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Interjecting some notes about physical space,
The Universe
Currently, physicists are beginning to believe that the universe isn't as infinite as we once thought. Most are starting to see it as a closed-boundary universe. What this means is that there is a boundary to the universe, but such a boundary that to those within its boundary it would seem infinite. If you got to the edge, you would either wrap around to the other side of the universe or, being that everything is rushing away from the pandimensional "center" of the big bang at an extremely high acceleration (yes, the universe is accelerating according to new measurements), you would either not be able to reach the edge of material space or you would become the edge.
For the first boundary, think of it like us living on the surface of the earth. You can look into the horizon and see a "boundary" there. You can walk towards it, run towards it, drive towards it, fly towards it, but it is always and forever beyond your reach. It is therefore infinite inasmuch as it is imaginary and non-existent. The world would just appear to be infinite in all directions because you never get to the end, but just keep wrapping around.
For the second, you have to be careful about how you define physical space. Is it the arena in which everything moves or is it everything that moves? Most would think it's everything that moves, and so, getting to the edge, you would be the edge. Nothing's saying it had to be a perfect edge, but it is one nonetheless. Could you go on from there? Perhaps, but it would be meaningless. Now is there an edge to this arena of spacetime? That deals with dimensions, and currently there's some ideas about whether or not ours is the only universe.
Parallel Universes
With M-theory, it's since been considered that we live in but one universe of a whole complex multiverse. One idea is that we live in a giant hyperdimensional bubble universe with the bubble boundary being the extent of the dimensions. Being how this turns out, it's very probable that you simply wrap around to the other side like as if you were going along the surface of a pandimensional sphere or bubble. Recently, Lisa Randall and Raman Sundrum postulated that the universe is just a module wrapped around a higher-dimensional "package," which helps reconcile why gravity is so weak.
With that said, I've read numerous times by physicists that nothing in the universe is infinte.
When physicists are working with their theories, the common mandate is that if you get an infinity as a result, it's wrong. Infinities in physics are meaningless.
Theory and Infinities
Einstein's theory of general relativity was a landmark in human ingenuity. However, when physicists began delving into its limits, the extremities of physics, infinities began popping up. When a star of three solar masses or more dies, it collapses into a black hole. When relativity goes to take a peek at what's inside a black hole, all it finds is a "singularity," a point in spacetime that has infinite mass, infinite density, infinite time, and is infinitesimally small. It was obvious, from the first time that this result was derived, that relativity breaks down in regions of extremely high-mass concentrations and that a new, better theory had to be created to replace it. So, with the coming of the quantum era, which described things very small, physicists began trying to piece the two theories together. They were met with failure. Each time they tried to put them together, the theory crashed and burned under the weight of infinity. For example, they would find that the probability that a photon would be deflected by a gravitational field was infinity, which is obviously meaningless.
For theoretical physicists working on creating the theory of everything, infinities are sure-fire signs that there's something wrong in the equation. They become discontinuous and can ruin an equation by exploding into a myriad of infinities. In the 60's and 70's when everyone was trying to make their own theory of everything and hundreds of theories were created as a result, almost every one was trashed because they contained infinities. The few that remained had to be checked and rechecked extensively, and now the single contender left is string theory (M-theory), leaving quantum gravity and loop quantum gravity in the dust.
Infinities are nothing more than an abstract placemarker for mathematicians that have applications only in mathematical theory. They don't occur in nature. Nothing in nature has been found to be infinite, including the universe.
Kaku, Michio. Parallel Worlds. New York: Doubleday. 2005.
Thorne, Kip. Black Holes & Time Warps. New York: W. W. Norton & Company, Inc. 1994.
Randall, Lisa. Warped Pasages. New York: HarperCollins. 2005.
Also, 0^0 = 1 while x/0 = undefined (how many times does zero go into x? If you have four apples and no children, how many apples does each child get? There are no children, so how can they get any apples? You can't say zero, since there aren't any children to deny apples to, and you can't say infinity, since, again, there aren't any children to give infinite apples to and you're probably not dividing such a big "number" anyways.)
