Is it possible to shrink something without removing anything ?

[NuklearWinter]

Help me settle a debate here at work. Can you think of anything that you can shrink, and in doing so, not remove anything (including air, molecules, etc.)?

The only example I came up with is this:
some scientists believe the universe is expanding, and eventually it will condense. When it does compact, nothing can be removed, but yet the universe will shrink. My co-worker doesn't accept this because it cannot be proven that the universe will shrink.