When did the consensus on the maximum recession speed in cosmology change?

In summary: I agree, it is quite a short and concise book, which can be both a positive and a negative depending on the reader's preferences.
  • #1
epovo
114
21
TL;DR Summary
In the first edition of Schutz (1985), the author states that the Hubble flow can't make galaxies recede faster than the speed of light.
In the last chapter of Schutz devoted to Cosmology, Schutz writes
Moreover, ## v = Hd ## cannot be exact since, for ##d\gt 1.2 ~10^{26}~\rm{m}= 4000~ \rm{Mpc}##, the velocity exceeds the velocity of light!
So it seems that in 1985 it was assumed as obvious that the recession speed could not exceed ##c##.
The consensus seems to have swiftly changed. When did that happen? Was it debated at all?
 
Space news on Phys.org
  • #2
I was still at primary school in 1985 so I can't speak to common beliefs, but I think Schutz isn't intending to be quite so emphatic as he sounds. I think he's criticising his cheap'n'cheerful derivation of the Hubble Law as being based on kinda-sorta Newtonian thinking. He expands a bit on it in a later paragraph. In the 2nd edition it's just before the section titled "The universe is accelerating!", but I suspect it might be the end of section 2.2 in your edition. It says "...in the attempt to translate the nonrelativistic formula ##v=Hd## into relativistic language, we were forced to re-think the meaning of all the terms in the equations and go back to the quantities we can directly measure."
 
  • #3
That paragraph is indeed in the 1st edition at section 2.3 (Cosmological observations). But, given that his book is titled 'A First Course in General Relativity', he could not possibly assume that the reader would understand that recession speeds >c are possible, especially after the quote I gave before. This was written at the time when we thought that the universe expansion must be slowing down, and the big question was why we were so close to the critical density. The quote suggests to me that the common understanding of the time was that recession speeds >c were impossible. But I have not been able to find any source that confirms or contradict my assumption and no trace of any debate in the scientific community about the topic.
 
Last edited:
  • #5
phyzguy said:
In the excellent paper by Davis and Lineweaver, they list all of the people that have gotten this wrong, including some big names.
This includes the very quote we're discussing - see Appendix B item 6.
 
  • Like
Likes vanhees71 and Jaime Rudas
  • #6
epovo said:
So it seems that in 1985 it was assumed as obvious that the recession speed could not exceed ##c##.
I don't think the reason is that in 1985 it was assumed as obvious that the velocity of the recession could not exceed c, because the quote is the same in the second edition (2009).

In fact, Schutz's quote is one of the common misconceptions in cosmology that Davis and Linewaver mention in their (highly recommended) article Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the universe (2003). See chapter 3.1 and Appendix B [6]
 
  • Like
Likes Ibix and epovo
  • #7
Thank you @Jaime Rudas . I'll be sure to read that article!
 
  • #8
I never understood what's the hype about Schutz's book...
 

1. What is the Hubble Flow?

The Hubble Flow is the outward expansion of the universe, first observed by astronomer Edwin Hubble in the 1920s. It describes the movement of galaxies away from each other due to the expansion of space.

2. How does Schutz's theory explain the Hubble Flow?

Schutz's theory, also known as the Friedmann-Lemaître-Robertson-Walker (FLRW) metric, uses Einstein's theory of general relativity to describe the expansion of the universe. It explains the Hubble Flow by showing how the rate of expansion is related to the density and curvature of the universe.

3. What evidence supports Schutz's theory?

There is strong observational evidence for the Hubble Flow and the expansion of the universe. This includes the redshift of light from distant galaxies, the cosmic microwave background radiation, and the abundance of light elements in the universe. Additionally, Schutz's theory has been tested and confirmed by numerous experiments and observations.

4. How does the Hubble Flow affect the motion of objects in the universe?

The Hubble Flow affects the motion of objects in the universe by causing them to move away from each other at an accelerating rate. This is due to the expansion of space, which creates a gravitational force that pushes galaxies apart.

5. What are the implications of the Hubble Flow for the future of the universe?

Based on current observations and theories, it is believed that the Hubble Flow will continue to accelerate, leading to a "Big Freeze" scenario in which the universe expands indefinitely and all matter is eventually torn apart. However, there is still much research being done to better understand the long-term fate of the universe.

Similar threads

Replies
39
Views
7K
Replies
9
Views
4K
Back
Top