- #31
Yukterez
- 85
- 14
Did I mix that up? If so, I of course meant it the other way around (:Bandersnatch said:
Edit: I see, I was obviously too stupid to read my own chart (:
I Are Galaxies Moving Faster Than Light Due to Space Expansion?
Click For Summary
Galaxies can appear to move faster than light due to the expansion of space, as described by Hubble's law, which allows for recession velocities exceeding the speed of light without violating relativity. Observers in different frames of reference can measure velocities relative to each other, but there is no absolute frame of reference to determine a "true" velocity. The speed of light remains a local limit, while recession velocities have no upper bound. The discussion emphasizes that both galaxies and space can have their own motions, but only local velocities are constrained by the speed of light. Ultimately, the concept of an absolute reference frame is ruled out by observations in physics.
Edit: I see, I was obviously too stupid to read my own chart (:
- #32
Dale
Mentor
- 36,553
- 15,337
No. It isn't correct. The 5km/s value is simply relative to some arbitrary reference frame.user9003 said:
- #33
PeterDonis
Mentor
- 49,316
- 25,352
Bandersnatch said:
Ah, got it.
- #34
Yukterez
- 85
- 14
On the x-axis you have the redshift (as observed today), and on the y-axis the recessional velocity (orange is the velocity at emission and brown at absorption)
You see that objects with z < 1.8963 are faster today than they were when they emitted the light we receive now (the relative distance since then has changed more than the scale factor), while objects with z > 1.8963 are slower now than they were when they emitted their light (the expansion rate fell more than the distance increased while the light travelled).
You see that objects with z < 1.8963 are faster today than they were when they emitted the light we receive now (the relative distance since then has changed more than the scale factor), while objects with z > 1.8963 are slower now than they were when they emitted their light (the expansion rate fell more than the distance increased while the light travelled).