Are WE the only life in the Universe?

[Tormod]

Originally posted by: TeleMad

Tormod: I think that the odds that there is life elsewhere in the universe is very good. In fact, I think the best proof of life in the universe is that we are here on Earth. With about 200 billion galaxies, each with perhaps 100-200 billion stars, I simply can't believe that life came about only on this planet.

 

But your logic is flawed. You are looking at only HALF of the picture: simply put, you are considering only how many "shots" there have been at life arising. You are leaving out of the calculation how improbable life arising is. For example, what if the probability of life arising is 1 in 10^120 in a single "shot"*? Then the 200 billion galaxies each with 200 billion stars doesn't even come close to being able to cover the possibilities. The proportionality of "shots" vs possibilities would be like only 1 ticket being bought in the PowerBall lottery and expecting a winner. Life arising spontaneously may be so improbable that it happened only once in the Universe.

 

(*Based on a "quick and dirty" back-of-the-envelope calculation of the probability of hitting upon a self-replicating RNA molecule.)

 

I've been on holiday so sorry for the late reply.

 

I have never used any argument which counted "shots". We nitpicked our way through a similar discussion when you joined this forum a while back.

 

The thing is that I don't think there is anything particularly special about the Earth. I think that there are many planets which can sustain life, and many of them can sustain life forms which we currently do not understand.

 

Another thing is that I don't assume (as you seem to do, even though you only have one single example, which is a pure basis for empirical knowledge) that RNA is the only possible way for life to arise. However, if it is, or if it is a *common* way for life to arise, I think it is as likely for RNA to evolve in this universe as it is for planets and stars to evolve. This has nothing to do with "shots", but with how I view this universe.

 

Yes, it may be science fiction but it is very interesting. In April I attended the Huygens conference (about the science of the Cassini/Huygens mission) at the European Space Agency's ESTEC center in Holland and one of the things they were discussing is what is going on Titan. Why is there so much methane there? On Earth, methane is a byproduct of living beings. Titan is shrouded in a cloud of it, and some speculate that there may be an ocean or lake of methane on the surface. It is not likely but it is *possible* - and maybe we will find out on January 15 2005 when the Huygens probe gets there.

 

The same happens on Mars. There is too much methane gas around - it should have evaporated. Some scientists wonder if this might be due to microbial activity.

 

We can only speculate until we know, but I think the most ignorant position to take in such a matter as this is the "it can't possibly happen because my calulator won't allow it".

[TeleMad]

Tormod: I have never used any argument which counted "shots".

 

Sure you did…here, read for yourself…

 

Tormod: With about 200 billion galaxies, each with perhaps 100-200 billion stars, I simply can't believe that life came about only on this planet.

 

Of course if you would now care to retract your claim that you based on large numbers of galaxies and stars, feel free.

[Tormod]

Sheesh, here we go again.

 

You probably did not read the rest of my post, which should make it obvious that I don't think the Earth is a unique place and that life arising here is not a cosmic accident but something that happens all over the place.

 

So I don't count "shots". I assume that life is a commonplace thing.

[Freethinker]

I remebeer when the arguement was whether there were other "solar systems". Stars with planets. We had not actuall detacted any and so had no direct proof one way or other. It was argued by some that the formation of a planetary system had a low numeric probablity. We now KNOW that planets are reasonably common and are detecting them all over.

 

I've tried to explain this before. Perhaps I need to re-read the book at more directly quote the statistical analysis. It was in "The Power of Logical Thinking" by Marilyn Vos Savant (worlds highest IQ) which amoung other things, covers statistics and analyzing them. She discusses life expectancies. Specifically how once a person is born they automatically have a significantly higher chance of a long life. e.g. it is estimated that over 65% of all fertilized eggs do not come to term. Thus every one that IS born automatically becomes part of the smaller set of those that were born and thus go from a 0% chance of a long life to a much higher % chance of a long life. The details go well beyond just this. But the idea is the same.

 

If you take the set of all possible universes, our's is one that has the potential for life at 100%. It therefore automatically becomes one that has the good chance for more than one planet having life.

 

The question is NOT "Is there a universe model in which there is more than one planet that would form life?" because the answer is unquestionably YES. The question is, "Of all the models of universes, is OURS one that has multiple formations of life?". The answer statistically would follow the life expectancy question. By being a universe that DOES have the ability to form life, we automatically become part of the set in which the formation of life becomes a higher probablity.

 

Thus the statistics of ANY life formation in ANY such universe, which is the way those that come up with astronomically low probablity numbers reach those numbers for a 2ND chance of life, is shown to be an incorrect approach. Since this model of a universe DOES form life, it AUTOMATICALLY ebcomes part of the set of universe that forms life anda 2nd formaton probablity becomes very high.

[TeleMad]

Tormod: You probably did not read the rest of my post...

 

You're not very good at probability, are you :-)

 

I did read the rest of your post. It sounded like - and in fact was - unsupported personal speculation. Let's see, there's methane in Titan's atmosphere - guess that means there's life there. When you do come up without something a little more convincing, let me know (I won't hold my breath).

[TeleMad]

FreeThinker: If you take the set of all possible universes…

 

Possible? No, actual. Only those that are real matter here.

 

FreeThinker: … our's is one that has the potential for life at 100%. It therefore automatically becomes one that has the good chance for more than one planet having life.

 

Our solar system is one that has the potential for there being a person who goes by the name FreeThinker, who lives in the state of Wisconsin in the United States of America, which is the central country of North America, a continent on the third planet from the Sun, who posts at an Internet discussion forum that has a main page at http://www.scienceforums.com, and who made a post on 08/03/2004 @ 6:34 am that started with the sentence “remebeer when the arguement was whether there were other "solar systems", at 100%. It therefore automatically becomes one that has the good chance for more than one planet having such a person. Doesn’t quite work: the logic your trying to co-opt doesn’t carry over to our discussion.

 

FreeThinker: The question is, "Of all the models of universes, is OURS one that has multiple formations of life?"

 

No, that’s not the question. We’re not talking about possible theoretical models, we’re talking about actual reality.

 

I can model anything I want in a computer: my kids have computer games where people fly around and shoot energy blasts out of their hands, killing the other person who then is back alive in the next round – this computer model combat defies gravity, the law of conservation of energy, and the reality that death is final. Also, I debated an astrophysicist who had a model of the universe he created in order to show how robust nature is to changes in the certain constants of nature – his model was bogus and it was easily demolished. Models are not reality in and of themselves: they need to coincide with reality to be of worth.

 

FreeThinker: Thus the statistics of ANY life formation in ANY such universe, which is the way those that come up with astronomically low probablity numbers reach those numbers for a 2ND chance of life,

 

I don’t recognize that as being my argument.

 

FreeThinker: Since this model of a universe DOES form life, it AUTOMATICALLY ebcomes part of the set of universe that forms life anda 2nd formaton probablity becomes very high.

 

First, possible models aren’t the topic of discussion, but rather things as they actually are. Second, we don’t know that even one other universe actually exists. Third, I showed that the “if it happens once then the probability that it happens twice is high” logic just doesn’t hold up here (actually, I had already explained this earlier).

[Freethinker]

Originally posted by: TeleMad

FreeThinker: If you take the set of all possible universes…

 

 

 

Possible? No, actual. Only those that are real matter here.

So it's OK to play probability games when YOU want to, but I have to stick to "one real world"?

 

OK, Then in this Universe we KNOW that life is possible and probably, 100% thus in THIS universe there is little doubt that other life forms exist, probablity 100% based on "those that are real", this one.

 

Or are you now going to want to use the "possibility" you want to stop me from using? Are you going to claim to calculate the possibility of life forming?

Possible? No, actual.

and that ACTUAL is 100%.

[Freethinker]

Originally posted by: TeleMad

FreeThinker: … our's is one that has the potential for life at 100%. It therefore automatically becomes one that has the good chance for more than one planet having life.

Our solar system is one that has the potential for there being a person who goes by the name FreeThinker, who lives in the state of Wisconsin in the United States of America, which is the central country of North America, a continent on the third planet from the Sun, who posts at an Internet discussion forum that has a main page at http://www.scienceforums.com, and who made a post on 08/03/2004 @ 6:34 am that started with the sentence “remebeer when the arguement was whether there were other "solar systems", at 100%. It therefore automatically becomes one that has the good chance for more than one planet having such a person. Doesn’t quite work:

You may not understand it yet but in fact statistically it DOES work. Do I need to explain it to you or can you figure it out for yourself?

[Uncle Martin]

I'm with TeleMad on this one. The topic was intended to be more of a "gut feeling response", but since you have taken it in this direction.........Staying completely within the known facts,...... We have one data set. Is it possible to extrapolate ANYTHING from one data set? I don't see it. Even if we find life on Mars or Titan or Europa, etc....our data would include one solar system. Should that extraterrestrial life prove to be very different than anything on Earth we could speculate, but that is really all we are doing now.

 

I have posted my intuitional feelings on this matter, and they are in line with Tormod and FT, but I truly think that if we stay within the known facts we have nothing but speculation. My intuition is biased by a desire to not be unique, that does not make it so. The mathematics has been brought up, what can we really extrapolate from 1? Claiming life elsewhere in the universe seems to be more of a leap of faith than science to me.

[Tormod]

Originally posted by: Uncle Martin

I'm with TeleMad on this one. The topic was intended to be more of a "gut feeling response", but since you have taken it in this direction.........Staying completely within the known facts,...... We have one data set. Is it possible to extrapolate ANYTHING from one data set? I don't see it. Even if we find life on Mars or Titan or Europa, etc....our data would include one solar system. Should that extraterrestrial life prove to be very different than anything on Earth we could speculate, but that is really all we are doing now.

 

Yes, our data would include one solar system. But it would create problems for TeleMad's argument, because according to his logic life can only exist in one place until proven otherwise - because he believes very strongly that RNA is a one-off accident and that it cannot possibly happen twice. So if it happened twice - in close yet isolated locations - the implications would be that life could arise in any solar system that has planets and comets.

 

It's sort of like this: If you happen to live on an island in the ocean, and you are unable to see any islands around you, and have no way to travel away from the island, but have a fair idea as to how islands are created, then you can theorize that there is very likely to be an island beyond your horizon.

 

However, if you're TeleMad, there is no reason to believe so, because empirically you have no evidence for there being any other islands. It is a strange application of logic, TeleMad.

[Freethinker]

Originally posted by: Uncle Martin

I'm with TeleMad on this one. The topic was intended to be more of a "gut feeling response", but since you have taken it in this direction.........Staying completely within the known facts,...... We have one data set. Is it possible to extrapolate ANYTHING from one data set? I don't see it.

From the very begining of Science we have had "one data set". That which is available from here on earth (ignoring the limited "space travel" we have done so far which ALWAYS confirms the "one data set"). Every mathematical, gravitational, particle, wave, .... theory we have developed has been based on universal application of those laws throughout the entire universe. We accept that the interaction between masses is a universal constant. That two bodies of a given mass at a given distance will apply the same gravitational attraction whether they are here on earth or some far away galaxy. That photons exhibit the same ascpects here on earth as they do in some distant galaxy. Einstein called this the "Principle of Equivalence" and it was the connection between his Special and General Theories. That Relatvity as applied to a frame of reference would be directly applicable to accelerating frames.

 

Yes we have ONE DATA SET and that ONE DATA SET is equally applicable throughout the entirety of our Universe.

 

And what do we KNOW from the ONE DATA SET? we know for a FACT, 100% certain, that it is favorable to intellegent life. We know that without ANY RESERVATIONS! It CAN NOT BE DISPUTED. To dispute it would require us to prove WE do not exist.

Even if we find life on Mars or Titan or Europa, etc....our data would include one solar system.

Wrong. It would expand the level of support for the continued application of the "Principle of Equivalence", of the application of phsyical laws of the one data set we have.

I truly think that if we stay within the known facts we have nothing but speculation.

But the result of that (science based) speculation is and has always been based on the "Principle of Equivalence". That the laws of nature are the same throughout the universe. And everthing we learn as we go along validates it.

My intuition is biased by a desire to not be unique, that does not make it so. The mathematics has been brought up, what can we really extrapolate from 1? Claiming life elsewhere in the universe seems to be more of a leap of faith than science to me.

We have ONE DATA SET. That data set PROVES that the universe and the laws it operates with-in favor the existence of intellegent life 100%. This can not be disputed. That is the ONLY FACT we can derive from it relative to the set of "possibility of the development of intellegent life". To accept that the "Principle of Equivalence" operates 100% for every aspect of that data set EXCEPT the formation of intellegent life is comepltely illogical.

[TeleMad]

TeleMad:

 

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FreeThinker: … our's is one that has the potential for life at 100%. It therefore automatically becomes one that has the good chance for more than one planet having life.

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Our solar system is one that has the potential for there being a person who goes by the name FreeThinker, who lives in the state of Wisconsin in the United States of America, which is the central country of North America, a continent on the third planet from the Sun, who posts at an Internet discussion forum that has a main page at http://www.scienceforums.com, and who made a post on 08/03/2004 @ 6:34 am that started with the sentence “remebeer when the arguement was whether there were other "solar systems", at 100%. It therefore automatically becomes one that has the good chance for more than one planet having such a person. Doesn’t quite work:

 

FreeThinker: You may not understand it yet but in fact statistically it DOES work. Do I need to explain it to you or can you figure it out for yourself?

 

Sure, go ahead and try.

 

But note that it could be argued that having one instance of something highly improbable makes it LESS LIKELY that there would be more. I'll resuse something I said earlier. Take a standard deck of 52 playing cards and thoroughly shuffle it - then deal yourself one card at a time until all 52 have been dealt: make sure to keep track of the order in which you receive each of the cards, noting the suite and value. Now, the probability that that particular sequence of cards would have appeared is less than 1 in 10^67. But it did happen - ONCE. Now go ahead and repeat the process until you get the same result...won't happen.

 

IF life arising spontaneously is as highly improbable as I believe it is, then having the one instance of life we know of could be argued to make it less likely that the same low-probability event occurred a second time somewhere else.

[TeleMad]

Tormod: Yes, our data would include one solar system. But it would create problems for TeleMad's argument, because according to his logic life can only exist in one place until proven otherwise…

 

Uhm, contrary to your assertion, that’s not my position.

 

Tormod: … because he believes very strongly that RNA is a one-off accident and that it cannot possibly happen twice.

 

Again, contrary to your assertion, that’s not my position.

 

Tormod: So if it happened twice - in close yet isolated locations - the implications would be that life could arise in any solar system that has planets and comets.

 

But just finding life on Mars or even Titan wouldn’t show that life arose elsewhere, it could have traveled there via “planet hopping”…

 

“Because planetary systems are formed by accretion, I think it unlikely that life on another body in the solar system arose independently of terrestrial life. It is now clear from meteorite studies that bodies can be transported from one planet to another, for instance from Mars to Earth, without excessive heating that would sterilize microbial organisms. Although such transfer events are now rare, they must have been far more frequent during the accretion of the planets. Large-scale infall, blasting ejecta throughout the forming solar system, probably extended until at least about 4 billion years ago and so probably overlapped with the processes that resulted in the origin of life. In principle, life, regardless of where it arose, could have survived interplanetary transport and seeded the solar system wherever conditions occur that are permissible to life. So, if we go to Mars or Europa and find living creatures there, and read their rRNA genes, we should not be surprised if the sequences fall into our own relatedness group, as articulated in the tree of life.” (Normal R Pace, The Universal Nature of Biochemistry, PNAS, January 30, 2001, vol. 98, no. 3, p805-808)

 

So if we find life elsewhere, we first have to confirm that it is sufficiently different from life here on Earth to warrant the conclusion that it arose independently.

 

Tormod: It's sort of like this: If you happen to live on an island in the ocean, and you are unable to see any islands around you, and have no way to travel away from the island, but have a fair idea as to how islands are created, then you can theorize that there is very likely to be an island beyond your horizon.

 

I like how when people try to use logic to show that there simply must be more X out there, they always use an example for which we KNOW there are more X out there. They pretend to be convincing but their logic is preloaded to deliver the result they are trying to show comes about when we DON’T know that other Xs are out there.

 

Tormod: However, if you're TeleMad, there is no reason to believe so, because empirically you have no evidence for there being any other islands. It is a strange application of logic, TeleMad.

 

Now if you could just stick to my actual position when you pretend to be 'refuting' me...

[Tormod]

Telemad, it is impossible to stick to your actual position because it is always unclear. I may appear to be refuting you, but my aim is to show that there is no reason to argue that life is something that happened on Earth only. Your quote seems to agree with me on this. It only pushes the location of life's appearance elsewhere (like the endless "what was before time" debate).

 

That life will need to be "different" there than here brings you back to your endless circle of logic of "one dataset" which for some reason you seem happy to be be allowed to define as true, although I mostly find it to be ignorant.

 

If life on Europa, say, turned out to be RNA-based, it will give us several possibilites. Either life was brought to Earth (once, twice, or many times), or it developed here independently (so RNA is commonplace, like I suggested - which implies it could happen anywhere), OR it comes from the enormous gas clouds floating around in interstellar space (wild speculation). There are many possibilities.

 

As for your "More X" argument, I read that as stating that yes, I was right about your logic there.

[TeleMad]

Tormod: Telemad, it is impossible to stick to your actual position because it is always unclear.

 

Only for people who think there are only two completely opposite positions and forget that other positions exist between the two extremes.

 

You've stuffed words of impossibility into my mouth....you've tried to push me way over to an extreme where my statements themselves simply don't put me.

 

Tormod: I may appear to be refuting you, but my aim is to show that there is no reason to argue that life is something that happened on Earth only.

 

So you are trying to show something that is wrong...I thought so.

 

Tormod: Your quote seems to agree with me on this. It only pushes the location of life's appearance elsewhere (like the endless "what was before time" debate).

 

You're confused. Read it again. And while you're at it, read what I said about the quote.

 

Tormod: That life will need to be "different" there than here brings you back to your endless circle of logic of "one dataset" which for some reason you seem happy to be be allowed to define as true, although I mostly find it to be ignorant.

 

I don't recognize that as being my position (and it was Freethinker who used the term "one dataset").

 

Tormod: If life on Europa, say, turned out to be RNA-based,...

 

Back up...If there is life on Europa, say, and it turned out to be RNA-based...

 

Tormod: ... it will give us several possibilites. Either life was brought to Earth (once, twice, or many times), or it developed here independently ( (so RNA is commonplace, like I suggested - which implies it could happen anywhere)...

 

You've left out what many would hold to be the most likely possibiility: that life arose on Earth and then "hopped" to Europa.

 

Tormod: As for your "More X" argument, I read that as stating that yes, I was right about your logic there.

 

Care to explain?

[Tim_Lou]

TeleMad: "But note that it could be argued that having one instance of something highly improbable makes it LESS LIKELY that there would be more"

 

life exist on earth doesnt affect the probability that life exist somewhere else. 2 "events" are independent.

just like if a get a certain set in a deck of card, the probability to have the same set doesnt decrease when i draw cards from it for a second time.

 

saying that life is improbably is simply calculated by math work... this is only a theoretical %, there is no data supportage behind it.

but like said b4, the experienmental value should be based on our data, which we only have one (as freethinker said b4).

 

maybe the universe has a tendency to start life, we dont know...

in your cards examples, you draw the cards many many times until a certain set appears.... from observation, the possibility is low.

 

but for life, we only konw that earth has it, the moon doesnt, couple planets dont... the experienmental possibility remains quite large.

[TeleMad]

TeleMad: "But note that it could be argued that having one instance of something highly improbable makes it LESS LIKELY that there would be more"

 

Let me explain my statement differently. I was paraphrasing the logic Richards Dawkins used in one of his books. He said that we are allowed only a certain amount of luck in our explanation for the OOL, but how much? He next pointed out that we have to have some luck left over in order to account for things like intelligence such as ours to develop. So we have only so much total luck we can rely on an still remain scientific - each time we rely upon more luck, the less scientific our explanations become - and this one lump of luck has to be able to account for everything (OOL, evolution of multicellular organisms, evolution of technological intelligence, for example). So if we use up all of our luck up on OOL, we have none left over to account for the others.

 

Now, let's follow through on that logic. If life's arising is as improbable as I believe, then we used up all of our luck for the OOL here on Earth; therefore, we wouldn't have any left over for OOL elsewhere.

 

That's the general idea I was aiming at with my statement "it could be argued that having one instance of something highly improbable makes it LESS LIKELY that there would be more."