So it seems there is only an either / or question regarding Life's origins.

Where do we stand as a community?

Either Life originated on earth through abiogenesis Or was transported here from elsewhere, aka panspermia.

Please vote.

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"Where the telescope ends, the microscope begins. Which of the two has the greater view?" - Hugo

"Men occasionally stumble over the truth, but most pick themselves up and hurry off as if nothing had happened." - Churchill

I voted abiogenesis.

Panspermia can mean 2 things: That life started in space (e.g. inside a nebula or high orbit of exo-planet and floated into space) OR it started by abiogenesis ON ANOTHET PLANET and survived a flight through space to reach Earth and rain down (e.g. Earth life came from Mars by meteorite originating from Mars' surface).

I'm going to apply Occam's Razor now, and pick abiogenesis on Earth as the most likely scenario. The right ingredients were all there. Nothing on Earth seems to have PREVENTED life from starting here, so abiogenesis on Earth seems a more likely option opposed to extra-planetary abiogenesis + surviving space flight.

I'm not sure about the odds of life forming in space itself. Is there any reason to suspect that a nebula passed through our solar system 4 or 5 billion years ago and deposited proto-life on Earth? If not, then the odds of panspermia don't seem so good for that option.

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This user is currently on a smooth slope of Mount Improbable

Are you asking the question about life on Earth, or life in general in the universe?
If it is the former, the answer could be either, with a somewhat smaller chance of life starting elsewhere in the solar system and migrating here. Mars is the most likely candidate.
Lithopanspermia between stars in a cluster is also a very small possibility.

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If it is about life in the universe as a whole, then all life started originally by abiogenesis, whether or not it has been subsequently transported by lithopanspemia or translocation by intelligent species.

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New Orion's Arm Site . The Starlark . Against a Diamond Sky (OA Novella Collection) . OA Flickr set

I know that life that supposedly came to Earth as in a panspermia-theory-like fashion would have started by abiogenesis in space. I'll aply the term abiogenesis a bit more careful

Would you say 1) the odds of life forming in outer space are bettr than the odds of life forming on Earth?
Or 2) do you think panspermia-theory a likely candidate for 'seeding' Earth because life would have had more time to develop? (The Universe is older than the Earth, and life has had more time to form in space/nebulae, etc, long before Earth existed.)

The options are not mutually exclusive per se, but I have my doubts about number one.

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This user is currently on a smooth slope of Mount Improbable

I should've capitlaized "Earth" in the OP; Life on Earth origins (to answer your question, eburacum), as in primordial soup hypothesis...

I find it a conundrum somehow but can't quite articulate it at this time...
more interested in the poll results really...

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"Where the telescope ends, the microscope begins. Which of the two has the greater view?" - Hugo

"Men occasionally stumble over the truth, but most pick themselves up and hurry off as if nothing had happened." - Churchill

I'd go with an Earthly origin, just because the conditions in space are less than conducive to life. Could early life have come here from Mars? Possible, but 1) it would need to survive the trip, which would be no easy matter even for today's highly-evolved lifeforms with 5 billion years of survival adaptations, and 2) there's no reason to think Mars would be more likely to develop life than Earth.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

Oh, forgot to address the comet hypothesis. No dice there, a comet wouldn't have enough energy or any liquid water to support life. Even heat from the sun only sublimes off the outer layers, taking both heat and volatiles into space.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

Occam's Razor tell us that 1. option; abiogenesis, is the most probable, but one don't know, it well might be panspermia..

So I vote abiogenesis, because it is the most probable..

But if you some take organics and water from meteors, asteroids and comets, as a variant of panspermia; then I will vote panspermia, but only precursors for life were transported to Earth - the rest was done here.

Abiogenesis. Even if it didn't start here, it started somewhere.

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The last time I felt a warm fuzzy feeling, I was informed by my doctor that it was just gas.

I suspect abiogenesis on Earth. It doesn't mean panspermia or CA is impossible, just unlikely, in my opinion.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Technically, since Earth was formed by planetoids which clumped into planetesimals and then into planets, all water and organic chemicals on Earth did start out in comets and asteroids.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

I vote abiogenesis, life as an inevitable extension of carbon chemistry, the properties of liquid water.

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plenty of woo, at the hotel hoagaland...

I'd guess abiogenesis on Earth, but there are so many varieties of possible, if unlikely, transfers of life between planets and other domains. Abiogenesis on Mars with a subsequent move to Earth would be interesting.

After that there are many conceivable levels right up to galactic or even universal panspermia. I don't think they are probable, but what do I know?

If I had to guess, I'd say sparsely distributed independent biospheres with occasional cross transfers within a solar system.

Our data, with a sample size of 1, are a little sparse. Abiogenesis on Earth seems to involve a smaller chain of unlikely events, so that's the way I'm voting. I'd put some money on it, but not all my savings.

Actually, I think we've got a sample size of three, maybe more. One of the planets shoes signs of life and another presents evidence of past life, but is itself too small a sampling to be sure. The other objects currently show no signs of present or past life.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

If you mean the Mars meteor, that hasn't been confirmed yet as having evidence of Martian life. What other planet has signs of life?

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

That's what I mean, it's inconclusive, but it is still part of the sample set, along with Luna and possibly Titan, Eros, and perhaps we should include Venus too since we've landed on all of them.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Um.

I guess I just don't understand what you mean. Earth is still the only planet confirmed to have evidence of life. Mars has questionable data that might show evidence, or might not. None of the other planets/moons mentioned have shown any evidence, at present all we have is speculation, based on a few possibilities.

That still leaves just one planet with life.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

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PW -- Plant Whisperer

You're excluding the other planets as samples. That leaves you with a 1 to 1 ratio of planets to life, which statistically means 100%. It's better to say that out of 5 terestrial objects, only 2 have evidence of life and only one is confirmed. You need to include negatives in your sample set or else you artificially skew the results.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

If it's not confirmed, by definition it's not evidence, it's incomplete data.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

I have a theory, but it's a bit woo woo.

What if the Universe really does need a conscious observer for it to exist?
Then since we DO exist then the BB would be forced to happen and the first cells would be forced into existence, against all the odds.
So from this theory I would say the life either started here on Earth or close by in space or maybe a long time ago soon after the BB, I dunno.

If this were the case, then the scary thing maybe that Earth is the only planet with life on. As we have "observed" the Universe and no other planet need have been involve.


told you it was a bit woowoo.

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But it's still part of the sample set.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Not of the set of planets known to have life! Maybe if we were talking about the set of planets in general, or planets with the possibility of life, that might apply.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

Uhm, what do you mean by a 'conscious observer'? Do you mean life forms (like humans) that can measure and interpret properties of the Universe, or do you mean 'god' as a necessary 'conscious observer'? Either way, I don't think either would make sense.

- If you mean that our observations of the Universe make it reality, then doesn't that mean that the Universe didn't exist before humans came along? So how did all those fossils get in the ground? How could we have evolved in the first place, if there was no-one to make the Universe a reality by observing it consciously?

- If god is the conscious observer you mean, why would it/he/she be required? I read an amusing quote about quantum physics: Measuring the quantum state of a particle means that you influence the state itself (by shooting photons-light- at it to observe it, you distort your original particle). The quote was that "the true (original) quantum state of a particle would be unknown even to god himself." (paraphrasing here). So technically god (if such a being existed) would have to by-pass the laws of nature if he wants to be a conscious observer of the Universe. Unless god of course limits his observations to observing large scale physics, and ignores observing the quantum states of things.

Nope, causality doesn't go back in time. We can't force a past event that already happened, now can we? Consider this: "I just drank some coffee. Therefore, coffee plants have to exist. I just forced the Universe to come into existence and produce both me, you and coffeeplants, because how else could I be drinking coffee and talking to you about it?" Doesn't make sense.

Life forms adapt to their environment. Environments (i.e. the Universe) came first, and later life started to inhabit the environment. There is no reason to suggest that we -physical processen among many other processes- somehow forced the Universe into existence. We're not that special

Anyway, not trying to pick a fight here, just agreeing with the 'woo woo' bit

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This user is currently on a smooth slope of Mount Improbable

This is like Barrow and Tipler's "Final Anthropic Principle":

"Intelligent information-processing must come into existence in the Universe, and, once it comes into existence, it will never die out."

It possible that endospores such as those formed by anthrax can survive for over a century on earth, but the longer the time spent as an endospore the more likely that their will be fatal damage to the endospore's DNA. Low temperatures could prolong this period, but since chunks of life spore containing rock blown off earth or mars are likely to spend a great deal of time wandering around the inner solar they are unlikely to reach the very low temperatures needed to preserve DNA for a very long time. Rocks closer than the asteroid belt or closer are likely to spend much of their time at 200K or higher which should be warm enough to allow the slow decay of DNA. Early life on earth didn't use DNA and it is possible that this life could be better at surviving space trips, but we can't really say. This makes panspermia by DNA based life very unlikely, but not impossible across interplanetary distances.

And there is another problem with panspermia, Ronald Brak.
Virusses, even if they survived the trip through space, require living cells. They 'hi-jack' living cells and use them to produce more copies of their own genetic material (i.e. to reproduce).

If there are no single (or multi)-celled organisms on the planet where it lands, the virus will still die out. Even if this other world is inhabited by life forms, the virus will most likely be unable to adapt to this unknown sort of 'DNA'. Most virusses are quite picky and require a very specific type of host.

The best candidate for panspermia would probably be a life form that lives off non-living matter. Spores that lay dorment, and that produce fungi that suck nutrients out of the ground might be likely candidates. Any life form that requires living cells for survival (like virussen that reproduce inside cells, or micro-organisms that feed on living matter) will most likely run out of food long before they reach their new home. And even if they get there, they might encouter an existing ecosystem, which might be very hard to 'infiltrate'.

But personally, I'm more of an abiogenesis fan.

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This user is currently on a smooth slope of Mount Improbable

Endospores are formed by bacteria and so might be able to survive if they landed in a favourable environment.