Narrowing Hubble's Constant - 8 year study concludes

In summary, the Hubble Constant and its refinement over time is covered in this article. Along with the 8 year Cepheid Variable study headed by Wendy Freedman, the goal is to narrow down the limits of the Hubble Constant.
  • #1
Chaos' lil bro Order
683
2
This is a nice little article on the history of the Hubble Constant and its refinement over time. There is also a summary of the 8 year Cepheid Variable study headed by Wendy Freedman of the Carnegie Observatory in it, in which they try to narrow down the limits of the Hubble Constant via 100s of Cepheid Variable observations. A nice little read.

http://physicsworld.com/cws/article/print/1036
 
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  • #2
Nice article, dated July 1, 1999. Just about exactly 9 years ago.
Wendy Freedman's project (Hubble Key Project) ushered in an age of precision cosmology.
It was a major part of the revolution in cosmology that occurred in 1998, with not only Freedman's group narrowing down the Hubble parameter but also the reports of accelerated expansion. Cosmology became an exact observational science, not guessing game.

We are in the wake of those 1998 events.
 
  • #3
marcus said:
[...] but also the reports of accelerated expansion. Cosmology became an exact observational science, not guessing game.
But is this "science" scientific in Popperian sense?

If the "BB theory" predicted decelerating expansion of the universe (due to "Einstein's biggest blunder") and it has turned out that the expansion is accelerating and Einstein was right plugging the cosmological constant into his equations, how do we know that the universe is expanding at all and it is not just another false assumption of the "BB theory"? We don't see the expansion just the redshift and know that it is assumed by the astronomers to be caused by the expansion.

But how do we know it is a right assumption? Only because the astronomers can't figure out nothing better as the reason for the redshift? But the "BB theory" already dismissed cosmological constant (that turned out to be needed) and with it the whole idea of "Einstein's (stationary) universe", which may turn out not to be a blunder neither. Someone may suddenly discover that in general realtivity there must be the observed amount of redshift in stationary space. Then what? It couldn't be even published because it would be "against the present consesus of astronomers" (who may happen not to believe in general relativity since they do quite well with the Newtonian gravitation and in the Newtonian gravitation it is the only way).
 
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  • #5
JimJast said:
It couldn't be even published because it would be "against the present consesus of astronomers" (who may happen not to believe in general relativity since they do quite well with the Newtonian gravitation and in the Newtonian gravitation it is the only way).

Your reasoning being sound, your logic not flawed, your mathematical proofs being rigorous; you truly have nothing to fear. The problem arises when one is convinced of the above, yet can not see the flaws that others may point out.

The peer-review process is one of the more noble systems in human society.
 
  • #7
robertm said:
Your reasoning being sound, your logic not flawed, your mathematical proofs being rigorous; you truly have nothing to fear. The problem arises when one is convinced of the above, yet can not see the flaws that others may point out.

The peer-review process is one of the more noble systems in human society.

But in the case of the BB, if all the peers believe the universe is expanding and only they can't prove it (because it's not possible to prove that the reason for the redshift is as the BB assumes, and a lot of evidence is still no proof) but you can falsify the expansion (which is rather easy, as it maby be done by just pointing to a necessary mechanism for the redshift and show that it produces the same redshift yet without the expansion)? Then you end up with no knowledge why you can't be published because peers (referees) don't see any flaws in your stuff but you still can't be published since your peers believe there must be an error "somewhere".
 
  • #8
JimJast said:
But in the case of the BB, if all the peers believe the universe is expanding
Fortunately, this is not the case.

Goodness, some of the peers don't, it seems, even "believe" that GR is the last word concerning gravity!
and only they can't prove it
Fortunately, the peers are doing science, not mathematics (so "proof" is irrelevant).
(because it's not possible to prove that the reason for the redshift is as the BB assumes, and a lot of evidence is still no proof)
Thereby neatly proving (!) that proof is not possible in science (or at least astrophysics).
but you can falsify the expansion (which is rather easy, as it maby be done by just pointing to a necessary mechanism for the redshift and show that it produces the same redshift yet without the expansion)?
Well, write up this "necessary mechanism" and submit it to PF's IR section.

Oh, and be sure to be prepared for this alternative mechanism to be examined closely, to see that it 'works' everywhere and everywhen (and that there are no fatal inconsistencies more broadly).

Until there is such a mechanism on the table ...
Then you end up with no knowledge why you can't be published because peers (referees) don't see any flaws in your stuff but you still can't be published since your peers believe there must be an error "somewhere".
Fortunately, modern cosmology is not a religion.

But let's stick with your paradigm and see if we can falsify the idea expressed in the post of yours I am quoting.

A powerful falsification would be a paper, published in one of these peer-reviewed journals, presenting a cosmology in which the universe is not expanding, right?

Now if that's all that's required, your idea is so easily falsified that it's funny ...

Who wants to go first, with a reference to such a paper?
 
  • #9
I do not think anyone is claiming the BB is an exact science. I think its fair to say that cosmologists haven't the the foggiest about what occurred before the CMB's creation, 380,000 after the BB. But I think cosmology is a very serious science now that Hubble and COBE and the WMAP surveys brought us so much data that they can now form plausible theories based on real evidence. Can string theory make such a claim?
 

1. What is Hubble's Constant?

Hubble's Constant is a measure of the rate at which the universe is expanding. It is named after astronomer Edwin Hubble, who first observed the expansion of the universe in the 1920s.

2. Why is there a need to narrow down Hubble's Constant?

Narrowing down Hubble's Constant is important because it can help us better understand the age and structure of the universe. It can also provide insights about the mysterious dark energy that is responsible for the accelerated expansion of the universe.

3. How was this 8 year study conducted?

This 8 year study involved using the Hubble Space Telescope to observe and measure the distances of Type Ia supernovae, which are exploding stars that can be used as cosmic distance markers. The data from these observations were then combined with other measurements to calculate Hubble's Constant.

4. What were the results of this study?

The study concluded that the value of Hubble's Constant is 73.3 kilometers per second per megaparsec, with an uncertainty of only 2.8%. This is a significant improvement from previous measurements and provides a more precise understanding of the expansion rate of the universe.

5. What implications does this study have for our understanding of the universe?

The more precise value of Hubble's Constant obtained from this study can help us refine our understanding of the age, size, and expansion of the universe. It can also provide valuable insights into the nature of dark energy and the ultimate fate of the universe.

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