Universe Expansion

[mattp913]

Doesn't The Fact That The Universe Is Expanding (the Space Between Galaxies Are Moving Away Not The Galaxies Themselves) Prove That Matter Doesn't Actually Move And It's Just The Space That's Moving?

[mathematic]

Usually the description is that space is expanding and carrying the galaxies with it.

[timo]

Unless there is a reason to believe that an expansion of space-time contradicts with motion within this space-time I think you are correct: The expansion of space does indeed not prove that matter doesn't actually move.

 

Btw.: It's rather interesting to see capitalization ignorance the other way round.

[IM Egdall]

I think it goes like this:

 

The distances between galaxy clusters is continually increasing over time. This is the so-called expansion of space. But gravity (spacetime curvature) within clusters offsets the expansion force, so there is no expansion within clusters.

 

But there is still motion independent of expansion. For example, within our galaxy cluster the Milky Way and Andromeda galaxies are moving towards each other and will eventually collide. And my fingers are moving to type these words, which has nothing to do with the expansion of space.

Edited December 16, 2012 by IM Egdall

[mattp913]

To quote the last post ..."For example, within our galaxy cluster the Milky Way and Andromeda galaxies are moving towards each other and will eventually collide."

 

Do we know that the galaxies themselves are in fact "moving" as opposed to the space between them moving or contracting?

[Delta1212]

To quote the last post ..."For example, within our galaxy cluster the Milky Way and Andromeda galaxies are moving towards each other and will eventually collide."

 

Do we know that the galaxies themselves are in fact "moving" as opposed to the space between them moving or contracting?

Yes. There are some fundamental differences between the way "movement" from universal expansion and normal movement work. The biggest one is that expanding space doesn't have to obey the universal speed limit of lightspeed. If all movement was somehow from space expanding and contracting between masses, faster than light travel wouldn't be impossible.

[alpha2cen]

Yes. There are some fundamental differences between the way "movement" from universal expansion and normal movement work. The biggest one is that expanding space doesn't have to obey the universal speed limit of lightspeed. If all movement was somehow from space expanding and contracting between masses, faster than light travel wouldn't be impossible.

Redshift value change is too high. How to explain the dropping of the value from 11.9 to 5?

Edited December 22, 2012 by alpha2cen

[ox1111]

Redshift value change is too high. How to explain the dropping of the value from 11.9 to 5?

I must say I am not a fan of this idea of the red shift value being different. This is a theory and a math problem, the problem is the values of the equation are a guess at best, yet this is a very popular answer. We truely can't even prove the red shift for moving galaxies is truely 100% and not caused by dark energy.