Our Expanding Universe

OG wrote:
[snip]
Now let's modify this to get closer to the *right* idea.
To change the mental image in your head, imagine that you are looking at
the movie frame where the firework has just filled the hall - everywhere
is filled with something. Now mentally play the movie backwards, but
imagine that the walls of the hall itself are moving back with the
firework. Instead of the explosion getting smaller inside the hall; the
whole hall and explosion are getting smaller at the same time.

Then, the hall is shrinking *IN SPACE*. The concept of expansion
(or its opposite contraction) are irrevocably tied to the concept
of SPACE. There is *NO WAY OUT* of this contradiction.

Mentally
play the movie forwards and backwards in your head seeing how the whole
thing is expanding/contracting as a single item. There is no need to
think about what the universe is expanding 'into', because there is
nothing 'outside' - the whole universe is 'inside' the model, it's just
getting bigger all the time.

There is no sense to something getting "bigger" if there is
no concept of an empty space where this thing is getting bigger into!

The intuition of BluMax is 100% right!

It's not a complete answer, and it's not perfect, but I hope you can see
how the two mental images differ. Don't expect to understand it straight
away, but keep plugging away with it .

Hope this helps.




It doesn't.