0
votes
0answers
25 views

World line displacement in Minkowski spacetime

Every particle travels along a world line. Obviously, this implies that every particle has a four dimensional relative displacement (which is called the invariant interval) and that any change in this ...
2
votes
1answer
49 views

How is CMB related to the temperature of the universe

As I understand it, CMB (cosmic microwave background) is the radiation emitted when matter decoupled at the early stages of the big bang. The thing I don't understand is do all stars emit this kind of ...
2
votes
4answers
95 views

Is it possible that galaxies' redshift is caused by something else than the expansion of space?

I was thinking that maybe photons loss energy naturally when they travel great distances. Or maybe the mass of all matter is increasing over time and therefore photons emitted in the past are ...
2
votes
1answer
40 views

Cosmological and gravitational redshift in physics

I am interested in knowing what are the differences between gravitational and cosmological redshifts?
1
vote
3answers
322 views

Redshift of light in dark matter

Following Edwin Hubble, it is widely believed that the universe is expanding, which is based on the red-shift of light from distant objects. Can dark matter cause light to be red-shifted and make it ...
4
votes
6answers
222 views

Why are distant galaxies not actually tiny bits of matter?

Distant galaxies are said to be moving away from the Milky Way (and us) at speeds approaching the speed of light. Since Special Relativity tells us that any object moving away from us at a velocity of ...
-1
votes
3answers
279 views

Reformulated: Universe expansion or collapse

I reformulate the question a little bit because I feel that I was misunderstood. There are cosmic observations that tell us the universe seems to expand. It also seems to expand always faster ...
5
votes
2answers
261 views

Expanding universe

If we know the universe is expanding in whatever direction we look, can't we reasonably estimate where the 'center' of the Universe is? Is the rate of expansions in all directions the same?