Has space changed in size?

I understand that the big bang is to be interpreted as an explosion of space
rather than an explosion in space. I am wondering why it should be seen that
way. I can see how the fact that galaxies that are further from us in all
directions are receding from us faster than those that are closer to us, and
that implies that the matter in space is, for the most part flying away from
a point. But what motivates the idea that space itself was ever compact.

Also, if space itself is inflating, then are stars, planets, cars, people,
and atoms also growing in three dimensions? If we are, are we able to detect
it? Does it have an effect on physics in the small?

So far I am unconvinced that space itself has changed in size.

Dear opin:

"opin" wrote in message
...
I understand that the big bang is to be interpreted as an explosion of
space rather than an explosion in space. I am wondering why it should be
seen that way.

Because objects are seen to be accelerating. Classically, how can one get
objects to accelerate? Forces, right? What *repulsive* force is capable
of accelerating expansion?

I can see how the fact that galaxies that are further from us in all
directions are receding from us faster than those that are closer to us,
and that implies that the matter in space is, for the most part flying
away from a point.

Not really. All objects *appear* to be flying away from us... a minor
difference.

But what motivates the idea that space itself was ever compact.

The CMBR filled the early Universe. The CMBR could be at most a few tens
of million light years thick, and produce the spectra that it does. Our
supercluster is larger than a "few tens of million light years"...

Also, if space itself is inflating, then are stars, planets, cars,
people, and atoms also growing in three dimensions?

Can't really say. Could be shrinking.

If we are, are we able to detect it?

No. Our measurement tools self-adjust to our frame of reference.

Does it have an effect on physics in the small?

No. The small Universe, quantum, could care less about distance.

So far I am unconvinced that space itself has changed in size.

OK. Try:
URL:http://www.astro.ucla.edu/~wright/cosmo_01.htm
.... when the server is back up ...

Just keep an open mind.

David A. Smith