Dealing with Infinity

How do we deal with the concept on infinity? It seems to linger about the limits of everything.

For me, this is the biggest problem in some sense. I wanted to ask the question in the context of the the multiverse. This is a big trend now in physics and cosmology and usually gets lots of people excited

Since we have now started saying that our Universe might not be the only one, haven't we simply pushed up the problem into a higher category. Let's just imagine that the Universe is a finite soap bubble and so as in common analogy, there are many bubbles/universes in the multiverse but if I ask whether all these bubbles are in finite bath tub? then the answer is equivalent to saying that our single Universe is infinite.

Suppose we did start saying that someday that our Multiverse is also a finite one, a really big bubble with lots of bubbles in it which share some common properties (superset, subset), then there would suddenly be the multi-multi verse! So really at this point, aren't we just pushing infinity higher and higher to avoid dealing with it?

Now suppose we take the brane theory and there are all these parallel branes stacked and they touch every once in a while creating big bangs, well these branes are supposed to stretch infinitely so where would they touch? Not to mention, there is an infinite stack of these membranes.

Then there is the black hole-white hole theory. Ok, some our Universe might be in a black hole opening into another realm the opposite side of which is a white hole and we see it as the big bang. So its like branching since we know lots of black holes are there in our Universe. Where then does the first black hole com from?

Of course, there are many theories but this infinity thing runs as a common thread. For me, dealing with infinity is the same as studying a black hole. The gravitational singularity comes into play right at the start of our Universe and we encounter the same thing at the center of black holes.

Why aren't we all just working on figuring out what happens at singularities. At this point we're pretty sure that black holes DO exist but how is infinite density possible/zero volume possible? What is its nature? Can it be described definitely rather than in infinite terms?

if something falls towards a singularity, what happens to it? does it emerge elsewhere in another form? We we could know, wouldn't we automatically know how things can come out of singularities like out Universe?

Is there a conceivable limit to what we can know and answer quantitatively and qualitatively?

Also, just a side question about our Universe itself? Isn't it supposed to have finite matter/energy? and there is a definite rate of expansion so it must be finite in the sense that it has only stretched so much? also, it has a definite age so it seems like that itself must impose a limit/boundary. I'm not hinting towards the sort of thing where I then ask what exists outside this boundary? I've seen posts before that asked this question and it was frowned upon but is there a distance from our point of view in every direction where the Universe has still not expanded to?

The CMBR should not exist at a certain point or rather, there should be a point where there is no temperature.
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 Quote by osxraider Is there a conceivable limit to what we can know and answer quantitatively and qualitatively?
There could be. We can try, and if after a million or so years there is no progress then I would be tempted to give up. But those in search of a PhD will still find something to write about, I suppose.

 Also, just a side question about our Universe itself? Isn't it supposed to have finite matter/energy?
If the Universe is finite then it has finite matter and energy.
If the Universe is infinite and homogeneous then it has infinite matter and energy.
 and there is a definite rate of expansion so it must be finite in the sense that it has only stretched so much?
It could have been infinite at creation in which case it is still infinite.
It could have been finite at creation in which case it is still finite and will very likely always be so.

 also, it has a definite age so it seems like that itself must impose a limit/boundary. I'm not hinting towards the sort of thing where I then ask what exists outside this boundary?
The future exists outside of the boundary of the Universe's age. There is also a limit as to how far we can see with telescopes, that's called the visible universe. Beyond the visible universe is the transvisible universe, I guess.

 I've seen posts before that asked this question and it was frowned upon but is there a distance from our point of view in every direction where the Universe has still not expanded to?
It could be that the universe is finite in which case it has a radius. Traveling in a straight line one would very roughly return to the point at which one started. It seems that the Universe would look pretty much the same at every point in the journey.

 The CMBR should not exist at a certain point or rather, there should be a point where there is no temperature.
The wavelength could eventually be close to infinity.

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Dealing with Infinity

You should review Cantor's theory on infinities.
 Most problems with infinity arise from the fact that it's frequently confused with 'very big' rather than what it really is. Infinity simply cannot exist in the same domain as dimensionality - and since we live in a universe with dimensions and dimensionality, infinity cannot exist within it. So within the universe, it's just a construct of the human mind - and cannot be used for calculations of realworld problems ... only in whole-universe theorisation. Understanding the origins of the universe will necessarily mean an understanding of the manner in which finity (dimensionality) and infinity sit 'relative' (for want of a better term) to one another.

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 Quote by Perchie Infinity simply cannot exist in the same domain as dimensionality - and since we live in a universe with dimensions and dimensionality, infinity cannot exist within it.
Are there not an infinite number of real numbers in the interval [0,1]?

 Quote by bapowell Are there not an infinite number of real numbers in the interval [0,1]?
Not in the real world, where there is a limit to the divisibility of matter ... assuming the existence of fundamental particles.
If something conceptual cannot be applied to the physical world, then it's virtual ... a construct of the human mind - it is not of the realm of reality.

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 Quote by Perchie Not in the real world, where there is a limit to the divisibility of matter ... assuming the existence of fundamental particles. If something conceptual cannot be applied to the physical world, then it's virtual ... a construct of the human mind - it is not of the realm of reality.
Why can't there be an infinite number of particles in an infinite universe?

 Quote by bapowell Why can't there be an infinite number of particles in an infinite universe?
No reason at all.
But there can't be an infinite number in a finite universe.

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 Quote by Perchie No reason at all. But there can't be an infinite number in a finite universe.
Sure. Who would dispute this?

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 But there can't be an infinite number in a finite universe.
Why not, our visible universe is finite, limited in time, but may be infinite at both extremes.

 Quote by bapowell Sure. Who would dispute this?
... ehem.

 Quote by petm1 Why not, our visible universe is finite, limited in time, but may be infinite at both extremes.
For the same reason you can't get a quart into a pint pot.
 Since we dont know if the universe is finite or infinite your argument seems mute.

 Quote by skydivephil Since we dont know if the universe is finite or infinite your argument seems mute.
My argument was that infinity is not a valid operand in calculations applied to the real world.
(And it's 'moot')

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