Is there life in the universe, and if so has it visited Earth?

[phyzmatix]

This is totally off-topic (forgive me), but I couldn't help thinking about this when I read Ivan's post on the methane found on Mars.

This is old knowledge, but to me it serves as a reminder that life can and does exist in the strangest, most extreme environments imaginable (even here on our watery, green planet):

These bacteria survive temperatures ranging from 147°F (64°C) to 225°F (107°C).

Bacteria are happy to exploit the crooks and crevasses of rocks. However, some bacteria don't just live inside these cracks, they live inside the actual rocks. They exist as the only organisms on the planet that are completely independent of any oxygen produced by photosynthesis.

http://www.calacademy.org/exhibits/xtremelife/life_on_earth.php

Microbes are known to grow at -12 °C, and they survive at -20 °C. Some studies even hint that a bacterium called Colwellia psychrerythraea strain 34H can withstand -196 °C, the temperature of liquid nitrogen.

http://www.newscientist.com/article/dn14208?feedId=online-news_rss20

Extremophiles

Intro to the Archaea

http://www.microbeworld.org/microbes/archaea/

 

[The Dagda]

This is totally off-topic (forgive me), but I couldn't help thinking about this when I read Ivan's post on the methane found on Mars.

This is old knowledge, but to me it serves as a reminder that life can and does exist in the strangest, most extreme environments imaginable (even here on our watery, green planet):





http://www.calacademy.org/exhibits/xtremelife/life_on_earth.php



http://www.newscientist.com/article/dn14208?feedId=online-news_rss20

Extremophiles

Intro to the Archaea

http://www.microbeworld.org/microbes/archaea/

Actually isn't that rather totally on topic?

 

[phyzmatix]

Actually isn't that rather totally on topic?

I wasn't so sure if I could, through implication, link extremophiles on Earth with life in (and visitors from) other parts of the universe and get away with it

 

[Ivan Seeking]

Yep, perfectly acceptable. This thread addresses the question of ET life in the broadest terms; including evidence on Earth that life could exist elsewhere in extreme environments.

 

[Ivan Seeking]

Panspermia.

Yes, I'm aware of the name, but is there any evidence for this?

 

[Ivan Seeking]

Discovering left handed amino acids or right handed RNA/DNA on a comet or asteroid would do it.

Am I remembering this about the DNA correctly; that the sense of the spiral is a function of the polarization of light from our sun?

Thinking about it, it could have been amino acids and not DNA that I read about.

 

[The Dagda]

Am I remembering this about the DNA correctly; that the sense of the spiral is a function of the polarization of light from our sun?

Thinking about it, it could have been amino acids and not DNA that I read about.

It seems odd that amino acids are left and DNA right handed exclusively. Not that it's a problem for science, it's more it's a gap in knowledge at this time.

 

[tormund]

Humans are a relatively young species. If we could evolve as evolutionists say we have in so short of time as we have, how much longer would extra-terrestrials have had to evolve, or how much longer to happen upon the right environment to be able to produce life? If they had this much extra time to evolve, who is to say they never got bored and venture into the realms of the less intelligent?

If intelligent life ever visited us, we wouldn't know, since it is not likely that it would be interested in us at all.

Why do we, as intelligent human beings bother with the bugs and the animals so far lower in intelligence?

 

[The Dagda]

Why do we, as intelligent human beings bother with the bugs and the animals so far lower in intelligence?

Probably because to the outside observer we don't seem to be any more good at adapting than the average bug, which at least doesn't rape its environment intentionally. An alien may look on us as primitive in comparison to them, because let's face it humanity are idiots. Perhaps if they were here they'd consider us an interesting experiment, but far from worth the effort to get to know on any higher level.

I like The Mothman Prophecies in this respect, or 2001: A Space Oddyssey, the "aliens" are trying to give us a step up or trying to communicate but we are just too stupid atm. As it says in The Mothman Prophecies it's the equivalent of us talking to an ant.

 

[baywax]

Am I remembering this about the DNA correctly; that the sense of the spiral is a function of the polarization of light from our sun?

Thinking about it, it could have been amino acids and not DNA that I read about.

Slightly different method of determining if an organism is from another planet.

The Meselson and Stahl Experiment... molecular biology.

http://books.google.ca/books?id=2c0...=X&oi=book_result&resnum=2&ct=result#PPA25,M1

Also:

From the perspective of how life got started on earth, it seems dauntingly unlikely that information-carrying molecules and reaction-catalyzing molecules would emerge at the same time and place. That impasse seemed to have been bridged with the discovery in 1982 that certain kinds of RNA have catalytic properties. It followed that a single RNA molecule could both carry information and catalyze reactions.

The concept of the RNA world, a phrase coined by Walter Gilbert of Harvard, held that in the beginning there were no proteins and no DNA, just RNA molecules that built more RNA molecules from chemical subunits known as nucleotides.

snip

Both Dr. Cech and Dr. Orgel, a leading authority on the origin of life, suggest that there was a pre-RNA world, in which the staring role was played by some other self-replicating, catalytic molecule.

Snip

The earliest known fossils exist in rocks that are 3.85 billion years old, leaving a mere 150 million years for life to have started.

And Dr. Crick (of Watson and Crick... co-discoverers of DNA) is touting the idea of panspermia here in the same article...

Dr. Crick then proposed that life might have started elsewhere in the universe, maybe on a planet whose chemical environment was more conducive to the genesis of life than was Earth's. The three kingdoms might represent the survivors of an assortment of microbes sent to colonize distant planets.

Dr. Crick's speculation that life originated elsewhere would provide an escape hatch for scientists trying to explain the origin of life on Earth should the available window of time be squeezed implausibly short. So far the idea has few takers, but nor is it being dismissed out of hand.

Oops... http://query.nytimes.com/gst/fullpa...5A35757C0A96F958260&sec=&spon=&pagewanted=all

 

[BoomBoom]

Dr. Crick's speculation that life originated elsewhere would provide an escape hatch for scientists trying to explain the origin of life on Earth should the available window of time be squeezed implausibly short.

Heh! Escape hatch?

I hope that biology never goes the way of cosmology, in which new parameters are "invented" to allow the preferred model to still fit the data (dark matter, dark energy etc.).
Maybe they will come up with some "dark DNA" that came from the heavens to seed life on earth?

 

[CEL]

Humans are a relatively young species. If we could evolve as evolutionists say we have in so short of time as we have, how much longer would extra-terrestrials have had to evolve, or how much longer to happen upon the right environment to be able to produce life? If they had this much extra time to evolve, who is to say they never got bored and venture into the realms of the less intelligent?

Why do we, as intelligent human beings bother with the bugs and the animals so far lower in intelligence?

Evolution and civilization are different things. Humans will continue the development of technology until levels unimaginable to us (provided that we don't extinguish ourselves in the process). There is no guaranty that we will evolve. Environmental pressure would be necessary for that. Sharks and turtles did not evolve in the past 300 million years, for lack of pressure.
Since humans are well adapted to the environment and have no predators (the same as with sharks and turtles), there is no need for further evolution.

 

[Ivan Seeking]

Heh! Escape hatch?

I hope that biology never goes the way of cosmology, in which new parameters are "invented" to allow the preferred model to still fit the data (dark matter, dark energy etc.).
Maybe they will come up with some "dark DNA" that came from the heavens to seed life on earth?

Crick had pursued a career in physics but that ended due to WWII. He was a biologist. And he was certainly not a cosmologist.

Are you changing majors now?

 

[BoomBoom]

Crick had pursued a career in physics but that ended due to WWII. He was a biologist. And he was certainly not a cosmologist.

Are you changing majors now?

Ummm, I'm not quite sure what you mean?

I was not suggesting that Crick was a cosmologist...that was just an ill-advised attempt at humor to compare how the science of cosmology is conducted in contrast to biology.

...my bad, it was not funny.


I just find the whole concept of explaining the origins of life by suggesting it flew in from outer space, rather than starting on the only planet we know of that hosts it, just a little absurd.

 

[Ivan Seeking]

I just find the whole concept of explaining the origins of life by suggesting it flew in from outer space, rather than starting on the only planet we know of that hosts it, just a little absurd.

Why? Crick was suggesting this as another avenue for life IF there are fundamental problems in explaining it. IF life didn't start here then it must have come from somewhere else.

In a much more quantitative sense, cosmologists infer the existence of dark matter and dark energy through the observations of other bodies. This is in large part how physics works: We make an observation and then suggest an explanation that can be tested. Also, how do you think most subatomic particles were found? Their existence was predicted and then verified.

 

[DaveC426913]

I just find the whole concept of explaining the origins of life by suggesting it flew in from outer space, rather than starting on the only planet we know of that hosts it, just a little absurd.

It is, but as was mentioned, this is getting pretty hard to swallow too:

The earliest known fossils exist in rocks that are 3.85 billion years old, leaving a mere 150 million years for life to have started.

 

[The Dagda]

I love the use of a mere 150 million years, lol. And how the hell do they know when conditions were adequate to begin abiogenesis.

By examining the time interval between such devastating environmental events, the time interval when life might first have come into existence can be found for different early environments. The study by Maher and Stephenson shows that if the deep marine hydrothermal setting provides a suitable site for the origin of life, abiogenesis could have happened as early as 4000 to 4200 Myr ago, whereas if it occurred at the surface of the Earth abiogenesis could only have occurred between 3700 and 4000 Myr.

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

 

[CEL]

I love the use of a mere 150 million years, lol. And how the hell do they know when conditions were adequate to begin abiogenesis.


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

First of all, there should be liquid water. Secondly, there should exist the chemicals necessary for the synthesis of organic components. Finally an environment where those chemicals could be concentrated enough to interact with each other.
Energy for the reactions is also necessary,but this was available from the very beginning.

 

[JorgeLobo]

Dagda is right - it is not possible to know the conditions that led to initiation of life - tho it was probably a process rather than an event (short of bibilical/extrterrestial intervention). There is certainly no generally accepted scientific theory that explains the phenomenon that we presume is no longer happening.
As we don't know the critical elements - we can't project the probability of life existing by the same process elsewhere - Carl Sagan's "bulllions and bullions" pomposity not withstanding.

 

[DaveC426913]

Dagda is right - it is not possible to know the conditions that led to initiation of life

Yes, but it is possible to look at what conditions might prevent it.
1] How the heck stable was the Earth a mere 150my after formation? It was mostly magma.
2] How the heck did life get so advanced as to leave fossils in a mere 150my?
3] How the heck did life get such an impressive foothold in a mere 150my? Widespread enough for us to find these fossils. (As a comparison, there are only about 5 complete T.Rex skeletons in the world. This is an indication of how rare preserved fossils really are.)

Nobody's arguing it's impossible, it is just getting implausible. So, an alternate possibility is put forth: perhaps it had all the time it needed - somewhere else.

And really, what's so ridiculous about that? It started somewhere, why must it have been here?

 

[The Dagda]

Yes, but it is possible to look at what conditions might prevent it.
1] How the heck stable was the Earth a mere 150my after formation? It was mostly magma.
2] How the heck did life get so advanced as to leave fossils in a mere 150my?
3] How the heck did life get such an impressive foothold in a mere 150my? Widespread enough for us to find these fossils. (As a comparison, there are only about 5 complete T.Rex skeletons in the world. This is an indication of how rare preserved fossils really are.)

Nobody's arguing it's impossible, it is just getting implausible. So, an alternate possibility is put forth: perhaps it had all the time it needed - somewhere else.

The age of the Earth is ~4.54 Billion years, that puts the time for formation between 4.2 billion and 3.7 billion years ago. I also believe the fossil record goes back to ~3.5 Billion years ago. As for when life was able to develop, I think the above estimates are accurate enough. I don't know how that quote can be that accurate anyway, seems a bit of a stretch on some pretty big assumptions.

And really, what's so ridiculous about that? It started somewhere, why must it have been here?

It's not ridiculous it's just one of many ideas.

 

[BoomBoom]

Yes, but it is possible to look at what conditions might prevent it.
1] How the heck stable was the Earth a mere 150my after formation? It was mostly magma.
2] How the heck did life get so advanced as to leave fossils in a mere 150my?
3] How the heck did life get such an impressive foothold in a mere 150my? Widespread enough for us to find these fossils. (As a comparison, there are only about 5 complete T.Rex skeletons in the world. This is an indication of how rare preserved fossils really are.)

Nobody's arguing it's impossible, it is just getting implausible. So, an alternate possibility is put forth: perhaps it had all the time it needed - somewhere else.

And really, what's so ridiculous about that? It started somewhere, why must it have been here?

While 150 million years sounds like the blink of an eye in astronomical terms, it really is quite a long time. Homonids evolved and spread throughout the world in just a few million. Besides, as mentioned by others, our estimates could leave a lot of "wiggle" room as the age of the Earth is an estimate that probably has a fairly large margin of error.

The postulation that life came from space can never be verified or proven, nor does it do anything to describe the process of abiogenisis. You are still left with the question of how life started.

 

[CEL]

Yes, but it is possible to look at what conditions might prevent it.
1] How the heck stable was the Earth a mere 150my after formation? It was mostly magma.
2] How the heck did life get so advanced as to leave fossils in a mere 150my?
3] How the heck did life get such an impressive foothold in a mere 150my? Widespread enough for us to find these fossils. (As a comparison, there are only about 5 complete T.Rex skeletons in the world. This is an indication of how rare preserved fossils really are.)

Nobody's arguing it's impossible, it is just getting implausible. So, an alternate possibility is put forth: perhaps it had all the time it needed - somewhere else.

And really, what's so ridiculous about that? It started somewhere, why must it have been here?

Dagda has already corrected the time. About the planet being mostly magma, this is an idea that was abandoned a long time ago. The accepted theory of planetary formation is no longer that of a ball of magma that cools down and solidifies. Planets are formed by accretion. Small bodies are attracted by gravity forming larger ones. When the body is large enough, the pressure melts the interior.

 

[JorgeLobo]

no dave - "implausible" is subjective and presumes some level of knowledge, It's as unsupportable as your claim of a remote "start" or boom boom's rejection.

 

[WhoWee]

Ahhhh...don't you love it when nobody really knows for certain...lot's of theories to put things into perspective...distances/speed of light, probability of life supporting planets, time requirements of evolution, dangers of technological advancements, etc.

Accordingly, I've always wanted to write a book with a title of something like: "I Believe...Yet Darwin Was Right?...some people absolutely evolved from apes and some from aliens" (by the way God by definition is an alien - not FROM this planet)...LOL.

...just saying.

 

[The Dagda]

Ahhhh...don't you love it when nobody really knows for certain...lot's of theories to put things into perspective...distances/speed of light, probability of life supporting planets, time requirements of evolution, dangers of technological advancements, etc.

Accordingly, I've always wanted to write a book with a title of something like: "I Believe...Yet Darwin Was Right?...some people absolutely evolved from apes and some from aliens" (by the way God by definition is an alien - not FROM this planet)...LOL.

...just saying.

Let's face it the question is so open that it involves all sorts of ideas, from the sublime to the ridiculous.

 

[harvellt]

I hope The James Webb Space Telescope finds Dyson spheres! :P

 

[phyzmatix]

Let's face it the question is so open that it involves all sorts of ideas, from the sublime to the ridiculous.

That is so true...And what I find interestingly ridiculous about this is that nobody will ever really know with absolute certainty and yet people will fervently defend their theories and hypotheses as if their particular opinions were fact...

 

[DaveC426913]

It's not ridiculous it's just one of many ideas.

Yes, that's my point. I was refuting BoomBoom's claim that we are reaching for a solution that is (granted facetiously) as "absurd" as "dark DNA".

 

[The Dagda]

That is so true...And what I find interestingly ridiculous about this is that nobody will ever really know with absolute certainty and yet people will fervently defend their theories and hypotheses as if their particular opinions were fact...

Never say never, if one day we manage to voyage to the stars, we may find that life develops according to a fairly predictable plan, science isn't about truth though, but enough circumstantial evidence will make virtually anything fairly certain. Let's not forget we may spark abiogenesis in the lab as well.

 

[phyzmatix]

Never say never, if one day we manage to voyage to the stars, we may find that life develops according to a fairly predictable plan, science isn't about truth though, but enough circumstantial evidence will make virtually anything fairly certain. Let's not forget we may spark abiogenesis in the lab as well.

True, but until that time, there is nothing but theory. I find this interesting though: Miller-Urey experiment

 

[CEL]

True, but until that time, there is nothing but theory. I find this interesting though: Miller-Urey experiment

We don't really need to go to the stars. Probes to the planets and satellites of our solar system may discover signs of life. If we find life similar to that on Earth, the panspermia hypothesis will be reinforced.

 

[baywax]

We don't really need to go to the stars. Probes to the planets and satellites of our solar system may discover signs of life. If we find life similar to that on Earth, the panspermia hypothesis will be reinforced.

There is the disputed fossil evidence of life from Mars in Meteorite ALH84001


http://nssdc.gsfc.nasa.gov/planetary/marslife.html

Looking at the numbers... over 9 billion years of opportunities for water based life to develop in the universe is astounding. I'd say that over that time it has become a "knee-jerk" development which the elements simply evolve into by way of the laws of thermodynamics, fluid dynamics and other sets of laws I am not qualified to talk about!

 

[The Dagda]

True, but until that time, there is nothing but theory. I find this interesting though: Miller-Urey experiment

Nothing but theory and hypothesis, let's keep theory in the science camp and hypothesis in the other camp, there's too much of that mixing the twain for my liking these days. Both are vital to science, but one is philosophy the other is science and philosophy.

We don't really need to go to the stars. Probes to the planets and satellites of our solar system may discover signs of life. If we find life similar to that on Earth, the panspermia hypothesis will be reinforced.

Very true.

 

[JorgeLobo]

The so-called fossil evidence from Mars is not disputed - it isn't even generally accepted as such. IF we find life ("signs" are subjective) AND we haven't found life so far.

 

[BoomBoom]

If we find life similar to that on Earth, the panspermia hypothesis will be reinforced.

Unless, of course, we find that the basic structure of life is universal.

However, any similar life we were to find in our solar system would have some claiming panspermia. So I guess we will have to find life outside our solar system that is similar to life on Earth to put that claim at rest? Or maybe that wouldn't do it either...maybe we need to find similar life outside our galaxy?

I guess since that theory (panspermia as the origin of life on earth) can never be proven or disproven, it will always be around...but it will never be anything more than pure speculation.

 

[The Dagda]

Unless, of course, we find that the basic structure of life is universal.

However, any similar life we were to find in our solar system would have some claiming panspermia. So I guess we will have to find life outside our solar system that is similar to life on Earth to put that claim at rest? Or maybe that wouldn't do it either...maybe we need to find similar life outside our galaxy?

I guess since that theory (panspermia as the origin of life on earth) can never be proven or disproven, it will always be around...but it will never be anything more than pure speculation.

If we find a load of humanoid races that are practically identical to us that might seal it, or The Greys tell us the truth or whatever. But let's face it we are unlikely to know possibly ever, but not never.

 

[baywax]

I guess since that theory (panspermia as the origin of life on earth) can never be proven or disproven, it will always be around...but it will never be anything more than pure speculation.

There must be a way to trace the origin of life with regard to abiogenesis vs panspermia. I think we've covered some methods using the configuration of a specimen's DNA or the single strand configuration of RNA and how it relates to the type of sunlight or mineral content in which it has evolved. Meteorites sporting apparent fossils tend to speak volumes about the relative ease life seems to have sprouting up in other regions of space.

 

[DaveC426913]

I guess since that theory (panspermia as the origin of life on earth) can never be proven or disproven, it will always be around...but it will never be anything more than pure speculation.

Of course it could be dis/proven (or at least satisafactorily resolved). It might take a fabulously advanced technology and knowledge base but, in principle, it's not much different from showing at Ebola arose out of an epicentre in Africa.

 

[Ivan Seeking]

Yes, there is no reason to think this can never be resolved. What's more, we could find a meteor containing alien bacteria, tomorrow.

 

[baywax]

Yes, there is no reason to think this can never be resolved. What's more, we could find a meteor containing alien bacteria, tomorrow.

Could it be determined if the meteor originated from an Earth impact or not?

 

[Ivan Seeking]

Could it be determined if the meteor originated from an Earth impact or not?

There may be situations where we couldn't be sure, but there are certainly indicators that would show it did not have terrestrial origins. For example, the meteor could be older than the earth. Or, we could find isotopic ratios not found on earth. Not my field but those are a couple of possiblities.

 

[CEL]

Unless, of course, we find that the basic structure of life is universal.

However, any similar life we were to find in our solar system would have some claiming panspermia. So I guess we will have to find life outside our solar system that is similar to life on Earth to put that claim at rest? Or maybe that wouldn't do it either...maybe we need to find similar life outside our galaxy?

I guess since that theory (panspermia as the origin of life on earth) can never be proven or disproven, it will always be around...but it will never be anything more than pure speculation.

There is no proof in empirical sciences. Observations are made, hypotheses derive from the observations and a theory is formulated. If subsequent observations confirm the theory, it is accepted. If in the future new observations don't fit the theory, it is reformulated or abandoned, but proof exists only in axiomatic sciences like Math or Logic.

 

[DaveC426913]

There is no proof in empirical sciences. Observations are made, hypotheses derive from the observations and a theory is formulated. If subsequent observations confirm the theory, it is accepted. If in the future new observations don't fit the theory, it is reformulated or abandoned, but proof exists only in axiomatic sciences like Math or Logic.

Well...

If we found a rock that had a markedly different composition from Earth, say it matched the composition of the Moon rocks to several decimals across a dozen elements, we can be pretty confident that rock is a meteorite.

You could bifurcate bunnies and claim "that's not proof" but frankly, if there's only one contender for theories and any other contender would require us throwing out centuries of well-established knowledge (such as: maybe it's a rock from a quarry that has an astonishingly coincidental elemental makeup to that of the Moon that heretofore has never been seen on Earth, and because, well, it's never been exposed to oxygen ... or water) then it's pretty much proven in my books.

 

[CEL]

Well...

If we found a rock that had a markedly different composition from Earth, say it matched the composition of the Moon rocks to several decimals across a dozen elements, we can be pretty confident that rock is a meteorite.

You could bifurcate bunnies and claim "that's not proof" but frankly, if there's only one contender for theories and any other contender would require us throwing out centuries of well-established knowledge (such as: maybe it's a rock from a quarry that has an astonishingly coincidental elemental makeup to that of the Moon that heretofore has never been seen on Earth, and because, well, it's never been exposed to oxygen ... or water) then it's pretty much proven in my books.

The only cases where you have only one contender to a theory is when this contender is the null hypothesis. In your example of a found rock: it is a meteorite or not. You can prove the null hypothesis if the rock was found in a quarry on Earth, where all he rocks have the same composition.
The hypothesis that it is really a meteorite cannot b proved, but we can accept it as very likely, in the case of an extraordinary match of its composition with that of a known extraterrestrial body. But very likely does not mean sure.

 

[The Dagda]

There is no proof in empirical sciences. Observations are made, hypotheses derive from the observations and a theory is formulated. If subsequent observations confirm the theory, it is accepted. If in the future new observations don't fit the theory, it is reformulated or abandoned, but proof exists only in axiomatic sciences like Math or Logic.

Just to be needlessly pedantic: math and logic are not really sciences unless they are applied to something real world. For example the death penalty why it is wrong, would be a sociological concern logical or not. And the aerodynamics of shuttle re-entry would be science, but n-dimensional topography may well be not, and neither is the ontological argument.

 

[baywax]

Well...

If we found a rock that had a markedly different composition from Earth, say it matched the composition of the Moon rocks to several decimals across a dozen elements, we can be pretty confident that rock is a meteorite.

You could bifurcate bunnies and claim "that's not proof" but frankly, if there's only one contender for theories and any other contender would require us throwing out centuries of well-established knowledge (such as: maybe it's a rock from a quarry that has an astonishingly coincidental elemental makeup to that of the Moon that heretofore has never been seen on Earth, and because, well, it's never been exposed to oxygen ... or water) then it's pretty much proven in my books.

Apparently its not that hard to tell the difference between terrestrial originating and extraterrestrial originating meteorites... from the Astrophysics Section..."When did H2O develop during the last 13.5 b y?"

On 28 September 1969, near the town of Murchison, Victoria in Australia, a bright fireball was observed to separate into three fragments before disappearing. A cloud of smoke and, 30 seconds later, a tremor was observed. Many specimens were found over an area larger than 13 km², with individual masses up to 7 kg; one, weighing 680 g, broke through a roof and fell in hay. The total collected mass exceeds 100 kg.

The meteorite belongs to the CM group of carbonaceous chondrites. Murchison is petrologic type 2, which means that it experienced extensive alteration by water-rich fluids on its parent body. before falling to Earth. CM chondrites, together with the CI group, are rich in carbon and are among the most chemically primitive meteorites in our collections. Like other CM chondrites, Murchison contains abundant CAIs. Over 100 amino acids (the basic components of biological life) have been identified in the meteorite. A 2008 study showed that the Murchison meteorite contains nucleobases. Measured carbon isotope ratios indicate a non-terrestrial origin for these compounds.

Measured purine and pyrimidine compounds are indigenous components of the Murchison meteorite. Carbon isotope ratios for uracil and xanthine of 44.5% and +37.7%, respectively, indicate a non-terrestrial origin for these compounds. These new results demonstrate that organic compounds, which are components of the genetic code, were already present in the early solar system and may have played a key role in life's origin.

More recent dating sets its age at nearly 4.95 billion years; nearly 500 million years older than the age of the Earth.

The Murchison meteorite contains 12% water.

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

 

[DaveC426913]

Apparently its not that hard to tell the difference between terrestrial originating and extraterrestrial originating meteorites.

Yep. I was impressed when I first read about the uniqueness of the composition of extraterrestrial rocks.

 

[CEL]

This is interesting:
http://edition.cnn.com/2009/TECH/space/02/25/galaxy.planets.kepler/index.html

 

[Karl G.]

In Richard Dawkin's "The God Delusion", he argues that even if the probability of life occurring is extermely small (sorry, can't remember exact figures!), there still is a good probability that life exists somewhere else in the universe. Assume, for example, that there are 1,000 civilizations dispersed evenly throughout the universe. The distances between us and them would be so huge that (keeping relativity in mind and ignoring the slim possibility that large organisms can travel through worm-holes) communication and travel between any two civilizations would remain highly improbable, even if several of the civilizations where highly advanced compared to Earth. So the fact that foreign organisms have never visited Earth (I tend to believe all accounts of UFO's are spurious) doesn't mean they don't exist.