expanding universe

[Zac67]

I've just had an idea, as-stupid-as-it-gets theory: perhaps universe isn't expanding, but everything in it is shrinking!

What's the difference? (No, seriously?)

Possibly the speed of light is just slowing and so it's taking increasing times to cover the distances. Anyway, we'll never know.

If the Higgs boson has really been discovered recently chances are the universe is instable enough to suddenly vanish. Or be replaced by something even more bizarre. Probably this has already happened. (SNCR)

[Zac67]

If an object of constant mass were to shrink, it would increase in density.

Not necessarily - if size/space and mass are tied on a fundamental level, the density could remain the same. Alternatively, the gravitational constant could be decreasing with decreasing space, thus higher density wouldn't lead to higher gravity. Or countless other funny things...

but an ongoing expansion of space is the easiest.

Exactly! Good ol' Occam's razor.