
The Amazing Trajectories of Life-Bearing Meteorites From Earth - wglb
http://www.technologyreview.com/blog/arxiv/27720/?ref=rss
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extension
Is there any plausible way an organism could survive an explosion with the
power of a million nukes _and_ a million years floating in space?

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TNO
Yes. For example: < <https://en.wikipedia.org/wiki/Deinococcus_radiodurans> >

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sp332
But if all life on earth is descended from something resistant to radiation,
why is most life on earth so vulnerable to it now?

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Qz
Why do we need to consume Vitamin C to avoid scruvy? Evolution abandons what
is no longer necessary.

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sp332
Most animals don't need to do that.

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showerst
We should evaluate the paper on its merits, but the reddit discussion did note
that this journal has some credibility issues -

[http://en.wikipedia.org/wiki/Journal_of_Cosmology#Reliabilit...](http://en.wikipedia.org/wiki/Journal_of_Cosmology#Reliability)

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JoeAltmaier
Hm. So life on Earth could have come from some other place!

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Retric
No, the life on earth was here to early for that. What they are suggesting is
after life evolved on earth sometime in the next 3 billion years single celled
organisms from another planet may have reached earth. Or in theory, life from
earth could have seeded another planet, and then a different impact could have
sent some of that life back after billion years or so. Granted, it's more
likely some life from one of those seed planets could visit another of the
seeded planets.

However, I suspect whatever made the trip is unlikely to be able to out
compete anything native to a planet.

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arethuza
"life on earth was here to early for that"

The Earth is only 4.5 billion years old and the Universe is 13.75 billion -
doesn't that give rather a long time for a generation or two of stars to cook
up the suitable elements for life and give it an opportunity to develop before
the Solar System was formed?

[Reminds me of the ending of the novel "Heart of the Comet"]

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Retric
First you need a galaxy to from. Then you need at least one generation of
stars to live and die before plants can form. You then need to give those
planets enough to to form and cool down before life can show up. That's the
start of the window of opportunity for life to show up. However, life on earth
is ~3.8 billion years at which time the window closes and such things become
visitors vs seeders of life. And this is important, all this needs to take
place outside of the center of the galaxy where things are a little to
energetic for life to flourish.

Not to mention you need a lot of stars to die to have enough material to
create a rocky planet. A single super nova is not enough because the material
is ejected over such a large an area.

Now, having said all this means is you shrink the window the distance such
things can travel. Earth could have been seeded by Mars no problem, but 1/2
the distance means 1/4th the stars. Ejecta just don't move vary fast so even
with a 1 billion year window you need to be really close to earth to seed it.
More importantly the window between when life could survive and when life
showed up less than 1/10th as long as life has existed. So, if we where seeded
then we have probably had many visitors after the fact which is what this guy
was saying.

PS: Of course if life is common enough both could have happened and even
ridiculously unlikely events can happen.

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arethuza
Apparently some physicists have come up with 4 billion years after the Big
Bang (i.e. about 10 billion years ago) for life to have been possible:

[http://www.dailygalaxy.com/my_weblog/2011/01/when-did-
proto-...](http://www.dailygalaxy.com/my_weblog/2011/01/when-did-proto-life-
emerge-in-the-universe.html)

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ZaftcoAgeiha
All i could think of was: "damn it, all that organic material we found on
other planets might have come from earth instead of those planets developing
life" we might be alone after all :( (at least in the near vicinity)

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jerf
Remember, "organic" means "contains carbon" (to a first approximation), not
"alive". Earth is well-known not to have anything like a monopoly on all the
carbon in the universe. We've _never_ had solid evidence of life on other
planets, so this is no change there.

It also raises another possibility not mentioned in the article, which is that
life is in fact rare, the only life anywhere near us is what developed on
Earth, and discovering life on Mars or the other possibly-hospitable locations
in the solar system may _not_ prove that life is common if it can be shown to
have derived directly from Earth life.

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webnrrd2k
There are supposedly a fair number of spores (and other small "critters" like
microbes, viruses, etc.) that make it through our atmosphere and into space. I
wonder how much, over the billions of years that life has existed, has made it
into space. I'd think that it would be far more than survived on rocks from
that meteor impact.

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b_emery
_more Earth ejecta must end up in interstellar space than all the other
planets combined_

Coolest thing I've read all week. Sort of suggests that 1) there _are_ earth
rocks on Mars, we just need to be very lucky to find them, and 2) if we're
really really lucky, they may still contain life.

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carguy1983
So is it possible that life is just being flung from planet to planet through
impact debris, over the course of billions of years?

