So the universe will eventually...

[Plat]

turn into one big vacuum right?

[antoniseb]

It will be big, and it will be more of a vacuum than it is today.

Were you thinking that it would be a perfect vacuum? Is a perfect vacuum allowed to contain photons, neutrinos, dark energy, or electrons? Is it still a perfect vacuum if electron-positron pairs are being created, and disappearing before Heisenberg says they certainly exist?

If you mean a perfect vacuum, I think the answer is never.

[astromark]

As I may be and probebly am wrong, I understand the concept like this.. Yes the known universe is expanding into the void. You can not create nor distroy mater, you can chang its form. So all of the material that is in the universe will still be there, just further away from its self. sort of bigger, never gone. Everything will be further apart, and very quiet.