The probability that alien life exits in the universe?

[Matt]

[Matt]

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Since the other thread got locked I'll rephrase the question away from belief.

What are your thoughts on the probability of alien life existing out there somewhere? What factors increase or decrease the chances of there being other forms of life in the universe? What are the chances for life existing out there somewhere against the chances that our planet is the only place in the universe where life exists? If you were to make a scientific estimate on how many places in the universe may harbour life what would it be and how would you come to your conclusion?

(just to clear things up this thread has no scope for discussion of religion as thats not what this or the previous thread was about)
 
Do you think, somewhere out there, little grey men post on holographic messageboards about the existence of other sentient life in the universe?
 
Almost certainly at some time, either past or future within this galaxy. Almost certainly right now among all the galaxies.

Right now in our galaxy? Less likely of course. I think Drake's equation overstates the number of planets per solar system which can support life, the number of solar systems which have planets, and the proportion of planets on which abiogenesis could occur.
 
What if we throw the panspermia hypothesis into the mix?
 
Within solar systems? Sure.
Between them...? Bit of a long shot.
 
Billions of stars in our galaxy alone and there are billions of galaxies. It's almost stupid to not believe in E.T.s
 
Like I said before, we don't know the probability. Our understanding of physics and of life is not comprehensive enough to determine the exact processes of spontaneous life. We have guesses only, and only one type of life to look at. Despite some claims of experimental success, we have not actually ever created life from nothing in lab conditions. For empirical data we have only a single data point, ourselves. You cannot extrapolate from a single data point. Some didn't quite understand this last time this topic came up, so I will try to elaborate this point for those to whom this is not immediately apparent.

It is similar to the reason, that when using an estimator to extrapolate population data from a sample, you use (n-1) as the sample size to reduce bias. Take a look at it this way. Say that we are looking at the Earth from the outside in as purely objective observers. For this theoretical case, we will say that there is a 50% chance of life on Earth. In the case that there is life on Earth, humans evolve, and begin to wonder about what the odds of life are. They have only themselves to look at, and they have only one planet to look at, so they conclude that 1/1 planets have life, so there must be a 100% chance of life. In the case where life does not evolve, humans don't exist and nobody asks the question about life. You see the problem? It would be the same situation if the chance of life on earth was 0.0000001% You can't use yourself to judge the probability of yourself existing. You cannot accurately make any inferences on the probability of your own existence. I know it sounds very obvious, but there are people who are saying that since there is life on Earth, and there are many planets out there, it is statistically certain that life exists, when there is no basis whatsoever for that statement. An infinite number of planets with an infinitely small probability of life may yield only 1 location for life.

I am not saying that there isn't any life out there. I am just saying that we have no way of determining the probability, and the number of potential planets is irrelevant without any probability. Also, we have certainly ruled out the possibility that the universe is teaming with life, at least in our neighbourhood.
 
Dan said:
Matt didn't quite understand this last time this topic came up, so he called it bullshit nonsense, so I will try to elaborate this point for those to whom this is not immediately apparent.
Click to expand...

When did i ever say that? :/
 
[Matt] said:
When did i ever say that? :/
Click to expand...

Sorry, it was someone else who said it. This guy:

Kadayi Polokov said:
No what you are, is talking out of your arse Dan, and your above argument is moronic in the extreme.

Probability is a universal law as much as the laws of physics or chemistry, not something particular to, or a bi-product of our existence or likely to be an aberration inherent only to our solar system alone. Gravity existed before Issac Newton coined the phrase, and the periodic table elements existed way before we categorized them. The probability of an event happening is a constant timeless force (the dice are always rolling, they never stop). The more positive/proven variables you throw into the mix the more likely you are to yield the same results eventually. The Earth was around for a good few years before those dice came up sixes and life evolved out of the chemical soup, it didn't occur from the offset. it's a proven yardstick, that over time the mix was conducive to biological life developing. Given an infinite amount of time, biological life in a form that we recognize as such, is as likely to develop on a planet similar to earth in terms of environment & chemical composition. Your argument seems to be, hey 'just because we made a cake with these ingredients doesn't mean Joe over there in Alpha Centuri will manage the same with exactly the same ingredients'. Sure Joe might not, but given he's got 15 Billion years in which to try (with those dice rolling constantly), you end up having to look at it in the reverse of what are the odds of Joe not making a cake like ours. Life developed on Earth as the resultant of simple chemical reactions, that evolved into more complex forms, that kept going. The great thing is, is that because it was the first form of life there wasn't anything out there to stop it from developing further, once it got a foothold. :dozey:
Click to expand...
 
Our models of abiogenesis are all of them still flawed.
 
I would tell you the real probability that life exists on other planets but you can't handle the truth!
 
Wow you're so broad minded, not like us with our limited imaginations penning us in. Please, teach us to be like you.
 
Even if the life is amaebic, or it's life "not as we know it", the answer's yes. It's highly probably.
 
Drake's equation.
Which is good, but people almost always use very optimistic guesstimates as the numbers.
 
That's just it, they are guesstimates. We will never have a good idea until we either find it or eliminate it. The entire concept as of now is nothing but speculative with a bit of logic and some rationality and philosophy thrown in. Interesting perhaps, but none the less ultimately pointless due to the mass uncertainties involved.
 
Eejit said:
Drake's equation.
Which is good, but people almost always use very optimistic guesstimates as the numbers.
Click to expand...

Indeed. But even with low guesses, it's still probably.

And my basis was the fact that the universe is a rather large place.

Considering the Drake's equation only covers our galaxy, there are a hell of alot more galaxies out there. And the Drake's equation also only accounts for life that we comprehend as being like ourselves. Who's to say that life couldn't evolve on Venus? Just in a way that we couldn't understand.
 
We can already comprehend all kinds of life different from ourselves. Some people even consider transposons to be alive in some ways.
We've imagined many fictional species hugely different from us - if there's life, we can understand it.

To be honest it matters even less if there's life outside the galaxy than there being life elsewhere in the Milky Way. It's even less likely that such life would ever affect us than the chance that it doesn't exist.
 
Eejit said:
We can already comprehend all kinds of life different from ourselves. Some people even consider transposons to be alive in some ways.
We've imagined many fictional species hugely different from us - if there's life, we can understand it.

To be honest it matters even less if there's life outside the galaxy than there being life elsewhere in the Milky Way. It's even less likely that such life would ever affect us than the chance that it doesn't exist.
Click to expand...

Would you reconise a four-dimensional being if it waved at you? :p
 
If aliens don't exist, humanity will die of boredom after getting tired of blowing each other up.
 
No, we'll spread across the galaxy. And then someone will create a virus-like toxin which will alter peoples' psychological mentalities. They'll go crazy, kill everyone, and a new race of humans will be born.
 
Dan said:
Like I said before, we don't know the probability. Our understanding of physics and of life is not comprehensive enough to determine the exact processes of spontaneous life. We have guesses only, and only one type of life to look at. Despite some claims of experimental success, we have not actually ever created life from nothing in lab conditions. For empirical data we have only a single data point, ourselves. You cannot extrapolate from a single data point. Some didn't quite understand this last time this topic came up, so I will try to elaborate this point for those to whom this is not immediately apparent.

It is similar to the reason, that when using an estimator to extrapolate population data from a sample, you use (n-1) as the sample size to reduce bias. Take a look at it this way. Say that we are looking at the Earth from the outside in as purely objective observers. For this theoretical case, we will say that there is a 50% chance of life on Earth. In the case that there is life on Earth, humans evolve, and begin to wonder about what the odds of life are. They have only themselves to look at, and they have only one planet to look at, so they conclude that 1/1 planets have life, so there must be a 100% chance of life. In the case where life does not evolve, humans don't exist and nobody asks the question about life. You see the problem? It would be the same situation if the chance of life on earth was 0.0000001% You can't use yourself to judge the probability of yourself existing. You cannot accurately make any inferences on the probability of your own existence. I know it sounds very obvious, but there are people who are saying that since there is life on Earth, and there are many planets out there, it is statistically certain that life exists, when there is no basis whatsoever for that statement. An infinite number of planets with an infinitely small probability of life may yield only 1 location for life.

I am not saying that there isn't any life out there. I am just saying that we have no way of determining the probability, and the number of potential planets is irrelevant without any probability. Also, we have certainly ruled out the possibility that the universe is teaming with life, at least in our neighbourhood.
Click to expand...

This.
 
Eejit said:
We're all 4-D, technically :P
Click to expand...

We could be anything, technically.

I'm referring to a four-dimensionally-spacial being. Time aside. Something like a hypercube/sphere.
 
I thought we were talking about life withing our universe? The only other dimensions I've heard of other than the main 3+time are ones curled in on themselves.

You might as well be talking about a God if you broaden the topic to beyond our dimensions and we don't want to go down that path again :P
 
Ah, fair enough. But it was a principle I stand by. We might not have the ability to see or detect certain forms of life, yet it may still be sentient. But I'm willing to bet that there's some form of amoeba on another planet in our galaxy, or very close to us, relatively.
 
I'm pretty sure we'd be able to recognise any life as life - unless we didn't bother checking :)

Btw guys amoebae aren't the simplest forms of life on earth if that's what you're trying to use as a comparison ;)
 
Dude, some of us don't take biology :p

Amoeba will do.
 
Druckles said:
No, we'll spread across the galaxy. And then someone will create a virus-like toxin which will alter peoples' psychological mentalities. They'll go crazy, kill everyone, and a new race of humans will be born.
Click to expand...

REAVERS?!? *runs*

Anyway, I laugh at people who think we are alone in the universe *My roommate*. I just find it completely retarded to believe we are all alone here.
 
Druckles said:
No, we'll spread across the galaxy. And then someone will create a virus-like toxin which will alter peoples' psychological mentalities. They'll go crazy, kill everyone, and a new race of humans will be born.
Click to expand...
/whisper
Miraaaandaaa
 
I have no real 'belief' on the issue. I doubt we're alone in the universe, but what does that matter if we may still be alone in the galaxy?
 
Eejit said:
I have no real 'belief' on the issue. I doubt we're alone in the universe, but what does that matter if we may still be alone in the galaxy?
Click to expand...

That's one of the reasons government SETI funding was supsended and now most SETI projects worldwide are all funded from the private sector. If we do get a signal from a few hundred light years away that announces we're not alone then how do we benefit from that knowledge if all they send is a message of hello?
 
[Matt] said:
That's one of the reasons government SETI funding was supsended and now most SETI projects worldwide are all funded from the private sector. If we do get a signal from a few hundred light years away that announces we're not alone then how do we benefit from that knowledge if all they send is a message of hello?
Click to expand...

You can't possibly see it like that. Confirmation of other intelligent alien life in the universe would be nothing short of the single greatest anything ever, even if it were only a "Hello". How do we benefit? By the conclusive proof that we aren't actually alone in the Universe. It would change so many things it would be scary.
 
Just the sheer size of our galaxy alone leads me to believe in other life.
 
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