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Space based life forms

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#1 Ilphi

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Posted 09 April 2003 - 05:55 PM

Do you think that space based lifeforms could ever exist? I don’t mean something silly like the cetus... but what do you guys think are the possibilities? Are there any?

If a species did exist, would there be any reason for humans to “hang around” them? Perhaps we could hitch a lift on them if they were big enough? Or could we get heat from them?

All opinions welcome :D
Yea, ere my hot youth pass, I speak to my people and say:
Ye shall be foolish as I; ye shall scatter, not save;
Ye shall venture your all, lest ye lose what is more than all;
Ye shall call for a miracle, taking Christ at His word.
And for this I will answer, O people, answer here and hereafter,
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#2 usmarox


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Posted 09 April 2003 - 08:04 PM

I can't think of any significant reason why life shouldn't exist in space, save for two things:

1) Life doesn't just pop up de novo.  It has to evolve from somewhere.  Now, there's no reason why evolution shouldn't happen in space, but it's a far more unforgiving habitat, and one in which evolutionary mistakes wouldn't result in a poor ecological competitor, but rapid extinction.  As an example, generally accepted scientific theory holds that life ultimately evolved from ribozymes (self-manipulating RNAs).  Now, those simply wouldn't work in space, where the ambient temperature is about 2.5K.  And if a species evolved on a planet, they would a) have to get themselves offworld, and b) have a compelling reason to do it.  Evolution doesn't allow organisms to do things "for the hell of it".

2) They would have to have a biochemistry so radically different to ours we might not even recognise it as life.  It would have to function at ambient temperatures, which caps the metabolic rate right away.  Although temperature-compensation mechanisms exist in Earthly organisms (why'd you think your body clock goes at the same rate, summer and winter), there is nothing approaching what would be required for life in space.  Ditto pressure.  The dearth of nutrients in space would limit them to a metabolism somewhat similar to that of oligotrophic bacteria, and would necessitate a well-developed starvation response.

In summary, then, life in space is horrifically unlikely.  But the law of averages says it'll happen anyway.  I kinda hope it does; it'd be very cool, and it'd give them to publish in the Journal of Xenobiology (no, really - it does exist :))
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#3 Delvo

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Posted 09 April 2003 - 08:36 PM

It would have to be so different from our kind of life that we'd need to first have a definition that allows for it. For example, I would define a life form as a thing that:
1. Consumes food and/or energy
2. Produces waste
3. Grows
4. Reproduces
5. Responds to changes in environment

Fire would seem to meet qualifications 1-5 but isn't a thing. It's an event. My metabolism is an event too, but it isn't a life form; I'm the life form.

If we could build machines that could completely build copies of themselves, they would not qualify under #3, because installing new parts isn't growing.

Note that I didn't say anything about intelligence, so Lieutenant Data doesn't automaticly qualify as Picard suggested based on that alone. Data did build another android, but I'm not certain we can call that reproduction, and he doesn't grow.

Responding to changes in environment is a tricky one. There are direct responses and indirect ones. If something is dropped on my leg and the leg breaks, that's a change in the life form, and it's in response to something from the outside! But it doesn't qualify. Bruising, blood clotting, the re-fusion of the bone, and the undoing of the clots and bruises to return the leg to normal do. Photosynthesis doesn't count as a response to light, but phototropism (a plant bending to receive as much light as it can) does.

Viruses might be suggested by some because their composition is chemically similar to ours, but I don't count that as a qualification for life. The only environmental change they respond to is being on a host cell, at which point they somehow get their DNA or RNA inside it, but, based on my standard outlined in the paragraph above, I don't know if this counts because I don't know the mechanism. If it counts, then viruses do #1, and if not, they don't. Whether they do #4 is debatable but I say they don't. But it doesn't matter because #2 and #3 disqualify them anyway.

So, on to the "in space" part...

First, let's start with the "thing" that has to meet these qualifications. Where's the matter? Space dust? Ice crystals? Drifting atoms of H, He, Li, and such? Not enough there to work with. What I see left is asteroids, and possibly the denser cases of nova/supernova cast-offs and matter streams falling into deep gravity wells.

Next we'll need energy; it's written in #1 and the other four would violate entropy without it. Orbiting a star works. Being near anything else that "shines" might too.

For the rest of the qualifications, I can't picture it and don't believe it would happen for various reasons that would require too much more typing for now ;), but this does narrow the possible options down...

#4 Christopher

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Posted 09 April 2003 - 10:41 PM

Bacteria can survive in space.  Early on, when they were evolving, huge asteroid impacts were routinely flinging clouds of ejecta out into space, and the bacteria with them.  So the bacteria had to evolve the ability to survive the vacuum and hard radiation of space.  They aren't metabolically active at the time, but they endure indefinitely in a dormant state.  Indeed, many of them would never fall back to the planet surface, but would remain in space, and be accelerated out of the system by light pressure.  It's estimated that it would've taken only a billion years for the bacteria blown off of Earth (or perhaps some earlier planet?) to spread throughout the galaxy, and settle on other worlds capable of supporting them (perhaps including Earth?).  So in that sense, there very well may be life in space.

As for something larger, more active... well, maybe it comes down to how we define "in space."  Check out Richard A. Lovett's science fact article in the May Analog -- apparently, it's now believed that even Pluto may have a liquid-water or ammonia-water ocean deep beneath the surface, heated by the decay of radioisotopes inside the planet and insulated from space by its sheer depth.  Recent theories suggest there could be rogue planets drifting through interstellar space, and many of them could perhaps have such internal oceans.  Rogue Jovian planets might have them too.

Does that really qualify as spacegoing life?  Not in the sense we're looking for, I guess.  But it might be a launching point for further speculation.
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#5 Ilphi

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Posted 09 April 2003 - 11:09 PM

Okay, great answers guys :D

Leaving aside any obvious problems, lets assume there is a wierd alien species out there...somewhere... we'l call them them the Bizzarites because they are. They decide to genetically create a huge space lifeform... or many different kinds of them... because they plan to build things on their back and use the heat and waste products as well as hitching a lift on them. Okay, I'm rambling here. It's just an idea I've been having. Any thoughts?  :ninja:
Yea, ere my hot youth pass, I speak to my people and say:
Ye shall be foolish as I; ye shall scatter, not save;
Ye shall venture your all, lest ye lose what is more than all;
Ye shall call for a miracle, taking Christ at His word.
And for this I will answer, O people, answer here and hereafter,
The Fool - Padraic Pearse

#6 tennyson

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Posted 10 April 2003 - 12:50 AM

Spoiler alert

Then you may want to chaeckout Peter F Hamilton's Fallen Dragon
"Only an idiot would fight a war on two fronts. Only the heir to the throne of the Kingdom of Idiots would fight a war on twelve fronts."

— Londo, "Ceremonies of Light and Dark" Babylon-5

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