Either Life Exists Elsewhere or The Universe is finite.

[Stuey]

I'm stuck.

What is an example of something "real" that is infinite? I understand the theoretical meaning of infinite, not very well mind you. But I cannot get past this...

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In an infinite universe, it is certain that a non-zero probability event will occur (repeatedly).

Therefore, either life exists elsewhere in the universe, or the universe is finite.

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Since I feel we can never know something is infinite with %100 certainty I must assume it has been found to be true to continue along with the line of reasoning. But any conclusions I reach using this as a starting point will not be facts or certianties they are simply what ifs imo.

As in what if we never find out that the universe is finite and we assume it is infinite then it is a possibility that a non-zero probability event will occur (repeatedly).

Therefore, either life could exist elsewhere in the universe, or the universe is finite and life could still exist elsewhere in the universe.

Unless of course you can tell me a method to find out if the universe is indeed infinite. I don't need proof that it is infinite I need proof that there is a method to prove it is infinite.

Yah I am to dumb to be posting on this topic, sorry feel free to ignore me. But I am serious and not just trying to cloud the waters if you can explain to me why I can discount this I would like to hear it. I enjoyed reading the thread however even if I don't follow the ideas presented properly and this I can say for certian. [img]/images/graemlins/smile.gif[/img]

[Piz0wn0reD!!!!!!]

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ok, after some thought i came up w/ a good analogy.

lets say the universe is a deck of cards (a finite deck, with infinite shuffles and deals). Our life is one unique deal of the cards. According to your reasoning the folling must be true:

1. given infinite shuffles and deals, every possible combination must happen eventually.
2. there must be a probability of the same deal being repeated,
3. therefore, there must be a probability of the same deal being repeated for infinity.

therefore your logic is flawed. assuming the universe is infinite, there could be or could not be non-zero probability events that must occur/repeat.

end of thread [img]/images/graemlins/smile.gif[/img]

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Premise #3 is redundant to #2.

I have no idea how your conclusion follows from the premises. In fact, I cannot even comprehend your conclusion.


My original argument is valid and sound. Accordingly, this thread actually 'ended' before it even started, with the title:

"Either life exists [or has existed] elsewhere, or the universe is finite."



Adam

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im sorry you that you dont understand. ill put it as simply as i can.

lets assume the universe is infinite. lets assume we somehow know for a fact that in the known universe there is no other inteligent life. the rest of the universe could be 100% flaming pile of cow poo for infinity more. just because its endless (and perhapse beginingless) doesnt mean that everything that has absolutly any probability whatsoever has to happen.

[Stuey]

I thought about it some more and I think everyone might be right and everyone might be wrong depending on the way they are using the assumption of infinity.

infinity

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Infinity in cosmology
An intriguing question is whether actual infinity exists in our physical universe: Are there infinitely many stars? Does the universe have infinite volume? Does space "go on forever"? This is an important open question of cosmology. Note that the question of being infinite is logically separate from the question of having boundaries. The two-dimensional surface of the Earth, for example, is finite, yet has no edge. By walking/sailing/driving straight long enough, you'll return to the exact spot you started from. The universe, at least in principle, might have a similar topology; if you fly your space ship straight ahead long enough, perhaps you would eventually revisit your starting point.

If the universe is indeed ever expanding as science suggests then you could never get back to your starting point even on an infinite time scale.


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usmhot stated this earlier but I am doing it again to be clear.

Now for the part that is causing the trouble.

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In an infinite universe, it is certain that a non-zero probability event will occur (repeatedly).


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adamstewart is right if his infinite universe has a infinite amount of time to expand and makes a infinite number of new solar systems without destroying existing ones where this new matter comes from we do not know but we assume it is possible.

BZ Zorro is right if his infinite universe does not have infinite time as in someone might make a tool to destroy everything someday but that day has not come yet but it will so we can not be sure enough time will pass to be sure life will exist elsewhere.

PizOwnOreD!!!!!! is right, as in his infinite universe there is not an infinite amount of diversity just an infinite amount of stuff.

The true idea of infinite possibilities makes your argument very strong adam but most of us are not willing to apply infinity to real items. Numbers and ideas yes but not to physical items.

So I return to my question.

What is an example of something "real" that is infinite?

And can you explain a method that could prove the universe is indeed infinite? You don't have to prove it just explain how given the proper advances in the future they would be able to prove it.

[adamstewart]

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ok, after some thought i came up w/ a good analogy.

lets say the universe is a deck of cards (a finite deck, with infinite shuffles and deals). Our life is one unique deck, all of the cards. According to your reasoning the folling must be true:

1. given infinite shuffles and deals, every possible combination must happen eventually.
2. there must be a probability of the same deal being repeated,
3. therefore, there must be a probability of the same deal being repeated for infinity.

therefore your logic is flawed. assuming the universe is infinite, there could be or could not be non-zero probability events that must occur/repeat.

end of thread [img]/images/graemlins/smile.gif[/img]

[/ QUOTE ]


Premise #3 is redundant to #2.

I have no idea how your conclusion follows from the premises. In fact, I cannot even comprehend your conclusion.


My original argument is valid and sound. Accordingly, this thread actually 'ended' before it even started, with the title:

"Either life exists [or has existed] elsewhere, or the universe is finite."



Adam

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im sorry you that you dont understand. ill put it as simply as i can.

lets assume the universe is infinite. lets assume we somehow know for a fact that in the known universe there is no other inteligent life. the rest of the universe could be 100% flaming pile of cow poo for infinity more. just because its endless (and perhapse beginingless) doesnt mean that everything that has absolutly any probability whatsoever has to happen.

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Your assumptions ("premises") are not true, or at least cannot be proven. Therefore, whatever argument stems from them is unsound.


Conversely, you cannot refute my premises: "I exist. Therefore, the probability of life is greater than zero," and "Given an infinite number of trials, it is certain that a greater-than-zero probability event will occur again (and again)."

Until you can show me that: 1. the universe is infinite, and 2. no other life exists in it, then my original argument stands.


Adam

[adamstewart]

[ QUOTE ]
Infinity in cosmology
An intriguing question is whether actual infinity exists in our physical universe: Are there infinitely many stars? Does the universe have infinite volume? Does space "go on forever"? This is an important open question of cosmology. Note that the question of being infinite is logically separate from the question of having boundaries. The two-dimensional surface of the Earth, for example, is finite, yet has no edge. By walking/sailing/driving straight long enough, you'll return to the exact spot you started from. The universe, at least in principle, might have a similar topology; if you fly your space ship straight ahead long enough, perhaps you would eventually revisit your starting point.

If the universe is indeed ever expanding as science suggests then you could never get back to your starting point even on an infinite time scale.



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I feel a problem with this guy's argument is that we know for certain that the Earth is not 2-dimensional. We know that at least a 3rd dimension exists (up and down).

And in fact, the 'two-dimensional' earth that he proposes requires that it be 'THREE-dimensional' already. If one sticks the to the contours of the earth, every movement made along its surface has an x, y, and z component. Otherwise, the person would NOT end up in the same place as they started.

Blah, the more I think about it, the more his analogy has no relevance whatsoever


Adam

[bugstud]

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ok, after some thought i came up w/ a good analogy.

lets say the universe is a deck of cards (a finite deck, with infinite shuffles and deals). Our life is one unique deck, all of the cards. According to your reasoning the folling must be true:

1. given infinite shuffles and deals, every possible combination must happen eventually.
2. there must be a probability of the same deal being repeated,
3. therefore, there must be a probability of the same deal being repeated for infinity.

therefore your logic is flawed. assuming the universe is infinite, there could be or could not be non-zero probability events that must occur/repeat.

end of thread [img]/images/graemlins/smile.gif[/img]

[/ QUOTE ]


Premise #3 is redundant to #2.

I have no idea how your conclusion follows from the premises. In fact, I cannot even comprehend your conclusion.


My original argument is valid and sound. Accordingly, this thread actually 'ended' before it even started, with the title:

"Either life exists [or has existed] elsewhere, or the universe is finite."



Adam

[/ QUOTE ]

im sorry you that you dont understand. ill put it as simply as i can.

lets assume the universe is infinite. lets assume we somehow know for a fact that in the known universe there is no other inteligent life. the rest of the universe could be 100% flaming pile of cow poo for infinity more. just because its endless (and perhapse beginingless) doesnt mean that everything that has absolutly any probability whatsoever has to happen.

[/ QUOTE ]


Your assumptions ("premises") are not true, or at least cannot be proven. Therefore, whatever argument stems from them is unsound.


Conversely, you cannot refute my premises: "I exist. Therefore, the probability of life is greater than zero," and "Given an infinite number of trials, it is certain that a greater-than-zero probability event will occur again (and again)."

Until you can show me that: 1. the universe is infinite, and 2. no other life exists in it, then my original argument stands.


Adam

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ok, here's the problem. An event with a probablility lesser than one, given an infinite amount of trials, can have an infinite succession of trials where the event does not occur.

edit - you can only prove that life did in fact begin was >0. Given that it's happened once does not mean it has to happen again. Example, Cubs World Series victories [img]/images/graemlins/tongue.gif[/img]

[Moon Double Comb]

There are some flaws in your deduction (as others have pointed out already).

First, you cannot deduce from the premise that the probability of life is greater than zero in a region of space it therefore must be greater than zero in other regions of space. I hope this is obvious.

Now you might make a physical argument and say the universe evolved in an entirely symmetric way in space and time. But, as currently is believed, is that quantum fluctuations played an essential role in the early, finite universe (which we hold responsable for the forming of galaxies etc), and therefore the universe is not necesarrily symmetric (but probably is on a large scale if one looks for instance at mass densities on large scales). But these are only physical arguments, not logical.

The second mistake you make is that if you assume that the universe is spatially infinite, there should have been an infinite number of trials. This, again, is only the case if the probability density is greater than zero at infinite points in space.

If, OTOH, there are a finite number of points with a probability greater than zero AND the time elapsed so far is finite, then it follows that the probability of life is less than 1. (Note that I'm speaking of space and time seperately and not about 4D space-time. But this does not change the principle point behind the argument).

If there are a finite number of points where the probability of life is greater than zero AND the time elapsed is infinite, there would be a infinite number of trials. But this is not the case.

This is all quite straightforward. Logically, your deduction doesnt hold.

[gumpzilla]

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Conversely, you cannot refute my premises: "I exist. Therefore, the probability of life is greater than zero,"

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The number sqrt(2) exists. Therefore, the probability of sqrt(2) is greater than zero.

Doesn't really make much sense, does it?

Suppose we have the following set of propositions:

1) Life exists in exactly one place in the universe.
2) Life exists in exactly two places in the universe.
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N) Life exists in exactly N places in the universe.

Your evidence is consistent with any of these propositions but can't do anything to suggest which one might be true. I think you need to sharpen up what you mean by probability. The probability that life exists somewhere in the universe is 1: it must exist, because here we are. But this doesn't address the probability that life would develop from raw materials, and it doesn't address the probability that it would do so over and over again. There's some anthropic principle style weirdness that goes into all of this. I think your notion of probability is a little oversimplified for arguing what you want to argue.

There are more sophisticated arguments than the one you're making. This article in Scientific American (if you can find a place to read it, I just remembered it from my roommate's copy) does a slightly better job saying essentially what you're trying to say, I think.

[danzasmack]

I'm no good with astrolody but I do know that at some point in the very distant future the sun is to grow very large and basically consume the earth. Say this event occurs at time t. Is this to say that at time t, P(life existing outside earth| universe is infinite) goes from 1 to 0? If so, then that would mean we are the only life forms in the universe.

This has to be wrong, somebody tell me why.

[durron597]

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edit - you can only prove that life did in fact begin was >0. Given that it's happened once does not mean it has to happen again. Example, Cubs World Series victories [img]/images/graemlins/tongue.gif[/img]

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Let Pr(Cubs win world series) = x, where 0 < x < 1.

Pr(Cubs win world series at least once in the next n trials) = 1 - Pr(Cubs never win series in next n trials) = 1 - (1-x)^n.

lim(1 - (1-x)^n, n -> oo) = 1.

Thus, the cubs will win the world series again, in an infinite amount of time.