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Old 10-11-2008, 11:07 PM
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sjastro
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Quote:
Originally Posted by xelasnave View Post
Seven you said.........

Hence space-time expands but space doesn't.

I dont see the difference between space and space time in so far as the space that remains after space time expands is still space...

I know that sounds strange and I see what you are saying... but simple space is surely what we seek to measure with the concept of space time..space is space and space time is a human method of enabling humans to quantify it. I may sound as if I make a statement but it is really a question as I still feel I miss something so fundamental it hides the rest.. Like the ballon expanding anology the air expandes and the spots on the ballon remain at relative distance ...let me think about it ..it comes down to how does space time define the edge of the Universe I guess... anyways its great to be thinking albiet some what duller than usual.... I think I am free of her so I can relax...so everything will fall into place.

alex
Space-time is definitely real. Cosmological redshift is a property of space-time. Doppler red shift is a property of space.

Space-time expansion velocity is proportional to distance.
Velocity through space is distance/time.

The inflating balloon is a good analogy by considering the surface to being equivalent to space-time. During expansion of the balloon the dots will move away from each other but not across the surface of the balloon. Spatially they are in the same position hence expansion spatially has not occurred.

Regards

Steven
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