided by a rigorous application of the scientific method. But more and more public policy issues are deeply rooted in science and do not have the luxary of time to wait for rigorous proof. Should we wait 150 years to prove out the computer models before we do something about global warning? Its an imperfect world and we often have to make decisions before we have all the facts. Everyday at work (I'm a chemist) I'm asked questions as to what do we do about this problem NOW - we got product to try to ship. An acceptable answer is not "well, let me research it for a year and get back to you".

I also find it interesting that this is all coming from Michael Crichton; I've only read one or two of his books (and of course seen some of the movies made from them) but my impression is that his science is mediocre to bad, even by fiction standards.

Alex W.
2003-Dec-18, 09:30 PM
It's the "glass of water" equation, in that you have no objective way of determining any of the values, so it's entirely subjective.

SETI, however, doesnt' deserve such accusations, as it allows objective determination of whether there is intelligent life in the universe, something the Drake Equation does not.

informant
2003-Dec-18, 09:31 PM
It's the "glass of water" equation, in that you have no objective way of determining any of the values, so it's entirely subjective.
We don't now, but we may have some day.

dgruss23
2003-Dec-18, 09:36 PM
Crichton's speech was outstanding! I don't agree with everything he said, but he makes a lot of thought provoking points in that speech. I'm not sure what his training has to do with the veracity of his comments. Alfred Wegener was a meteorologist, not a geologist - yet he's known for his impact on the field of geology. Why on Earth do scientists write popular books and textbooks if not so that others can read those books and learn enough to talk intelligently about the issues? But someone makes some criticisms and all of the sudden what matters is a piece of paper certified by a university?

If that's the litmus test than there are a great many things being said on this board by people that have no business saying them. Why even have BABB - I guess you should only be allowed to talk astronomy if you're an astronomer and talk geology if you're a geologist .... ? :-?

Alex W.
2003-Dec-18, 10:01 PM
It's the "glass of water" equation, in that you have no objective way of determining any of the values, so it's entirely subjective.
We don't now, but we may have some day.

It's not going to be particularly useful if we figure out those values by going out and counting alien races, planets with conditions capable of supporting life etc. :wink:

Spaceman Spiff
2003-Dec-18, 10:03 PM
Crichton's speech was outstanding! I don't agree with everything he said, but he makes a lot of thought provoking points in that speech. I'm not sure what his training has to do with the veracity of his comments. Alfred Wegener was a meteorologist, not a geologist - yet he's known for his impact on the field of geology. Why on Earth do scientists write popular books and textbooks if not so that others can read those books and learn enough to talk intelligently about the issues? But someone makes some criticisms and all of the sudden what matters is a piece of paper certified by a university?

If that's the litmus test than there are a great many things being said on this board by people that have no business saying them. Why even have BABB - I guess you should only be allowed to talk astronomy if you're an astronomer and talk geology if you're a geologist .... ? :-?

That wasn't my point at all. It's that he gives these "lectures" at Caltech (of all places) on how physical science is conducted. There is a big difference between wondering "hey what's going on here?" and standing up and making pronouncements on the merits of conducted research, then pointing and wagging fingers.

Besides, I think he has quite a few misconceptions himself -- because he does not do research in a physical science (and apparently hasn't bothered to find out how that's done).
For example, one of his points is that through history consensus has often stood against what turned out to be the "right" idea. He even gave an example of the consensus ignoring the work of a Jew. Well, that's a social science (problem in society) problem, not the fault of science. Because he doesn't do science himself he also doesn't understand the necessarily conservative nature of science. YES it often does take a long time for a paradigm shift to occur. Extraordinary ideas require extraordinary evidence. No progress would be made if we jumped every time somebody burped. It is generally an avalanche of evidence that shifts the mountain of science. As for all the rest of his "anecdotes", I cannot evaluate the reasons various "correct ideas" were rejected by the "consensus". So I cannot comment as to what the reasons were. Were they scientific reasons? or non-scientific ones? He just lumps them all together, and points a lot of fingers and wags his.

Of course, an idea is accepted in science once there is an overwhelming amount of evidence for it, and then, yes there is a consensus. Though that does not mean that the book is closed and placed upon a dusty shelf. Research continues....So his contention that consensus has nothing to do with science is bunk. But it is consensus built upon evidence (for or against), not one built upon opinion or authority. Again, I contend because he hasn't done science, nor, apparently, has he bothered to learn from somebody who has.

NOW, where I completely agree with him is his disgust at the occasional (too often) invasion of science by politics or ideology. Neither has any place within science.

ToSeek
2003-Dec-18, 10:36 PM
Because he doesn't do science himself he also doesn't understand the necessarily conservative nature of science.

Don't underestimate Crichton - I don't know if he actually published any peer-reviewed papers, but he's an MD who's done post-doc work and lectured at Cambridge (which may help explain why so many of his examples are medical ones). So he has some idea what he's talking about.

dgruss23
2003-Dec-19, 01:57 AM
Sorry Spaceman, I misunderstood you.


Of course, an idea is accepted in science once there is an overwhelming amount of evidence for it, and then, yes there is a consensus. Though that does not mean that the book is closed and placed upon a dusty shelf.

I think the important point he made regarding concencus was simply that evidence should not be ignored because of "concensus" The example with the women dying from infections after childbirth was an interesting one. You're right that its hard to know exactly what the reasons were that the idea was rejected for so long, but it seems that regardless of explanation, they ought to have been curious as to why his mortality rate was so much lower than everyone elses. What was the concensus that prevented them from exploring that further?

What he was really talking about was not a problem of closing the book and placing it on a shelf, but instead the problem of refusing to take at look at other books. Its easy to keep adding chapters to the book of the concensus, but that doesn't mean there aren't other good books out there.

Normandy6644
2003-Dec-19, 03:14 AM
About the Drake Equation, I will not go as far as to say that it isn't science, because I do think it has some merit in it. However, inddeed it is presently not testable and does not belong in the realm of other "scientific" quantities like Maxwell's equations or the like. The Drake Equation is not meant to be a completely accurate model, rather a general idea. Perhaps I'm not articulating this well, but what I' mean to say is that perhaps the Drake Equation will come to mean more after more research has been done on the subject of extrasolar planets and potential for civilization.

russ_watters
2003-Dec-19, 07:00 AM
The first measurements of the speed of light were extremely inaccurate, but that didn't make them unscientific. There is no set standard of accuacy as a prerequisite for a theory being scientifically sound. All that is required is an honest and scientific approach to the uncertainty.

So speculative as the Drake equation is, I think it is scientific. And later as our data gets better, I think we will indeed be able to refine the equation to make reasonable predictions.

And SETI, though not associated with the Drake equation works the same way: its speculative, but its speculation conducted scientifically. And it can be used to help refine the Drake equation. Every piece of data it collects adds to our assessment of the probability of nearby life.

Diamond
2003-Dec-19, 08:38 AM
The first measurements of the speed of light were extremely inaccurate, but that didn't make them unscientific. There is no set standard of accuacy as a prerequisite for a theory being scientifically sound. All that is required is an honest and scientific approach to the uncertainty.

So speculative as the Drake equation is, I think it is scientific. And later as our data gets better, I think we will indeed be able to refine the equation to make reasonable predictions.

And SETI, though not associated with the Drake equation works the same way: its speculative, but its speculation conducted scientifically. And it can be used to help refine the Drake equation. Every piece of data it collects adds to our assessment of the probability of nearby life.

This is where I have to disagree: science is not about making assumptions as to values in equations like that. Speculation is one thing, but where have any of the quantities been testable?

I side with Crichton: an equation like that which could have any answer is worse than useless - it's the polar opposite of science and the scientific methods. The values that anybody assigns to these numbers are prejudice and reflect beliefs, not science.

ToSeek
2003-Dec-19, 03:47 PM
I side with Crichton: an equation like that which could have any answer is worse than useless - it's the polar opposite of science and the scientific methods. The values that anybody assigns to these numbers are prejudice and reflect beliefs, not science.

The equation cannot have any answer. Given a specific set of parameters, it only has one answer (just like most equations). I think the equation is fine; it's how it's used that is the issue. I think the problem is with people who think that when speculative parameters are put through an equation the result is something better than speculation. I bristle myself when people say things like "The Drake Equation proves...". But that's a misuse of the equation, not something the equation should be blamed for.

Spaceman Spiff
2003-Dec-19, 06:34 PM
Sorry Spaceman, I misunderstood you.


Of course, an idea is accepted in science once there is an overwhelming amount of evidence for it, and then, yes there is a consensus. Though that does not mean that the book is closed and placed upon a dusty shelf.

I think the important point he made regarding concencus was simply that evidence should not be ignored because of "concensus" The example with the women dying from infections after childbirth was an interesting one. You're right that its hard to know exactly what the reasons were that the idea was rejected for so long, but it seems that regardless of explanation, they ought to have been curious as to why his mortality rate was so much lower than everyone elses. What was the concensus that prevented them from exploring that further?

What he was really talking about was not a problem of closing the book and placing it on a shelf, but instead the problem of refusing to take at look at other books. Its easy to keep adding chapters to the book of the concensus, but that doesn't mean there aren't other good books out there.

In the case of women dying in childbirth via infection, there is at least one reason for what happened. Plain and simple, the whole phenomenon of infection by bacteria (etc) was frontier medical science. The fact that a whole other world of life on the microscopic scale exists, can infect the human and sometimes result in disease and then death required a huge shift in paradigm (read: avalanche of evidence, as a start). Stir in the conservative nature of science PLUS human nature -- the latter not the fault of science or its methods -- and you get the result that Crichton speaks of. Why is he so surprised that revolutions in science are so revolutionary?

Honestly, though, these are all short anecdotes, and together these cases of the "guys on the outside" regarding our understanding of infectious disease would make for an interesting book. Since medical science is much closer to his training, why doesn't he write that book? (or has somebody already written an excellent version of such?)

crazy4space
2003-Dec-19, 08:57 PM
I agree with dgruss 23 I think it was an outstanding speach. In addition, I think all he did was defend the scientific process vs politics / emotion getting in the way of the scientific process. I must admit that the title " Aliens Cause Global Warming " caught my eye. :o

A.DIM
2003-Dec-19, 10:30 PM
A year ago it was suggested that there are 30 Billion earths (http://www.space.com/scienceastronomy/astronomy/jupiter_typical_020128.html) and then little more than a week ago, news that earth-like planets are common (http://www.space.com/scienceastronomy/earth-like_planets_031211.html).

So, without invoking the Drake Equation, how many of these might have "intelligent life?" :)

SeanF
2003-Dec-19, 10:35 PM
A year ago it was suggested that there are 30 Billion earths (http://www.space.com/scienceastronomy/astronomy/jupiter_typical_020128.html) and then little more than a week ago, news that earth-like planets are common (http://www.space.com/scienceastronomy/earth-like_planets_031211.html).

So, without invoking the Drake Equation, how many of these might have "intelligent life?" :)

If they're exactly like Earth, all of them!

(Or none of them, depending on how you feel . . . )

kilopi
2003-Dec-20, 01:30 AM
This is where I have to disagree: science is not about making assumptions as to values in equations like that. Speculation is one thing, but where have any of the quantities been testable?
Isn't SETI testing some of them? And some of the quantities are fairly well known.

RBG
2003-Dec-20, 01:52 AM
While I think the Drake equation has many unknown or speculative variables to it, it may have validity as a scientific hypothesis. It might be dead wrong. But you have to start somewhere and come up with something before it can be tested. I think science is all about starting from a very general - often (strictly speaking) incorrect - position and then slowly evolving to a better truth. Perhaps Newton's & Einstein's ideas and formulas are examples of this.

RBG

ToSeek
2003-Dec-20, 03:46 AM
I don't think the Drake equation could be "dead wrong," though there may be parameters we haven't considered. John Kierein rightly points out that Earthlike planets may not be the only home for life, and the equation doesn't consider the possibility of colonization or panspermia. So the equation may need additional or modified parameters. I can't see tossing it out entirely, though.

DALeffler
2003-Dec-20, 04:37 AM
Doesn't the result of the Drake equation have to be >= 1? The result can't be less than one; "we" count as one.

And doesn't that mean that every term on the right side of the equation has to be greater than zero?

Isn't that the entirety of what the equation really says?

The equation says that life has to exist in the universe (because we exist) and that nothing in the universe precludes us from existing.

Right?

That's what I got from the linked article.

informant
2003-Dec-20, 04:17 PM
Here (http://www.seti-inst.edu/science/drake-bg.html) is a better explanation of the Drake equation, and a simulator (http://www.seti-inst.edu/seti/seti_science/drake_calculator.html).

What I think the Drake equation says is something like this. According to this site (http://www.seds.org/messier/more/mw.html), there are roughly 400 billion stars in the Milky Way (N=400 billion). Suppose the Zetans told you that:

- of all the stars in the galaxy, 70% have planets (fp=0.70);
- of those, 10% have planets capable of supporting life (ne=0.10);
- life actually develops in 60% of those planets (fl=0.60);
- of those, 2% develop intelligent life (fi=0.02);
- of all intelligent life, 30% eventually becomes capable of communicating with other stars (fc=0.30)
- intelligent life is capable of communicating for 10% of its presence in a given solar system (fL=0.10);

Then there are

400 billion * 0.70 * 0.10 * 0.60 * 0.02 * 0.30 * 0.10 = 10.08 million stars

in the galaxy where intelligent life that communicates can be found at a given time.

This is a triviality. There is really nothing to test in the equation. Itís just a way to organize the information. The Zetans might as well have told you that 0.00252% of all stars have planets with civilizations that communicate at a given moment.
The only logical problem I can see with it is that, as John Kierein pointed out, it may happen that life is found in interstellar space too. Even so, we could be only interested in life inside solar systems.
The practical problem is obvious: we have no Zetans to tell us what the true percentages are.

(Edited because I forgot one variable.)

kilopi
2003-Dec-20, 04:22 PM
Doesn't the result of the Drake equation have to be >= 1? The result can't be less than one; "we" count as one.
Multiply, not add. :)

beck0311
2003-Dec-20, 05:47 PM
SETI is unquestionably a religion. Faith is defined as the firm belief in something for which there is no proof.

I have a few problems with what Crichton has to say here, but the above gives me the most trouble. He spends most of the article complaining about a lack of evidence, yet he makes a broad sweeping statement that SETI is unquestioably a religion. He is treading dangerously close to a false dilemma here-SETI is not science, so it must be a religion.

Now, I have only met one SETI researcher, he is a person with an advanced degree in astronomy who, as part of a team, is using scientific methods to search the sky for signals that might be coming from other civilizations. He never claimed to me that he was performing any rigorous scientific research, and I never got the impression that he is certain that there is intelligent life outside Earth-of course, if there is it would certainly be the greatest discovery in the history of mankind. But, there have been times when SETI researchers have received signals that have seemed promising, and have been determined by the very SETI researchers themselves to be natural phenomena. This does not sound like a religion to me. Again, it is not necessarly hard core science, but just because something isn't science doesn't make it a religion.

Conversely, since my Father first got cancer I have met several cancer researchers who have an abundance of faith that they will some day find a cure for cancer. I am inclined to agree with them. But applying Crichtons simple test to cancer research I guess I am forced to conclude that cancer research is religion, not science.

[edited to complete a sentence]

kilopi
2003-Dec-20, 06:03 PM
SETI is unquestionably a religion. Faith is defined as the firm belief in something for which there is no proof.

I have a few problems with what Crichton has to say here.
Well, he wrote Timeline. <shudder> :)

He's guilty of the very thing that he seems to be railing against. He's trying to turn a consensus against SETI, based upon whether it is a religion or not.

I have absolutely no problem with any sort of investigation. One friend in Wyoming spent years helping Carey develop expanding earth models--but he was a geophysicist first, an advocate for the theory second. He didn't rail against the establishment, accuse them of fraud or poisoning children's minds with nonsense. He stated his case, and we discussed it. He was disappointed that I didn't "believe" his favorite theory, but he didn't turn around and insinuate that I was a crank or a troll.

informant
2003-Dec-20, 06:15 PM
Doesn't the result of the Drake equation have to be >= 1? The result can't be less than one; "we" count as one.
Multiply, not add. :)
It still should be at least one.

kilopi
2003-Dec-20, 06:45 PM
Doesn't the result of the Drake equation have to be >= 1? The result can't be less than one; "we" count as one.
Multiply, not add. :)
It still should be at least one.
Ah, I see what you mean now. Since we are here, then N must be at least one.

Still, that's not true. Look at all the factors. They include rates averaged over billions of years, and the last factor (what Crichton calls fL) is the average length of time that each civilization releases detectable signals into space. So, what would the equation say if that average time (fL) was ten thousand years, but such a civilization/technology only came around every hundred thousand years (the product of all the other factors)? Then, because N is an average value, N would equal 0.1.

We could still be here, sending out detectable signals, but then the equation would say that we only have a ten percent chance of actually seeing another signal, from everywhere else in the galaxy.

informant
2003-Dec-20, 06:54 PM
Doh! You're right. Yes, the output is an average over time.

Ian Goddard
2003-Dec-20, 07:04 PM
There is really nothing to test in the equation. Itís just a way to organize the information.
Informant's analysis looks right to me. Here's an excerpt from the thread-leading page (http://www.crichton-official.com/speeches/speeches_quote04.html):


I take the hard view that science involves the creation of testable hypotheses. The Drake equation cannot be tested and therefore SETI is not science. SETI is unquestionably a religion. Faith is defined as the firm belief in something for which there is no proof.
There is certainly evidence, indeed (dare I say) proof, that advanced life exists in the universe, us. Scientific hypotheses are generated by inductive inferences that extrapolate to the possibility that patterns existing in the known set of data (in known set: life on Earth) might also exist in an unknown set of data (in unknown set: life beyond Earth?). That's SETI, and that's scientific. There's also no falsifiability problem for SETI. The hypothesis "Jones may be in the next room" can be falsified by an exhaustive search of the next room; likewise, the hypothesis "There may be detectable signals from advanced ET life" can be falsified by an exhaustive search of detectable bandwidths; and thus, again, SETI is scientific.

SETI is also not founded on the assertion that there is ET life, and claims to that effect are nothing but straw men. Crichton opines further: "There is not a single shred of evidence for any other life forms, and in forty years of searching, none has been discovered. There is absolutely no evidentiary reason to maintain this belief. SETI is a religion." However, SETI searches to date are not sufficiently sensitive to detect internal radio communications that may exist on distant planets (see (http://www.badastronomy.com/phpBB/viewtopic.php?p=156950&highlight=#156950)). Using ourselves as proxy, if there are advanced ETs, the vast majority of their radio output would probably not be of the "Here we are" intergalactic-radio-beacon signals SETI could detect. There are of course many more points that could be raised in counter to Crichton's anti-SETI views.

kilopi
2003-Dec-20, 07:20 PM
SETI is also not founded on the assertion that there is ET life, and claims to that effect are nothing but straw men. Crichton opines further: "There is not a single shred of evidence for any other life forms, and in forty years of searching, none has been discovered. There is absolutely no evidentiary reason to maintain this belief. SETI is a religion." However, SETI searches to date are not sufficiently sensitive to detect internal radio communications that may exist on distant planets (see (http://www.badastronomy.com/phpBB/viewtopic.php?p=156950&highlight=#156950)). Using ourselves as proxy, if there are advanced ETs, the vast majority of their radio output would probably not be of the "Here we are" intergalactic-radio-beacon signals SETI could detect. There are of course many more points that could be raised in counter to Crichton's anti-SETI views.
Exactly. Crichton explicitly ignores our own existence, as a piece of evidence. His attitude--that the human race is somehow more "special" and outside the purview of science--is historically on the side of religion and philosophy, not science. It is a typical anti-science argument, to turn this on its head and use it to attack whatever whipping post is being assailed.

Diamond
2003-Dec-22, 08:16 AM
SETI is unquestionably a religion. Faith is defined as the firm belief in something for which there is no proof.

I have a few problems with what Crichton has to say here.
Well, he wrote Timeline. <shudder> :)

He's guilty of the very thing that he seems to be railing against. He's trying to turn a consensus against SETI, based upon whether it is a religion or not.

I'm sorry, but that's just plain silly. He's just expressing an opinion, and nothing more.

BTW I didn't like Timeline either....


I have absolutely no problem with any sort of investigation. One friend in Wyoming spent years helping Carey develop expanding earth models--but he was a geophysicist first, an advocate for the theory second. He didn't rail against the establishment, accuse them of fraud or poisoning children's minds with nonsense. He stated his case, and we discussed it. He was disappointed that I didn't "believe" his favorite theory, but he didn't turn around and insinuate that I was a crank or a troll.

Nevertheless, an equation which could mean anything at all is viridically meaningless. What the Drake Equation does encapsulate, in my view, is the biases and predispositions of the person calculating. It says nothing at all, about whether there is life out there, still less if we could communicate with it.

Diamond
2003-Dec-22, 08:36 AM
There is really nothing to test in the equation. It’s just a way to organize the information.
Informant's analysis looks right to me. Here's an excerpt from the thread-leading page (http://www.crichton-official.com/speeches/speeches_quote04.html):


I take the hard view that science involves the creation of testable hypotheses. The Drake equation cannot be tested and therefore SETI is not science. SETI is unquestionably a religion. Faith is defined as the firm belief in something for which there is no proof.
There is certainly evidence, indeed (dare I say) proof, that advanced life exists in the universe, us.


True.


Scientific hypotheses are generated by inductive inferences that extrapolate to the possibility that patterns existing in the known set of data (in known set: life on Earth) might also exist in an unknown set of data (in unknown set: life beyond Earth?). That's SETI, and that's scientific.

You extrapolate from a dataset of only one? Science advances with hypotheses which in principle can be tested. Virtually none of the parameters can be isolated, even in principle, to a theory with predictive ability.


There's also no falsifiability problem for SETI. The hypothesis "Jones may be in the next room" can be falsified by an exhaustive search of the next room

Hypothesis -> Prediction -> Testing -> Result


; likewise, the hypothesis "There may be detectable signals from advanced ET life" can be falsified by an exhaustive search of detectable bandwidths; and thus, again, SETI is scientific.

Hypothesis -> Prediction? ->Testing ? -> Result?

The assumptions are faulty. In the first case, the prediction is of an exact nature (Jones is in the next room), a prediction that can be tested (and if necessary can falsify the theory).

Question: How do you falsify a theory with no results and no criteria for deciding true or false statements?


SETI is also not founded on the assertion that there is ET life, and claims to that effect are nothing but straw men.

...is a straw man. It certainly isn't there to falsify the hypothesis, since that would require proof of (literally) a Universal negative. SETI is unfalsifiable.


Crichton opines further: "There is not a single shred of evidence for any other life forms, and in forty years of searching, none has been discovered. There is absolutely no evidentiary reason to maintain this belief. SETI is a religion." However, SETI searches to date are not sufficiently sensitive to detect internal radio communications that may exist on distant planets (see (http://www.badastronomy.com/phpBB/viewtopic.php?p=156950&highlight=#156950)). Using ourselves as proxy, if there are advanced ETs, the vast majority of their radio output would probably not be of the "Here we are" intergalactic-radio-beacon signals SETI could detect. There are of course many more points that could be raised in counter to Crichton's anti-SETI views.

OK. Lets form a group called "The Search for God", searching the skies trying to find evidence of a Supreme Being. Do you think this has any more scientific validity than an experiment without theoretic underpinning, proof or falsifiable hypothesis?

What you've done is actually prove Crichton's point. A whole series of unjustifiable statements of your own beliefs does not a scientific argument make.

kilopi
2003-Dec-22, 11:41 AM
Nevertheless, an equation which could mean anything at all is viridically meaningless. What the Drake Equation does encapsulate, in my view, is the biases and predispositions of the person calculating. It says nothing at all, about whether there is life out there, still less if we could communicate with it.
D*ng, I thought I'd learned a new word today! :)

I always considered the Drake equation as a heuristic device--once they started playing with it, and realized how large some of the number were, and how small they had to make other numbers in order for the result to be too small, a lot of people came away from it convinced in the idea that there just might be other life out there.

A great deal of science is just searching, with skepticism thrown in. Crichton can rail against SETI all he wants--his opinion--but for him to call it a religion, now, that's silly.

Diamond
2003-Dec-22, 11:52 AM
Nevertheless, an equation which could mean anything at all is viridically meaningless. What the Drake Equation does encapsulate, in my view, is the biases and predispositions of the person calculating. It says nothing at all, about whether there is life out there, still less if we could communicate with it.
D*ng, I thought I'd learned a new word today! :)

I always considered the Drake equation as a heuristic device--once they started playing with it, and realized how large some of the number were, and how small they had to make other numbers in order for the result to be too small, a lot of people came away from it convinced in the idea that there just might be other life out there.

..on the basis of what? If I construct an equation to demonstrate that the probability of God existing is non-zero, does that mean that God exists?


A great deal of science is just searching, with skepticism thrown in. Crichton can rail against SETI all he wants--his opinion--but for him to call it a religion, now, that's silly.

Crichton calls it religion because it fulfills the criteria of religion: a set of unproven and probably unproveable propositions that require prior belief in those propositions being true.

kilopi
2003-Dec-22, 12:07 PM
..on the basis of what? If I construct an equation to demonstrate that the probability of God existing is non-zero, does that mean that God exists?
No, but that doesn't follow either...and there is one difference that others have pointed out: life definitely exists somewhere.

Crichton calls it religion because it fulfills the criteria of religion: a set of unproven and probably unproveable propositions that require prior belief in those propositions being true.
We've had a similar debate (http://www.badastronomy.com/phpBB/viewtopic.php?t=5404) over whether science itself is a religion--an equally silly proposition.

Would you say mathematics is a religion? It seems to to fulfill that criteria also--mathematics makes it explicit, certain axioms from which all other propositions procede. Besides, which proposition within SETI requires prior belief?

ToSeek
2003-Dec-22, 06:05 PM
..on the basis of what? If I construct an equation to demonstrate that the probability of God existing is non-zero, does that mean that God exists?
No, but that doesn't follow either...and there is one difference that others have pointed out: life definitely exists somewhere.

That's a fair point: the Drake equation can't come up with any answer because any result less than 1 is in error.

kilopi
2003-Dec-22, 06:17 PM
That's a fair point: the Drake equation can't come up with any answer because any result less than 1 is in error.
I don't think that follows. We discussed that earlier (http://www.badastronomy.com/phpBB/viewtopic.php?p=182355#182355).

informant
2003-Dec-22, 07:04 PM
He's guilty of the very thing that he seems to be railing against. He's trying to turn a consensus against SETI, based upon whether it is a religion or not.

I'm sorry, but that's just plain silly. He's just expressing an opinion, and nothing more.
Well, heís saying that SETI is not scientific. I donít think thatís a matter of opinion.



Nevertheless, an equation which could mean anything at all is viridically meaningless.
The meaning of the equation is clear and objective. We just donít know the values of most quantities in it. There is a difference.
Besides, SETI is not grounded on the Drake equation in any way. It can do without it entirely.



It says nothing at all, about whether there is life out there, still less if we could communicate with it.
I think we all agree with that, but I must reiterate what Ian wrote earlier:


SETI is also not founded on the assertion that there is ET life, and claims to that effect are nothing but straw men.
SETI does not assume that there is life elsewhere, or that we can communicate with it. In a way, SETI is the name we give to the search itself.



Hypothesis -> Prediction? ->Testing ? -> Result?
[Ö]
Question: How do you falsify a theory with no results and no criteria for deciding true or false statements?


SETI is also not founded on the assertion that there is ET life, and claims to that effect are nothing but straw men.

...is a straw man. It certainly isn't there to falsify the hypothesis, since that would require proof of (literally) a Universal negative. SETI is unfalsifiable.
[Ö]
OK. Lets form a group called "The Search for God", searching the skies trying to find evidence of a Supreme Being. Do you think this has any more scientific validity than an experiment without theoretic underpinning, proof or falsifiable hypothesis?
Extraterrestrial intelligence can be detected from their radio emissions, so there is an objective way to test it. The criteria are based on that.

eburacum45
2003-Dec-22, 07:10 PM
[Extraterrestrial intelligence can be detected from their radio emissions, so there is an objective way to test it. The criteria are based on that.

That might be more difficult than some people believe;
How far away could we detect radio transmissions? (http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html)...

nevertheless detecting an alien civilisation by whatever method would flip SETI over from being an act of faith to being a scientific search;

quite simply, no-one knows if this will ever happen.

Ian Goddard
2003-Dec-22, 07:37 PM
You extrapolate from a dataset of only one?
At one time we had only one sample of a planetary system. That did not render ampliative inferences of the possibility of extrasolar planets pseudoscientific.


Question: How do you falsify a theory with no results and no criteria for deciding true or false statements?
The statements that radio signals from advanced life (a) are produced in the universe, and (b) can be differentiated from natural radio noise have been confirmed. The SETI hypothesis is that the casual mechanism of the said phenomenon might not be confined to one location (Earth).


It certainly isn't there to falsify the hypothesis, since that would require proof of (literally) a Universal negative. SETI is unfalsifiable.
Life can be detected. Anything that could be detected is not outside scientific inquiry. Sure, whether given ET data are from life or not is something that would be and is debated (as they come in). But the fact that terrestrial artificial radio signals can be detected against background noise demonstrates that life-sourced radio signals can be detected.


OK. Lets form a group called "The Search for God", searching the skies trying to find evidence of a Supreme Being. Do you think this has any more scientific validity than an experiment without theoretic underpinning, proof or falsifiable hypothesis?
Once again, life has already been detected, on Earth. On the other hand no God or Gods have ever been detected; so the analogy is false.

informant
2003-Dec-22, 07:58 PM
[Extraterrestrial intelligence can be detected from their radio emissions, so there is an objective way to test it. The criteria are based on that.

That might be more difficult than some people believe;
How far away could we detect radio transmissions? (http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html)...
As long as we have some objective way to do it, there's nothing unscientific about it.


nevertheless detecting an alien civilisation by whatever method would flip SETI over from being an act of faith to being a scientific search;

quite simply, no-one knows if this will ever happen.
I agree that no one knows if it will ever happen. It may never happen.
I disagree that SETI won't be a scientific search until it happens. To me, that's like saying that the search for an 8th planet wasn't scientific until Neptune was found.

George
2003-Dec-23, 02:41 PM
Life can be detected. Anything that could be detected is not outside scientific inquiry. Sure, whether given ET data are from life or not is something that would be and is debated (as they come in). But the fact that terrestrial artificial radio signals can be detected against background noise demonstrates that life-sourced radio signals can be detected.

Ditto. The hypothesis is valid because it is contradictable. If radio communications in this region of the galaxy can be detected that are not ours, then eureka! If not, then a new hypothesis might be altered to change radio to visible light as a carrier. This will be contradictable as well. It is not irrational to suppose they exist. It is not even unbiblical.

Regardless, it is not "religion". If Chrichton would have said "philosophical" I would have more respect for the statement. No one is trying to transcend the universe here, just meet neighbors. :)

informant
2003-Dec-23, 08:53 PM
The hypothesis is valid because it is contradictable. If radio communications in this region of the galaxy can be detected that are not ours, then eureka! If not, then a new hypothesis might be altered to change radio to visible light as a carrier. This will be contradictable as well.
Well, it depends on what we mean by hypothesis. If the hypothesis is "There is inteligent life elsewhere in the galaxy", then eburacum45 and Diamond are right that this hypothesis can't be proven false. But that does not mean that it isn't scientific.

We're used to hearing that a hypothesis must be falsifiable in order to be scientific, but this is not always true. A better word would be testable. As long as we can prove it wrong or right, it's a scientific hypothesis.

What happens is that most "hypotheses" in science are laws: the're universal statements that are supposed to apply to an infinite/large number of objects. E.g.: "Stars with a mass not greater than that of the Sun end their existence as white dwarfs". We can't prove this right, because we can't observe all stars in the universe, present, past, and future. But we can prove it wrong: just find one counter-example.

That's what a scientific hypothesis usually is. But in the case of SETI, the hypothesis under study is that "There is inteligent life elsewhere in the galaxy". This is not a hypothesis of universality; it's a hypothesis of existence. This time around, we can never prove it wrong, but we can prove it right - by finding one example.

George
2003-Dec-23, 10:50 PM
Well, it depends on what we mean by hypothesis. If the hypothesis is "There is inteligent life elsewhere in the galaxy", then eburacum45 and Diamond are right that this hypothesis can't be proven false. But that does not mean that it isn't scientific.


I agree. Given enough million years, it possibly could be proven false. Don Meredith used to say..."if ifs and buts were candy and nuts, we would all have a merry christmas". [I tend to remember this quote this time of year.] :) The hyposthesis you quoted involves too many ifs to be a really "good" hypothesis. However, the hypothesis specific to radio communication is valid and scientific a one. On this we seem to agree.

Ian Goddard
2003-Dec-24, 08:32 PM
Well, it depends on what we mean by hypothesis. If the hypothesis is "There is inteligent life elsewhere in the galaxy", then eburacum45 and Diamond are right that this hypothesis can't be proven false. But that does not mean that it isn't scientific.
But in that case "can't be proven false" is a function of technological limits that could conceivably be overcome. In the early twentieth century it would also have been said that the hypothesis of intelligent life on Mars "can't be proven false" due to technological limits. But that "can't be proven false" is different than pseudoscientific unfalsifiability where falsification cannot even be conceived. For example, I cannot conceive of falsifying the proposition that invisible (ie, undetectable) spirits exist; yet I can conceive of examining the EM spectrum from distant regions or even sending spacecraft there (however horrendously long that may take) to look for signs of intelligent life.

So SETI critics are equating the "can't be proven false" due to transient constraints imposed by current technology and time with the "can't be proven false" of claims for which no pass-fail test can be conceived and thereby produce the pseudoargument that SETI is pseudoscientific.

Dickenmeyer
2003-Dec-27, 04:35 AM
My TurboTax program isn't mathematically unsound just because I don't have my 1099s and W-4s and mortgage interest statements to plug into it. I can guess, even with some measure of accuracy, what some of those numbers are from data that I have on hand but if I fill out my taxes now I'll probably be audited. The Drake Equation is a similar beast. If we don't have accurate data to plug into it the results are mostly meaningless, but that doesn't make the equation, in and of itself, unsound. Garbage In, Garbage Out. It's just not very useful now, with the data we have. It can still have value as a thought exercise though, and that's all any reasonably well informed person will use it for. It isn't religious canon, I think Crichton is taking it a tad too seriously and probably hasn't talked to many astronomers about it. That SETI is a religion is, as has been said by others before, just silly. A group of astronomers are using technical means to examine the possibility that radio broadcasts of a non-natural, extraterrestrial source might be detectable. So what makes that a religion? Most of them certainly hope they succeed, most of them think that the existance of ET life is possible or even likely. So what? Faced with the question "Is anyone out there?" you can either close your eyes and say "Yes" or "No" or you can fire up a radio telescope and go look.
The Astro-Potentate doesn't put on a big hat and bless the dishes at dawn and pray for a message from his Celestial Brethren, they put in a lot of late hours and hard work crunching numbers in a rigorously scientific way and it is a bit petty and mean-spirited, as well as simply incorrect, to call SETI a meaningless, useless religion.

Manchurian Taikonaut
2004-Mar-04, 06:35 PM
good post :o

Manchurian Taikonaut
2004-Jul-06, 08:23 PM
some good ideas but

well, who can say about what will happen next ?

SETI will take a very long time to do this

RBG
2004-Jul-07, 04:35 PM
A difference may be that those who search for ETI and use Drake's Equation to inspire some of their research, will all say "we haven't found anything", as compared to religion.

RBG

bacterium-in-spaceship
2004-Jul-24, 09:34 PM
Drake's equation, as normally interpreted, is trivially false: it doesn't take into account interstellar colonization by ETIs. Surprisingly few people seem to realize this.

(That is, it's false unless you include the possibility of being colonized in the "probability of intelligent/technological life" or "lifetime of an average civilization" factors, but no one does that).

I'd agree that SETI is a religion, not because it makes untestable claims, but because it makes testable and false claims. If intelligent, communicating life were common enough that we could hear its radio signals, some of it should have been here long ago. The Fermi/Tipler argument seems conclusive to me.

RoboSpy
2004-Jul-24, 10:03 PM
I'll admit that the Fermi Paradox is a bit troubling, but I think that it's no more (or less) valid than something like the Drake Equation when we're talking about intelligent, communicating civilization. How common does intelligent life have to be for us to hear its radio signals? Perhaps far less common than it would need to be for us to expect it to have left traces within our own star system. There are many of reasons why both the Drake Equation and the Fermi Paradox are edgy at best, and I think it folly to presume one or the other as being an accurate indicator of finding and/or contacting ETIs.

Regardless of all of that, I believe SETI to be an important scientific investigation of the whole matter. It's certainly far better to go and do something about it than to sit and argue about Drake and Fermi.

If we listen, we MIGHT hear something. If we don't, we WON'T hear anything.

http://setiathome.ssl.berkeley.edu/

Come on. You're not using ALL your flops. :)

bacterium-in-spaceship
2004-Jul-24, 10:19 PM
There are many of reasons why both the Drake Equation and the Fermi Paradox are edgy at best, and I think it folly to presume one or the other as being an accurate indicator of finding and/or contacting ETIs.

The Drake equation, as a way to calculate the number of communicating civilizations, is simply incorrect unless no ETI civilization ever colonizes a different star system than the one where it was born.

Something similar to the Drake equation can be used to calculate the probability that an average galaxy contains at least one civilization, but even there it doesn't really say anything. There are multiple terms in it with several orders of magnitude of uncertainty.

I don't think the Fermi Paradox is edgy. Many of the arguments I've seen against it seem bad to me; some seem reasonable, but not strong enough to challenge the main point.

I don't think people should stop looking, just to be sure. But I think it's extremely unrealistic to expect any alien communications. (And even if we do get a message, there's a chance they won't have our best interests at heart.) If they really want us to know of their existence, they can just send some sort of interstellar probe instead of messing around with radio signals.

gritmonger
2004-Jul-24, 10:54 PM
The Fermi/Tipler argument seems conclusive to me.

Those arguments are fallacious in that in the Fermi case it assumes we haven't found them yet, therefore they don't exist; if this were applied to particle physics we would have stopped looking a long time ago.

Tipler's hypothesis and argument is based on a single concept of how intelligent life might explore the univers- one which doesn't make a whole lot of sense and assumes to know more than the assumptions in the Drake equation about how intelligent life should behave. And because we don't see exactly what he says a hypothetical intelligent race should have built, it kills any argument for intelligent life in the galaxy.

The problem with a physicist addressing a question of biology/sociology (growth rate vs. a fission reaction for instance) is that the argument assumes no upper limit/bounding/limiting factors on biological growth, and attempts to fit a simple mathematical curve to what is a complex and difficult to calculate scenario as well as assuming that colonization is the only possible goal of any advanced life. Similar problems arise with projecting population growth without taking into account limits on resources, self limiting factors like technology and standard of living reducing family size, and so on.

[EDIT: Corrected for grammer/tense]

RoboSpy
2004-Jul-24, 11:05 PM
Why would they send an interstellar probe? That would take hundreds, maybe thousands of years to get here from wherever they are, unless they've discovered the secret to FTL space travel, not to mention that they have to know exactly where we are to make the probe of any use. Otherwise, they just launch a probe and HOPE it hits something of interest. With radio, they can effectively shotgun the stars with a message, and don't have to worry about where everyone else is. Their only worry then is whether or not they have a powerful enough signal that we'll be able to pick it up from our distance. Of course, that's assuming that they're sending out radio signals with the express intent of alerting other civilizations to their presence. It's probably far more likely that if we ever do receive a signal it will be some internal communication that we're intercepting from it source, like if an ETI picked up a transmission of "I Love Lucy" or the first words of Neil Armstrong as he stepped on Luna; we'd be picking up the equivalent of something like that.

As for your assertion that the Drake Equation doesn't take into account civilizations that have expanded to other star systems, I'll have to agree with you. However, I don't see how we could ever hope to add this variable to the equation. Consider all the things we would have to know to predict the rate of expansion of an ETI. We would first off have to know how quickly they reproduced, as well as how quickly their nervous systems reacted. Both of those variables are probably dependent directly on this civilization's metabolism rate, which is most certainly related to the biochemistry extant on their homeworld. This is probably dependent upon the type of planet they originated on, which depends upon the type of star that planet orbits. We should take into account the length of a year on their homeworld, the distance from their star which their homeworld lies, whether their homeworld has a considerable axial tilt, whether their homeworld has any moons, and probably a dozen or so other things regarding the nature of their homeworld and star system. We also have to determine whether or not FTL travel is possible, because if it isn't, this is a lmiting factor to how quickly a civilization can possibly expand beyond their home star. AND...we have to do that for every individual civilization in existence in the galaxy, because I'm sure they all must expand at different rates simply because there ARE so many variables. If we took human values for all these variables to be supposed average values, and worked up a base value for population growth and interstellar expansion, we STILL don't know if FTL is possible.

Another thing, we don't know how large these creatures are, so we don't know what the carrying capacity of a planet is for them - an ETI as large as a mouse would probably be able to live for a long time on their homeworld before they found colonizing another world necessary - especially if its homeworld were many times larger than Earth. There's also the possibility that other civilizations have the technology to build pseudoplanetary structures, like ringworlds, Dyson spheres, and Jovian bubbles, which curb the necessity for interstellar expansion.

I guess what I'm getting at is that the Drake Equation is a thought experiment, and probably shouldn't be taken to seriously. But on the other hand, all the things we need to know to make the Drake Equation valid we also have to know to make the Fermi Paradox valid, which is why I don't take either one too seriously.

bacterium-in-spaceship
2004-Jul-24, 11:26 PM
The Fermi/Tipler argument seems conclusive to me.

Those arguments are fallacious in that in the Fermi case it assumes we haven't found them yet, therefore they don't exist; if this were applied to particle physics we would have stopped looking a long time ago.

Bad analogy: particles don't have goals, and they're too small to see.

The assumption that if we haven't found them yet, then they don't exist isn't based on nothing; it's based on the idea that at least one being in at least one of the civilizations could have created a colonization wave, and colonized the galaxy in a relative eyeblink. There are enormously many reasons why one could want to do this: safety, ethics, gathering resources for building or computing things, ...


The problem with a physicist addressing a question of biology/sociology (growth rate vs. a fission reaction for instance) is that the argument assumes no upper limit/bounding/limiting factors on biological growth,

That colonizing the galaxy is possible at all should already prove that until that stage, there are no limits to biological growth. There may or may not be limits to growth; until the galaxy has been colonized, they certainly haven't been reached yet.

I don't think it's helpful to think of this in terms of biology anyway; it depends on the motivations of intelligent beings.


and attempts to fit a simple mathematical curve to what is a complex and difficult to calculate scenario


as well as assuming that colonization is the only possible goal of any advanced life.

The argument in no way depends on these assumptions. (I don't think I've read all of Tipler's writings on this, so he may have made some unnecessarily restrictive assumptions).

If there is only one individual in only one sufficiently advanced extraterrestrial civilization in this galaxy (or one close by) who prefers a colonized universe to a non-colonized universe and acts on this without being stopped, then we should expect the solar system to have been colonized. It doesn't even have to be a colonized universe; it could be any change we would have noticed.

gritmonger
2004-Jul-24, 11:39 PM
Bad analogy: particles don't have goals, and they're too small to see.

"Too small to see?" I'm not sure I understand your objection to Enrico Fermi being held to his own criteria for proving something exists. His criteria appears to be: if we can't see it now, it never existed, when much of the Standard Model has had to wait on new detection technologies to test for particles existing.



The assumption that if we haven't found them yet, then they don't exist isn't based on nothing; it's based on the idea that at least one being in at least one of the civilizations could have created a colonization wave, and colonized the galaxy in a relative eyeblink. There are enormously many reasons why one could want to do this: safety, ethics, gathering resources for building or computing things, ...


But you're throwing groundless assumptions in again: the premise of the Cosmological Principle, to fall back to physics, pretty much says: go by the examples we have, assume they are valid everywhere/everywhen. The one example we have (us) is too cheap to get off the planet, and unwilling to throw lives away into the void. The one example we have is often what is used in the Drake Equation, which is why the "lifetime" of radioteloscopic age is often fifty years or so.




The problem with a physicist addressing a question of biology/sociology (growth rate vs. a fission reaction for instance) is that the argument assumes no upper limit/bounding/limiting factors on biological growth,

That colonizing the galaxy is possible at all should already prove that until that stage, there are no limits to biological growth. There may or may not be limits to growth; until the galaxy has been colonized, they certainly haven't been reached yet.

Except that we don't know about resource distribution, minimum colony size, colony growth rates, required resources... to get around all of this, it appears that Tipler assumed a non-biological but geometrically growing "life-form" as his model. To do this, he had to presume the resources, the will, the desire, the motivation, and the design of an alien culture that is not our own: we certainly haven't done this yet. It seems more of a violation of the Cosmological Principle than the Drake equation.

bacterium-in-spaceship
2004-Jul-24, 11:42 PM
Why would they send an interstellar probe?

1) They don't know whether we'll be listening to radio signals.

2) Even if they're not interested in colonizing, there are still very good reasons to explore the galaxy, which means you need such probes anyway.


It's probably far more likely that if we ever do receive a signal it will be some internal communication that we're intercepting from it source, like if an ETI picked up a transmission of "I Love Lucy" or the first words of Neil Armstrong as he stepped on Luna; we'd be picking up the equivalent of something like that.

True enough. The argument doesn't work for unintentional messages. They will probably be vastly more advanced than us, however, and if they don't want us to find out about them, then we probably won't.


We also have to determine whether or not FTL travel is possible, because if it isn't, this is a lmiting factor to how quickly a civilization can possibly expand beyond their home star.

I'm assuming FTL isn't possible. If it is, the Fermi paradox becomes much worse: the number of aliens whose absence we need to account for becomes vastly larger.

Even at STL speeds, the galaxy can still be colonized very quickly. Its radius is only on the order of 10^5 light years, compared to timescales on the order of 10^9 years.


There's also the possibility that other civilizations have the technology to build pseudoplanetary structures, like ringworlds, Dyson spheres, and Jovian bubbles, which curb the necessity for interstellar expansion.

If exponential growth keeps going on, this will only help for some thousands of years. Of course, exponential growth may not keep going on. My argument isn't based on exponential growth; it's based on my estimate that at least one of such civilizations would prefer a colonized to a non-colonized galaxy.

bacterium-in-spaceship
2004-Jul-24, 11:53 PM
"Too small to see?" I'm not sure I understand your objection to Enrico Fermi being held to his own criteria for proving something exists. His criteria appears to be: if we can't see it now, it never existed, when much of the Standard Model has had to wait on new detection technologies to test for particles existing.

I understand what you're saying, but intelligent aliens are different enough from elementary particles that the same principles don't necessarily apply to both.


The one example we have (us) is too cheap to get off the planet, and unwilling to throw lives away into the void.

We've only been in space for a few decades, which makes us not representative of intelligent life in general. I certainly expect us to be off the planet in, say, 1000 years, if we're not extinct by then.


The one example we have is often what is used in the Drake Equation, which is why the "lifetime" of radioteloscopic age is often fifty years or so.

That's just silly. You're comparing the lifetime-up-to-now (in our case) to the total lifetime over the history of the civilization (in the case of the aliens).


Except that we don't know about resource distribution, minimum colony size, colony growth rates, required resources...

We don't know exactly, but the final outcome seems to me to be almost completely independent of such details: colonization can happen in much less time than billions or hundreds of millions of years.


To do this, he had to presume the resources, the will, the desire, the motivation, and the design of an alien culture that is not our own: we certainly haven't done this yet.

Again: not representative. We don't have the technology yet, and the parts that we do have, we have had for only decades.

To defeat his argument, you don't just have to argue that not all civilizations have such motivations; you need to argue that not one civilization, or part of a civilization, has such motivations, and that not one starts a colonization wave by accident.

Main message: by cosmic standards, we're extremely young as a technological civilization, and lessons learned here often don't carry over to millions-of-years-old extraterrestrial civilizations.

gritmonger
2004-Jul-25, 12:15 AM
The one example we have (us) is too cheap to get off the planet, and unwilling to throw lives away into the void.

We've only been in space for a few decades, which makes us not representative of intelligent life in general. I certainly expect us to be off the planet in, say, 1000 years, if we're not extinct by then.


Except, and I'll keep coming back to this, you are assuming things for which there is no basis. Expecting us to be off the planet. Expecting that to be our goal in 1000 years.

In analyzing a sample or hypothesis against the real world, you use data. Real data. Unfortunately, we only have one data point for intelligent civilization: us. Your arguments attempt to fit a line to one data point and infer all possible conclusions from your line. My point is: it takes a minimum of two points to define a line; making up a point doesn't count. Saying our goals or resources will be different in 1000 years does not apply to an argument using real data. Speculating on our goals 1000 years from now is even more presumptive than the values in the Drake equation.



To defeat his argument, you don't just have to argue that not all civilizations have such motivations; you need to argue that not one civilization, or part of a civilization, has such motivations, and that not one starts a colonization wave by accident.

I disagree. His argument is one that is similar to "This rock repels tigers: well, you don't see any tigers around here, do you? It works!"

He assumes that even one civilization of this type - the one that produces the self-replicating purposeless probes - would show up in our solar system and be detectable by now. Since there isn't any such probe, there has never been a civilization other than ours in the galaxy. He makes an assumption without any data: "Civilizations produce detectable probes that self-replicate geometrically and travel at sublight." You have to accept premise one before accepting premise two, that their probes would have gotten here by now if they existed. I don't need to refute the reasoning of premise two if I don't accept the reasoning of premise one. He has plotted an imaginary data point, then asked me to deny the line between the two points. I don't have to if I deny the second point. The line is automatically invalid.



Main message: by cosmic standards, we're extremely young as a technological civilization, and lessons learned here often don't carry over to millions-of-years-old extraterrestrial civilizations.

The funny thing is, the same reasoning could be used to argue that intelligent life has a way of observing from a distance that neither requires probes, nor colonization. That intelligent life has no interest in corporeal bodies, but would rather live in a virtual fantasy world. Or that they found a much more interesting place to go.

Using your own argument, there are plenty of reasons why an advanced civilization wouldn't litter the galaxy with out-of-date before out-of-the-system probes. I kind of doubt that we'd be satisfied with the Pioneer 10 design today given our technology; given the premise of doubling of technological capability every eighteen months, a self-reproducing probe would be out of date before it was even to its first nearby system.

bacterium-in-spaceship
2004-Jul-25, 12:49 AM
Except, and I'll keep coming back to this, you are assuming things for which there is no basis. Expecting us to be off the planet. Expecting that to be our goal in 1000 years.

"Our goal" -- as if all of humanity has only one goal. As technology advances, it will become ever cheaper to go to the stars. If no one else will be interested in this for the next one thousand or one million years, I will. To keep everyone on the planet on such timescales requires a totalitarian, extremely long-lasting government.


In analyzing a sample or hypothesis against the real world, you use data. Real data. Unfortunately, we only have one data point for intelligent civilization: us.

By that reasoning, all aliens have ten fingers, and many speak English. This won't do. Since we have only one data point, extrapolations from e.g. comparing timescales and making educated guesses as to the limits of technology become more important. I'm not drawing lines through data points, and don't need to.


He makes an assumption without any data: "Civilizations produce detectable probes that self-replicate geometrically and travel at sublight."

Even if this is true for only, say, one in a thousand of them, then typical estimates by SETI advocates of millions of civilizations are wrong.

And it isn't an assumption out of the blue: it only seems reasonable that some inhabitants of a technological civilization will, at some point during millions of years, decide that they slightly prefer a colonized to a non-colonized universe.

While it's possible that we're in a galaxy with a few (say, three) other civilizations for whom this isn't true, this would be rather a coincidence: it would mean the probability of an intelligent civilization arising is large enough that there are more than one in the galaxy, but small enough that none of them want to make colonization efforts. If uncertainty in e.g. the probability of life arising is more or less uniform on a logarithmic scale, then this very probably won't be true. Besides, if this is true, then there will probably be civilizations in other nearby galaxies. Intergalactic travel also seems possible to me.


That intelligent life has no interest in corporeal bodies, but would rather live in a virtual fantasy world.

Virtual worlds run on computers made of matter. There are still the other reasons to colonize, or make oneself known to other species, such as safety, ethics, doing large-scale physics experiments, building larger brains, ...


Or that they found a much more interesting place to go.

If a civilization can escape the universe (or live in intergalactic space, or whatever), then I'm sure it will be only a trivial cost to them to also have a noticeable presence here, although the advantages will probably also be small.


I kind of doubt that we'd be satisfied with the Pioneer 10 design today given our technology; given the premise of doubling of technological capability every eighteen months, a self-reproducing probe would be out of date before it was even to its first nearby system.

Undoubtedly, but if you keep using this reasoning forever, it defeats the point. If there are advantages in sending probes, then these advantages can't be had by waiting for better technology forever.

gritmonger
2004-Jul-25, 05:33 AM
Bacterium, I'm done. You use bizarre futurist logic to say it must be one way, but when the same logic can be used to say it could be any other way you balk.

You want to believe that this fellow is correct. Any attempt to cast doubt is refuted by this future you keep referring to in which civilizations last a million years and have cheap space travel and wander the stars. A future, which I might add just as a final aside, for which you have no proof other than your own very firm belief - and maybe a few episodes of Star Trek. A belief which extends to their motivations- but falls short in assuming that in any other way they could be like us.

Like being cheap.

Yet somehow you claim that the Drake equation is complete fancy.

Have fun. With yourself.

Diamond
2004-Jul-25, 11:56 AM
I think the above posters prove my point: The Drake Equation is is religion and not science since none of its components can be reliably and accurately ascertained. So all we have left is a discussion of which components we have a prior belief in, and why (which is what religion is all about - prior belief in unproveable and unlikely assumptions).

This is very similar to a recent attempt to quantify the existence of God using Bayes' Theorem: http://www.sciam.com/article.cfm?chanID=sa006&articleID=000E350F-2F66-10CF-AD3D83414B7F0000&colID=13

Again, the assumptions put in (none of which can be measured) produce any output you want.

Religious belief really can be buried in an equation or a graph.

bacterium-in-spaceship
2004-Jul-25, 01:36 PM
Bacterium, I'm done. You use bizarre futurist logic to say it must be one way, but when the same logic can be used to say it could be any other way you balk.

You want to believe that this fellow is correct. Any attempt to cast doubt is refuted by this future you keep referring to in which civilizations last a million years and have cheap space travel and wander the stars. A future, which I might add just as a final aside, for which you have no proof other than your own very firm belief - and maybe a few episodes of Star Trek. A belief which extends to their motivations- but falls short in assuming that in any other way they could be like us.

Like being cheap.

Yet somehow you claim that the Drake equation is complete fancy.

Have fun. With yourself.

Ah, yes: when all else fails, resort to ridicule.

(That wasn't even a remotely accurate description of what I've actually been saying, by the way.)

eburacum45
2004-Jul-25, 03:32 PM
So the Fermi Paradox suggests one of three things;

civilisations are rare, and the closest one that has produced self replicating probes is several billion light years away (or does not exist);

civilisations are rare or common, but none ever produce self replicating probes;

civilisations are rare or common, but if any try to produce self replicating probes they fail for technical reasons.

We can't really get much information out of those choices; it is certainly possible that the last one is correct, as interstellar travel is very very very very difficult;
also self replicating technology doesn't exist, and little is known about its viability.
Of course humans and lichen are both examples of self replicating devices, so self-replication on interstellar scales may be possible to an extent.

But consider the lichen; it colonises bare rock, and would be a good model for an interstellar replicating device; but it is practically invisible from a distance. Perhaps the self replicators are here and we have mistaken them for something else.

bacterium-in-spaceship
2004-Jul-25, 04:18 PM
I think your second and especially third options are implausible.

Is interstellar travel really very very very very difficult? I don't see the difficulties: you can just keep going, and with a bit of patience you'll reach your destination. Whether the maximum feasible speed is .01c or .99c shouldn't matter.

One problem might be long travel times, but this isn't an issue for artificial intelligences or uploads, who can just switch themselves off. Other possible solutions are generation ships, life extension, and suspended animation.

As you point out, we already know self-replication is possible: humans and other life are an example. I'm also assuming artificial intelligence is possible, whether in the short or in the long run.

It's possible that probes are already here, but we're mistaking all of them for something else, or just not seeing them. None of them seem to be exploiting a significant fraction of the energy or matter resources available in the solar system, or preserving energy for later use, though, and no one seems to have done any large-scale engineering of nearby star systems either. It seems to me that at least some would want to do this.

None of these probes, if they exist, are initiating contact. Statistically speaking, we should expect most of them to have been here for millions of years; if necessary, they could long have reported back to the home world, or wherever. This is why I think such civilizations really don't want to be seen by us if they exist; in that case, they're not going to send radio signals either.

eburacum45
2004-Jul-25, 05:17 PM
Is interstellar travel really very very very very difficult? I don't see the difficulties: you can just keep going, and with a bit of patience you'll reach your destination. Whether the maximum feasible speed is .01c or .99c shouldn't matter.



A major problem for even a small probe is decelerating when you get there; decelerating from 0.01c would be a major task, even for a payload as big as Opportunity. Adding enough fuel to decelerate makes the payload when you are accelerating from Earth much bigger, which makes the rocket much bigger.
I know I have written fiction about massive anti-matter catalysed fusion type rockets propelling ships to nearby stars, but there are many real dificulties, not least that such a fierce drive system would melt the rocket ship itself.

Perhaps a sensible civilisation realises that the difficulties involved produce little or no return on investment.
No slower than light colonisation strategy could do anything to decrease overpopulation within a solar system, it cannot be fast enough nor carry enough people out of the system to make a difference, even at 0.99c...
either you solve the problem of population growth within that system or you die of overcrowding.

Once you have solved the problem of population growth within a solar system there is little incentive to go to another star.

bacterium-in-spaceship
2004-Jul-25, 07:17 PM
A major problem for even a small probe is decelerating when you get there; decelerating from 0.01c would be a major task, even for a payload as big as Opportunity. Adding enough fuel to decelerate makes the payload when you are accelerating from Earth much bigger, which makes the rocket much bigger.

I see various ideas, like magnetic sails, being pushed around. Do you think something like these could help?


either you solve the problem of population growth within that system or you die of overcrowding.

Agreed, though this might change somewhat in case of uploads (who can be transferred at light speed, I think).


Once you have solved the problem of population growth within a solar system there is little incentive to go to another star.

But this isn't true at all, I think. The potential returns are enormous: the energy output of a star is huge, even compared to the energy costs of interstellar travel (which is only needed once). Potential living space is also enormous, even though for an exponentially reproducing civilization it won't solve overpopulation. Then, there's the incentive of simply learning more about the universe, whether for its own sake or to achieve other things.

eburacum45
2004-Jul-25, 07:52 PM
A major problem for even a small probe is decelerating when you get there; decelerating from 0.01c would be a major task, even for a payload as big as Opportunity. Adding enough fuel to decelerate makes the payload when you are accelerating from Earth much bigger, which makes the rocket much bigger.

I see various ideas, like magnetic sails, being pushed around. Do you think something like these could help?

Possibly; but they only work for very light payloads.




either you solve the problem of population growth within that system or you die of overcrowding.

Agreed, though this might change somewhat in case of uploads (who can be transferred at light speed, I think). Destructive uploads are tantamount to killing the person and assembling them elsewhere; non-destructive uploads do nothing to affect population.
edit-
additionally neither are proven technology.



Once you have solved the problem of population growth within a solar system there is little incentive to go to another star.

But this isn't true at all, I think. The potential returns are enormous: the energy output of a star is huge, even compared to the energy costs of interstellar travel (which is only needed once). Potential living space is also enormous, even though for an exponentially reproducing civilization it won't solve overpopulation. Then, there's the incentive of simply learning more about the universe, whether for its own sake or to achieve other things.
But little benefit returns to the originating system, except knowledge.
That would be reason enough in my book; and once the entire energy of a star was available then interstellar exploration could be started almost as a hobby.

But we haven't seen any Dyson Swarms, yet. Perhaps we aren't looking hard enough.