Quote:
Originally Posted by EvilEye
To force the air out of the jar...yes.
But space itself is already a vacuum.
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If inflation is the expansion of space itself, and if you accept that a vacuum requires space (and time), then the jar isn't even really a vacuum, but something...else?
The 'expanding universe' explanation I've most often heard is that spacetime has its own intrinsic 'vacuum energy' or pressure that drives expansion; so as spacetime expands so does the amount of pressure--hence the accelerating universe. It all sounds pretty tidy, but I must confess inflation has always seemed just a little arbitrary. There is something about 'phase transitions' (like when water turns to ice) which sounds appealing as a way to explain the difference between inflation and expansion, that may also be related to the fundamental forces 'condensing' out of the grand unified force. (Think of the universe as frozen energy, cooling from its original hot-dense state. The universe as a giant popsicle!)
I've also heard the 'vacuum energy' of spacetime linked to the idea of 'virtual particles'. I'm sure others more knowledgeable than me can elucidate.
I haven't had a chance to download the cast yet so apologies if I'm off topic.