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A.DIM
2011-Aug-30, 04:49 PM
and their collision probability with different Solar System bodies (http://arxiv.org/PS_cache/arxiv/pdf/1108/1108.3375v1.pdf) revises upwards the probability and amount of lifebearing ejecta from Earth reaching other bodies.

From a BBC article (http://www.bbc.co.uk/news/science-environment-14637109):

"Previous studies are definitely 'lower bounds'," Dr Sigurdsson told BBC News, explaining that new limits on impacts come not from new physics, but from better computers.

"They were computationally limited, in the sense that you could only do so much with what you could do back then. The numbers [in the new study] are in the right ballpark. We're getting even higher impact rates than they are, because we're going for much longer. They're doing a large number of particles for short times; we're going to 10 million years."

The real question is whether any ejecta will carry living cargo that can fulfil the "panspermia" hypothesis, but Dr Sigurdsson says that evidence of the hardiness of life has already been found closer to home.

"There are viable bacterial spores that have been found that are 40 million years old on Earth - and we know they're very hardened to radiation."

R.A.F.
2011-Aug-31, 05:58 PM
...revises upwards the probability and amount of life bearing ejecta from Earth reaching other bodies.

Have you changed your opinion regarding this??...I thought you were looking for signs that life bearing ejecta was coming to Earth from other places.

A.DIM
2011-Aug-31, 06:24 PM
My thread was moved and no explanation was given!
Damned BAUT.

There is nothing ATM about the paper I linked or the reporting thereof. Life is on this planet. Impacts have ejected material from Earth. What is ATM about the model? I suspect someone complained or whined because it strengthens a type of panspermia theory.

R.A.F.
2011-Aug-31, 06:38 PM
I suspect someone complained or whined...

It wasn't me...ask the mods.


...because it strengthens a type of panspermia theory.

That has yet to be discussed...



So how about answering my question??

Moose
2011-Aug-31, 08:54 PM
Are we going to have to go through this every single time you choose to post here, A.DIM?

First: Panspermia is categorically an ATM topic. It is not appropriate for LiS. You know this. Do not pretend you don't know better by now.


Effective immediately, claim advocacy regarding the existence, nature, and origin of extraterrestrial life now bear a Rule 13 burden. Depending on the precise nature and defensibility of such claims, these posts and threads may be moved to CT or ATM as appropriate and will bear the full responsibilities of claims made in those forums, as detailed by Rule 13. Specific claim threads or posts made here and left here may be assumed to bear the same evidential burden as they would in the CT forum.

Examples of topics bearing a Rule 13 burden are:

* Advocacy of specific ET visitations.
* Advocacy of the existence of intelligent extra-solar life.
* Advocacy of microbial life on Mars/Jupiter's moon(s)/Saturn's moon(s), etc.
* Advocacy of panspermia.
* Advocacy of knowledge of specific values for Drake's Equation.
* Other similar topics for which a non-mainstream claim is asserted.

Second: Don't pretend you're not indirectly advocating for panspermia. I don't think there's anybody left who doesn't see right through that little game.

Third: You also know that you've had several "kicks at the can", and you're entitled to one. By rights, I should also be closing this thread. Still, I'll permit this paper to be examined for a while (probably _not_ the full 30 days, but we'll see) so long as the discussion stays _very_ focused on the paper in question.

Fourth: If you have something to ask or dispute, you do it via PM or the reports mechanism, never in thread. This, also, you know.

If you have any other questions or concerns, PM or report. Do not create more of a fuss in thread.

A.DIM
2011-Sep-01, 05:09 PM
I’m sorry, I should’ve known better. I failed to see how impact ejecta from Earth reaching other planets is itself against the mainstream. I suppose I need clarification. Has Earth not been impacted at the scales considered here? I thought material exchange in our system was accepted fact; do we not possess material from Mars, Moon and meteorites?

The question, or so I thought, was whether or not life can survive the trip. Certainly extremophiles like tardigrades and D Radiodurans have shown they might survive but we don’t know yet. But as pointed out in the BBC article some bacterial spores remain viable up to 40M years. The model given here simply suggests a little more material in more places at shorter times (10M years), from Earth. If these estimates are accurate, it appears habitable environments (habitable for extremophiles of course) on Mars and various moons could well have been recipients of Earth life by now (no doubt its detritus!), raising questions about the likelihood that any life found elsewhere in our system being already related to us (alas, lower chances of a holy grail finding: abiogenesis off planet).

In the end, I don’t know why this should be ATM and I’m unsure what I might defend necessarily. This is the stuff discussed in astrobiology and origins of life research, seemingly appropriate LiS subjects, yet it remains in the ATM corner here at BAUT. And I truly do not understand.
Anyway, in the spirit of BAUT, please, someone point out what I don’t understand and what it is we should be debunking in this paper. It strikes me as good science but what do I know? Thanks!

R.A.F.
2011-Sep-01, 06:06 PM
...yet it remains in the ATM corner here at BAUT. And I truly do not understand.

You truly don't understand why we don't "embrace" an idea that lacks supporting evidence?

stutefish
2011-Sep-02, 01:32 AM
What is ATM about the model? ... it strengthens a type of panspermia theory.

SQ1. A.DIM, is it your claim that the model cited in the OP strengthens a type of panspermia theory?

SQ2. If so, what is the specific type of panspermia theory it strengthens?

SQ3. In what way(s) does it strengthen this theory?

SQ4 (bonus question). In what way is this type of panspermia theory not ATM?

A.DIM
2011-Sep-02, 03:49 PM
SQ1. A.DIM, is it your claim that the model cited in the OP strengthens a type of panspermia theory?
Of course it is; being shoved into ATM, I can't simply say "hey I agree with this new model let's discuss" - no, I am forced to advocate.


SQ2. If so, what is the specific type of panspermia theory it strengthens?

Ballistic or Litho-panspermia.


SQ3. In what way(s) does it strengthen this theory?

The model suggests more material (containing earth life) escaping Earth's gravity, and actually reaching other bodies in our solar system.


SQ4 (bonus question). In what way is this type of panspermia theory not ATM?

High velocity Earth impacts have occurred, no doubt. Material exchange in our system occurs, no doubt. Life is on Earth and is ejected during such impacts, no doubt.
The paper in question suggests more material reaching more places, and within time frames which are survivable for some extremophile life.

Whether or not life actually survives its interplanetary journey and finds a habitable niche on other bodies remains to be seen.

R.A.F.
2011-Sep-02, 05:00 PM
Of course it is; being shoved into ATM, I can't simply say "hey I agree with this new model let's discuss" - no, I am forced to advocate.

Please, enough of this...


High velocity Earth impacts have occurred, no doubt. Material exchange in our system occurs, no doubt. Life is on Earth and is ejected during such impacts, no doubt.
The paper in question suggests more material reaching more places, and within time frames which are survivable for some extremophile life.

Whether or not life actually survives its interplanetary journey and finds a habitable niche on other bodies remains to be seen.

So you now believe that life originated on Earth, and "moved" to other worlds?

Garrison
2011-Sep-02, 05:40 PM
High velocity Earth impacts have occurred, no doubt. Material exchange in our system occurs, no doubt. Life is on Earth and is ejected during such impacts, no doubt.
The paper in question suggests more material reaching more places, and within time frames which are survivable for some extremophile life.

Actually surely there is doubt as to whether any spore could survive the ejection event itself? Wouldn't these energetic ejection events tend to destroy anything as complex as a spore? Have these questions been addressed?

Moose
2011-Sep-02, 06:52 PM
Actually surely there is doubt as to whether any spore could survive the ejection event itself? Wouldn't these energetic ejection events tend to destroy anything as complex as a spore? Have these questions been addressed?

Thanks to Phil's second show, we already have a pretty good idea (I'd reserve judgement on "know" until there's replication of those results) that Earth extremophile bacteria (if I can't pronounce it, I can't remember it) won't survive the energy involved in a simulated impact. Pretty sure an ejection event from our gravity well would require more energy than produced by the impact they simulated.

A.DIM
2011-Sep-02, 08:22 PM
Actually surely there is doubt as to whether any spore could survive the ejection event itself? Wouldn't these energetic ejection events tend to destroy anything as complex as a spore? Have these questions been addressed?

I think it's been shown some bacteria and microorganisms can survive all stages of such an event (impact, ejection ... reentry, impact) except for the travel times in between.
This paper discusses some aspects Survivial of bacteria exposed to extreme acceleration:implications for panspermia. (http://academics.skidmore.edu/blogs/bi-378-s11-hchen/files/2011/04/sdarticle.pdf)

Here's a more recent, and pertinent, study: Microbial rock inhabitants survive hypervelocity impacts ... first phase of lithopanspermia experimentally tested (http://www.ifa.hawaii.edu/~meech/a281/handouts/panspermia.pdf).

Unless Phil has published a peer reviewed paper like these, to go along with his tv show presentation, I'm inclined to dismiss his results ...

Van Rijn
2011-Sep-02, 09:32 PM
Thanks to Phil's second show, we already have a pretty good idea (I'd reserve judgement on "know" until there's replication of those results) that Earth extremophile bacteria (if I can't pronounce it, I can't remember it) won't survive the energy involved in a simulated impact. Pretty sure an ejection event from our gravity well would require more energy than produced by the impact they simulated.

Issues with his demonstration have been discussed on BAUT before. The demonstration was probably too limited to be very useful (as I recall, he qualified it as being "suggestive"). Size and mass of impacters matter (for one thing, lower mass objects will reach terminal velocity and can have quite gentle impacts on Earth, and probably could on early, thick-atmosphere Mars as well). And the test for survivability was quite limited, apparently using a lab strain of metabolizing E. coli. A better test would probably be to use endospores of a variety of species and attempt to reactivate and grow them after the impact experiment.

R.A.F.
2011-Sep-02, 09:43 PM
Unless Phil has published a peer reviewed paper like these, to go along with his tv show presentation, I'm inclined to dismiss his results ...

Well, it's no "surprise" that you would disagree with anyone who disagrees with you.

R.A.F.
2011-Sep-02, 09:46 PM
A better test would probably be to use endospores of a variety of species and attempt to reactivate and grow them after the impact experiment.

Even better....before re-activation subject said spores to the "rigors" of space for a few million years.

It's the only way to be sure. :)

Van Rijn
2011-Sep-02, 10:07 PM
The model suggests more material (containing earth life) escaping Earth's gravity, and actually reaching other bodies in our solar system.


An important qualification, however:


Gladman et al. (2005) estimated the collision rate with Mars to
be about 2 orders of magnitude lower that found on the
basis of our simulations. However, as also noted in their
paper, our results for Mars are within the known typical
errors of such probability estimations.

So I'd be interested in what they've done to verify their higher collision rate estimate is a valid and novel result.

Van Rijn
2011-Sep-02, 10:19 PM
Even better....before re-activation subject said spores to the "rigors" of space for a few million years.

It's the only way to be sure. :)

Well, that's probably too much. One of the interesting things about this article (and I do think it is worth reading) is that they don't count any transfer/impacts that would take longer than 30,000 years. They do that specifically because that's probably about as long as an endospore can last without accumulating too much DNA damage. That, of course, is one of the reasons interstellar panspermia is implausible.

R.A.F.
2011-Sep-02, 11:19 PM
One of the interesting things about this article (and I do think it is worth reading) is that they don't count any transfer/impacts that would take longer than 30,000 years.

That just adds another "if"....as in...


If a supposed impact excavated some form of life, and...

If that life remained viable for thousands of years, and...

If that life landed "somewhere" where it could flourish, and...

See where I'm going with this?....just too many "if"s" for me to seriously consider it.

PaulLogan
2011-Sep-02, 11:48 PM
Issues with his demonstration have been discussed on BAUT before. The demonstration was probably too limited to be very useful (as I recall, he qualified it as being "suggestive"). Size and mass of impacters matter (for one thing, lower mass objects will reach terminal velocity and can have quite gentle impacts on Earth, and probably could on early, thick-atmosphere Mars as well). And the test for survivability was quite limited, apparently using a lab strain of metabolizing E. coli. A better test would probably be to use endospores of a variety of species and attempt to reactivate and grow them after the impact experiment.


Van Rijn is right. unfortunately, i saw this example of a bad tv show (-off). his "experiment" is not even worth mentioning. he did use e. coli, which hardly qualifies as an extremophile. he used a very small projectile, which was probably a man-made spherical bullet without any surface structures that would offer protection (i.e. no cracks for possible extremophiles to hide), etc, etc.

basically it was a show of explosions and shooting stuff around. there was little science in it.
furthermore, mr. plait has demonstrated publicly that his knowledge of elementary physics is rather lacking. i am referring to the show where he felt moved to fly around in an f-16 to show that he doesn't know what he's talking about. this was discussed at length even on this forum:
http://www.bautforum.com/showthread.php/108362-Bad-Astronomy-s-BAD-Facts-and-Points-made-on-his-TV-show-are-really-BAD!

A.DIM is absolutely right and justified to dismiss this "experiment".

A.DIM
2011-Sep-03, 12:02 AM
An important qualification, however:

So I'd be interested in what they've done to verify their higher collision rate estimate is a valid and novel result.

Yes, it appears more work lies ahead, as stated in their conclusion. That the results, using different numerical codes, generally agree is interesting ...

Gladman et al. (2005) has performed a similar calculation
to the one conducted in this paper using a different
numerical code, initial conditions and a smaller
number of test particles in each simulation. In general,
our results agree well with those they report. Two notable
exceptions, most likely attributable to the greater
number of test particles we follow in our simulations,
are that we find collisions with Mars, one particle in
Cases B and C, and also, we find collisions with Jupiter,
0.06% of all ejecta in Case D and 0.05% in Case E. Using
an ®Opik collision probability calculation,

... (here is from where your quote comes)

Both results, definite collisions withMars and Jupiter,
are of astrobiological significance, owing to the possible
presence of life sustaining environments in early Mars
and in Jupiterís moons Europa and Ganymedes. Also
worth noting is the fact that the single particle colliding
with Mars, does so towards the end of our simulation,
between 25 and 30 thousand years after being ejected
from Earth. Collisions with Jupiter are characterized by
a wider range of collision times, one half reaching the
giant planet in less than 10,000 years. In future studies
we will extend our analysis of both cases to determine
the statistical significance of these results.


To me it seems Gladman's et al. work has been expanded and filled in a little more fully, just as science theories go.

Anyway, we know impacts like Chicxulub ejected material from Earth. We know bacterial and micro life inhabit the crust of the Earth. We now know some of this life can survive the conditions of space: B Subtillus, D Radiodurans tardigrades. etc.
We don't know for how long life could survive during interplanetary transport (the paper describes a case where Jupiter is reached by particles in less than 10K yrs - wow!) but it appears we've got some pretty good candidates.

Only if, I guess.

R.A.F.
2011-Sep-03, 12:08 AM
...mr. plait has demonstrated publicly that his knowledge of elementary physics is rather lacking...i am referring to the show where he felt moved to fly around in an f-16 to show that he doesn't know what he's talking about. this was discussed at length even on this forum:

Phil being wrong in no way validates panspermia, but you know that.

Do you have any opinions about the topic being discussed?

R.A.F.
2011-Sep-03, 12:10 AM
Only if, I guess.

Which is why I base my opinions on evidence and not on speculative "if's".

Garrison
2011-Sep-03, 12:21 AM
Issues with his demonstration have been discussed on BAUT before. The demonstration was probably too limited to be very useful (as I recall, he qualified it as being "suggestive"). Size and mass of impacters matter (for one thing, lower mass objects will reach terminal velocity and can have quite gentle impacts on Earth, and probably could on early, thick-atmosphere Mars as well). And the test for survivability was quite limited, apparently using a lab strain of metabolizing E. coli. A better test would probably be to use endospores of a variety of species and attempt to reactivate and grow them after the impact experiment.

Especially important as the long dormant spores that have been brought up all seem to have survived in rather special conditions. How well would that preservation stand up to being ejected in an impact? And of course as far panspermia goes there's the not so small matter of surviving the rigors of entry into another planets atmosphere.

PaulLogan
2011-Sep-03, 12:21 AM
Phil being wrong in no way validates panspermia, but you know that.
of course i do. and you know of course that i did not suggest that. i was only questioning your source and i explained why i think his "experiment" has no relevance here.


Do you have any opinions about the topic being discussed?

opinions, yes. but i can not back them up as well as A.DIM can because i haven't studied the topic at any length.
i have read the article from the OP independent of this thread and as far as i am concerned it makes interplanetary panspermia a very viable possibility. i certainly share A.DIM's concern of panspermia being categorically atm on this board.

personally, i don't think interstellar panspermia is very likely (but certainly not impossible). interplanetary panspermia, however, i would consider very likely.

as i said: just my opinions. i am not prepared to back it up because i lack the background in this field.

R.A.F.
2011-Sep-03, 12:48 AM
of course i do. and you know of course that i did not suggest that. i was only questioning your source and i explained why i think his "experiment" has no relevance here.

Then why didn't you simply state that?

PaulLogan
2011-Sep-03, 12:58 AM
Then why didn't you simply state that?

i'm not a simple man. ask my wife! :)

Van Rijn
2011-Sep-03, 01:31 AM
To me it seems Gladman's et al. work has been expanded and filled in a little more fully, just as science theories go.


I don't see where they've made theoretical breakthroughs. They might have run longer simulations, which is a different thing.

Yes, they do say they've done more extensive simulations, and yet, the numbers are quite small. That's why I'm concerned about the statement I quoted, that "However, as also noted in their paper, our results for Mars are within the known typical errors of such probability estimations."

Think of it this way: If your study shows two impacts out of 10,000, and an older study shows one impact out of 10,000, you can say your study shows twice as many impacts. And yet, it's still a small number, so it could just be within the error boundaries and be entirely meaningless. They're probably going to need to do longer simulations to show that their increase isn't just noise, and, of course, they will need to show they haven't introduced errors into the process.

Van Rijn
2011-Sep-03, 03:39 AM
Especially important as the long dormant spores that have been brought up all seem to have survived in rather special conditions. How well would that preservation stand up to being ejected in an impact? And of course as far panspermia goes there's the not so small matter of surviving the rigors of entry into another planets atmosphere.

On Earth, some meteorites impact at fairly low velocity, having long since reached terminal velocity, and the interior of some can remain quite cool. Mars has lower gravity and once had a thicker atmosphere, so much the same might once have been possible there.

So, if there were spores inside a meteorite, they might not be ejected on impact or have a difficult time during the travel through the atmosphere.

Paul Beardsley
2011-Sep-03, 08:47 AM
Then why didn't you simply state that?

I don't think he could have made it any clearer than he did.

A.DIM
2011-Sep-07, 01:22 PM
I don't see where they've made theoretical breakthroughs. They might have run longer simulations, which is a different thing.

Yes, they do say they've done more extensive simulations, and yet, the numbers are quite small. That's why I'm concerned about the statement I quoted, that "However, as also noted in their paper, our results for Mars are within the known typical errors of such probability estimations."

Think of it this way: If your study shows two impacts out of 10,000, and an older study shows one impact out of 10,000, you can say your study shows twice as many impacts. And yet, it's still a small number, so it could just be within the error boundaries and be entirely meaningless. They're probably going to need to do longer simulations to show that their increase isn't just noise, and, of course, they will need to show they haven't introduced errors into the process.

I understand and don't disagree, but I think their intent was more to verify Gladman's results rather than break through theory; peer review if you will. Certainly I'm interested to see how their future work "to determine the statistical significance of these results" - particles reaching Mars and Jupiter - shakes out but personally, I don't doubt material from Earth reaches multiple bodies in our system, even while the number may be small. The question in my mind is whether what gets there is dead or alive.
Do you not think Earth ejecta can reach Mars, or perhaps moons of Jupiter?

R.A.F.
2011-Sep-07, 10:40 PM
....personally, I don't doubt material from Earth reaches multiple bodies in our system, even while the number may be small.

I don't doubt that, either.


The question in my mind is whether what gets there is dead or alive.

Good question.


Do you not think Earth ejecta can reach Mars, or perhaps moons of Jupiter?

Well, if we're going to "play" statistics/odds...taking into account the massive gravity well that is the Sun, wouldn't it be more "likely" that of any material, ejected, the majority of that material would fall further into the Solar System?...to perhaps Venus and Mercury??

So why single out Mars and the satellites of Jupiter?

PaulLogan
2011-Sep-07, 11:18 PM
So why single out Mars and the satellites of Jupiter?

from the bbc article:

The real question is whether any ejecta will carry living cargo that can fulfil the "panspermia" hypothesis, but Dr Sigurdsson says that evidence of the hardiness of life has already been found closer to home.

it seems to me they focused on mars and the jupiter satellites because they are considered the most likely candidates for having (or having had) conditions that may support life.
the article does not mention they focused exclusively on those objects.

A.DIM
2011-Sep-07, 11:29 PM
I don't doubt that, either.

Then why all the squawking at the outset?
:)


Good question.

It most certainly is, and deserves serious scientific consideration.


Well, if we're going to "play" statistics/odds...taking into account the massive gravity well that is the Sun, wouldn't it be more "likely" that of any material, ejected, the majority of that material would fall further into the Solar System?...to perhaps Venus and Mercury??

What does "play" statistics / odds mean? Is that what you consider N-body simulations (http://www.scholarpedia.org/article/N-body_simulations) to be? Did you not read the paper, or even the abstract?

From the abstract:
The Mercury 6 code is used to compute the dynamics of test particles under the gravitational effect of the inner
planets in the Solar System and Jupiter. A series of simulations are conducted with different ejection velocity, considering
more than 10^4 particles in each case. We find that in general, the collision rates of Earth ejecta with Venus and
the Moon, as well as the fall-back rates, are consistent with results reported in the literature. By considering a larger
number of particles than in all previous calculations we have also determined directly the collision probability with
Mars and, for the first time, computed collision probabilities with Jupiter. We find that the collision probability with
Mars is greater than values determined from collision cross section estimations previously reported.

and from Part 2. Model description:

We consider ejecta as test particles moving under the action of the gravitational field of the Sun, the Moon, and all planets of the Solar System. No other forces are considered in the present study. Particles are assumed not to collide with each other, but may impact any of
the massive bodies. The dynamics of the planets and test particles system is calculated using the Mercury 6.2 code developed by Chambers (1999).

Do you have a reason to suspect their calculations, or the code they used, is in err?


So why single out Mars and the satellites of Jupiter?

Uh, because they're the most likely candidates for habitable environments ...
was that a serious question?

Here's why (http://www.technologyreview.com/blog/arxiv/27092/).

Van Rijn
2011-Sep-08, 12:06 AM
I believe the article looks at impact probabilities for Venus, Earth, the Moon, Mars, and Jupiter. There is not, as far as I'm aware, anything in the article about Jupiter's moons (which are, of course, far smaller targets than Jupiter). The article does mention the far higher impact velocities you'd have for Jupiter versus Mars, which (even if the planet Jupiter were potentially habitable) would be a serious problem for transferring living material.

A.DIM
2011-Sep-08, 12:37 AM
I believe the article looks at impact probabilities for Venus, Earth, the Moon, Mars, and Jupiter. There is not, as far as I'm aware, anything in the article about Jupiter's moons (which are, of course, far smaller targets than Jupiter). The article does mention the far higher impact velocities you'd have for Jupiter versus Mars, which (even if the planet Jupiter were potentially habitable) would be a serious problem for transferring living material.

In the Discussion the authors do mention Europa and Ganymedes (sic) when pointing out the astrobiological significance of their results, but say nothing else. No doubt they will be considered in future modeling.
I need to reread Survivability of Bacteria in Hypervelocity Impact (http://www.docentes.unal.edu.co/pfdeb/docs/Icarus%20paper.pdf) to be sure, but I'd guess the speeds we're talking won't necessarily be lethal.

R.A.F.
2011-Sep-08, 01:06 AM
Then why all the squawking at the outset?

Can't really answer that question, and it's not because I don't have an answer.


It most certainly is, and deserves serious scientific consideration.

That's debatable...


What does "play" statistics / odds mean?

It means...if I were to speculate, then I would have to say there is more of a likelyhood of material moving toward the Sun rather than away from it based on gravity. That and because Jupiter and it's satellites are really far away.


Is that what you consider N-body simulations (http://www.scholarpedia.org/article/N-body_simulations) to be? Did you not read the paper, or even the abstract?

So you expect me to "just accept it" even though it is counter-intuitive?

Sorry...not wired that way...

PaulLogan
2011-Sep-08, 01:17 AM
It most certainly is, and deserves serious scientific consideration.
That's debatable...

no, it isn't. not for a scientist anyways. the possibility of extraterrestrial life is one of the most fundamental and fascinating questions.



It means...if I were to speculate, then I would have to say there is more of a likelyhood of material moving toward the Sun rather than away from it based on gravity. That and because Jupiter and it's satellites are really far away.

clearly, that is not what they found in the simulations. whether you find them counter-intuitive or not, the numbers don't lie.


So you expect me to "just accept it" even though it is counter-intuitive?

Sorry...not wired that way...

guess what? nature doesn't care if you or anybody else finds it counter-intuitive. check out quantum physics.
i guess you are not "wired" for science then...

A.DIM
2011-Sep-08, 01:48 AM
Can't really answer that question, and it's not because I don't have an answer.

Forget I asked; I'm not really interested.


That's debatable...

Eh? You say it is a good question and then follow with "that's debatable" as to whether or not it deserves serious scientific consideration?


It means...if I were to speculate, then I would have to say there is more of a likelyhood of material moving toward the Sun rather than away from it based on gravity. That and because Jupiter and it's satellites are really far away.

Well, according to their models, of the 5 scenarios, 0% ejecta fall into the sun in four of them. Only the high velocity event which sends material to Jupiter also results in material falling into the sun.
You didn't even look at the chart they provide, did you?


So you expect me to "just accept it" even though it is counter-intuitive?

No. I expect you to read the paper and have a little more insight into the material you argue against, or for, whichever .... if it's a "good question."


Sorry...not wired that way...

I can only imagine the schematic ...

R.A.F.
2011-Sep-08, 01:52 AM
no, it isn't. not for a scientist anyways. the possibility of extraterrestrial life is one of the most fundamental and fascinating questions.

...with no supportive evidence....fascinating...


whether you find them counter-intuitive or not, the numbers don't lie.

Oh really??


Let's look at the "if's"...

"If" the Earth was impacted in just the right place...and

"If" that ejected material contained life...and

"If" that ejected material moved against gravity toward the outer system...and

"If" it came anywhere near Mars, or Jupiter...and

"If" that life could survive the travel time...


With all these unproven "If's", and you can't understand my skepticism?


i guess you are not "wired" for science then...


I'll let the mods handle this...

R.A.F.
2011-Sep-08, 02:08 AM
Forget I asked; I'm not really interested.

Hey..I knew that. :)


Eh? You say it is a good question and then follow with "that's debatable" as to whether or not it deserves serious scientific consideration?

Paradoxically, the older I get, the more irrelevant "the ET life question" is to me. I figure I have maybe 30 years left here, and I just don't think the "question" will be answered in that time.

So...to me...not that interesting...





...according to their models...

So these models have been real world proven beyond ANY doubt?

Seriously doubt that...


...of the 5 scenarios, 0% ejecta fall into the sun in four of them...

,,,and that seems rational to you?

PaulLogan
2011-Sep-08, 02:12 AM
...with no supportive evidence....fascinating...

wow! so, according to you, without supportive evidence science is not supposed to ask questions?



Oh really??


Let's look at the "if's"...

"If" the Earth was impacted in just the right place...and

"If" that ejected material contained life...and

"If" that ejected material moved against gravity toward the outer system...and

"If" it came anywhere near Mars, or Jupiter...and

"If" that life could survive the travel time...


With all these unproven "If's", and you can't understand my skepticism?


don't change subject. you were questioning their results because you found them counter-intuitive.
you were not questioning their methodology.
n-body simulation is a tried and tested method applied in many areas of physics and especially in astrophysics.
there are always ifs in simulations; it's inherent and unavoidable.
and some of your ifs simply show that you do not understand the method the used.
e.g.

"If" the Earth was impacted in just the right place...
not an assumption. that's part of the simulation. they simulated projectiles coming from different (random) angles and with different (random) velocities.


"If" that ejected material moved against gravity toward the outer system...
"If" it came anywhere near Mars, or Jupiter...
again: no assumption, those are results of the simulation.


Guess you're not wired to argue a "point" without being insulting...
yeah, sorry about that. couldn't resist dishing you some of the insults you so freely dish out on this forum but i shouldn't have.

R.A.F.
2011-Sep-08, 02:27 AM
don't change subject. you were questioning their results because you found them counter-intuitive.

Yes...as anyone without bias would.


you were not questioning their methodology.

So you get to decide what I can, and what I can't post? Careful Icarus. :)



...there are always ifs in simulations; it's inherent and unavoidable.

Then why the conscious choice to ignore those "if's"?


...and some of your ifs simply show that you do not understand the method the used.

Method?? So my questions are ignorant? I think you were better off with sticking with your previous insult. :)


...they simulated projectiles coming from different (random) angles and with different (random) velocities.

With non-random results?? Does this really make sense to anyone other than the current participants in this thread??



yeah, sorry about that. couldn't resist dishing you some of the insults you so freely dish out on this forum but i shouldn't have.

Accepted....I think..:)

Van Rijn
2011-Sep-08, 05:42 AM
"If" that ejected material contained life...and


I'm afraid this "if" is outside the scope of the paper's argument. It's specifically modeling material transfer and impact probabilities. If they get something wrong, it would be because they made an error in calculation, didn't have enough precision, or something of that nature.



"If" that ejected material moved against gravity toward the outer system...and

"If" it came anywhere near Mars, or Jupiter...and


RAF, this is what the paper is modeling. It starts with groups of particles near Earth with substantial starting velocities (the simulated effect of a large impact on Earth - see the paper for the justification of the starting conditions). The velocities are such that much of the material can escape Earth and move in as well as out-system. They follow the particles and see where they end up over time.

korjik
2011-Sep-08, 06:07 AM
no, it isn't. not for a scientist anyways. the possibility of extraterrestrial life is one of the most fundamental and fascinating questions.



clearly, that is not what they found in the simulations. whether you find them counter-intuitive or not, the numbers don't lie.



guess what? nature doesn't care if you or anybody else finds it counter-intuitive. check out quantum physics.
i guess you are not "wired" for science then...

If numbers didnt lie, I would have proved the universe dosent exist three or for times now. Numbers will lie all over the place if they arent treated right.

Also, counterintuitive means different things to different people. What a scientist thinks is counterintuitive isnt what you will think is counterintuitive.

Van Rijn
2011-Sep-08, 06:09 AM
With non-random results?? Does this really make sense to anyone other than the current participants in this thread??


Non-random? I'd call them probabilistic results.

Van Rijn
2011-Sep-08, 06:34 AM
In the Discussion the authors do mention Europa and Ganymedes (sic) when pointing out the astrobiological significance of their results, but say nothing else.


They really shouldn't have mentioned them at all, given the scope of the model.



I need to reread Survivability of Bacteria in Hypervelocity Impact (http://www.docentes.unal.edu.co/pfdeb/docs/Icarus%20paper.pdf) to be sure, but I'd guess the speeds we're talking won't necessarily be lethal.

That appears to be looking at the effect of velocity [edit: that should be "extreme acceleration"] on the function of bacteria, and the velocities seem to be more in the range of what you'd get with Earth or Mars. I was thinking of the problem of atmospheric entry heating - a big issue with Jupiter.

Jim
2011-Sep-08, 12:16 PM
yeah, sorry about that. couldn't resist dishing ... but i shouldn't have.


Accepted...

I'm glad you two worked this out before someone(s) got in trouble.

A.DIM
2011-Sep-08, 01:04 PM
...with no supportive evidence....fascinating...

Science is the method we use to understand and describe ourselves, the world we live in, the cosmos. I find it fascinating, from a social science perspective, that one could suggest the search for life elsewhere is not a worthy
scientific pursuit.
And of course you understand our single example of life in the universe tells us exactly nothing about its prevalence?


Oh really??

Let's look at the "if's"...

"If" the Earth was impacted in just the right place...and

What do you mean by "just the right place?"

It is thought Impact Event (http://en.wikipedia.org/wiki/Impact_event), a large one, occurs every 10 million years. So, of those that we know of, which do you think were not in "just the right place?"


"If" that ejected material contained life...and

What?!
Life is in every nook and cranny of the Earth's crust. Where do you think no life persists?
Read up on Tardigrades and B Subtillis.


"If" that ejected material moved against gravity toward the outer system...and

"If" it came anywhere near Mars, or Jupiter...and

Well, there is this new study, which builds on others, and shows more material and a higher probability than previously thought ...


"If" that life could survive the travel time...

Yes! A good question.



With all these unproven "If's", and you can't understand my skepticism?

I think understand it, RAF, all too well.
I just don't think it's based on much, let alone "all these unproven "Ifs"

A.DIM
2011-Sep-08, 01:16 PM
They really shouldn't have mentioned them at all, given the scope of the model.

Indeed I found it curious, perhaps foreshadowing future studies.


That appears to be looking at the effect of velocity on the function of bacteria, and the velocities seem to be more in the range of what you'd get with Earth or Mars. I was thinking of the problem of atmospheric entry heating - a big issue with Jupiter.

Yes you're right, the velocities appear lower in that study. And I wonder what kind of temperatures could be reached in entering Jupiter's atmosphere. Of course, that depends on velocity and impact speeds, angle, leading or trailing face ...
yeah, at this time, it appears only detritus would reach Jupiter.

Luckmeister
2011-Sep-08, 06:31 PM
Paradoxically, the older I get, the more irrelevant "the ET life question" is to me. I figure I have maybe 30 years left here, and I just don't think the "question" will be answered in that time.

So...to me...not that interesting...

Then why do you bother to take part in this discussion? Actuaries predict that I have maybe 5 to 10 years left, so should I argue against any project or study that will take longer on that basis? Of course not.

R.A.F.
2011-Sep-08, 07:56 PM
Then why do you bother to take part in this discussion? Actuaries predict that I have maybe 5 to 10 years left, so should I argue against any project or study that will take longer on that basis? Of course not.

I'm not arguing against any...oh never mind...


I'll be back (to this thread) in time for Rosh Hashanah

A.DIM
2011-Sep-08, 08:39 PM
Really, you came back half an hour later to add "(to this thread)" ??

What's the point in that post to begin with?
I don't give two sheets about Rosh Hashanah or the Judeo Christian mythos.
Keep that tripe out of my thread please.
Thanks.

R.A.F.
2011-Sep-08, 09:02 PM
I don't give two sheets about Rosh Hashanah...

We will see...

Swift
2011-Sep-08, 09:11 PM
I'll be back (to this thread) in time for Rosh Hashanah

I don't give two sheets about Rosh Hashanah or the Judeo Christian mythos.
Is it possible for you two to behave? Both of you keep this stuff out of the thread and stick with the topic. And I know both of you know how to report posts if you have problems with the others' posts. You both get zero point infractions for this.

R.A.F.
2011-Sep-08, 09:14 PM
Is it possible for you two to behave? Both of you keep this stuff out of the thread and stick with the topic. And I know both of you know how to report posts if you have problems with the others' posts. You both get zero point infractions for this.

Sorry, Swift...I had hoped that A.DIM would note the "significance" of the date Rosh Hashanah falls on, but i guess not....

A.DIM
2011-Sep-08, 09:42 PM
Yeah, sorry Swift (for responding in-kind).
RAF intended no religious context in posting that.
He's simply looking forward to the day that my thread gets locked.

John Mendenhall
2011-Sep-09, 01:22 AM
Gentle folk, it's a delightful idea, but until we get to Mars, and pick up a meteorite from Earth, and find viable spores inside, it's speculation. But oh my, I do hope it turns out to be true!

grapes
2011-Sep-09, 03:19 AM
I'm here to loc... OK, we'll try one more time.

R.A.F.
2011-Sep-09, 06:08 PM
You'll regret it...:)

A.DIM...if you have something you want to discuss, do so on the open board.

In other words, I have nothing to discuss with you via PM, so you might as well stop sending them.

Garrison
2011-Sep-09, 07:03 PM
Thing is saying this new study increases the likelihood of panspermia is akin to saying the Kepler data increases the likelihood of aliens landing on the Whitehouse lawn. It may be true but it doesn't allow us to quantify the odds and of course there may still be an insurmountable obstacle in the necessary chain of circumstances. In essence panspermia is going to remain decidedly ATM without a lot more evidence.

A.DIM
2011-Sep-09, 09:49 PM
You'll regret it...:)

A.DIM...if you have something you want to discuss, do so on the open board.

In other words, I have nothing to discuss with you via PM, so you might as well stop sending them.

RAF, you're clearly not interested in discussing anything which regards this topic. You admitted not being interested, yet here you are ...

Oh, and as far as PMs go: so long as you refrain from sending them yourself, claiming a "win" when my thread gets locked, I'll not have anything more to say to you.

Back to iggy you go!

A.DIM
2011-Sep-09, 09:52 PM
Thing is saying this new study increases the likelihood of panspermia is akin to saying the Kepler data increases the likelihood of aliens landing on the Whitehouse lawn. It may be true but it doesn't allow us to quantify the odds and of course there may still be an insurmountable obstacle in the necessary chain of circumstances. In essence panspermia is going to remain decidedly ATM without a lot more evidence.

Ballistic panspermia is generally accepted in the mainstream, hence the reason we can find numerous peer reviewed papers studying it.
Because BAUT deems it ATM doesn't actually mean it is ATM.

Van Rijn
2011-Sep-09, 10:28 PM
Ballistic panspermia is generally accepted in the mainstream, hence the reason we can find numerous peer reviewed papers studying it.


Define "generally accepted."

From what I've seen, interstellar panspermia is generally considered too implausible to warrent much consideration or research. The material would be in space too long because, among other things, radiation will damage DNA. And space is big, so the probability of a rock finding another habitable target is very low.

Interplanetary panspermia, on the other hand, looks a lot more interesting. The time span is shorter, the probabilities of impact higher. The possibility seems to be taken seriously *for research purposes*. It isn't generally accepted that life was transferred in the solar system, but it generally is considered a question worth looking into.

I agree with that: The subject is interesting and should be discussed. That's far different than accepting panspermia has happened, however.


Because BAUT deems it ATM doesn't actually mean it is ATM.

Well, I personally don't think discussions about possibilities and mechanics of interplanetary panspermia should be considered ATM as long as participants don't draw ATM conclusions or argue ATM mechanisms. However, I do consider discussions of interstellar panspermia to be ATM, especially given that such discussions usually include other ATM claims that seem to be part of a common agenda (like arguments against abiogenesis, or a claim that the universe has existed in its current form forever).

R.A.F.
2011-Sep-09, 11:34 PM
RAF, you're clearly not interested in discussing anything which regards this topic. You admitted not being interested, yet here you are ...

Well, if I'm not taking or sending you PM's, how in the heck was I suppose to tell you to stop??


...claiming a "win" when my thread gets locked...

Yes...a "win" for rationality.* :)


*While not posted in "confidence", I didn't expect you to try and "use" my PM in an attempt to embarrass me.

...and you wonder why I want to keep this to the open board??...sheesh.

R.A.F.
2011-Sep-09, 11:39 PM
Because BAUT deems it ATM doesn't actually mean it is ATM.

Because A.DIM deems it mainstream, doesn't actually mean it is mainstream.

R.A.F.
2011-Sep-09, 11:41 PM
...I personally don't think discussions about possibilities and mechanics of interplanetary panspermia should be considered ATM as long as participants don't draw ATM conclusions or argue ATM mechanisms.

Aye...there's the "rub".

A.DIM
2011-Sep-09, 11:56 PM
Define "generally accepted."
...
Interplanetary panspermia, on the other hand, looks a lot more interesting. The time span is shorter, the probabilities of impact higher. The possibility seems to be taken seriously *for research purposes*. It isn't generally accepted that life was transferred in the solar system, but it generally is considered a question worth looking into.

That's much like my definition for "generally accepted." I would add that the idea seems to be a central tenet of Astrobiology, given the spate of research over the last 10-15yrs. Things like Mars material reaching Earth, extremophiles surviving conditions of space, potentially habitable environs elsewhere in the solar system and more lend to the idea as well.


I agree with that: The subject is interesting and should be discussed. That's far different than accepting panspermia has happened, however.

I agree with that.


Well, I personally don't think discussions about possibilities and mechanics of interplanetary panspermia should be considered ATM as long as participants don't draw ATM conclusions or argue ATM mechanisms. However, I do consider discussions of interstellar panspermia to be ATM, especially given that such discussions usually include other ATM claims that seem to be part of a common agenda (like arguments against abiogenesis, or a claim that the universe has existed in its current form forever).

Certainly I recognize ballistic panspermia as being far more likely but I don't simply discount the possibility of interstellar panspermia either. Yes, the time spans seem insurmountable but comets and wayward planets / moons are potential mechanisms for such transport. I don't really consider that ATM in thought. Of course, I understand BAUT does.

Garrison
2011-Sep-10, 09:41 AM
Certainly I recognize ballistic panspermia as being far more likely but I don't simply discount the possibility of interstellar panspermia either. Yes, the time spans seem insurmountable but comets and wayward planets / moons are potential mechanisms for such transport. I don't really consider that ATM in thought. Of course, I understand BAUT does.

And that is where your ideas cross the line from a reasonable conjecture to wild fantasy, there may be a small possibility that interplanetary panspermia could happen, though none that it has of course. Interstellar panspermia is orders of magnitude more complex, to the point indeed where it is reasonable to reject it without compelling evidence.

A.DIM
2011-Sep-10, 01:10 PM
And that is where your ideas cross the line from a reasonable conjecture to wild fantasy, there may be a small possibility that interplanetary panspermia could happen, though none that it has of course. Interstellar panspermia is orders of magnitude more complex, to the point indeed where it is reasonable to reject it without compelling evidence.

Well, this thread isn't about interstellar panspermia so let's not get sidetracked.
I will however point out that A mechansim for interstellar panspermia (http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2966.2004.07287.x/abstract) was published in Monthly Notices of the Royal Astronomical Society, a mainstream peer reviewed journal.
Do you think the RAS is in the business of publishing wild fantasy?

Garrison
2011-Sep-10, 01:27 PM
Well, this thread isn't about interstellar panspermia so let's not get sidetracked.
I will however point out that A mechansim for interstellar panspermia (http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2966.2004.07287.x/abstract) was published in Monthly Notices of the Royal Astronomical Society, a mainstream peer reviewed journal.
Do you think the RAS is in the business of publishing wild fantasy?

I think they may well publish things that
turn out to be fantasy, yes. The paper is 7 years old, has anything emerged to support this hypothesis? And I must say you have an odd way of avoiding getting sidetracked...

A.DIM
2011-Sep-10, 01:49 PM
I think they may well publish things that fantasy, yes.
Yes, I suppose then the same could be said for any mainstream peer reviewed journal.


The paper is 7 years old, has anything emerged to support this hypothesis? And I must say you have an odd way of avoiding getting sidetracked...
Well, I only wanted to leave you with something that might have you rethink dismissing it as "wild fantasy."

I think I had a thread here specifically on this paper. You could look there for other info I likely provided on the topic; certainly independent research helps too.

Garrison
2011-Sep-10, 02:01 PM
Well, I only wanted to leave you with something that might have you rethink dismissing it as "wild fantasy."



Are you prepared to state a case in your own words for interstellar panspermia as a credible theory and defend it? So far I've seen nothing to make me take it seriously so until you choose to do so I'm going to it regard it as, perhaps far fetched speculation is the better description.

Paul Beardsley
2011-Sep-10, 02:07 PM
This is a bewildering thread.

If I understand it correctly, it began as no more and no less than a discussion about a realistic set of simulations to work out how material might behave if dislodged from the Earth's surface.

Now anybody who has read any of A.DIM's previous threads will know his motivation for presenting this. However, never mind the motivation, the fact remains that it is a legitimate and interesting topic, and I think the hostility is, in this case, unwarranted, and I don't believe this thread belongs in ATM.

This thread considers the possibility (or otherwise) of ejected material reaching other worlds. That is not the same as asserting that this has indeed happened, is how life reached Earth and so on.

Credit to A.DIM for attempting to keep on track, and bonus points for not mentioning The Copernican Principle or Mediocrity. But oh, how I wish you'd finished post 70 two sentences earlier!

captain swoop
2011-Sep-13, 11:56 AM
This thread puzzles me.

A.DIM Can you tell me what your ATM idea is within the rules of the Forum and show what support you have. As far as I can see it is just some general musing mixed in with a lot of noise.
If you can't or won't present a coherent ATM idea to defend and advocate then I am closing this thread

A.DIM
2011-Sep-13, 01:31 PM
This thread puzzles me.

A.DIM Can you tell me what your ATM idea is within the rules of the Forum and show what support you have. As far as I can see it is just some general musing mixed in with a lot of noise.
If you can't or won't present a coherent ATM idea to defend and advocate then I am closing this thread

You're puzzled? Join the club!
The thing is, captain swoop, there is nothing inherently ATM about the paper I shared.
This thread doesn't belong here, as indicated by several other members, and I still don't know which Mod (although I assume it was Moose) is responsible for moving it, or what reasoning.

This thread should be in LiS. Life is on Earth. Earth has been impacted. Material exchange in our system is factual.
This is merely a model which suggests more material reaching more places.
Is that ATM?
If so, why?

Swift
2011-Sep-13, 02:09 PM
Sorry if that warning was not clear. After some discussion among the moderators, here is the deal.

The thread is to narrowly stay focused on what A.DIM mentioned in the first sentence of the OP - "the probability and amount of lifebearing ejecta from Earth reaching other bodies". That's it, Earth-to-elsewhere panspermia. It is not to become a general discussion of panspermia. As long as it stays on that focus, it will have its 30 days.

A.DIM
2011-Sep-13, 03:07 PM
Sorry if that warning was not clear. After some discussion among the moderators, here is the deal.

The thread is to narrowly stay focused on what A.DIM mentioned in the first sentence of the OP - "the probability and amount of lifebearing ejecta from Earth reaching other bodies". That's it, Earth-to-elsewhere panspermia. It is not to become a general discussion of panspermia. As long as it stays on that focus, it will have its 30 days.

Thanks Swift.
Although I'd still like an explanation as to why this topic should be considered ATM to begin with.

I don't have much else to say about the topic so after an explanation feel free to lock it.

Swift
2011-Sep-13, 03:15 PM
Thanks Swift.
Although I'd still like an explanation as to why this topic should be considered ATM to begin with.

I don't have much else to say about the topic so after an explanation feel free to lock it.
Moose covered the why in this post (http://www.bautforum.com/showthread.php/120301-Dynamics-of-escaping-Earth-ejecta-...?p=1929946#post1929946). It will not be debated any more in this thread. If you want to debate the policy, start a thread in Feedback.

I'll leave the thread open for the moment, in case there are any other questions about the specific topic of this thread, or you change your mind and want to add something.

HenrikOlsen
2011-Sep-13, 05:08 PM
So basically we have a paper showing, through computer simulation, that ejecta from the Earth, assuming it can be generated, has a reasonable chance of reaching bodies (The Earth, The Moon, Venus, Mars, Jupiter) in the solar system within 5-30 thousand years, which time frame was picked in part because it's considered the maximum survival time for biological organisms in space.

And the new thing that paper showed is that the previous estimate for how much material would end up on Mars and Jupiter was too low.

Methinks the media seriously oversold this story.

transreality
2011-Sep-20, 12:49 AM
Do i understand the results here? The table of data seems to show that in the narrow ejection range of velocities that life is assumed to be able to survive, that effectively nothing leaving will hit any inner system target within the 30,000 year putative survival period (0.01% to Mars for example), but that just about everything that goes somewhere in that period will return to the Earth, or hit the Sun or be ejected from the inner system, and that most things will still be floating in the inner system, for much much longer. The fastest Mars to earth bolide recorded is about around 115,000 years, so that may support that finding. Also that ejecta will preferably head in system rather than out, making Earth not a great source of material to Mars and Jupiter. Not great prospects for interplanetary transport of hitchhiking microbes.

If space wasn't such a hostile environement to life, it could be a repository for old microbe species, like influenza virus, ejected then fall back to earth 30,000 years later, ready to re-infect now that resistance has vanished.

HenrikOlsen
2011-Sep-20, 07:33 AM
I think you do understand the result, the only thing new in the paper is that, if the assumptions for their calculations are correct, the rate of transport of material to Mars and Jupiter is a bit larger than previously calculated. But still really, really small.