Slashdot: Scientists Study Trajectories of Life-Bearing Earth Meteorites

[The Caretaker]

It's been my anecdotal experience (over a wise range of circles/venues with this being a regular topic for me for 50 years) that people who are highly skeptical about life on other planets were more often religious believers than not (mainly Christians in my case, logically, but not exclusively of course). And what access I have to data from actual studies, some tangential to my profession, supports that---just to comment on that side issue.

Have to add (as Larry will know) that more than a few cool science fiction stories has addressed how organized religion might handle the appearance of an advanced alien civilization with either the same/similar God mythos, or a way different one, or none, or (of course a common theme in the genre) that the aliens are "God" in terms of being responsible for life on earth and how that new found knowledge then impacts our world.

I too support the math and certain other extrapolations of logic that make it seem pretty damn likely it's out there. But at this point I lean towards the side of the math and logistics and species developmental dynamics (limited to our understanding of them) that suggest contact may be highly unlikely for many many millennium (the odds, based on those aforementioned factors, being very small). Love to be wrong about the contact.

Yea I agree, direct contact seems unlikely for quite a bit, barring a technological revolution that breaks the speed of light law, or utilizes the wormhole theory. Our best chance for contact would be through radio waves via the S.E.T.I project, atleast with intelligent creatures. Our first contact, assuming that life elsewhere exists will most likely be with microbiota. Mars and the moon Europa (of Jupiter) seem like the best bets in our cosmic neighborhood, Europa in particular is facinating, the idea of a massive H2O based ocean underneath a miles-thick frozen surface, filled with oceanic life is something that needs to be explored.

We will probably have to wait for one or more additional missions to Jupiter and Europa to verify the presence of liquid water and life on Europa. The planning for these missions is just getting underway. Current plans call for the use of radar to identify possible ice-water and water-rock interfaces on Europa and for the return samples of the surface ice. The mission, currently called the "Europa Ice Clipper," is scheduled for launch in 2001 and could return ice samples to Earth by 2009. Europa's distance from the Earth and Sun and its thick layer of ice will make exploration difficult. However, discovering life on Europa would double the number of planets we know of with endogenous life. Even if no evidence of life on Europa is found, its exploration would provide a wealth of information about the chemistry and planetary physics of a very interesting body. Such information could help us better understand the atmospheric chemistry (with implications for global warming models), geophysics and other practical issues here on Earth.

http://people.msoe.edu/~tritt/sf/europa.life.html

Digging through miles of ice, all the way in Jupiter's neighborhood is a bit of an issue though with current technology , doesn't help that NASA gets little in the form of funding, which is a shame.

[Bang]

I think you misunderstand the scientific process.

When Einstein came up with general relativity, it was not "real" either. There was certainly little if any solid proof for it. Over the next century, he was eventually proven right, but the scientific process requires that theories be proposed before they are tested. A lot of people guessed what the moon was like before we landed on the moon. The standard model of particle physics predicts that the Higgs Boson exists, but we have never detected a Higgs Boson. Astrobiologists dream up theories of how life could reach other planets, and we wait for ways to test their theories. That is how science moves forward.
.

I get it, but I think there's a large difference in this.. Higgs Bosun for example is predicted because there IS an effect to which we have no explanation as to cause. So they hypothesize this particle is what is causing the effect that IS there, and then look to prove that.

In the case of extraterrestrial life, there is no effect to which we hypothesize the cause. There is nothing we have ever discovered to lead anyone to believe "somehing must have caused" this impression of life elsewhere.
Right now the only effect is that the numbers seem to indicate the odds are very high that life exists elsewhere, simply because of how large "elsewhere" is.
The only actual effects that have been caused by life of which we've ever had any observation is here on earth.

In the case of Einstein's theory, unless I'm way off base, it is a theory predicated on some constants that we already know exist. They provide the launching point from which to discover the cause of the effect.
In the case of extraterrestrial,, like i said above,, the alien life may be so alien we don't even recognize it as life. The possibilities of what it might be are endless, and not bound by the constraints of human imagination. There is no launching point. It is all entirely and completely speculative, and any science applied to it can't possibly begin to provide that point.

So I find it hard to swallow the notion of AstroBiologty as a study, because there is no other biology we know of at all out there to form any basis of theory at all, other than calculating the odds it's there.


But I may be in over my head.

~Bang

[DjTj]

Even as a Christian, I was with you until right here.

I believe that, but I surely don't believe it's a "proven fact."

That is an interesting stance to me, but I suppose I think about Christianity from more of an Apologetic perspective, and I prefer to ground my beliefs in facts. It perhaps shows that there is great diversity even among those who call themselves religious or call themselves Christians.

I disagree with much Dj's last paragraph. Along with what you said, and even if he didn't intend to convey this, there's an implication (to my reading of it) that in the claim of "believers" being less likely to accept evolutionary or climate theories is based on skepticism of the nature of being more demanding about precision of evidence. The more logically/factually supportable premise for such, when/if so, is that far more often they'd likely do so more out of the very nature of how their religious beliefs (their way of internalizing and structuring those beliefs) make them simply highly resistant to any science (or other matters) they find disturbing to some aspect that faith/belief system (including how the cocnept of man overvaluing or "glorifying" himself and his works is "dangerous" and even sinful) for one reason or another.

I think my broader point is that religious and non-religious people can't be neatly divided into "people willing to believe things without evidence" and "people not willing to believe things without evidence." Religion affects how people value certain types of evidence, and I think it's incorrect to think of religious people as those willing to believe things on faith and faith alone. There are many spiritual (but not religious) people who put a lot of trust in their feelings, and there are religious people who base their faith on evidence.

I think you properly characterize the motivations for many Christians' opposition to science, but the way it manifests itself is not as a request for more faith but a request for more evidence. The arguments are that the Bible (or some other more trusted authority) provides a more reliable fact than the fossil record (or some other untrusted authority). It plays out in the public sphere as a fact vs. fact debate rather than a faith vs. fact debate. It's not really a dispute about precision of evidence, but about reliability of evidence. And peoples' fundamental assumptions differ in that respect.

[alexey]

Considering the numbers, it seems EXTREMELY unlikely that our planet is the only planet with life on it in the Universe.

---------- Post added April-12th-2012 at 12:50 PM ----------

I think it's incorrect to characterize religious faith as a belief in things without proof.

More like, different standards of proof.

Some people have serious reservations about those standards. Specifically, their apparent slant to provide a desired theological conclusion in favor of a particular religion.

Does it not seem strange when people say you know, I studied these things long and hard. I examined evidence for all major religions of the world. I applied the same criteria to all of the them, and I can honestly say that the religion into which I happen to be born is the correct one? Who are you to say that Mohammed had hallucinations while followers of Jesus witnessed a real miracle?

(a miracle that was documented 30+ year later, in a different location, written in a different language, by different people, with the purpose of conveying the good news and converting other people)

Christians don't believe in Jesus Christ without proof. The birth, death, and resurrection of Jesus are historical facts, corroborated by many different accounts.

I devoted a great deal of time discussing historical basis for resurrection with techboy here. I am familiar with William Lane Craig and his "probability calculus" baloney. Resurrection of Jesus is not a historical fact.

[Teller]

That is an interesting stance to me, but I suppose I think about Christianity from more of an Apologetic perspective, and I prefer to ground my beliefs in facts. It perhaps shows that there is great diversity even among those who call themselves religious or call themselves Christians.

Oh certainly. And look, no one composes their arguments around here with more factual support than you do. We don't get Teej opinions for the most part. We get Teej saying "Here are the facts. And here's a reliable link to back it up."

I guess it surprises me that you would simply accept the Resurrection as historical fact. (Pleasantly surprises me, BTW.) But this is a case, IMO, where you can't put forth a reliable link that provides reliable evidence. That's not to be critical, but it just surprises me that someone so factually-grounded would just accept the eyewitness accounts in the Bible. But as I said, I don't consider that a bad thing either.

[DjTj]

More like, different standards of proof.

Some people have serious reservations about those standards. Specifically, their apparent slant to provide a desired theological conclusion in favor of a particular religion.

I don't think history is a science, and I don't think it is possible to prove something about history to the same extent that it is possible to prove something in science. You are correct that there are very different standards of proof between the sciences and the humanities. History cannot be tested by experiment, since history is trying to recount things that have already happened, rather than make predictions about the future.

Does it not seem strange when people say you know, I studied these things long and hard. I examined evidence for all major religions of the world. I applied the same criteria to all of the them, and I can honestly say that the religion into which I happen to be born is the correct one? Who are you to say that Mohammed had hallucinations while followers of Jesus witnessed a real miracle?

(a miracle that was documented 30+ year later, in a different location, written in a different language, by different people, with the purpose of conveying the good news and converting other people)

I am pretty universalist in my beliefs, and I don't think that believing in Jesus's resurrection necessarily relegates Mohammed's experiences to hallucinations. From what I understand, Jesus and Mohammed agreed on a great many things. I won't make any claim to have studied all religions long and hard or to have applied the same criteria to all of them. I will only claim to be comfortable in my beliefs right now, and remain open to further changes.

I devoted a great deal of time discussing historical basis for resurrection with techboy here. I am familiar with William Lane Craig and his "probability calculus" baloney. Resurrection of Jesus is not a historical fact.

I'll admit to not being as well versed in this subject matter as techboy, but from what I can read about Dr. Craig's "probability calculus" theory, I don't agree with it. And generally I think that applying science directly to religion, or even to many of the humanities, is unreliable. But I do think that everyone would have to admit that there is historical support for the resurrection, and that there are also reasons to seriously question it.

History is a funny thing and is really different from science in some ways. Because in history things actually happened, even though it is hard for us to determine what those things actually were. Who killed JFK? How did they build the pyramids? What really happened between George Zimmerman and Trayvon Martin? We can't even be totally sure about things that happened a few weeks ago, even though something specific definitely happened.

I think that reasonable people can disagree about whether Jesus was resurrected, and it is reasonable to be agnostic about it, but it either happened or it didn't. We can assign some probabilities to it, but it's not quite like science where we can set up an experiment that proves (or disproves) things one way or the other. And at this point it is even pretty unlikely that much additional historical evidence is going to turn up that really pushes the probability in one way or the other. I'll admit that I have gone back and forth on the idea in the past, but I have found enough evidence to believe.

Oh certainly. And look, no one composes their arguments around here with more factual support than you do. We don't get Teej opinions for the most part. We get Teej saying "Here are the facts. And here's a reliable link to back it up."

I guess it surprises me that you would simply accept the Resurrection as historical fact. (Pleasantly surprises me, BTW.) But this is a case, IMO, where you can't put forth a reliable link that provides reliable evidence. That's not to be critical, but it just surprises me that someone so factually-grounded would just accept the eyewitness accounts in the Bible. But as I said, I don't consider that a bad thing either.

It seems to me that, to be a Christian, you need to believe that the resurrection was a historical fact. You have to believe that it actually did happen. And it doesn't seem like you can just believe it based on faith because that seems circular to me. The fact of the resurrection is really the basis for Christian faith, and it seems crazy to rest your faith only on faith.

You're probably right that other people don't need as much factual support as I do to believe in things, and I believe you if you say that it leads you both to religion and to a belief in aliens. But it doesn't seem like there is generally a high correlation between religious belief and belief in aliens, so most people probably aren't thinking about it in the same way you are or the way that I am. We're probably in different minorities in our thinking on both of these issues.

[Renegade7]

Even if ejecta did reach Europa and Enceladus, that doesn't mean the life was able to make it to their possible sub-surface oceans. There surface is still sub-freezing, and look to of still been that way 65 million years ago.

The reality is, we keep debating about whether or not we're the only place in the entire universe to have life when we haven't even finished the proper research on our own solar system yet. All that SETI stuff is nice, but if we really want to see if there's extraterrestrial life or not, we need to drill a hole through Europa to prove whether or not there's liquid water there, then go further to find any volcanic surface vents that might harbor life around it. Life doesn't need much...

I wonder if and what effect that ejecta would have on Titan. Hmmmm...

[PeterMP]

Life doesn't need much.

We know that life doesn't need much once it is up going at some sort of substantial level. We have no idea what it really takes to start life. We really have no idea how many times on this planet there was some sort of "life" that went "extinct" without progressing to the level that it doesn't need much.

With respect to life on planets, we have a single data point essentially (all life as we know it on Earth today is believed to have come from a single common ancestor), and most of our conclusions are based on very distant extrapolations (i.e. we are looking at life after it has been around for a very long period of time and trying to say something about how easy it is for it to start).

I'd be hesitant drawing conclusions about the probability of an event based on a single data point that requires such extrapolations.

[Corcaigh]

But at this point I lean towards the side of the math and logistics and species developmental dynamics (limited to our understanding of them) that suggest contact may be highly unlikely for many many millennium (the odds, based on those aforementioned factors, being very small). Love to be wrong about the contact.

We are already here.

[alexey]

I'll admit to not being as well versed in this subject matter as techboy, but from what I can read about Dr. Craig's "probability calculus" theory, I don't agree with it. And generally I think that applying science directly to religion, or even to many of the humanities, is unreliable. But I do think that everyone would have to admit that there is historical support for the resurrection, and that there are also reasons to seriously question it.

In order to see historical evidence for resurrection, you must have a preexisting faith that there is a God, and that God can will a supernatural event to happen.

In other words, if you do not believe in the supernatural, then there can be no evidence of the supernatural. There can only be evidence of the natural but yet unknown.

History is a funny thing and is really different from science in some ways. Because in history things actually happened, even though it is hard for us to determine what those things actually were. Who killed JFK? How did they build the pyramids? What really happened between George Zimmerman and Trayvon Martin? We can't even be totally sure about things that happened a few weeks ago, even though something specific definitely happened.

Besides actual facts, things that can be recorded with a videocamera, there are also interpretations.

For example, if grieving people who really loved Trayvon Martin reported experiencing visions of Trayvon or hearing Trayvon's voice, or both, there would be several different ways of interpreting the fact of that experience (real experience, mind you!). Some may say that such things are well known and are actually quite frequent. Others may say that Travyon got resurrected. And actually, if that happened, he kind of did get a little bit resurrected.

I think that reasonable people can disagree about whether Jesus was resurrected, and it is reasonable to be agnostic about it, but it either happened or it didn't. We can assign some probabilities to it, but it's not quite like science where we can set up an experiment that proves (or disproves) things one way or the other. And at this point it is even pretty unlikely that much additional historical evidence is going to turn up that really pushes the probability in one way or the other. I'll admit that I have gone back and forth on the idea in the past, but I have found enough evidence to believe.

You need to have faith that such things are possible in order to even go there.

And once you open that door, with a little bit of faith, you can grow that faith by finding evidence to believe some more.

It seems to me that, to be a Christian, you need to believe that the resurrection was a historical fact. You have to believe that it actually did happen. And it doesn't seem like you can just believe it based on faith because that seems circular to me. The fact of the resurrection is really the basis for Christian faith, and it seems crazy to rest your faith only on faith.

I think the opposite. You pretend that your faith is based on historical evidence, but your interpretation of evidence relies on faith to begin with.

Faith is faith. It is supposed to be circular, self-reinforcing, etc. Wear it with pride.

[Larry]

We know that life doesn't need much once it is up going at some sort of substantial level. We have no idea what it really takes to start life. We really have no idea how many times on this planet there was some sort of "life" that went "extinct" without progressing to the level that it doesn't need much.

Agreed.

Fire doesn't need much, once it's started. Starting it when you don't have any can be a serious ****.

That's why I raised the possibility that maybe life on Earth came from somewhere else.

The [i]simplest[/u] life forms that we recognize as such, are incredibly complex. So much so that, IMO, the creationists who point out the incredible odds of those exact chemicals just happening, through random chance, to come together in that exact pattern, are astronomical, actually have a bit of a point.

Now, if that "primitive, but still incredibly complex" chemical happened to come from some place else? It would certainly explain the "where did the first one come from?" question.

---------- Post added April-13th-2012 at 11:49 AM ----------

I too support the math and certain other extrapolations of logic that make it seem pretty damn likely it's out there. But at this point I lean towards the side of the math and logistics and species developmental dynamics (limited to our understanding of them) that suggest contact may be highly unlikely for many many millennium (the odds, based on those aforementioned factors, being very small). Love to be wrong about the contact.

Actually, I recall a scientific/philosophical piece I'd read, some time ago, regarding what the author says is known as "The Fermi Question".

Background: Enrico Fermi was known for asking what came to be referred to as "Fermi questions". An example of a Fermi question was "How many golf balls will fit in a car?"

Now, note. Fermi did not specify a car. Or even a type of car. And he didn't specify whether he was referring to the capacity of the trunk, the passenger compartment, or both.

But, one of the rules of a Fermi question was that he was looking for a very rough approximation. Typically, it was agreed that all he was looking for was an order of magnitude.

He wanted to know if the number of golf balls that would fit in a car, was closer to 1,000, or 10,000, or 100,000.

So, to solve the golf ball question, it is suffecient to assume that the passenger compartment of a car, is 5 feet by five feet by 3 feet, yielding a volume of 75 cubic feet. You assume that 20% of that volume is occupied by seats and things, leaving 60 cubic feet, or 103,000 cubic inches. You assume that a golf ball has a volume of 1 cubic inch, and that golf balls achieve a "packing factor" of 75%. (Meaning, when you "fill" a container with golf balls, 25% of the volume is still "space between golf balls".)

This gives you an estimate of 78,000 golf balls, so you conclude that the answer is closer to 100,000 than it is to 10,000

Now (according to this column I read), the Fermi question involves looking at "the odds of life"

Scientists say that the average galaxy contains billions of stars. And that there are billions of galaxies. Resulting in (rough estimate) 10^18 stars

If you assume that the odds of a star having a planet in the "comfort zone" is 1 in 1,000, then you've got 10^15 "comfortable planets".
If you assume that the odds of a "comfortable planet" developing organic chemicals are 1 in 1,000, you get 10^12 planets.
If you assume that the odds of those chemicals forming single-celled organisms is 1 in 1,000, you get 10^9 planets.
Assume that the odds of those organisms forming multi-celled organisms is 1 in 1,000, you get 10^6 planets.
Assume that the odds of human-level intelligence are 1 in 1,000, you get 10^3, or 1,000 human-level civilizations.

Now, though, the catch is, if you assume that humanity is simply the product of random chance, (Maybe rare random chance. Like winning the lottery rate.), then you still get the result that human-level civilization has occurred thousands (millions? billions?) of times.

And, if you assume that humanity is "average", then that would mean that half of those civilizations are older than ours.

And, that's older, by an astronomical time scale.

Half of those civilizations should be older than humanity, not just by 100 years or two, but by millions of years.

So, The Fermi Question is "Where are they?"

The planet Earth, right now, emits more radio frequency energy than the sun does, And that usage is growing exponentially.

Fermi's point is that, if you subscribe to the "humanity is just random chance" theory, then there ought to be intelligences, out there, which have been broadcasting their intelligence, simply by their technology. And they should have been doing so for millions of years.

[PeterMP]

Agreed.

Fire doesn't need much, once it's started. Starting it when you don't have any can be a serious ****.

That's why I raised the possibility that maybe life on Earth came from somewhere else.

The [i]simplest[/u] life forms that we recognize as such, are incredibly complex. So much so that, IMO, the creationists who point out the incredible odds of those exact chemicals just happening, through random chance, to come together in that exact pattern, are astronomical, actually have a bit of a point.

Now, if that "primitive, but still incredibly complex" chemical happened to come from some place else? It would certainly explain the "where did the first one come from?" question.

The general problem with that reasoning is there is no reason to believe that some other place non-biologically will have more complex molecules than on Earth.

Saying they might have come from some place else doesn't really help because we don't of any where else that is a better place for them to have come from.

The easier way to deal with the problem is to say that maybe life doesn't need the level of complexity that we see today.

The largest level of complexity in life is the 3 biopolymers that all life (not including viruses) that we know of today are dependent on: DNA, RNA, and proteins.

Of the three, the most complex is proteins because they are polymers, but are made from 20 different monomers, which while similar also show a diverse set of chemical functionality.

So if you set the bar for life is that it requires proteins, you've set a very high bar.

However, we know today that RNA can do most of the general jobs that proteins do in basic living organisms. It doesn't do it as well, but it can do it, and in no case have the proteins been completely replaced by RNA by humans (at one point in time there was an effort to remove proteins and find RNA molecules to replace them with and see how many proteins you could replace and than still get something alive.).

If you can get rid of proteins as a pre-req for life, then you've simplified the problem.

Imagning getting rid of DNA is even easier. DNA and RNA are very similar. There isn't really anything that DNA can do that RNA can't. DNA is actually better because it is less reactive. DNA is used as the genetic information of every living thing, but there are viruses that use RNA as their genetic information.

If you can say we need a single polymer to have life, then you have even fewer issues.

The other nice thing about RNA is that it is known that, under the right conditions, it will catalyze the formation of other RNA molecules. Not- itself, but other molecules.

And people have even created a self-repicating RNA molecule (under very specific conditions w/ human made pre-cursors though).
http://www.sciencedaily.com/releases...0109173205.htm

If you can imagine a single self-replicating molecule coming about where the progeny aren't exact replicates of itself (which is almost certainly assured because of entropy) and are independent of the parent when produced, then you have a system where natural selection will take over, and you'd get "life".

Though, I'd imagine to get life to really expand, you'd need to reach some sort of critical mass in terms of diversity.

Now, there are issues with life starting on Earth. The evidence for life is being pushed further and further back on a geological time scale. Biologists are now finding "fossils" that are indications of life that are dating not to long after the geologists think the Earth cooled, which would seem to suggest that if life started on Earth, it did so pretty quickly as most don't believe that you could have life on uncooled Earth.

Or somebody is wrong (the biologists aren't really finding "fossils" of life, they have their dating wrong, or the geologists are wrong about how long it took the Earth to really cool).

[DjTj]

In order to see historical evidence for resurrection, you must have a preexisting faith that there is a God, and that God can will a supernatural event to happen.

In other words, if you do not believe in the supernatural, then there can be no evidence of the supernatural. There can only be evidence of the natural but yet unknown.

I don't quite agree with this, because completely rejecting the supernatural is an assumption as well. I would say that we have evidence of something occurring but whether it is natural or supernatural is unknown. The evidence itself is agnostic unless you make an assumption either that supernatural forces exist or do not exist.

I think the opposite. You pretend that your faith is based on historical evidence, but your interpretation of evidence relies on faith to begin with.

Faith is faith. It is supposed to be circular, self-reinforcing, etc. Wear it with pride.

I think you have stated this well. I disagree with your use of the word "pretend," here, but I would say that my faith is based on a historical event. Whether that event actually occurred or not is a matter of historical evidence, but I would agree that my trust in a certain interpretation of that evidence is aided by a self-reinforcing faith and some personal biases. I can understand how people can reach the opposite conclusion, and sympathize strongly with an agnostic view.

...and nobody's claiming visions of Trayvon Martin. You at least have to agree that it's more likely that Jesus was resurrected than that Trayvon Martin was resurrected.

To try to bring this back to the topic of the thread, it has always been my belief that modern science is wholly compatible with the supernatural. With our current understanding of the probabilistic nature of quantum physics and the rejection of a clockwork universe theory, we seem to live in a world that we can describe pretty well with mathematical rules but where many things remain unexplained and unpredictable, and of course science explains some of the "how" and "what," but not the "why." It seems like we may never be able to clearly distinguish between certain things that could be supernatural or, as you say, natural but unknown.

In the case of extraterrestrial life, there is no effect to which we hypothesize the cause. There is nothing we have ever discovered to lead anyone to believe "somehing must have caused" this impression of life elsewhere.

There is some astrobiological data we're collecting around the solar system. We keep sending rovers to Mars in search of evidence of life:

http://www.msnbc.msn.com/id/45437842.../#.T4hV5-1x56s

And we recently dropped a probe on Titan to examine some interesting chemistry:

http://www.nature.com/nature/journal...l/438756a.html

Astrobiologists need to come up with hypotheses to tell those probes what to look for. If we didn't have a working theory for how life might have arisen on these planets, and what it might look like, we wouldn't be able to design instruments to look at it. And once we get some data, scientists need to interpret it to determine whether it is evidence for life. So astrobiologists do studies like this:

http://news.nationalgeographic.com/n...o-acids-bases/

Theories and experiments about astrobiology on earth can help guide our exploration of other worlds, and if you're really looking for a problem that astrobiologists need to solve, that is it: When we send a probe to Mars or Titan or Europa and search for life, what should we look for? How do we know whether it originated there or on earth? How do we interpret the data that we receive? And we do need scientists to try to answer those questions before we build the probes, because you can't swap out different tools when you're millions of miles away.

[PeterMP]

Fermi's point is that, if you subscribe to the "humanity is just random chance" theory, then there ought to be intelligences, out there, which have been broadcasting their intelligence, simply by their technology. And they should have been doing so for millions of years.

With respect to life, the issue is better known as the Fermi paradox.

http://en.wikipedia.org/wiki/Fermi_paradox

I'd be curious in terms of how fast planets cool in terms of their distance form the Big Bang. Is there an expectation that there is a lot of variation on how fast Earth-like planets cooled in different galaxies.

I don't know?

[DjTj]

With respect to life, the issue is better known as the Fermi paradox.

http://en.wikipedia.org/wiki/Fermi_paradox

I'd be curious in terms of how fast planets cool in terms of their distance form the Big Bang. Is there an expectation that there is a lot of variation on how fast Earth-like planets cooled in different galaxies.

I don't know?

There is also the issue of how easily planets formed closer to the Big Bang. In general, it took some time for heavier elements to form, so a planet like ours, with an iron-nickle core was less likely to form earlier in the universe's history.

We're only now starting to find planets that are much older than our solar system: http://www.msnbc.msn.com/id/46910290.../#.T4hja-1x56s