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
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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?
 
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  • #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.
 
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  • #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.
 
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  • #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]
 
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  • #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...
 

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

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

The consensus on the maximum recession speed in cosmology changed primarily with the development of the theory of General Relativity in the early 20th century, which allowed for the concept of space itself expanding. This was further solidified by Edwin Hubble's observations in 1929, which showed that distant galaxies are receding from us, leading to the understanding that there is no upper limit to the recession speed when considering the expansion of space.

What scientific discoveries led to the change in consensus about maximum recession speed?

The key discoveries were Albert Einstein's General Theory of Relativity and Edwin Hubble's observation of the redshift of distant galaxies. Einstein's equations allowed for an expanding universe, and Hubble's empirical data provided the evidence that the universe is indeed expanding, leading to the realization that distant galaxies can recede from us at speeds greater than the speed of light due to the expansion of space itself.

How does the concept of space expansion affect the understanding of maximum recession speed?

Space expansion implies that the distance between distant objects in the universe can increase over time, not because the objects are moving through space, but because the space itself is expanding. This means that there is no upper limit to the recession speed because it is the space between objects that is growing, allowing for superluminal (faster-than-light) recession speeds without violating the principles of relativity.

What role did Edwin Hubble's observations play in changing the consensus?

Edwin Hubble's observations of the redshift of light from distant galaxies provided the first strong empirical evidence for an expanding universe. By plotting the redshifts against the distances of galaxies, he found a linear relationship, now known as Hubble's Law, which showed that galaxies are moving away from us at speeds proportional to their distance. This was a critical piece of evidence that supported the idea of an expanding universe and led to the acceptance that recession speeds can exceed the speed of light.

Why does the expansion of space allow for recession speeds greater than the speed of light?

The expansion of space allows for recession speeds greater than the speed of light because it is the metric of space-time itself that is changing. In General Relativity, the speed limit of light applies to objects moving through space, not to the expansion of space itself. As space expands, distant galaxies can appear to recede from us at speeds greater than the speed of light without any object actually traveling faster than light through space.

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