Celestia Forums

Posted: **19.10.2005, 23:22**

Anyone think that some day we may infact come in contact with Alien life? And this probably goes in the purgatory section. im not sure.

Posted: **19.10.2005, 23:37**

Definitly. So many stars out there, what are the odds there is no life at all? And who knows, maybe we'll be able to make the warp drive (watcch Ster Trek) thing possible! I've heard Stephen Hawking plans to work on the possibility of warp drive.

So I think we'll definitely encounter "new life and new civilizations" on our journey "to boldly go where no man/one has gone before".

Posted: **19.10.2005, 23:58**

Alien life? Probably, in microbe form at least. I think life at that level at least is pretty common in the universe.

But alien INTELLIGENT life, that we can communicate with and learn from/teach? Maybe not. There's a lot of things that can work against advanced lifeforms, and we've been pretty lucky in our evolution so far. It would have taken just one nearby supernova or GRB or asteroid impact a few thousand years ago to wipe us out before we started our societies.

Posted: **20.10.2005, 00:02**

You think that, the universe isn't that old. i mean, it took us 4 billion years to create what we are, and we are still pretty primitive.

Posted: **20.10.2005, 01:36**

Malenfant wrote:Alien life? Probably, in microbe form at least. I think life at that level at least is pretty common in the universe.

But alien INTELLIGENT life, that we can communicate with and learn from/teach? Maybe not. There's a lot of things that can work against advanced lifeforms, and we've been pretty lucky in our evolution so far. It would have taken just one nearby supernova or GRB or asteroid impact a few thousand years ago to wipe us out before we started our societies.

Look, where did I say there would be intelligent life? (assuming you thought I said that)

WildMoon wrote:Definitely. So many stars out there, what are the odds there is no life at all? And who knows, maybe we'll be able to make the warp drive (watch Star Trek) thing possible! I've heard Stephen Hawking plans to work on the possibility of warp drive.

So I think we'll definitely encounter "new life and new civilizations" on our journey "to boldly go where no man/one has gone before".

Why does life out there have to be either highly advanced or microbial to everyone? Why not neanderthals? Why not people as advanced as us? Why not civilizations similar to the Greeks, and the Romans, and the Egyptians?

I think it's good to have the hope that we'll meet someone out there while we're exploring the galaxy and universe. Kinda gives you a warm fuzzy feeling, unlike that cold lonely feeling when you wonder if we're alone.

I thought also that blue giants didn't even live long enough for life to develop much or even at all anyway? Or do they live longer than simply millions of years instead of billions like I heard?

Posted: **20.10.2005, 01:46**

If we explored other planets and moons elsewhere in the Universe and we encountered life on those bodies, the most likely form of life we would encounter would be microbial. The Earth had microbial life only (no multicellular life) for most of its history.

Posted: **20.10.2005, 03:54**

WildMoon wrote:Look, where did I say there would be intelligent life? (assuming you thought I said that)

Because, in discussions like this, the question of intelligence almost always turns up. Probably because the ramifications of intelligent life are so much greater even than non-intelligent life.

WildMoon wrote:Why does life out there have to be either highly advanced or microbial to everyone? Why not neanderthals? Why not people as advanced as us? Why not civilizations similar to the Greeks, and the Romans, and the Egyptians?

Why do we inevitably think that such examples as these are less advanced than us? Technological know how does not lessen the sophistication of the biology involved in sapiency. And strictly speaking, any multicellular form is a remarkably advanced form of biology.

There is a HUGE leap between the development of multicellular forms and the earliest sapient forms. The odds will always be greater of encountering non-sapient forms than spaient ones, regardless of their cultural level.

...John...

Posted: **20.10.2005, 04:54**

WildMoon wrote:Look, where did I say there would be intelligent life? (assuming you thought I said that)

Well for a start, I was replying to the original question, not to you

.

And all the original question asked was "Alien life", without specifying whether or not it was intelligent (though I got the impression that this was implied in the question).

Why does life out there have to be either highly advanced or microbial to everyone? Why not neanderthals? Why not people as advanced as us? Why not civilizations similar to the Greeks, and the Romans, and the Egyptians?

Neanderthals are highly advanced in the grand scheme of things. So are dinosaurs or insects or reptiles or birds. The point is that by 'advanced' I mean 'evolved'. It's kinda like how astrophysicists refer to 'heavy elements' as anything heavier than hydrogen or helium. It's probably really easy to make microbes out of the right combination of organic compounds, lightning bolts, amino acids, liquid water (or something else maybe) and clay templates or whatever have you. But if you look at it, life has been present on Earth for about 4 billion out of the 4.6 billion years that the planet's been around - but complex multicellular life? Stuff that isn't microbial? That's only been around for the last 1 billion years. For three billion years or so, life was just sitting at the microbial stage - probably evolving like crazy, reaching plateaus and then getting nearly wiped out several times by asteroid impacts or having no place to go til circumstances allowed evolution to really get into gear (eg oxygen in the atmosphere, possible changing of the earth's tilt, the sun warming up enough, who knows...).

So for a good 70-75% or so of our planet's history, complex macroscopic life didn't even exist. And complex macroscopic life intelligent enough to form technological societies has only really existed for the past 200 to 10,000 years (depending on how generous you want to be in your definition of "technological"). That's a barely noticeable blip in our planet's history. As Carl Sagan put it in Cosmos, if our planet's history so far was condensed into the span of a year, all of human history would fit into the last couple of minutes of December 31st. And for all we know, some celestial catastrophe could happen in the next few hundred or thousand years to wipe us all out.

I was just reading an article in this month's Astronomy magazine about how a Gamma Ray Burst over 6,000 lightyears from Earth could cause a mass extinction. 10 seconds of exposure to that kind of radiation from something that far away, that we wouldn't even see coming, and it'd be all over for most of life on Earth within 15 years. That is how fragile life is in the universe, it can be snuffed out just like that.

Given that kind of timescale and those kinds of odds, we're damn lucky to be here still (pity many of us don't seem to appreciate that

). So is it really that likely we'd find anyone else out there?

I think it's good to have the hope that we'll meet someone out there while we're exploring the galaxy and universe. Kinda gives you a warm fuzzy feeling, unlike that cold lonely feeling when you wonder if we're alone.

Well, unfortunately science doesn't really work by what 'feels nice', it goes by how physics and planetary and stellar evolution work.

And to be honest, it's just as important if we really are the only ones here. We could be the first world to evolve intelligent life, because things have calmed down enough in the galaxy to allow life long enough to evolve into an intelligent form. I think confirmation of that (if it were true) would mean as much to us - if not more - as if we found a universe teeming with intelligent life.

I thought also that blue giants didn't even live long enough for life to develop much or even at all anyway? Or do they live longer than simply millions of years instead of billions like I heard?

Massive stars have short lives. Heck, if you look up at the sky then the bright stars we see today won't even be around in a few million years. Betelgeuse and Antares would go supernova probably within the next million years. The most massive stars - the 'blue giants' (though they don't stay that way for long - they evolve from massive O and B main sequence stars into blue then yellow then red supergiants) would probably get through their entire lifespan in about 10-15 million years. They don't even last long enough for planets to FORM around them (and they couldn't anyway because the stellar wind would blast away any planet forming material).

Posted: **20.10.2005, 11:03**

Given the size of the Universe, and the infinite number of stars, planets and
combinations of circumstances out there, I personally think that the
possibility of intelligent life (besides ourselves) has to be 100%

Even if we evolved because of a random series of events which might
only occur only once in a billion solar systems, there are still (as far as we
know now) an infinite number of solar systems in the universe aren't there?

In this case, the chances of intelligent life evolving somewhere else simply
have to be 100% do they not?

In any case, whether there is other intelligent life in the universe or not,
the answer to this question either way causes dumb-founded amazement
here...

Either there are other intelligent life forms (WOW!) or there are not (also
WOW!)

Thanks

Posted: **20.10.2005, 17:52**

BrainDead wrote:Even if we evolved because of a random series of events which might only occur only once in a billion solar systems, there are still (as far as we know now) an infinite number of solar systems in the universe aren't there?

Well, there's a FINITE number of stars etc out there. There's a heck of a lot of them, but it's not infinite.

Again it boils down to what you assume about how life forms (think of the Drake Equation) - that 'one in a billion solar systems' chance could be the chance that any macroscopic life forms at all, or it could be the chance that any macroscopic life that COULD end up being intelligent and technological could form, or that any macroscopic life forms that IS intelligent and technological.

Heck from what we're seeing it seems that we'd be lucky if 1 in 100 stars have solar systems like our own that could even have a habitable planet in them (instead of a hot jupiter or a gas giant in an eccentric orbit). So that adds a couple of zeroes to your 1 in 1,000,000,000 right there.

Either there are other intelligent life forms (WOW!) or there are not (also WOW!)

Yeah, confirmation of either would be a rather major discovery.

Posted: **20.10.2005, 19:16**

I guess one part of the problem may be how Earthlike does a planet have to be to stand a chance at supporting advanced life. If this planet is anything to go by, prokaryote-type life can survive just about anywhere, but eukaryotes (which includes all multicellular life) are much less flexible.

So while a terrestrial world on an eccentric orbit (e.g. a moon of 16 Cyg B b) could probably retain water oceans, eukaryotic life may be confined to the oceans because conditions on land (particularly in continental interiors) could easily enter the lethal range for eukaryotes. Then again, you might get the most spectacular migrations in the galaxy.

Obliquity is another way you could get problems - if Earth had a much more tilted axis, the seasons could become extreme, with the poles alternating between frigid wasteland and baked desert over the course of a year. Then again, giving the planet a thick atmosphere might even things out enough to give you something that might just about be habitable.

Then consider the carbon dioxide greenhouse - once organisms start photosynthesising they remove carbon dioxide. Earth may have got lucky with a mere slushball glaciation: the habitable zone appears to extend outwards a lot further than it does inwards, but colder planets (which under current understanding would seem to be the majority of "habitable" planets) might have incredibly severe snowball glaciations that reset everything to the anaerobic level.

Hot Jupiters may or may not be a problem, some simulations suggest that it is possible to form terrestrials after a gas giant has migrated through the inner system from remaining material. Inner system gas giants might cause superflares (probably not good for anything living on the surface), but this link has not been proven.

You then have the balance between delivering enough volatiles so the planet ends up with oceans and keeping the frequency of dinosaur-killer impacts low enough that life can achieve high levels of development. Then again, Earth's oceans may not have been from comets so, who knows? In any case, some systems (e.g. Tau Ceti) apparently contain a lot more debris belts than our system. Depending on how much reaches the inner system, this may or may not be a problem.

Personally I think the evidence is that the possible configurations of solar systems are far more varied than was originally thought, and that science-fiction scenarios which seem to have a habitable world of some kind around practically every vaguely suitable star are wildly optimistic.

Posted: **20.10.2005, 22:27**

Malenfant wrote:Well, there's a FINITE number of stars etc out there. There's a heck of a lot of them, but it's not infinite.

Well now... That's interesting. Can you tell me how you know that
please? Seriously, I have never heard that we know the universe is
finite. Can you direct me to more information please?

Thanks

Posted: **20.10.2005, 22:43**

BrainDead wrote:
Malenfant wrote:Well, there's a FINITE number of stars etc out there. There's a heck of a lot of them, but it's not infinite.
Well now... That's interesting. Can you tell me how you know that
please? Seriously, I have never heard that we know the universe is
finite. Can you direct me to more information please?

Thanks

Well there's this...
http://www.space.com/scienceastronomy/u ... 31008.html

I'd also ask you what evidence there is that the universe is infinite - or at least, that the amount of stars and matterin the universe is infitite. There's a hell of a lot of them sure, but that's not the same as infinite. AFAIK there's no evidence that the big bang released an infinite amount of energy, so there is no evidence that an infinite amount of matter from which to form stars coalesced from that.

Posted: **20.10.2005, 22:44**

If there's an infinite number of stars out there, then our universe would be so flooded with stars they'd all be touching (well, for truly infinite, I don't know, but if infinite meant the number of stars to fill up the universe, they'd be touching).

Since our universe is not infinite, there cannot be an infinite number of stars.

Also, the Big Bang theory says our universe is expanding - and what is infinite cannot get any bigger. And there is evidence that our universe is expanding, and that backs up the Big Bang theory.

EDIT: Drat, Malenfant posted before I did.

Posted: **20.10.2005, 23:06**

Malenfant wrote:Well there's this...
http://www.space.com/scienceastronomy/u ... 31008.html

Thanks very much for the link. Honestly, this is the first I've heard of the
new theory. Sorry, but I don't have as much time as l'd like to explore.

Malenfant wrote:I'd also ask you what evidence there is that the universe is infinite - or at least, that the amount of stars and matterin the universe is infitite. There's a hell of a lot of them sure, but that's not the same as infinite. AFAIK there's no evidence that the big bang released an infinite amount of energy, so there is no evidence that an infinite amount of matter from which to form stars coalesced from that.

I can direct you to the same site you sent me to...

But the new theoretical conjuring is no joke. It's based on real-world observations of radiation leftover from the Big Bang, data that do not fit the current leading view of an infinite universe.

It appears that this question is another of those that haven't been
settled yet, but I agree that it certainly looks as if the universe
is finite.

Again, thanks for the update. Interesting stuff here.

Posted: **21.10.2005, 00:00**

Malenfant wrote:
BrainDead wrote:Even if we evolved because of a random series of events which might only occur only once in a billion solar systems, there are still (as far as we know now) an infinite number of solar systems in the universe aren't there?

Well, there's a FINITE number of stars etc out there. There's a heck of a lot of them, but it's not infinite.

Again it boils down to what you assume about how life forms (think of the Drake Equation) - that 'one in a billion solar systems' chance could be the chance that any macroscopic life forms at all, or it could be the chance that any macroscopic life that COULD end up being intelligent and technological could form, or that any macroscopic life forms that IS intelligent and technological.

Heck from what we're seeing it seems that we'd be lucky if 1 in 100 stars have solar systems like our own that could even have a habitable planet in them (instead of a hot jupiter or a gas giant in an eccentric orbit). So that adds a couple of zeroes to your 1 in 1,000,000,000 right there.

Either there are other intelligent life forms (WOW!) or there are not (also WOW!)

Yeah, confirmation of either would be a rather major discovery.

Well, not all places need earthlike conditions to create life. Lets say, that, Venus ahd life on it. You would think 'It would just die because its to hot and the atmosphere is full of poisonus stuff'. Well, for all we know, there could be life forms that need the specific things in the atmosphere to live.

Posted: **21.10.2005, 00:06**

Hunter Parasite wrote:Well, not all places need earthlike conditions to create life. Lets say, that, Venus ahd life on it. You would think 'It would just die because its to hot and the atmosphere is full of poisonus stuff'. Well, for all we know, there could be life forms that need the specific things in the atmosphere to live.

It's been suggested that microbes might be able to survive in the upper layers of Venus' atmosphere.

But there are physical and chemical limitations to life. You can't just make it out of random stuff and have it work. For example, although silicon based life is a staple of scifi, it's unlikely in practise because silicon can't form long chains like carbon can, and you need that for life.

Posted: **21.10.2005, 00:09**

It might not be just silicon, lets say Boron or Arsenic.

Posted: **21.10.2005, 00:17**

Hunter Parasite wrote:
Malenfant wrote:
BrainDead wrote:Even if we evolved because of a random series of events which might only occur only once in a billion solar systems, there are still (as far as we know now) an infinite number of solar systems in the universe aren't there?

Well, there's a FINITE number of stars etc out there. There's a heck of a lot of them, but it's not infinite.

Again it boils down to what you assume about how life forms (think of the Drake Equation) - that 'one in a billion solar systems' chance could be the chance that any macroscopic life forms at all, or it could be the chance that any macroscopic life that COULD end up being intelligent and technological could form, or that any macroscopic life forms that IS intelligent and technological.

Heck from what we're seeing it seems that we'd be lucky if 1 in 100 stars have solar systems like our own that could even have a habitable planet in them (instead of a hot jupiter or a gas giant in an eccentric orbit). So that adds a couple of zeroes to your 1 in 1,000,000,000 right there.

Either there are other intelligent life forms (WOW!) or there are not (also WOW!)

Yeah, confirmation of either would be a rather major discovery.
Well, not all places need earthlike conditions to create life. Lets say, that, Venus had life on it. You would think 'It would just die because its to hot and the atmosphere is full of poisonus stuff'. Well, for all we know, there could be life forms that need the specific things in the atmosphere to live.

Hunter Parasite's right. We only know what life on one planet needs to survive, defined as the Goldilocks Conditions. Maybe hte Goldilocks Conditions for one planet are different than those of another planet.

And also, ya'll've said that in certain conditions only single-celled life would exist and that all multicelled life would die. How do you know that multicelled life would not be able to adapt so it can survive on another planet? If single celled life could exist there, why can't it evolve and be a multicellular organism yet still be able to survive?

Also, who's to say that life can't maybe be in the form of energy? Ghosts are nuthin' but energy. And some ghosts seem to even be sentient (watch Ghost Hunters - they actually go about trying to disprove ghosts and have alot of equipment that'll detect weird things that have been known to happen around ghosts. They also don't go around like other ghosts groups and say everywhere they go is haunted). So why can't there be life in the form of energy too?

Posted: **21.10.2005, 00:46**

Hunter Parasite wrote:It might not be just silicon, lets say Boron or Arsenic.

No, it can't. Because Boron and Arsenic and everything else can't even form any kind of long chains or be the base for reactions that produce energy for life.

You seem to find this strangely difficult to understand but there are actually physical and chemical restrictions to what can drive life. The universe does not operate by armwavy 'anything-goes' wishful thinking.

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