[Henchster]

"Expansion of the Universe."

Now, only an over-funded scientist could come up with a silly statement like that, if it's infinite, it can't "expand," and if it's expanding, what is it expanding into?

[Eternal_Bear]

maybe our universe will run into another another universe? Anyway, we have billions of years to worry about this problem.

[RadioAstronomer]

The best model we have to date for the universe is that it started with the Big Bang and has been expanding ever since. Time itself also started with the Big Bang so there is no "before" the Big Bang.

[Doctor Stochastic]

I need not expand into anything. It is just expanding.

[Salgak]

Actually, it can. The mathematics, formally known as "calculus of infinities", allows it. But in a more practical sense, the Universe as we know it is but a bubble in a sea of "quantum foam". While infinite in span, the bubble STILL grows, stretching the underlying space-time fabric, and increasing the distance between two given point, even if those two points are stationary, relative to each other. Astrophysics is literally mind-blowing stuff. . .

[NC_Libertarian]

Is the universe infinite?

[powderhorn]

... if it's infinite, it can't "expand," and if it's expanding, what is it expanding into?

It's not infinite. There is a theoretical end to the known universe.

It is expanding like a balloon expands, everything goes farther out, and individual galaxies move farther away from each other as the universe expands. The essential qualities of space include: gravity, the strong force, the weak force and electromagnatism. Without these forces, time and space cannot exist.

[RightWhale]

what is it expanding into?

Why should there be a what into which to expand? You will probably get a kick out of some new lab experiments involving measuring the 5th dimension, now being designed and performed at Princeton [and many other research centers are scrambling their own projects.] Accepting the 5th dimension shouldn't be difficult for those who have accepted dimensions 1, 2, and 3, not to mention accepting time as the 4th dimension.