What is the probability of life in Universe?

[Viva-Diva]

Hello to all scientists here,

I am not a physicist and am new to the forum.

Considering the Universe is so huge, isn't the probability of having life on other planets in the universe equally high?

Please share your opinion.

Thanks to all in advance,
Viva-Diva

 

[marcus]

at least 99.999 % if you consider the entire observable universe (just an informal guess).

but we still might be the only life in our GALAXY, at least that has evolved to the point of being able to measure the speed of light and imagine inhabiting other planetary systems and stuff like that.

there are billions of galaxies, and each galaxy contains billions of stars (actually more in both cases, like hundreds of billions, but not to be overprecise)

so if life is extremely rare for some reason we don't understand, then it's conceivable that Earth might be the only planet with life in the Milkyway galaxy. (I can hardly see how life could be so rare, but let's pretend we are alone in the galaxy).

even then, you still have all those billions of other galaxies. but we may never interact with life in other galaxies because they are so far away. in some sense it seems almost not to matter.

what seems to matter to me is what other life and what other civilizations are there in the Milkyway. they are the ones we might someday (if they exist) talk with or learn about

======================
Viva, I almost wish you had asked a slightly different question (which would be a LOT harder to answer) namely
what do you estimate is the probablility of other life in the Milkyway galaxy?

for the universe as a whole, it is almost certainly 100 percent. it isn't even an interesting question, as I see it.

but if you just ask about other life in Milkyway, how prevalent is it? does it exist at all? if it exists are we talking like 5 other civilizations in the whole galaxy, or hundreds? because at this level, the level of galaxy, how you answer is constrained by the socalled Fermi question---this puts some nittygritty meaning into it and gives some traction to the mind. then you can't just say anything that comes into your head.

 

[mgb_phys]

This is known as the drake equation http://en.wikipedia.org/wiki/Drake_equation, basically the number of stars * the probablility that the star could have life on planets around it.

 

[cristo]

I agree with marcus: it is far more interesting to try and find out if life exists in our galaxy since we may, at some point in the future, be able to contact them.

The study of exoplanets (planets outside our own solar system) is somewhat of a new field of research, and one that there are a growing number of astronomers turning their expertise to. We are discovering more exoplanets within the Milky Way each month. In fact, I remember a talk I went to a couple of months ago where a project called DARWIN was mentioned. This is scheduled to start in the next decade and, I think, is something to do with what used to be called PPARC (the Particle Physics and Astronomy Research Council) here in the UK. The aim of this mission is to try and seek out earth-like planets orbiting nearby stars.

All in all, it's an exciting period for astronomy/cosmology at the moment.

 

[Chronos]

The vast majority of scientists would concede the probability of extraterrestrial life is 100% in the universe at large, and probably 90% that some form of life existed on Mars at some point in the past. Intelligient life is, however, a sticky wicket. It takes a very long time to arise and requires improbable events. Placing odds on these events is very difficult. I would guess it is very probable we are the only technologically accomplished species in this galaxy at this time. Civilization, as we know it, has only existed on Earth for a handful of thousands of years. And civilizations capable of extraterrestrial communication has only existed here for about 50 years. This is an incredibly tiny slice of time in the life of a galaxy [or universe]. Furthermore, the window to detect our EM emissions by accident could easily close within the next 100 years. Assigning only slightly pessimistic values to the Drake equation yields a value of less than one comparably accomplished civilization to any given galaxy in the universe at such a tiny slice of time. The background noise of the universe yields long odds that any of them are detectable to us.

 

[Viva-Diva]

Thank you all for your views and nice links that you all directed me to.

But Chronos, why did creation of Universe make a lot of people angry?:-)

 

[Feonix12]

Personally i would think there is a 99.9% probability of life on another planet. I am assuming life has to have the right conditions and the right timing but so many chances in the universe you would think there would be more than one.

 

[zankaon]

The possibility and near reality perhaps of detecting an oxygen signature of atmosphere of terrestrial exoplanets is quite amazing. The following is excerpt of previous post in astronomy:
How far away from Earth might the oxygen signature of our atmosphere be spectographically detectable? The flip side is how far away might an exo-terrestrial planet's atmospheric oxygen signature be detectable? For example,Gliese 581 c,d are larger (5-7x earth) terrestrial planets at 20 lyrs distance.http://en.wikipedia.org/wiki/Gliese_581_c Hence a fast and easy extensive way of surveying for surface life; thus for our planet, over 2 billion years of significant oxygen signature exposure.

 

[Dan Tee]

If there is intelligent life in our Galaxy, how could we communicate considering the distances likely to be involved ?? it could be a one sided communication

 

[marcus]

If there is intelligent life in our Galaxy, how could we communicate considering the distances likely to be involved ?? it could be a one sided communication

one sided sounds good to me.

When I read Jonathan Swift book Gulliver's Travels, he is communicating oneway to me. from back around 1700s.
I'm happy, you have problems with it?

If there is other intelligent life in our Galaxy, I hope they thought to radio us a copy of their equivalent of Wikipedia, or the Encyclopedia Britannica. If they did, and we get it in a few thousand years, we'll have a ball with it.
Onewayness not withstanding!

 

[Wallace]

Interesting, I'd never thought about 'one-way' communication with ET's like this before. I guess the issue is that it's quite an investment in time and money to send the signal out if you have no idea where to send it or whether there is anyone to listen.

At least in writing a novel you know that people do read novels, and indeed that people exist!

I believe (though correct me if I'm wrong) that the sensitivity of SETI programs on Earth would not pick up the kind of signals that Earth sends out (TV, radio etc) if these signals where sent from even the closest stars to us. So for instance, ET could be watching telly on a planet orbiting Alpha Centauri and we wouldn't pick it up with SETI.

We don't actively send out high powered signals into space to try and send info to ET (though this has been done for small periods of time in the past) even though we do spend a fair bit of time listening. What if all the civilisations in the galaxy are waiting for the call, but no one has tried dialing yet, kind of like a post first date phone stand off

 

[Dan Tee]

one sided sounds good to me.

When I read Jonathan Swift book Gulliver's Travels, he is communicating oneway to me. from back around 1700s.
I'm happy, you have problems with it?

No, I do not have a problem with one way it is the only way for those distances and if we could actually communicate we would probably only argue. I do like your analogy to a novel, perhaps they would send a comprehensive history of themselves and a few usefull tips say some does and don’ts.

Re comments by Wallace concerning SETI, can I ask "Does SETI only pick up certain types of signal??"

Perhaps the huge distances that we are faced with are Natures way of keeping us out of trouble

 

[Chronos]

SETI limits detection modes to the most probable wavelengths - like the neutral hydrogen 21 cm band. Other modes are less attractive because of detectability limits. We make the fairly reasonable assumption ET is aware of these limits.

 

[Zenparticle]

Thank you all for your views and nice links that you all directed me to.

But Chronos, why did creation of Universe make a lot of people angry?:-)

I think it's just a quote that he finds amusing/interesting..But I can not answer for him just what my logic tells me.

 

[mgb_phys]

From Restaurant at the end of the Universe ( 3rd hitch hikers book)

"The story so far:
In the beginning the Universe was created.
This has made a lot of people very angry and been widely regarded as a bad move"

 

[Chronos]

mgb has me cornered. It is ironic humor. Douglas Adams is very good at this sort of thing. I loved the part where the cosmic octopus revealed the secret to the TOE - 42. Hard to argue with that kind of logic. The Drake equation is a very logical approach to estimating the abundance of life in the universe. The sun is a very common type of star [small, dim, invariant output, and long lived], planets are the rule, not exception, and planets occupying 'goldilocks' orbits are assuredly abundant throughout this galaxy and the universe. So the probability of ET life forms within the milky way is virtually 100%, and nearly 100% life forms do, or did, exist on other bodies within our own solar system.

The probability of intelligent [as in technologically capable of communicating with us] life forms has a very poor probability of existing. The chances of it having existed elsewhere at any time during the lifetime of our solar system is virtually zero. Our ability to even calculate the probability of it existing anywhere else in our galaxy is also close to zero. The fact the skies are not abounding with signals from alien civilizations - priceless. Fermi raised a very good argument. Not only do we lack irrefutable physical evidence of their visits to earth, we also lack radio evidence they exist. Granted detection of an alien TV station is a shot in the dark, we most certainly have the technology to detect such broadcasts emanating from anywhere in the galaxy, if our big 'ears' were pointed in the right direction. Obviously it will take centuries to scan the entire sky, but the evidence is clear. Civilizations like our own a rare. Statistically speaking, no more than five like our own currently exist within this galaxy. The absence of signals also has statistical significance and this the pure number crunching result.

 

[Chronos]

mgb has me cornered. It is ironic humor. Douglas Adams is very good at this sort of thing. I loved the part where the cosmic octopus revealed the secret to the TOE - 42. Hard to argue with that kind of logic. The Drake equation is a very logical approach to estimating the abundance of life in the universe. The sun is a very common type of star [small, dim, invariant output, and long lived], planets are the rule, not exception, and planets occupying 'goldilocks' orbits are assuredly abundant throughout this galaxy and the universe. So the probability of ET life forms within the milky way is virtually 100%, and nearly 100% life forms do, or did, exist on other bodies within our own solar system.

The probability of intelligent [as in technologically capable of communicating with us] life forms has a very poor probability of existing. The chances of it having existed elsewhere at any time during the lifetime of our solar system is virtually zero. Our ability to even calculate the probability of it existing anywhere else in our galaxy is also close to zero. The fact the skies are not abounding with signals from alien civilizations - priceless. Fermi raised an excellent argument. Not only do we lack irrefutable physical evidence of alien visitors, we also lack radio evidence. Granted detection of an alien broadcast is a shot in the dark. But, we have the technology to detect such broadcasts emanating from almost anywhere in this galaxy - if our big 'ears' are pointed in the right direction. Obviously it will take centuries to scan the entire sky, but the evidence so far is clear. Civiliations technologically equivalent to our own are rare. Statistically speaking, no more than five such civiliations are likely to currently exist within this galaxy, and zero is still not excluded.[/QUOTE]

 

[baywax]

The probability of intelligent [as in technologically capable of communicating with us] life forms has a very poor probability of existing. The chances of it having existed elsewhere at any time during the lifetime of our solar system is virtually zero. Our ability to even calculate the probability of it existing anywhere else in our galaxy is also close to zero. The fact the skies are not abounding with signals from alien civilizations - priceless. Fermi raised an excellent argument. Not only do we lack irrefutable physical evidence of alien visitors, we also lack radio evidence. Granted detection of an alien broadcast is a shot in the dark. But, we have the technology to detect such broadcasts emanating from almost anywhere in this galaxy - if our big 'ears' are pointed in the right direction. Obviously it will take centuries to scan the entire sky, but the evidence so far is clear. Civiliations technologically equivalent to our own are rare. Statistically speaking, no more than five such civiliations are likely to currently exist within this galaxy, and zero is still not excluded.

[/QUOTE]

The stats are fine but if we're looking for radio signals we might be looking for the wrong thing. There's more than one way to send a signal... many of which we have not thought of, no doubt.

Its particularly heartening to hear that we have turned our search for exoplanets into our own galaxy. I wondered if that was happening.

 

[dilletante]

The probability of intelligent [as in technologically capable of communicating with us] life forms has a very poor probability of existing. The chances of it having existed elsewhere at any time during the lifetime of our solar system is virtually zero. Our ability to even calculate the probability of it existing anywhere else in our galaxy is also close to zero. The fact the skies are not abounding with signals from alien civilizations - priceless. Fermi raised a very good argument. Not only do we lack irrefutable physical evidence of their visits to earth, we also lack radio evidence they exist. Granted detection of an alien TV station is a shot in the dark, we most certainly have the technology to detect such broadcasts emanating from anywhere in the galaxy, if our big 'ears' were pointed in the right direction. Obviously it will take centuries to scan the entire sky, but the evidence is clear. Civilizations like our own a rare. Statistically speaking, no more than five like our own currently exist within this galaxy. The absence of signals also has statistical significance and this the pure number crunching result.

Hi Chronos,

Do we actually have the technology to detect alien TV signals from anywhere in the galaxy, and have we made any attempt to do so? I am hoping you have more information on SETI than they provide on their website, which seems pretty meager. I have been unable to find how many stars they have looked at, for how long or at what frequencies. They did mention one study of 100 nearby stars. It is my impression that they are concentrating on the frequency of neutral hydrogen, which earthlings are not allowed to broadcast on. If aliens think like us, then they are listening to the same frequency and not broadcasting on it either :)

I have been unable to determine whether we actually have made an attempt to listen to normal broadcast channels, or if we are capable of hearing anything broadcast on those channels beyond our neighborhood. Certainly if we are restricted in the bandwidth we listen to and have covered only a small number of stars, it seems premature to conclude that intelligent life is rare or nonexistent. Sagan did not seem to think so, and he was involved with SETI. It would be great to have some additional factual information!

 

[keinve]

The probability of intelligent [as in technologically capable of communicating with us] life forms has a very poor probability of existing. The chances of it having existed elsewhere at any time during the lifetime of our solar system is virtually zero. Our ability to even calculate the probability of it existing anywhere else in our galaxy is also close to zero. The fact the skies are not abounding with signals from alien civilizations - priceless. Fermi raised a very good argument. Not only do we lack irrefutable physical evidence of their visits to earth, we also lack radio evidence they exist. Granted detection of an alien TV station is a shot in the dark, we most certainly have the technology to detect such broadcasts emanating from anywhere in the galaxy, if our big 'ears' were pointed in the right direction. Obviously it will take centuries to scan the entire sky, but the evidence is clear. Civilizations like our own a rare. Statistically speaking, no more than five like our own currently exist within this galaxy. The absence of signals also has statistical significance and this the pure number crunching result.

Where do i begn? first, as others have stated, other civilizations might use different EM waves for the same purpose. Second, since all EM waves travel at the speed of light, they might simply be too far to reach us yet. Third, EM waves can be disrupted by large amounts of physical matter, or by extremely large gravity wells, such as black holes. I will give you one point. Civilizations like our own are rare. But you didn't specify the technology, which is why i agreed with you on that point. A civilizations technology could be high enough to go faster than the speed of light(just exaggerating for the purpose), yet have a completely, no joke intended, alien civilization. One other thing. By 'communication', do you mean they would be able to understand us, or anything we do? Or do you mean contact us, regardless of if we undersand it? Because, if you mean the second one, a civilization could have already threatened us to put down our arms, or be killed, we just might not have noticed. If it's the first one, then the chances are, litterally, next to none. An alien species might not even notice us, or we them.

 

[robertm]

Finding intelligent life would only be slightly more exciting for me than simple life. Just a few replicating bacterial type lifeforms would be absolutely magnificent!

Our solar system seems quite promising for simple ET lifeforms.

 

[davidjess]

The probability of life in the universe is exactly 1

The probability of life in the universe is exactly 1.

I will not bore you with the proof (but it is a fact recognized by all fields of science).

I think that that is the best place to start any analysis. For purposes of creative and critical thinking, we should re-frame the question as what is the probability that life formed only on 1 planet and no others?

 

[baywax]

Finding intelligent life would only be slightly more exciting for me than simple life. Just a few replicating bacterial type lifeforms would be absolutely magnificent!

Our solar system seems quite promising for simple ET lifeforms.

I agree. It would be a monumental event to verify living organisms on a planet other than our own. I'd say there's a 100% probability of life in the rest of this galaxy.

What are the chances of using spectrometry to determine if there is life on one of the earthlike exoplanets being observed these days?

 

[emc2cracker]

one of the Gliese red dwarfs has a planet in its goldy locks zone, regretably its not a transit planet and its 20 light years away I think in Libra. One planet is very close.. like a venus, one is on the outer edge of the zone and there is debate about wether its tidaly locked or not. I wish someone would build an efficient anti matter generator and engine to launch a few probes soon! Would be nice to live long enough to have some answers would it not?

 

[bapowell]

Our lack of understanding about abiogenesis kind of renders this line of questioning moot. While there are most certainly plenty of other 'Earth's' out there capable of harboring carbon-based life, it is rather unclear at present how organic life evolved from inorganic molecules (don't get me wrong -- there have been tons of very interesting advancements in this theory over the past several years). Even if we developed a theory of how the replicators (RNA and DNA) came to be, the follow-on question of whether or not intelligent life would evolve is far from obvious. The emergence of intelligent life on Earth apparently resulted from several contingencies (had the dinosaurs not been killed of 65 mya, it's unlikely that mankind would have evolved), and so it's hard to say just how generic any of it is.

Of course, the zeroth order question is: are there more Earth's in the universe/galaxy?
But the harder, 1st order question is more like: given another planet identical to ours in every way, would life inevitably evolve, and if so, would it eventually become intelligent?

 

[IcedEcliptic]

The only purely honest answer is: unknown.

 

[phyzguy]

The only purely honest answer is: unknown.

I agree completely. The Drake equation is pretty meaningless, since we have no idea of the magnitude of most of the coefficients. At this point in our history, the only logical path is to just keep gathering data.

 

[emc2cracker]

Well said bapowell,

Right now it seems rare Earth hypothesis might have the edge at least when related to intelligent life. However that may simply be because we lack abilities to detect rocky planets around sun like stars.. who knows.

 

[baywax]

Here's some thoughts from Stephen Hawking with regard to the topic...

We are used to thinking of intelligent life, as an inevitable consequence of evolution, Hawking emphasized, but it is more likely that evolution is a random process, with intelligence as only one of a large number of possible outcomes.

Intelligence, Hawking believes contrary to our human-centric existece, may not have any long-term survival value. In comparison the microbial world, will live on, even if all other life on Earth is wiped out by our actions. Hawking's main insight is that intelligence was an unlikely development for life on Earth, from the chronology of evolution: "It took a very long time, two and a half billion years, to go from single cells to multi-cell beings, which are a necessary precursor to intelligence. This is a good fraction of the total time available, before the Sun blows up. So it would be consistent with the hypothesis, that the probability for life to develop intelligence, is low. In this case, we might expect to find many other life forms in the galaxy, but we are unlikely to find intelligent life."

Another possibility is that there is a reasonable probability for life to form, and to evolve to intelligent beings, but at some point in their technological development "the system becomes unstable, and the intelligent life destroys itself. This would be a very pessimistic conclusion. I very much hope it isn't true."

Hawkling prefers another possibility: that there are other forms of intelligent life out there, but that we have been overlooked. If we should pick up signals from alien civilizations, Hawking warns,"we should have be wary of answering back, until we have evolved" a bit further. Meeting a more advanced civilization, at our present stage,' Hawking says "might be a bit like the original inhabitants of America meeting Columbus. I don't think they were better off for it."

http://www.dailygalaxy.com/my_weblog/2009/07/-stephen-hawking-why-is-the-milky-way-not-crawling-with-selfdesigning-mechanical-or-biological-life.html

 

[Chaballa]

Personally i don't think we are the most evolved creature in Milky Way. According to wiki there are at least 200 billion stars in Milky Way alone, so what are the chance of Sun/Earth being the most habitable solar system? 200,000,000,000:1?

We are very lucky that Earth is in goldilock zone, but I'm sure there are plenty of planets in goldilock zone, n many of em are probably older and/or have better condition for evolution compared to Earth.

 

[DaveC426913]

Personally i don't think we are the most evolved creature in Milky Way. According to wiki there are at least 200 billion stars in Milky Way alone, so what are the chance of Sun/Earth being the most habitable solar system? 200,000,000,000:1?

We are very lucky that Earth is in goldilock zone, but I'm sure there are plenty of planets in goldilock zone, n many of em are probably older and/or have better condition for evolution compared to Earth.

It's not about most habitable, or about conditions for evolution. At least, it deosn't start there.

It's about life spontaneously springing from non-life.

 

[DaveC426913]

I agree. It would be a monumental event to verify living organisms on a planet other than our own. I'd say there's a 100% probability of life in the rest of this galaxy.

What are the chances of using spectrometry to determine if there is life on one of the earthlike exoplanets being observed these days?

You are agreeing with an opinion that is 2+ years old. :-)

 

[Gannet]

Found attached link and remember seeing this thread and not seeing it previously cited.

http://hyperphysics.phy-astr.gsu.edu/hbase/astro/wcearth.html#c2"

It is interesting all the variables which have to be just right for life to exist. But this site is based carbon base lifeforms.

It is my hypothesis that there could be other chemical based lifeforms which we have not discovered yet. My definition of life is it has a beginning and end and in between those endpoints: it consumes resources, produce waste, and reproduce.

 

[DaveC426913]

Found attached link and remember seeing this thread and not seeing it previously cited.

http://hyperphysics.phy-astr.gsu.edu/hbase/astro/wcearth.html#c2"

It is interesting all the variables which have to be just right for life to exist. But this site is based carbon base lifeforms.

It is my hypothesis that there could be other chemical based lifeforms which we have not discovered yet. My definition of life is it has a beginning and end and in between those endpoints: it consumes resources, produce waste, and reproduce.

Yes, there is a possibility that there is some life that is non-carbon-based. Hoever, you will likely have to wade hip-deep in planets with carbon-based lifeforms before finding one that is otherwise.

Think of it this way:

We're sayin' I wonder if this 100-acre wood has any 3-leaf clover in it...
And you're saying Why concentrate on only 3-leaf clover, there's surely some 4-leaf clover out there too, let's throw a wider net.

 

[Dickfore]

It's 1 since there is life on Earth.

 

[DaveC426913]

It's 1 ...

No, that's the probability of you not reading the opening post.

...the probability of having life on other planets..

 

[DaveC426913]

Ahahah. too late. I saw that.

 

[Dickfore]

Ahahah. too late. I saw that.

Did you see the reason for deletion? Instead of the op, I saw the first post on the 3rd page.

 

[Chronos]

I like the idea of a high probability of life anywhere liquid water is found, and an extreme probability where oxygen exists in the atmosphere of an exoplanet. Both are the subject of study by exobiologists. Evidence of liquid water has already been found on the moons of Jupiter and Saturn. An undersea volcano would provide sufficient energy to fuel carbon based life forms. Current evidence suggests this is how life originated on earth. It is unlikely any element other than carbon would permit the complex molecules necessary for life. Silicon runs a very poor second.

 

[ranrod]

Thinking about this makes my head spin!

From the 200 billion stars in the milky way, how many planets on average for each? From the ones with planets, how many are stable solar systems? From those, how many will remain relatively uninterrupted for billions of years (not only the central star(s) but uninterrupted from outside-the-solar-system influences)? From those how many have a 'free' goldie locks area (no asteroid fields, no collisions for billions of years, no gas giants, no highly elliptical or irregular orbits)? From those how many have giant outside planets, such as Jupiter and Saturn that shield the life-bearing planets from asteroids and other planet killers? From those how many have a lot of water? From those how many have the other ingredients for life?

I can see the 200 billion stars yielding zero or a handful of candidates before we even ask if intelligent life can arise in them.

I'd like to know when do we think scientists will be able to come up with a more accurate estimate? 100 years from now? 50? 25?

 

[baywax]

I like the idea of a high probability of life anywhere liquid water is found, and an extreme probability where oxygen exists in the atmosphere of an exoplanet. Both are the subject of study by exobiologists. Evidence of liquid water has already been found on the moons of Jupiter and Saturn. An undersea volcano would provide sufficient energy to fuel carbon based life forms. Current evidence suggests this is how life originated on earth. It is unlikely any element other than carbon would permit the complex molecules necessary for life. Silicon runs a very poor second.

I agree Chronos. Its great that we have such close neighbours to study that are in the infant form of a possible abiogenesis. I am also convinced that panspermia is a definite player in the appearance of (carbon based) life. The liquid water and oxygen atmosphere not only provide good conditions for it but also provide a familiar environment for any visiting bacteria or large virus.

It is entirely probable that Mars seeded Earth or that Earth seeded Mars with life during the last 4.5 billion years. Especially since Mars shows signs of having been hit and having lost half her crust and all her oceans. At least some of her ejected bacteria or megaviruses could have made it here and began to colonize again.

 

[baywax]

Thinking about this makes my head spin!

From the 200 billion stars in the milky way, how many planets on average for each? From the ones with planets, how many are stable solar systems? From those, how many will remain relatively uninterrupted for billions of years (not only the central star(s) but uninterrupted from outside-the-solar-system influences)? From those how many have a 'free' goldie locks area (no asteroid fields, no collisions for billions of years, no gas giants, no highly elliptical or irregular orbits)? From those how many have giant outside planets, such as Jupiter and Saturn that shield the life-bearing planets from asteroids and other planet killers? From those how many have a lot of water? From those how many have the other ingredients for life?

I can see the 200 billion stars yielding zero or a handful of candidates before we even ask if intelligent life can arise in them.

I'd like to know when do we think scientists will be able to come up with a more accurate estimate? 100 years from now? 50? 25?

Like Dr. Stephen Hawking says, intelligence may not be the ultimate result of evolution and may actually be a mutation that hinders the survival of our species. This may not bode well in the search for other intelligent beings. He does hold out hope of finding life on other planets mind you.

 

[ranrod]

Like Dr. Stephen Hawking says, intelligence may not be the ultimate result of evolution and may actually be a mutation that hinders the survival of our species. This may not bode well in the search for other intelligent beings. He does hold out hope of finding life on other planets mind you.

That statement may work locally, but bacteria (used in his example) can't see the giant asteroid that will wipe out the planet. Intelligence allows us to protect Earth, as well as make other homes elsewhere in the galaxy (though we may not be doing a good job at either). Besides, on what grounds could we claim there's an ultimate goal to evolution? I can make the converse case - what good are all the amazing wonderments of the universe if there's no one out there to comprehend them?

 

[baywax]

That statement may work locally, but bacteria (used in his example) can't see the giant asteroid that will wipe out the planet. Intelligence allows us to protect Earth, as well as make other homes elsewhere in the galaxy (though we may not be doing a good job at either). Besides, on what grounds could we claim there's an ultimate goal to evolution? I can make the converse case - what good are all the amazing wonderments of the universe if there's no one out there to comprehend them?

Its true that there is, in all probability, no ultimate goal of evolution... except that it seems to be "survival". With regard to "what good are all the amazing..."... "good" is only relative to an observer, if and when there is one.

 

[Dmitry67]

My view is pessimistic: We exist, and probability of life in INFINITE Universe is 1, and there are infinitely many inhabited planets, however, probably even in the whole observable Universe there are no other planets with life.

There is a BIG GAP between complex molecules and primitive cell organisms. Very likely first bacteria was created by PURE CHANCE - in any case, nobody AFAIK was able to split that big gap into simpler steps

 

[Gannet]

Here is another site I found on this subject which I like. http://www.tufts.edu/as/wright_center/cosmic_evolution/docs/fr_1/fr_1_chem.html"

In section Qualities of Life it makes the following profound statement

... The reason is that living systems are so much more complex than any inanimate objects; a potted plant is more complicated than the most splendid galaxy.

 

[TubbaBlubba]

Here is another site I found on this subject which I like. http://www.tufts.edu/as/wright_center/cosmic_evolution/docs/fr_1/fr_1_chem.html"

In section Qualities of Life it makes the following profound statement

That's a bizarre statement in every imaginable way. I'm not even sure what they mean by it... By galaxy, do they mean everything that happens on every cosmic body at any given time? Just the shape? The gravitational forces keeping them together? The shape?

Any way, Milky way. I think we can consider the statement irrefutably disproved now.

 

[ranrod]

My view is pessimistic: We exist, and probability of life in INFINITE Universe is 1...

That is a very depressing statement

I would think if that "PURE CHANCE" you were talking about was 1 in 1,000 trillion, there would still be other planets with intelligent life. I guess that makes me optimistic

 

[DaveC426913]

I like the idea of a high probability of life anywhere liquid water is found, and an extreme probability where oxygen exists in the atmosphere of an exoplanet.

Can you clarify? It seems you are saying that life should have a high probability of forming where there is oxygen.

IIRC, oxygen is not a requirement for life; life on Earth started in a CO2 and ammonia atmo.

The reason exobiologists are interested in it is because its presence in an atmo is a sign of life - but it is a waste product.

So the cause-effect relationship is the other way 'round: first life, then oxygen.

 

[baywax]

Can you clarify? It seems you are saying that life should have a high probability of forming where there is oxygen.

IIRC, oxygen is not a requirement for life; life on Earth started in a CO2 and ammonia atmo.

The reason exobiologists are interested in it is because its presence in an atmo is a sign of life - but it is a waste product.

So the cause-effect relationship is the other way 'round: first life, then oxygen.

True Dave... however, the oxygen content of H2O is not a waste product and as someone or some paper has already pointed out in this thread amino acids are hydrophobic which probably coaxes them to bond together and form a primitive VRNA, RNA or DNA.