Are we alone in the Universe?

ChaosKnight · Post by **ChaosKnight** » Wed Nov 19, 2003 12:06 am

A common argument used by pro-lifers. The universe is so big, so there must be intelligent life out there. Or life exists in very harsh conditions, so there must be intelligent life out there.

But this is looking at only half the problem. The other half is that life is very difficult to form in the first place. How easy is it to form a self-replicating molecule out of a jumble of random atoms? Not easy at all.

True, life exist in very hash conditions. But they didn't form there. They spread there.

In the end, the crux of the whole issue is: Is the universe larger than life is difficult to form? These two factors must be considered.

So far, I can convincingly say that the formation of (intelligent) life in our universe is not improbable (at least 0.64 chance of forming).

The probability of another intelligent life out there is about at least 0.264.

Area503 · Post by **Area503** » Wed Nov 19, 2003 1:05 am

well, possiblilty of us been around is 1.0
Seriously, using your agrument, the possiblitily of us been around in the first place is 0.264. From what i understand for possibility, 0.264 is the possiblity that a planet similar to earth can form a intelligent life being. then considering the possibility of a similar planet NOT forming is 0.736. if we assume that the number of planets similar to earth is around 1 million. Caculations shows that B~(1000000, 0.736)
possibility of 1 million planets similar to earth Not having any intelligent life is = zero. (elementary stats)

If we were to follow our agrument base on probility, there IS intelligent life forms out there. Actually, if we use a more resonable number of 500 planets, it is 2.747306847 X 10 to the power of -67 for not having ANY intelligent life froms. So it is absurd to use probability to caculate such questions. Btw, life need not spread there. organic materials have been spotted by NASA floating in Massive clouds in space. organic material is present on mars, although not direct proof of life (which i don't belive in life on mars), it shows organic material need to form life is abundant in space. so mathematical attemps breaks down once again. for TOO much planet can be considered into the equation.

However, its up to you to believe in whether intelligent life exist out there. If we can exist on this insignifance piece of rock call earth, who to say there isn't any out there. ChaosKnight does have a valid point no douth, but seriously, maths cannot be use to solve any question which is not mathematicly based, but of a more philosophically type of question.

Post by **weixing** » Wed Nov 19, 2003 1:49 am

Hi,
Look like the old question of "Are we alone??" is getting "Hot" again...

From my point of view, the possibility of life out there may be small, but there are just too many stars out there to say "we are alone". The big question is whether are they intelligence life near by and can we find them??? We, human, have try a lot of methods to look for them, from sending out radio message( I think this is a bad idea

) to search for radio signal from space to find the sign of intelligence life. But the universe is just too big and the stars are just too far apart....

By the way, some scientist believe that we don't need to look for alien else where... they are already here.... Where??? We are the alien to earth!!!

Since bacteria and some virus can stay in a suspended animation until they met the right condition.... So, some scientist believe that when the comet, meteor or asteroid crash to earth, the bacteria in the comet, meteor or asteroid became alive again. Also, bacteria is small enough to escape earth gravity without using rocket

So, don't be surprise if scientist found bacteria that we known in other planets of the solar system...

retro · Post by **retro** » Wed Nov 19, 2003 1:23 pm

weixing wrote:Hi,
By the way, some scientist believe that we don't need to look for alien else where... they are already here.... Where??? We are the alien to earth!!! Since bacteria and some virus can stay in a suspended animation until they met the right condition.... So, some scientist believe that when the comet, meteor or asteroid crash to earth, the bacteria in the comet, meteor or asteroid became alive again. Also, bacteria is small enough to escape earth gravity without using rocket So, don't be surprise if scientist found bacteria that we known in other planets of the solar system...

I think the cosmic theory of the origin of life is still being debated. There was one guy who once statistically attributed seasonal influenza outbreaks to passing comets. There is an issue that falling objects from the sky, could actually just be bring back rubbish we left in previous space explorations. I would be more convinced if they could scoop material from these rocks much further from Earth, only then test and find if in fact these organisms exist. But then, that's just me.

Post by **weixing** » Wed Nov 19, 2003 2:23 pm

Hi,
That's why they attempt to land the NEAR Shoemaker spacecraft on the asteroid, Eros, when the spacecraft is running out of fuel a few years ago. This will allow the scientist to access the possibility of sending a spacecraft to land on asteroid and to take sample of rock for testing.

Anyway, the spacecraft landed successfully...

ChaosKnight · Post by **ChaosKnight** » Wed Nov 19, 2003 6:25 pm

Area503 wrote:well, possiblilty of us been around is 1.0
Seriously, using your agrument, the possiblitily of us been around in the first place is 0.264. From what i understand for possibility, 0.264 is the possiblity that a planet similar to earth can form a intelligent life being. then considering the possibility of a similar planet NOT forming is 0.736. if we assume that the number of planets similar to earth is around 1 million. Caculations shows that B~(1000000, 0.736)
possibility of 1 million planets similar to earth Not having any intelligent life is = zero. (elementary stats)

If we were to follow our agrument base on probility, there IS intelligent life forms out there. Actually, if we use a more resonable number of 500 planets, it is 2.747306847 X 10 to the power of -67 for not having ANY intelligent life froms. So it is absurd to use probability to caculate such questions. Btw, life need not spread there. organic materials have been spotted by NASA floating in Massive clouds in space. organic material is present on mars, although not direct proof of life (which i don't belive in life on mars), it shows organic material need to form life is abundant in space. so mathematical attemps breaks down once again. for TOO much planet can be considered into the equation.

However, its up to you to believe in whether intelligent life exist out there. If we can exist on this insignifance piece of rock call earth, who to say there isn't any out there. ChaosKnight does have a valid point no douth, but seriously, maths cannot be use to solve any question which is not mathematicly based, but of a more philosophically type of question.

I'm afraid you don't get what i'm trying to say.

Firstly, an event already happened doesn't mean the probability of it happening is 1. Like when you toss a dice and you got a six. It doesn't mean the probability of you getting a six is 1. The definitions of the events are different.

I said the probability of at least one (intelligent) life in the entire universe is at least 0.64. This value is a lower bound. And the probability of at least two (intelligent) lifeforms in the entire universe is 0.264. Again a lower bound.

I didn't say the probability of life forming around any star is (1-0.264 = 0.736). Again the events under consideration is different.

Actually for both cases, the lifeforms may be intelligent or not. Strictly, the mathematics doesn't say.

And i'm assuming the probability of (intelligent) life forming around any star is 0.000000000=>infinity0001. This is why all values are lower bounds.

I think it is fairly reasonable for probability to be used for such an issue, where we don't know the underlying mechanisms. If probability cannot be used, then why have people for 4 decades been discussing the Drake equation? Probability, at least for now, is the best tool we have.

Post by **weixing** » Wed Nov 19, 2003 8:28 pm

Hi,

well, possiblilty of us been around is 1.0

I think what Area503 want to say is: The probability of intelligent life out there is 1... which is correct. What this topics are trying to discuss is: The probability of OTHER intelligent life in other stars.

The probability of another intelligent life out there is about at least 0.264.

Care to share with us what you mean "out there"... within our galaxy?? And how you get this figure...

ChaosKnight · Post by **ChaosKnight** » Wed Nov 19, 2003 11:27 pm

Please let me clarify.

Probability of (intelligent) life forming is at least 0.64.
Probability at least 2 (intelligent) lifeforms form is at least 0.264. One of the lifeforms represent us, the others represent alien civilizations.
These values are from mathematical calculations.

By "out there" i mean the entire universe. Unfortunately the maths does not give any reasonable prediction for the probability of another intelligent lifeform within our own galaxy.

If you are interested in the math it's all here:

http://www.singastro.org/viewtopic.php?t=288

http://www.sciforums.com/showthread.php ... adid=29675

Post by **weixing** » Thu Nov 20, 2003 12:55 am

Hi,
OK... I'm not going to check your math, I'm not good at probability...

But I think there is some mistake in your calculation especially the part:

p(there is one system with intelligent life) = x(1/x)[(x-1)/x]^(x-1).

Because p(there is one system with intelligent life) = 1(that's us).

Anyway, the model you use is just too purely "probability math".... Since there will be less time for observation in raining season, may be you can try to put in more parameters to form a better equation...

ChaosKnight · Post by **ChaosKnight** » Thu Nov 20, 2003 5:41 pm

weixing wrote:Hi,
OK... I'm not going to check your math, I'm not good at probability... But I think there is some mistake in your calculation especially the part:
p(there is one system with intelligent life) = x(1/x)[(x-1)/x]^(x-1).
Because p(there is one system with intelligent life) = 1(that's us).

Anyway, the model you use is just too purely "probability math".... Since there will be less time for observation in raining season, may be you can try to put in more parameters to form a better equation...

Actually that part calculates the probability one intelligent lifeform forms in the universe.

In all the math calculates the probability at least 2 intelligent lifeform forms in the universe.

What you say is very interesting. Since we are here, the lower bound of that probability may be higher, by how much i can't say now.