the universe and infinity...

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the universe and infinity...

Postby highrealizations » Mon May 06, 2002 3:18 am

recently i was talking to my friends about something that seemed had a logical answer but still seemed very strange. the universe is thought of as and infinite stretch of planets, stars and such. if it is truly infinite like it is said to be, then it would be safe to assume that there is another world similar to our own. if it is infinite, then actually it would be safe to say that there would be and infinite amount of worlds similar to ours. in all of these worlds similar things must have happened it they are made up of the same stuff earth is made of. theoretically it would also be safe to assume that there are many worlds that are almost exactly the same as ours just because of the infinite stretch of space and infinite amount of planets.
in these worlds the odds are if there are an infinite amount of them, that there would be one with a person exactly the same as me and everyone else on this planet. the amount of things that would be the same and different would be mind boggling to think about considering the infinite amount of possibilities. its weird to think about but i believe my friend glodfarb had many points that i think make sense.
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yes, but

Postby Cool Hand Luke » Mon May 06, 2002 6:18 am

you're exactly right, if the universe were indeed infinite, there would be an infinite amount of earth's, and an infinite amount of you's. there would also be an infinite amount of planets that are not earth, and an infinite amount of people that are not you. and so on and so on. but several studies of the size of the universe using the hubble and chandra telescopes show that the universe is not infinite. also, most theoretical physicists believe in the "big bang" theory, which does not allow for an infinite universe, in spacial terms.

it is definatly not disproven though, and it's pretty mind boggling to think about, eh? if the universe is infinite, than an infinite amount of me's would be typing this right now! also an infinite amount of me's would have left out this last sentance!![/i]
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Postby alex » Mon May 06, 2002 6:14 pm

hhhhhhhhhhhm...I'm not sure that I buy this. It sounds like we're talking about parallel universes but in the form of parallel planets. I don't follow the logic of this statement to be honest:

you're exactly right, if the universe were indeed infinite, there would be an infinite amount of earth's, and an infinite amount of you's


Surely there are an infinite number of numbers and yet no two numbers are the same. I'm not a physicist so I'm sure I can't give a very accurate answer to this but my simple knowledge of maths suggestst that what you have both said is incorrect. Even if the Universe was infinite in space then it doesn't mean that there need be an infinite number of identical planets to this one. There are enough different 'things' out there to not need to replicate 'things.' Clearly no infinte universe can be entirely filled and therefore I don't see why replication of existing planets is needed to explain an infinite universe. Those of you with some special physics knowledge on the matter, can you please illuminate me.
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Postby kjeevah » Mon May 06, 2002 6:44 pm

coolhandluke - please do not use apostrophes for pluralisation. this really is a pet hate of mine.. why is it that so many people today seem incapable of retaining even basic primary school english?
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c'mon...

Postby Cool Hand Luke » Mon May 06, 2002 6:45 pm

if the universe is infinite, there is an infinite amount of everything. I suggest just typing 'infinity' into a search engine, you will find out a lot. it's an intresting subject, but you obviously have a lot of misconceptions about it.
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Postby alex » Mon May 06, 2002 6:53 pm

From the way you wrote that last post it sounds as if you are an expert in the field. From the way you wrote your first one it sounds like you are not. An infinite universe means nothing more than that there is an infinite amount of matter in the universe. It does not mean that there must be someone else in the universe with the exact same genetic attributes as me or you. NO ONE has proved what you are suggesting so the fact that you have written about it so simplistically as if people shouldn't challenge it seems ridiculous to me. Do you honestly think that you have answered the question in the few hundred words that you have written? Anyway please counter-argue my example of the infinite number of numbers.
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Postby jawaad » Mon May 06, 2002 8:31 pm

Al, your numbers example is a good one. However, numbers are not governed by chaos; they follow a structured progression which excludes the possibility of duplicates. If the universe was infinite in the mathematical sense, then there would have to be an infinite number of clones of earth and clones of you, since events of even negligible probability must occur by definition (because, for example,
1x10^-1000000000000*infinity = infinity).

However, this seems absurd. If everything that could possibily happen had happened, surely we would have made contact with alien civilisations by now - but we haven't. So, the premiss that the universe is infinite leads to a false conclusion. Logic (and my own intuition) prompts me to reject that premiss. This is why I believe that the universe is not infinite in the mathematical sense. Scientists themselves try to calculate the age of the universe, because it has existed for a finite length of time. And they believe it is expanding. If something is infinite, how can it increase in size?

I agree with Alex that there is no reason for the universe to contain an infinite number of 'you's and 'me's, because, as Cool Hand Luke suggested was possible, it is not infinite in the true mathematical sense.
Last edited by jawaad on Mon May 06, 2002 8:49 pm, edited 1 time in total.
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Postby Pangloss » Mon May 06, 2002 8:39 pm

i agree with jawaad,
therefore jawaad agrees with me.

~

the universe is therefore, not infinite,

~
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Postby jawaad » Mon May 06, 2002 8:56 pm

Never one to shy away from a bandwagon, Pangloss is in there with the logic. BUT, (I'm being picky now), just because we agree on the the universe's manifest non-infinity, it doesn't follow that we are correct. What if the premiss that we agreed on is false? That would make our conclusion false...

ps. Leo, the next big bad bodyrocking bandwagon is evaluation of one's own arguments (good for econ a-level). Just thought I'd let you know.
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Postby HVD » Mon May 06, 2002 9:17 pm

If everything that could possibily happen had happened, surely we would have made contact with alien civilisations by now

But then again, an infinite number of us have, and the same number haven't, so maybe we fall into the latter category.
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Postby ben » Mon May 06, 2002 9:31 pm

To be honest, there are probably differing contemporary theories on the nature of the universe but I think the most popular one at the moment is that the universe is NOT infinite in the sense that is being suggested.

I think the answer lies in a distinction between an actual infinite and a potential infinite. An actual infinite can be used in mathematics (and maybe physics) but in reality it falls down (See Hilbert's Hotel Thought Experiment). A potential infinite is one which is restricted by time. For example, the universe had a beginning (time restriction) but theoretically will have no end. If you tried to reach the "edge" of the universe you could not because it is expanding at the speed of light. Therefore the universe is POTENTIALLY infinte, but is not an ACTUAL infinite.

Obviously this is only one view but I think it is the logical conclusion of those with rational thought. The Infinite number of worlds may work in a philosophical sense but I think it falls down in reality.
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Postby JP » Tue May 07, 2002 5:15 am

The universe is infinite, the amount of matter is not.

That is, the universe extends infinitely far in every direction (theoretically obviously) but matter simply occupies an ever-increasing "sphere" of existence within the universe. Matter (and time) was created, for all intents and purposes, in the big bang, and has been expanding - from a singularity - ever since.

Therefore, the logical problems you present with regards to infinity, assuming I have it right, need no longer apply.
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ugh..

Postby Cool Hand Luke » Tue May 07, 2002 6:15 am

kjeevah:

my philosophy of language is that as long as you are understood, there's no need to get all nitpicky about shit like that. I think many philosophers spend far too much time analyzing language.

everyone else:

I'm hardly an expert in the field, but the subject of infinity does pique my intrest. anyway, if the universe IS in fact infinite (all signs point to 'no') than there would be literally an infinite amount of EVERYTHING. that means there would be an infinite amount of me's that typed this exact response, but didn't caplitalize the 'everything.'

HVD is right, JP is not. Let me explain why JP is wrong:

what i like to call 'GCS' or the 'grand cosmic situation' (it's called by many other names in physics texts; superspace, hyperspace, multiverse, ect...) is basically reality as we know it. Quantum mechaics reigns supreme in this arena, and nothing strictly forbidden not only can happen, it HAS TO happen. anyway, our universe is just one universe amoung many other universes. I bet a lot of you have heard of this concept before, it's called 'The Anthropic Principle' for those who havn't. Anyway, time and space are unlimited in this 'GCS,' in any number of dimensions. our universe just happens to be in 3 dimensions of space, and one dimension of time.

(this is all theoretical information of course, but in the realm of modern physics, it's the best guess of the leading people)
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Postby JP » Tue May 07, 2002 6:50 am

our universe is just one universe amoung many other universes. I bet a lot of you have heard of this concept before, it's called 'The Anthropic Principle' for those who havn't. Anyway, time and space are unlimited in this 'GCS,' in any number of dimensions. our universe just happens to be in 3 dimensions of space, and one dimension of time.


Correct. There may be an infinite number of universes, but, with our current understanding of astrophysics there is absolutely no way to demonstrate this.

At the moment, any theories that propose the exitence of "other universes" or of a universe that extends well beyond what we currently know and understand about our little pocket of it, are highly speculative, and corrborating evidence is difficult to find. Therefore, given that the only universe we know is the one in which we currently reside (given that the existence of any other universes is highly speculative and somewhat dubious) my point was simply that our universe, as we understand it, contains only a finite amount of matter which makes the infinity principles you propose entirely undemonstrable.

The anthropic principle simply suggests that the only reason we are here, and able to view the universe, is because its natural laws (gravity, thermodynamics, matter exceeding antimatter etc.) just happened to be perfect attuned to the conditions necessary for the existence of beingssuch as ourselves. We shouldn't take this as any major miracle though (as many short-sighted Christians do), for if the universe had turned out even slightly differently, we wouldn't be here to view it and there would be some other sentient being - suited to its GCS - saying exactly the same thing.

Keep in mind though, that the anthropic principle makes no predictions about the existence of other universes. Just because the universe could have turned out differently, it doesn't mean that every possible universe must necessarily exist, as you, in some way, seem to be suggesting.

Even if it could be proven that there is such a thing as a "greater universe" - i.e. a universe that extends beyond our small pocket of it - that is still no guarantee that this greater universe must necessarily be infinite in size, time or both. There may well be a very large number of universes, but even if we assume that there are 1000^1000^1000 universes it is still a long way from reaching the concept of infinity and the paradoxes you presented above.

I'm not saying you're wrong, just that you're making some fairly grandiose assumptions that will either need to be justified or toned down.
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Postby Turing » Tue May 07, 2002 11:15 pm

I am not going to give a long winded re definition of what everybody above has said because they have all said it far better than i could. however what you are all assuming is that the concept of a hyper sphere and the laws of thermodynamics are correct. only by these things can you make the premises that the universe os infinite or not. im not an expert in physics (so much so i dont know if i have spelt it correctly...) but i am going to make a little statement i thought of the other night whilst trying to sleep. what if the universe is not an infinite hyper sphere as we have imagined or one part of and ever shifting mulitiverse created by energy shifts on the many dimensions blah blah blah... but that the universe contains a fold somewhere within it, hence created the illusion off the infinite. if you cant break free of the loop and are continually retracing yourself it would give the impression off the hyper sphere and of ever increading mass if the loop was growing larger. actually im lost now and tired, il rethink that and come back to it. feel free to criticize as muc as you like
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Postby Cool Hand Luke » Wed May 08, 2002 6:08 am

JP:

Yes, all of that stuff is extremely theoretical, but it's still very good guesses from the leading minds in physics...mind boggling stuff to ponder.

Anyway, you are correct about the anthropic principle, but when people have explained it to me, they've taken it one step further with "wormhole genesis," which basically means that since this universe seems to have all the right conditions to sustain life. But if you look at the universe as a whole, it seems as if the main purpose is to produce black holes, because theres so many of them, and they are being created constantly. One would assume looking at our universe that it's purpose is to make these things called black holes. Well, when a black hole forms, it also creates a 'wormhole,' which is a break in the fabric of space and time,and this wormhole branchs off and forms another universe. (again, this is all pure theory) so universes with the right conditions to make black holes can kind of 'reproduce' throught these wormholes, and make more universes that have similar conditions.

The point of this, is that taken to it's extreme, the anthropic principle suggests that life is just a side effect for the creation of new universes. i'm not sure if i explaned this very well, if i didn't, let me know and i'll try to explain better.
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Postby JP » Fri May 17, 2002 5:57 pm

Yep, I understand where you're coming from Luke - and you have some interesting ideas - but I'm still not sure I agree with you.

The point of this, is that taken to it's extreme, the anthropic principle suggests that life is just a side effect for the creation of new universes.


The anthropic principle - by definition - is simply a way to account for the actuality of the GCS given our human mode of perception. It cannot have any application beyond humanity. It is simply used to describe why the GCS is how it is, and why it seems to conform so neatly with what we humans need in order to exist. It cannot be used as a predictive tool, nor can it be applied to anything other than humans without grossly changing its fundamental elements.

If you wish to advocate the notion that the universe seems to exist purely to facilitate the creation of further universes, then firstly you're going to have to demonstrate that the universe has any purpose at all (which goes against the passive-nihilistic philosophy of recent times) and incorporate a different principle to demonsrate this. The universe is not bound to the laws of the anthropic principle, the anthropic principle is bound to the laws of the universe. So, as such, the anthropic principle cannot dictate what the universe should and shouldn't "be", rather it is dictated by what the universe "is". If the universe was any different, either the anthropic principle wouldn't exist (as we wouldn't be here) or, at the very least, it would have to be different to accomodate the universe's different actuality.

Er, so I hope you understand where I'm coming from. I also hope I understand where you're coming from otherwise this post isn't going to make much sense. :-?
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Postby Slartibartfast » Wed Jun 05, 2002 9:41 pm

Here's my theory:

First of all, i would like to point out that i am 14, and not an educated physicist or anything (yet). I have, however, done a large amount of research on physics, and i own quite a few books by steven hawking.

I don't like the theory that the universe has a finite size, because that seems too simple. I also don't like the big bang theory, because i think the universe is infinite in time and space.
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Re: the universe and infinity...

Postby ssivakami » Fri Jun 07, 2002 1:31 pm

highrealizations wrote:recently i was talking to my friends about something that seemed had a logical answer but still seemed very strange. the universe is thought of as and infinite stretch of planets, stars and such. if it is truly infinite like it is said to be, then it would be safe to assume that there is another world similar to our own. ...


No, thats not true. Our universe contains a finite number of galaxies, each containing a finite number of star systems, each containing a finite number of planets and satellites.

- Sivakami.
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Postby Slartibartfast -- Guest » Fri Jun 07, 2002 11:02 pm

prove it
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Postby Matthew » Sat Jun 08, 2002 11:00 pm

Surely everything tangible is finite. It is just easier for us to say it is infinite because there is such a large number of objects (e.g. grains of sand), or the number of objects is increasing at a large or unpredictable rate, or we are unable (or just can't be bothered) to locate and count them.

I'm not against infinity at all. It is a very important concept in mathematics, but I feel it is very much overused with topics such as space where, lets face it, we don't know much for certain, and so "infinity" is perhaps a quick and easy get out clause.

I am fully expecting someone to find a counter-example for the above!
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Postby Natsilicious » Sun Jun 09, 2002 2:49 am

Oh... and you have counted them?.

Give me a ballpark figure. :-?
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Postby Matthew » Sun Jun 09, 2002 6:08 pm

No of course I haven't.

It's people like you asking people like me how many of something exists that causes words like "infinite" to be thrown about.

I stand a much better chance of giving you a ballpark figure than you do bringing me an infinite number of anything.
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Postby Natsilicious » Mon Jun 10, 2002 1:23 am

Sorry, not to you. To the doctor from India. She totally dismissed his view, so I want her to prove it.

But since you went there, I wouldn't have asked to count it, if I didn't know that there are two meanings to the word infinite. Infinite meaning boundless/endless and also greater than any pre assigned finite value however large. Have we ever counted the stars?. Nooooo why?, because someone kinda stopped when it reached 999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999............................

just a thought.
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Postby ssivakami » Tue Jun 11, 2002 4:40 am

Slartibartfast -- Guest wrote:prove it


You can do so yourself. Learn a little astronomy and physics and you can estimate the number of galaxies and star systems in our universe.

Counting them directly is not necessary (and not possible either). Very often what we think we're seeing is not necessarily true. Just think of a magic show and you'll understand what I'm talking about. ;)

Objective evidence is the key. Thats what science uses. You measure the effects of a phenomena and verify it.

How do you think scientists discovered the BB ? And about black holes ? By directly observing them ? You must be joking ... :D

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