Christianity vs UFOs

[Myrddraal]

I'm completely on the fence about intelligent life being out there. The argument "The universe is huge, therefore statistically there must be intelligent life somewhere in it" is flawed imo. If we're going to talk statistics, we need a decent sample size before we can make any conclusions. If we looked at this solar system, we could say that one in 8/9 planets has intelligent life on it. If we looked at the X planets we have identified as uninhabited, we could say that 1 in X planets has intelligent life on it. Whatever we choose as our sample, we only have 1 planet with intelligent life, so we don't have a sample size big enough to make any conclusions. That's not to say there isn't intelligent life elsewhere in the universe, but to say that there must be because the universe is big doesn't make much sense to me.

Does that make sense?

[Aemilius Paulus]

I'm completely on the fence about intelligent life being out there. The argument "The universe is huge, therefore statistically there must be intelligent life somewhere in it" is flawed imo. If we're going to talk statistics, we need a decent sample size before we can make any conclusions. If we looked at this solar system, we could say that one in 8/9 planets has intelligent life on it. If we looked at the X planets we have identified as uninhabited, we could say that 1 in X planets has intelligent life on it. Whatever we choose as our sample, we only have 1 planet with intelligent life, so we don't have a sample size big enough to make any conclusions. That's not to say there isn't intelligent life elsewhere in the universe, but to say that there must be because the universe is big doesn't make much sense to me.

Does that make sense?

Yes, perfectly so, but it is not a scientifically valid conclusion, even if it conforms to logic - unfortunately, we make do with what we have, that is the real truth. Some things are not even remotely testable or provable within the limits of statistics, so a bit of out-of-the-box deductive logic may help. Inductive logic is more comfortable, but it is not as commonly applicable, alas.

If we are truly alone in this universe, then that means there is a God, because only that could explain how in a nearly infinite (nearly, because although the space is infinite, the question of whether matter is likewise infinite is not certain, although very likely) space there is but a single sentient species, and I seriously doubt there is a God, as proven by what happens on our planet...

Read about the Drake equation. It is more elegant than you think, although no more accurate.

[Myrddraal]

I haven't heard of the Drake equation, but I'll certainly look it up.

Let me explain my argument a little more scientifically, and looking a the question entirely statistically without bringing God into it.

We have some probability that a planet supports intelligent life which is not zero since we have Earth. As our population (size of the universe) approaches infinity, so does the number of planets supporting intelligent life. But the universe isnot infinite. It has some finite number of planets in it.

So what can we deduce about the number of planets with intelligent life in the universe? Without some notion of the probability of a planet supporting intelligent we cannot deduce anything. However big the universe may be, that probability can still be insignificant. We have no idea what that probability is, because we don't have a significant sample size.

The argument "the universe is nearly infinite so..." is flawed because the universe is not nearly infinite. Nothing is nearly infinite if it is finite, and even if we say (incorrectly) that the universe is so big it might as well be infinite, then we must come to the conclusion that there is also an infinite number of planets supporting intelligent life which is as ridiculous as it sounds.

We're talking probabilities here, so nothing in this argument says that intelligent life elsewhere is impossible. I'm just refuting the argument: The universe is very big therefore the existence of other intelligent life is likely.


On what has become a side note, the original link is really interesting, thanks!

EDIT: I just re-read your post and noticed this: "(nearly, because although the space is infinite, the question of whether matter is likewise infinite is not certain, although very likely)".

Is that so? I didn't realise that infinite matter was very likely, I thought the opposite was true. Haven't estimates been made of the mass of the universe?

If matter is infinite the argument that there are an infinite number of intelligent life supporting planets is not ridiculous at all, but I thought it was ridiculous because I thought the universe was generally thought to be of finite mass.

[Aemilius Paulus]

EDIT: I just re-read your post and noticed this: "(nearly, because although the space is infinite, the question of whether matter is likewise infinite is not certain, although very likely)".

Is that so? I didn't realise that infinite matter was very likely, I thought the opposite was true. Haven't estimates been made of the mass of the universe?

If matter is infinite the argument that there are an infinite number of intelligent life supporting planets is not ridiculous at all, but I thought it was ridiculous because I thought the universe was generally thought to be of finite mass.

Yes, thank you for noticing that - I was about to post before I saw you edit: tongue:

And yes, Universe is certainly infinite - or else it would have already collapsed on itself, and while we cannot prove that matter is infinite, it is the next logical step for a physicist to say so, and there is but a small probability that matter is not infinite - so the current model considers matter infinite, even if, for now, there is no direct mathematical proof for it. Now, density is not infinite (or at least not now - it could have been during the beginning of the Big Bang), but matter still is.

Do you still say intelligent life is unlikely, or even that our model is flawed? It would be mind-numbing if we were the only ones out there. As I said, only the existence of God could explain the absence of intelligent life in places other than Earth.

If I understood you correctly, your post was protesting the notion that life has to be there, and your point was that life could be there, but does not have to be? Right?

And why did you think matter was not infinite (was it sheer disbelief? - heh, that is what happened to me the first time I read it )? Also, if you agree that matter is infinite, then how can we make an estimate of mass?






Let me propose you start off your reading on this, if you wish to do so, with Stephen Hawking. Not only is he the leading astrophysicist of today (damn cancer to hell for taking the last greatest astrophysicist [well, actually more of an astronomer] and also the greatest atheist [well, actually agnostic IIRC], Carl Sagan), but he also writes marvellous books on the depths of cutting-edge physics with a language that is both understandable, to us, mortals (no joke here), and at the same time not 'dumbed-down', or at least in comparison with other texts (I am sure real physicists are laughing at me now - to them Hawking's books may as well be Physics for Dummies ).

And then, of course, you can go on to Sagan. Or in the opposite order. But A Brief History of Time is always a good place to start.



To summarise: for astrophysics, read Hawkings; for Drake equation and aliens, read Sagan; for practical application of space-travel and colonisation, read Robert Zubrin - he is certainly the best in his field, and unlike many of his comrades, he is actually a NASA engineer, so he knows what he is speaking of.

[Major Robert Dump]

Jesus was an alien. So is Tammy Faye.

[Myrddraal]

Universe is infinite, check. Density is finite (perhaps not at big bang), check. I knew that, but I didn't know that matter was considered to be infinite.

Please correct me if I'm wrong in this next paragraph, though I'm familiar with physics I'm not familiar with astrophysics so I might say things which might be commonly known to be wrong, but here goes anyway:

I'm not sure that the existence of infinite matter is an obvious next step for the physicist. It seems to me the universe has to be infinite almost by definition, since the universe is not defined by anything more than our three(/four) dimensions. I don't see the next step (saying that matter is therefore infinite) as obvious. Is it then thought that there was infinite energy in the Big Ban? As I'm sure you appreciate there's an awfully big difference between a very very large amount of matter and an infinite quantity. That was the essence of my previous argument: we must not be so daunted by the size of the universe as to apply arguments which are only valid when considering infinite systems.

Do you still say intelligent life is unlikely, or even that our model is flawed? It would be mind-numbing if we were the only ones out there. As I said, only the existence of God could explain the absence of intelligent life in places other than Earth.

Well if the number of potential inhabitable planets is truly infinite (something I'm naturally dubious about) and there is some non zero probability that a planet supports intelligent life then, as I said, the logical conclusion is that there is an infinite number of intelligent species 'out there'. The only explanation for intelligent life being truly unique to earth would be some external force (which we can call God if you like ).

My point was that if the number of planets is finite, however large it is we cannot make any reasonable or logical conclusions as the the likelihood of the existence of other intelligent life. We cannot conclude that it is unlikely, but more importantly a large universe (however large) is not sufficient to make the existence of other intelligent likely. This is an argument which I've heard put forward a lot, most often in the form "The universe is really really big therefore there must be intelligent aliens". This is the argument which I'm saying is flawed.

As to it being mind numbing, the possibility of us being the only intelligent life-forms in a finite number of planets is not nearly as mind numbing as a universe with infinite mass

[Myrddraal]

Well this has prompted me to read a bit about the nature of the universe and boy does it get complicated very quickly. If you thought the concept of an infinite universe as tricky, what about a finite universe with no boundaries? That seems to be one of three possibilities if I'm understanding what I'm reading.

Here's a comment from another internet user which I found interesting:

As I understand the physics of space-time (and IANAP), the universe is not thought to be infinite, properly speaking. It is thought to be finite but unbounded. That is, there is a finite amount of space, but no boundary to it. You cannot reach the edge of the universe, beyond which would lie some metaphysical no-man's land, I guess. Space-time bends back on itself in other spatial dimensions of the manifold. In other words, think of peeling off the surface of a globe and laying it flat on a table. It would be a finite amount of 2-dimensional space on the table before you. Now take it and wrap it around the globe again; it is still a finite amount of space, but it has no boundaries because it has been wrapped back upon itself in three dimensions. Likewise, if you think of the three dimensions of space-time we are accustomed to experiencing being wrapped back upon themselves in a fourth dimension of the manifold, you could have a finite amount of space with no boundaries. Not that you could reach any such boundary anyway; you'd have to have been traveling the speed of light since the Big Bang just to catch up with the expansion. And you're certainly going to fit only a finite amount of matter into a finite amount of space.

Really interesting stuff. I will try to read more and see if general opinion agrees with this guy, but if it does I stand by what I said at the start: there is no way we can state that it is likely that other intelligent life forms exist

[Aemilius Paulus]

thought that there was infinite energy in the Big Ban?

Damn, am I getting perma-banned again? Frack, I knew I should not have been such a smart-mouth







P.S. I think I will get to a real reply out, Myrddraal if carpal tunnel has not killed me from spending the whole day in the Backroom - a busy day this was

EDIT: your name is not helping my carpal tunnel

[gaelic cowboy]

I'm not sure that the existence of infinite matter is an obvious next step for the physicist. It seems to me the universe has to be infinite almost by definition, since the universe is not defined by anything more than our three(/four) dimensions. I don't see the next step (saying that matter is therefore infinite) as obvious. Is it then thought that there was infinite energy in the Big Ban? As I'm sure you appreciate there's an awfully big difference between a very very large amount of matter and an infinite quantity. That was the essence of my previous argument: we must not be so daunted by the size of the universe as to apply arguments which are only valid when considering infinite systems.:

Any part of an infinity can be broken into what we would say for want of a better word a smaller infinity it is however correct to call this infinity also.

[Tellos Athenaios]

The problem with inifinity is that it bends & breaks other conventions. IOW: it is possible to fit inifinitely many things on a finite space:

Consider this mapping (excuse the lack of proper Mathematical notation):

f= [ x/(1 + |x|) | x<-R]

This fits maps all numbers in the set of Real numbers (cardinality: c, i.e. the continuum, i.e. 2^N with N the aleph-nought, i.e. the cardinality of the powerset of the set of all natural numbers) unquely onto the interval [-1,1]. This mapping is bijective: for every x in R there is only one f(x) (injectivity/one-to-one); and for every y in f there is an x such that f(x) is y (surjectivity/onto).
Thus: there are as many Real numbers between [-1,1] as there are Real numbers at all!

Change the 1 to 0.5 and the same magic shows that the same thing holds for [-0.5, 0.5]. Change 1 to any finitely small number as you wish it will still hold. But as we know the interval [-1,1] is very much finitely large.