Infinite Universe = Impossible

[K^2]

Big Bang and infinite universe do not contradict each other. It all goes to question of how an infinite universe can expand. Expansion is not just boundaries, if they exist, moving out. Every point of space experiences expansion. This is a feature of differential geometry our space has. And it goes back to analysis. Can infinitely many regions of space add up to zero volume before the Big Bang? They can, if initial expansion rate was a "greater" infinity. It is all about measures and limits.

[*Aqua*]

Can infinitely many regions of space add up to zero volume before the Big Bang?

I read spacetime came into existence "during" the Big Bang. That means there was no "before". So is it possible to ask your question?

[K^2]

Bad wording on my part. "At the exact instance off..." would be more correct.

Though, with a finite universe, there are some interesting interpretations of "before". In a finite universe, Big Bang can work like a center of a sphere, with each instance of time being a new layer. It automatically has expansion built in, and has some other nice features. Most importantly, the question of what's "before" or "outside" disappears naturally.

These bits are just speculation, though. Both finite and infinite universes are consistent with observations and theory.

[Technical Ben]

It's fundamental for our understanding of the universe. You just can't exclude that.

Unknown but the probability is greater than 0.

The probability is zero. As by definition if there was an exact copy, then there would be no defining feature for the universe (let alone us) to distinguish the difference. So there has to be one of every unique "thing" in the universe, and no recurrence. There can be 2 things similar, but they must have a defining feature (and I would assume a flat universe has no preferential frame so you cannot say there is a separation of space between original you and clone you).

PS, there can be a "before" of the visible universe. But considering what is before it, is considering what is unobservable, so kind of beyond scientific questions. In a similar sense you can ask "what came before the start of the book", within the book there is no "before" the start, but outside that system, there can be any number of pre-existing/pre-dating systems and books.

[Chiboko]

On the topic of the original question (rather than the complicated physics of expanding space): yes in an infinite universe the creation of an event that destroys/damages the universe would happen an infinite number of times but so would an event that completely cancels out the first event. This works in all cases leading the 'everything happening in an infinite universe' problem to neatly cancel itself out.

[worir4]

On the topic of the original question (rather than the complicated physics of expanding space): yes in an infinite universe the creation of an event that destroys/damages the universe would happen an infinite number of times but so would an event that completely cancels out the first event. This works in all cases leading the 'everything happening in an infinite universe' problem to neatly cancel itself out.

So then nothing would happen?

Thanks for all the responses.

What is our boundary for the Universe, Is it the furthest detectable body or is there something else that we use to estimate the size?

In my original question i was referring to both infinite in space an time as both would have the same effect on probability so it can't be infinite in either?

[Chezburgar7300]

I personally believe that there is only one universe and it is infinite, but I do realise from a scientific/mathematic view that is more than likely ludicrous. To be fair, though, a lot of science eventually either gets disproved or proven and we currently don't have the technology to determine this or not and probably never will in our lifetimes.

I am going a little (lot) off topic from the OP here, and to talk about the OP, I think you're wrong. The infinity you're talking about is time not distance. As one of the first commenters said, time is not infinite and I agree with them. Although I think distance can be infinite I do not think time can be.

And who knows? Beyond the border of the expanding galaxies there could just be empty space which is still the universe, just no matter in it yet.

Edited January 18, 2015 by Chezburgar7300

[AngelLestat]

in my opinion, infinite is a concept that has only meaning in the abstract mathematical frame.

I cant imagine a case where infinite may had sense in reality. Those are the cases where our math fails to describe the object of study.

[sndrtj]

I'd suggest OP reads this: http://arxiv.org/pdf/astro-ph/0302131v1.pdf

It's old, but doesn't make it less valid.

In a nutshell, yes, OP, in an infinite universe reality repeats itself several times. That's not odd. Imagine the observable universe to be a Rubik's cube. A Rubik's cube can technically have about 519 quintillion states. Now, however, consider a room FULL of Rubik's cubes. Every single state in the original Rubik's cube can now be duplicated in any of the (probably thousands of) Rubik's cubes in the room. In effect, we have duplicted our observable universe with many instances of the same. Now imagine an entire house full of rubik's cubes, an entire city, entire country, and entire planet full of Rubik's cubes. The number of duplications of our observable universe is now, for all practical purposes, gargantuan.

This is exactly the case of reality. Within a bubble with a radius of approximately 10^10^91m, there should be a sphere of space exactly duplicating our entire stellar neighbourhood of 100ly. An identical copy of you is roughly 10^10^29m* away, and an identical copy of our entire observable universe should exist in a bubble of space with a radius of 10^10^115m.

Besides that, there is a much much much older argument for an infinite universe, known to the ancient Greeks. Consider the universe being a spherical room with a diameter of 5 meters. What happens when I step outside of it? I still exist, so my universe must have become bigger. And I can step further and further and futher, and each time I step further, I'll expand my universe. There is no end to this. You can always step further.

*: I've once asked a physicist about the following problem tho: I know the Pleiades exist, several hundred light years from here. An exact copy of me should also know that the Pleiades exist. Shouldn't that exact copy of me also be placed within an exact copy of the entire observable as it is known to me, to be actually an exact copy of me; thus necessitating the entire observable universe to be duplicated (10^10^115m)? I never really got an answer to this question. So, if someone here has an answer to this rather philosophical question, please tell me!

Edited January 19, 2015 by sndrtj

[AngelLestat]

No matter how big is the number you wrote or imagine, is just a number.

Infinite goes beyond that.

Our universe has a finite time, it has a finite amount of matter, it has a finite space.

Then we can said, ahh but it seems that we live in a multiverse, so it may be infinite universes; but we later discover that are generated by a finite number of actions in a superior brane. But then we can said that those branes are infinite..

Is like the concept of god, when we reach our limit of understanding, then we need to quote concepts like "it must be the work of a creator" or "infinite".

[K^2]

If you spend a little bit of time actually studying measure theory, and then take a good look at modern cosmology, you'll understand that infinite universe is entirely within realm of possible.

[Brotoro]

Astronomical observations to date favor a universe that is infinite in spatial extent. And if it is infinite now, it would have been infinite at the time of the big bang...it has just been stretching larger over time. It is not infinitely old in time, however, since its current arrangement of space-time formed in the big bang. Such a universe would contain an infinite amount of matter.

The "visible universe" is finite in spatial extent, since it only includes a subset of the whole universe out to a distance from which light could have reached us during the age of the universe...about 13.8 billion years ago. This is not a distance of 13.8 billion light years, as one might expect, because the matter that radiated that light 13.8 billion years ago has been carried far away by the expansion of the universe since then...so that matter is currently out at a distance of about 46.6 billion light years. The amount of matter/energy contained in the visible universe is finite. The size of the visible universe is constantly increasing as there has been more time for light to reach us from more distant objects, and as the expansion continues to stretch space.

When people talk about "the universe was smaller than an atom such and such a fraction of a second after the big bang," they are referring to how large the chunk of universe that makes up our current visible universe was at that time.

It's possible that the whole universe is not infinite...but it would have to be much, much, much larger than the current size of the visible universe in order for it to appear as flat as it does over the distances we can observe. And while it has been speculated in the past that the whole universe may be closed and curve around on itself if you go far enough out (this is what Einstein thought, based on the observations available at the time), current observations do not favor this.

[K^2]

Astronomical observations to date favor a universe that is infinite in spatial extent. And if it is infinite now, it would have been infinite at the time of the big bang...

That is a fallacy, as I've pointed out. Universe could have had zero or finite size at Big Bang and then inflate to infinite size during Big Bang. In fact, all of our observations seem to confirm that universe started out as a single point.

Another thing, we have evidence that suggests boundless universe. That doesn't mean infinite. Universe can be closed on itself and have a finite volume. That is entirely consistent with every observation that we've made.

[Bill Phil]

But points have zero size...

Oh, and zero size doesn't mean no size.

[Duxwing]

Big Bang and infinite universe do not contradict each other. It all goes to question of how an infinite universe can expand. Expansion is not just boundaries, if they exist, moving out. Every point of space experiences expansion. This is a feature of differential geometry our space has. And it goes back to analysis. Can infinitely many regions of space add up to zero volume before the Big Bang? They can, if initial expansion rate was a "greater" infinity. It is all about measures and limits.

Nitpick: Infinitesimal volume.

-Duxwing

[Waterlimon]

I believe that every mathematical expression (of course not in terms of our mathematical notation, but the basic idea remains, more like a system than expression) exists, with the universe being a part of one (the universe could be an infinitely tiny part of such a system if infinity is involved, which I believe is, with an infinite number of 'levels' below and above our level of existence, like quantum physics and large scale planetary interactions).

Think of the systems like the real numbers. Theres only one of each, but theres infinite possibilities. And each of those infinite possibilities is another infinite sequence of systems, just like you always have a real number in between two real numbers.

Consider the most basic computer (turing machine), and consider there are an infinity of them, each with infinite memory (infinite-dimensional memory? lets use that, just to be sure), each with a unique set of instructions, starting from simple programs and continuing to ever more complex ones. Consider the game of life, with infinite grid size, as one of the systems, with ever more complex behavior emerging as you look at the simulation on higher and higher levels.

This means that the 'metauniverse' where these systems exist never changes (since there is no time or anything, the metauniverse is not a system in itself). If you had an expression that perfectly described the universe, the universe would exist without ever evaluating that expression. The entire universe in its entirety and all moments of existence in it are encoded in that expression, even if the universe was not finite, like pi.

All that exists is a rule out of which can be generated every system possible, every mathematical expression and every simulation, and expand that rule to infinity, with the systems generated by the rule containing infinities themselves.

We may exists as a system, we may exist as a distant branch in an infinitely larger system, as a tiny emergent behavior spawning in a complex system with an infinite amount of other just as insignificant side effects, like the life here on earth just emerges from the underlying patterns, and more patterns emerge out of it, continuing infinitely in both directions, just one of [a number for which youd use up arrow notation to represent] other complex systems emerging from the laws of the universe, laws which describe the behavior of a single layer, a single level of detail, in an infinity of them.

I think you get the general idea. The only issue I have is the fundamental 'rule' out of which all the systems can be generated. Sure it can be very simple, using only the concept of infinity and some simple turing machine like thing, but it doesnt really make sense until its so simple that it doesnt exist. Dunno.

Also time is not really advancing (the metauniverse and systems just exist, theyre static) even if thats intuitive, its like in an arithmetic progression the next terms depend on the previous terms, the future depends on the past, but the universe is never AT some particular point in time, its at all of them at once, but we are not the universe and for us, we are at a single point, like every term in an arithmetic progression would feel like its the current one and the other ones are not in the present, except they feel just the same. Poor AP terms.

Some stuff that follows from this:

-Since all systems exists, we would expect to find ourselves in a really weird one. But ours seems relatively elegant. So it can be concluded that the 'weird' systems either never work very well, or the weird systems give rise to many simpler ones.

-Our universe may or may not be cyclical

-When our universe 'dies' in that our chemistry or life like we know it wouldnt work anymore, it doesnt mean a new universe cannot form on a higher level, with different laws and properties. Though its possible that you cant go 'up' in terms of complexity anymore (our universe would be a dead end in terms of emergent systems forming on top of emergent systems).

-Errything is deterministic, go away probabilistic quintum mechanics

I think this is enough rambling. Can I join some club now?

[AngelLestat]

If you spend a little bit of time actually studying measure theory, and then take a good look at modern cosmology, you'll understand that infinite universe is entirely within realm of possible.

You can said that if you travel in one side by the universe, you will never see the end, this is due that the own gravity bend the universe so is like walk over the surface of earth, and the second reason is that at the same moment is expanding (space and time) more faster that you move.

So it will looks like is infinite.. but is not. you just need to define your frame of reference to compare.

Seeing from the bulk the universe is not infinite.

If the universe is infinite larger, then we can also said that something can be infinite small?

I guess particle physsics would not be very happy to hear that.

I think physicists in these cases need help from philosophers. In the edge of discovery, merging reality with the abstract of math, is not hard to lose your self in a loop between old definitions and new ones.

[K^2]

AngelLestat, that's a bunch of speculation on your part with not a shred of evidence. Again. Please, learn to distinguish between scientific method and making stuff up.

Nitpick: Infinitesimal volume.

Nitpick accepted, conditionally. The limit is clearly zero volume at zero time. But whether exact zero time actually exists is a separate question. Singularities are, well, singular. Infinitesimal volume at infinitesimal time from Big Bang is less flimsy.

[Iskierka]

*: I've once asked a physicist about the following problem tho: I know the Pleiades exist, several hundred light years from here. An exact copy of me should also know that the Pleiades exist. Shouldn't that exact copy of me also be placed within an exact copy of the entire observable as it is known to me, to be actually an exact copy of me; thus necessitating the entire observable universe to be duplicated (10^10^115m)? I never really got an answer to this question. So, if someone here has an answer to this rather philosophical question, please tell me!

I suspect this is something to be resolved by considering probabilistically the odds of exact duplications occurring. I assume the numbers given consider only random chance and the possible arrangements of atoms - in theory, your clone could know of the Pleiades without having ever seen them, a weird phantom memory that has appeared by random chance, but this is unlikely, which would therefore make your exact clone significantly less likely. Adding in consideration of another dimension, time, presumably your exact clone would need to have an identical history to be truly identical. This calls into question exactly where your nearest clone could be, depending on how much has to happen and whether it's possible atoms could just randomly arrange themselves into an exact duplicate by chance.

The exact duplicate of our observable universe is similarly questionable, but may, depending on variance allowed, still be at a similar distance. Quantum effects over time make it questionable, as well as -exact- particle conditions, versus simply being entropically equivalent with functionally identical particle arrangement, would call into question the exact distance this is likely to occur at. It's a weird question - in theory you can use probability to determine these distances, but do you actually know the odds you're calculating, or even the steps to determining the true chance?

[vitekc45c]

What if the universe itself IS infinite, but the amouth of matter is finite? Then what we see as closed and ever expanding universe, may in fact be spherical "cloud" of matter (and antimater) expanding into absolute vacuum of infinity.

[rtxoff]

What is space?

If the universe started out from a singularity in the big bang, what was there before it created the space?

Our universe might be finite but the space that contains it should be infinite?

If we find out that there are more universes beside our own then we have to rethink the use of the word universe cause universe is by definition the totality of everything that exists including other "universes" that might exist?

To find the proper answers someone has to ask the proper questions.

[YNM]

Probably my own answers to those using distances as a base : think about comoving coordinates. That is, a coordinate system that stays static even if the space expands. Think about it : how many numbers (or units) there exist in the lines of this coordinates on Big Bang, is it finite or infinite ?

In fact, it can be either one; for the infinite, while big bang leads to a conclusion that the universe starts from a single point, this point is there because light can't move around yet at all, and what mass-energy can affect is just that point - there are infinitely many other points. For been finite ? the same - it'll be a point again, but there could be other points (ie. more than one yet finite), most likely to happen when our Universe is positively curved and have a larger than zero (uh, positive) curvature radius at start. There could be actually just a point because at the time of Big Bang, the curvature is positive, and the radius is zero (whatever units). Sounds silly, but that's it : we don't see the same objects many times (ie. had it been closed the horizon distance is less than it's "circumference", or it's simply infinite) and it's isotropic and homogeneous on large (like, <100 Mpc) scales (means there's no way there could be a border, because that'd be a preferred direction, and that the center of the Universe exist).

You could even take infinitesimals and then says it's undecided. Which is far better than betting, or debating - go observe !

[KerikBalm]

Somebody needs to take more math and understand limits, l'hopitals rule, etc.

Consider f(x)= x, and g(x)= x^2

Both are infinite... that is to say Lim (x-> infinity) = infinity

Yet f(x)/g(x) approaches zero as X goes to infinity.

Something can become infinitely less likely faster than the infinite expansion of the number of possibilities that actually become reality.

[K^2]

Our universe might be finite but the space that contains it should be infinite?

Nothing contains the universe. It's not an embedded manifold. In fact, GR pretty much states that our universe cannot be embedded.

What if the universe itself IS infinite, but the amouth of matter is finite? Then what we see as closed and ever expanding universe, may in fact be spherical "cloud" of matter (and antimater) expanding into absolute vacuum of infinity.

Possible, but very arbitrary and somewhat boring. If you are going to go with finite matter in infinite space, a fractal universe is much more elegant. Non-uniform structure is a requirement for infinite universe, by the way. Otherwise, sky would be infinitely bright.

[AngelLestat]

AngelLestat, that's a bunch of speculation on your part with not a shred of evidence. Again. Please, learn to distinguish between scientific method and making stuff up.

haha, as always very spicy.

There is also a bunch of speculation on your part too, not forget that!

If you accept that your infinite universe is only based on perspective. Then I will be agree.

In other case, prove me that all your principles were are you based apply also to anything that did not originate in the Big Bang.

Nitpick accepted, conditionally. The limit is clearly zero volume at zero time. But whether exact zero time actually exists is a separate question. Singularities are, well, singular. Infinitesimal volume at infinitesimal time from Big Bang is less flimsy.

Singularities are just things that our theories can not explain.

Example black holes singularities, big bang singularity, etc.

We can not even talk about infinite time, because we dont understand if there is a limit to the physsics properties in our universe with such stretch.

If we apply the infinite concept to reality it leads to the sort of blinkered thinking which results in the repetition of mathematic rationale as though it were a final true answer to something that it does not address.

Infinity is a concept that we use as an approximation. When something is so small or large that it is reasonable to regard it as infinite.