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

[Frame Dragger]

They could do that in order to live on elsewhere in the universe. Suppose you are a machine and you transmit the information in your digital brain and the information on how to manufacture the hardware that is running you from scratch. If this signal is picked up billions of years later by a civilization on the other side of the observable universe, then you will find yourself there in what seems to you to be just an instant.

That sounnds like the sub-FTL version of Richard K. Morgan's 'Takeshi Kovacs' trilogy. Highly unrealistic, but a lot of fun. Essentially, elite soldiers are SPECIFICALLY trained to be "resleeved" into new bodies on distant worlds. The "fi" in the sci-fi enters in the form of FTL transmission of that information and ignoring Relativity. That said, it's an interesting view of a world in which the very rich never really fear death, but at the same time the very nature of life is uncertain to the point of madness.

 

[Ivan Seeking]

Let's stay on-topic.

 

[Frame Dragger]

Well, if we assume life, in whatever form, is limited by Relativistic physics as we are, then the motivation to explore really does fade. Why wouldn't an advanced civilization focus on their local system? With technology to "buzz us" (RIP Douglas Adams), aliens would have no need to do so, and why would they have a motivation to find other life? We're curious, but that's a very "monkey" trait... who's to say an alien would share that motivation... never mind to the point of vising us and returning home to a "Planet of The Apes" scenario.

@Ivan: Understood.

 

[Dav333]

So the crackpots who claim to be abducted dozens of times throughout their life say. Their special people.

 

[Bored Wombat]

I think that if we hadn't hit the evolutionary dead end of trying to thread the brain through a pelvis at the beginning of life, we would have ventured to the stars.

... They do http://www.youtube.com/watch?v=zSgiXGELjbc" ...

And there's no reason why they shouldn't. Afterall genetic configurations that lead to space-faring races are much more likely to spread across the galaxy. A medium sized asteroid through the international space station would spread bowl fauna and skin mites across the whole ecliptic.

Some little bacteria that came to Earth four billion years ago is palmfacing a bit because of the brain through the pelvis thing though.

 

[Frame Dragger]

I think that if we hadn't hit the evolutionary dead end of trying to thread the brain through a pelvis at the beginning of life, we would have ventured to the stars.

... They do http://www.youtube.com/watch?v=zSgiXGELjbc" ...

And there's no reason why they shouldn't. Afterall genetic configurations that lead to space-faring races are much more likely to spread across the galaxy. A medium sized asteroid through the international space station would spread bowl fauna and skin mites across the whole ecliptic.

Some little bacteria that came to Earth four billion years ago is palmfacing a bit because of the brain through the pelvis thing though.

I find it hard to imagine that any lifeform which evolves in a "gravity well" could be suited for sustained freefall, vacuum, etc... There really is very little of us that doesn't break (mind included) under those conditions. To be "suited" for space (PUN), really does require one to have evolved under very VERY different circumstances, or to have cut off the processs around saaaay... proto-bacteria and a handful of proteins/viruses.

Your view is nice, but anthrocentric even as it considers the benefit to life which (if it's on our space station) is dependant partly on us anyway... and no more suited to life in vacuum, or re-entry. It's one thing for a comet(etc) to "carry a payload" of the basic molecules which could later become, what would later become... ... ... bacteria. It's another to imagine the little buggers dealing with hard radiation in a vacuum, AND that those same would find other hosts! Inert genetic material spread across the ecpliptic, as you say, is really not what bacteria do.

Finally, underlying this is the notion that the "mites" of one space-faring being wouldn't be harmless, fatal, or nothing at all to us or visa versa? The molecules which may (or maybe ALWAYS?) give rise to the "building blocks of life" (amino acids and such )... that I can see being universal, but I hesitate to assign a life-like evolution to them.

For the record: life-like to be distinguished from "stellar, galactic, etc..."

 

[Bored Wombat]

So the crackpots who claim to be abducted dozens of times throughout their life say. Their special people.

I'm not sure that alien abductees are fantasy prone. They are much more likely to have experienced sleep paralysis than a random group, and I think that the experience is probably attributable to sleep paralysis plus false memory rather than fantasy prone and crackpot.

But it could be either.

 

[Bored Wombat]

I find it hard to imagine that any lifeform which evolves in a "gravity well" could be suited for sustained freefall, vacuum, etc... There really is very little of us that doesn't break (mind included) under those conditions. To be "suited" for space (PUN), really does require one to have evolved under very VERY different circumstances, or to have cut off the processs around saaaay... proto-bacteria and a handful of proteins/viruses.

NASA reckons they found some bacteria that were quite happy after days in space on the outside of one of their ships. A virus could probably do much better. Of course a virus couldn't seed life onto a planet. I don't think that a human will colonise a barren rock and terraform it, but a bacteria could after a billion years or so.

Your view is nice, but anthrocentric even as it considers the benefit to life which (if it's on our space station) is dependant partly on us anyway... and no more suited to life in vacuum, or re-entry.

Well, maybe. Of course of all the living cells in and on a human only 10% are human http://arjournals.annualreviews.org/doi/abs/10.1146%2Fannurev.mi.31.100177.000543, so there's a lot more mite and bacteria up there than humans, and with that a lot more biodiversity. And some of them live in fairly hostile parts of the gut. And some of them live in skin mite's guts, and a dead skin mite doubles as a space ship, if you're okay with freezing.

It's one thing for a comet(etc) to "carry a payload" of the basic molecules which could later become, what would later become... ... ... bacteria. It's another to imagine the little buggers dealing with hard radiation in a vacuum, AND that those same would find other hosts! Inert genetic material spread across the ecpliptic, as you say, is really not what bacteria do.

Hard vacuum is surprisingly tolerable to some bacteria.

"Unknown to mission planners in 1967 a small colony of Streptococus bacteria traveled to the moon aboard Surveyor 3, stowed away inside the spacecraft 's TV camera. Three years later when Apollo 12 astronauts returned the camera to Earth, scientists were astonished to find that the bacteria were viable." - http://science.nasa.gov/science-news/science-at-nasa/1999/msad13jan99_1/"

Not sure if they could do the decades required to colonise Rigil Kent., but there's probably a few that could do it. You've just got to try with a few. And with all the fauna in and on a human, that's heaps of tries just by flinging a few corpses about space. Or pieces of corpses.

Finally, underlying this is the notion that the "mites" of one space-faring being wouldn't be harmless, fatal, or nothing at all to us or visa versa? The molecules which may (or maybe ALWAYS?) give rise to the "building blocks of life" (amino acids and such )... that I can see being universal, but I hesitate to assign a life-like evolution to them.

I'd guess fairly harmless at this late stage. But it might be that we are such mites, or their bowel fauna. (Only evolved a bit.)

 

[Frame Dragger]

NASA reckons they found some bacteria that were quite happy after days in space on the outside of one of their ships. A virus could probably do much better. Of course a virus couldn't seed life onto a planet. I don't think that a human will colonise a barren rock and terraform it, but a bacteria could after a billion years or so.



Well, maybe. Of course of all the living cells in and on a human only 10% are human http://arjournals.annualreviews.org/doi/abs/10.1146%2Fannurev.mi.31.100177.000543, so there's a lot more mite and bacteria up there than humans, and with that a lot more biodiversity. And some of them live in fairly hostile parts of the gut. And some of them live in skin mite's guts, and a dead skin mite doubles as a space ship, if you're okay with freezing.



Hard vacuum is surprisingly tolerable to some bacteria.

"Unknown to mission planners in 1967 a small colony of Streptococus bacteria traveled to the moon aboard Surveyor 3, stowed away inside the spacecraft 's TV camera. Three years later when Apollo 12 astronauts returned the camera to Earth, scientists were astonished to find that the bacteria were viable." - http://science.nasa.gov/science-news/science-at-nasa/1999/msad13jan99_1/"

Not sure if they could do the decades required to colonise Rigil Kent., but there's probably a few that could do it. You've just got to try with a few. And with all the fauna in and on a human, that's heaps of tries just by flinging a few corpses about space. Or pieces of corpses.



I'd guess fairly harmless at this late stage. But it might be that we are such mites, or their bowel fauna. (Only evolved a bit.)

The best theories as to how life evolved is to posit basic molecules first. If you want to call those mites, it's a bit misleading as you can reduce mites to cells, and proteins... You break molecules and you get more molecules, then atoms. Unless you're aiming for a "We're in the eyelash of god" angle, the 'seeding' hypothesis is based on molecular biology, not introduction of viable life.

Of course, a mite could survive the trip, or not, or a bacteria... once it reaches a destination however, your theory requires one of three things occurs:

1.) Surving entry into an atmosphere, and interstellar radiation (one pass through the Van Allen belts is one thing) the microbe finds a viable living host, either directly or after some period of continued dormancy.

2.) See #1, but instead of a living host, conditions are similar to that of a its ideal 'petri dish'. This would seem more likely than #1, but it's really quite similar, and very unlikely. Bacteria depend on interfaces common to species. Staph may have been viable, but not if you're on a Carbon Earth, or a moon such as Titan.

3.) Survival and viability are NOT the issue, but some of the basic organic molecules act as a scaffold, catalyst, or just "soup in waiting" for life of some kind. Number #3 is already happening, many believe, thanks to comets, and other passages or bombardments. In that sense, there is no need to even posit the space-faring bacteria.

I might add... a virus is MUCH more likely to be a source of life for a planet than a bacterium. A virus seems to be that intermediate stage between simple organic molecules (prions, and basic amino acids) and life (proto-bacteria, etc). The thing is... that kills the hypothesis that there is any benefit to space-faring life... it doesn't need it, and is unlikely to be anything other than raw material.

Then there is the classic: Evolution is based on natural selection, and that cannot kill or help what it can't effect. A single staph Colony in a vacuum can't mutate and benefit from the mutation, because it cannot replicate. Never mind a single bacterium.

As for sling corpses into space, unlike a bacteria or virus, that would simply burn in an atmosphere, assuming it made it that far. Complete bodies would be torn to shreds eventually, making that really just a different way of throwing mites.

 

[Bored Wombat]

The best theories as to how life evolved is to posit basic molecules first.

You don't even need exogenisis if that is what you want.

The whole idea of exogenisis is to get from amino acid to reproducing cell.

And that's a bacteria. A virus doesn't cut the mustard because it still needs to encounter a cell to live.

The whole idea is that it increases the field of where the first cell might have appeared from somewhere on Earth to somewhere.

And there are plenty of algae or photoplanktons that would be fine in the upper atmosphere of venus. You don't have to hypothesise that they need to fall to the ground. (And neither does a bacteria fall very fast once wind resistance kicks in).

I mention a human corpse because human technology brings lifts them occasionally up a gravity well, and they contain a vast biodiversity. If you drop them into a planet, it doesn't all die. Wind lifts bacteria from the skin and hair and they drift off into the atmosphere, even if you don't have the bowel exposed.

And even once it does hit the ground or reaches an atmosphere dense enough for it to stop falling, you've got a lot of bioactivity. You've got aerobic and anaerobic bacteria, you've got an easy food source to give them a foothold, and you might even have some photo-synthesisers, if you're lucky. All you need is a energy source. (And geothermal is probably fine) and you've colonised a planet.

But survivability and viability very much are the issue.

 

[Frame Dragger]

You don't even need exogenisis if that is what you want.

The whole idea of exogenisis is to get from amino acid to reproducing cell.

And that's a bacteria. A virus doesn't cut the mustard because it still needs to encounter a cell to live.

The whole idea is that it increases the field of where the first cell might have appeared from somewhere on Earth to somewhere.

And there are plenty of algae or photoplanktons that would be fine in the upper atmosphere of venus. You don't have to hypothesise that they need to fall to the ground. (And neither does a bacteria fall very fast once wind resistance kicks in).

I mention a human corpse because human technology brings lifts them occasionally up a gravity well, and they contain a vast biodiversity. If you drop them into a planet, it doesn't all die. Wind lifts bacteria from the skin and hair and they drift off into the atmosphere, even if you don't have the bowel exposed.

And even once it does hit the ground or reaches an atmosphere dense enough for it to stop falling, you've got a lot of bioactivity. You've got aerobic and anaerobic bacteria, you've got an easy food source to give them a foothold, and you might even have some photo-synthesisers, if you're lucky. All you need is a energy source. (And geothermal is probably fine) and you've colonised a planet.

But survivability and viability very much are the issue.

That last sentence really is the kicker... and the first is true, but people still seem to look to it for the origins of basic organic molecules. I'm not selling a theory, I don't believe in exogenesis for precisely the reasons encapsulated in your first sentence.

That said, while a virus can't reproduce outside of a cell, it is still a genetic payload. A single virion is never going to make it, but going with your corpse notion (you've sold me in terms of the possiblity, if not the likelihood), it very well could.

Bacteria don't need to find cells, a virus does, but a virus (even shattered beyond reproductive viability) could still contribute to the formation of life on a planet, and their information is in OUR DNA, so the whole corpse may be a factor. With viruses, your payload is now orders of magnitude larger... that said, it does so in a way that that does not seem to match the kind of exogenesis you're talking about.

As for the algae and such, yes, but they would be more likely to make the journey as a result of some major bombardment, than space-flight. Given the interest of sterility the latter, natural forces seem to be the best candidates.

Remember, this all comes back to the notion that spacefaring life has some intrinsic advantage.

 

[baywax]

You don't even need exogenisis if that is what you want.

The whole idea of exogenisis is to get from amino acid to reproducing cell.

And that's a bacteria. A virus doesn't cut the mustard because it still needs to encounter a cell to live.

The whole idea is that it increases the field of where the first cell might have appeared from somewhere on Earth to somewhere.

And there are plenty of algae or photoplanktons that would be fine in the upper atmosphere of venus. You don't have to hypothesise that they need to fall to the ground. (And neither does a bacteria fall very fast once wind resistance kicks in).

I mention a human corpse because human technology brings lifts them occasionally up a gravity well, and they contain a vast biodiversity. If you drop them into a planet, it doesn't all die. Wind lifts bacteria from the skin and hair and they drift off into the atmosphere, even if you don't have the bowel exposed.

And even once it does hit the ground or reaches an atmosphere dense enough for it to stop falling, you've got a lot of bioactivity. You've got aerobic and anaerobic bacteria, you've got an easy food source to give them a foothold, and you might even have some photo-synthesisers, if you're lucky. All you need is a energy source. (And geothermal is probably fine) and you've colonised a planet.

But survivability and viability very much are the issue.

... right then! We'll just jettison our dead into deep space and say we've done our part in bring life to the universe...

 

[Frame Dragger]

... right then! We'll just jettison our dead into deep space and say we've done our part in bring life to the universe...

I have to say, that was my first reaction too... Still, it's a grapic illustration of his point I challenged regarding how the organisms (or molecules) hitch rides.