Where Did We Come From?

[arissa]

I was half asleep watching Cosmos last night but I remember part of it talking about how it is possible that smaller particles can be pulled from planet to planet and it is very well possible that certain pieces (including maybe us) could have came to Earth this way. I remember it saying something like once the particles hit water they would come alive again, or something to that sort. Anyone believe it? Anyone not believe it? Even better of someone could link me to some more information like this it would be great. I am slammed at work but I was telling a co-worker about it too and can not find the current episode for him.

[Eclogite]

This is the concept of pan spermia. I think the ancient Greeks may have proposed it, but the first solid scientific discussion of the concept came from Sven(?) Arrhenius at the the turn of the last century. 

 

Briefly the idea is that life is abundant in the universe and that, as a consequence of collisions of bolides with planets, some microscopic life is ejected into space. A minute proportion of this life survives in stasis till, by chance, it encounters another planet. If it survives the penetration of the planet's atmosphere, the impact with the surface and then encounters suitable conditions it may reanimate.

 

Various "vessels" for the transport could include within meteors, asteroids or comets. Fred Hoyle and Chandra Wickramasinghe postulated that much of the interstellar dust consisted of 'hibernating' micro-organisms, although their ideas have not gained acceptance with the majority of the science community.

 

I have always found the idea attractive, since I find the time for life to develop from a few basic chemicals to the first detectable organisms appears unreasonably short at only a few hundred million years.

 

If you google pan spermia, you should find a host of links discussing it.

 

It is worth noting that the interstellar medium has a wide range of organic molecules. I think over one hundred compounds have been detected already. These are building blocks for life, so that even if pan spermia turns out to be a failed hypothesis we shall likely find that life started as a consequence of these molecules being delivered to a young Earth by comets and meteors.

[Buffy]

Yah, I thought the Cosmos folks did a good job with this without getting to technical. They do point out that complex organisms can't really survive million year journeys between stars, but that lots of the more complicated organic molecules necessary to getting the life party started have no problem with the somewhat toxic intergalactic environment.

 

The show also pointed out that there was likely lots of cross contamination of more complex building blocks of life that could easily survive the short trips necessary between Earth, Mars and Venus. 

 

I really love the new Cosmos. Even though it really pretty much parallels the old one exactly on topics, it's got a very different take on some things that makes it more relevant to current attitudes (e.g. climate and evolution denialism), and includes new info on things we understand better.

 

 

We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology, :phones:

Buffy

[Eclogite]

They do point out that complex organisms can't really survive million year journeys between stars,

This is the conventional wisdom, but I have not yet seen what I consider to be adequate research to establish this as beyond reasonable doubt. Most workers in the field seem happy to take this as a given.

 

I readily confess that my position is partly motivated by my liking for the notion of pan spermia, plus an enormous affection for Sir Fred Hoyle, who though often wrong had the capacity to be wrong in really big ways. (And when he was right he was brilliant.) However, one cannot get away from the constraint imposed on emergence of life in a biologically short period on the early Earth. until and unless we can demonstrate a complete, detailed pathway by which this may have occured, I believe the jury should remain out.