Universe Expansion Diagram

[Widdekind]

If spacetime was shrinking, everything inside spacetime would be approaching towards everything else... and so they would all see each other's light blue-shifted.

 

Spacetime is expanding. Spacetime is curved. To visualize that curvature, you need (at least) one higher dimension, than those you are visualizing (<= 3 for space, <=1 for time).

[Spyman]

If spacetime was shrinking, everything inside spacetime would be approaching towards everything else... and so they would all see each other's light blue-shifted.

 

Spacetime is expanding. Spacetime is curved. To visualize that curvature, you need (at least) one higher dimension, than those you are visualizing (<= 3 for space, <=1 for time).

Nobody is saying that spacetime is shrinking but if our meterstick would be shrinking then it would also look like if spacetime is expanding. If the scale of the equipment receiving would be smaller than the scale of the equimpment emitting a lightray, then the light would appear redshifted compared to equal size.

 

We don't know if spacetime on large scales are curved, measurements of curvature reveals a nearly flat geometry but the precision of our observations are not good enough to rule out whether space is closed, flat or open.

Edited December 18, 2010 by Spyman

[michel123456]

Nobody is saying that spacetime is shrinking but if our meterstick would be shrinking then it would also look like if spacetime is expanding. If the scale of the equipment receiving would be smaller than the scale of the equimpment emitting a lightray, then the light would appear redshifted compared to equal size.

(...)

 

I am surprised that you admit this possibility.