Universe expansion discrepancy vs accelerated expansion

[overzealous]

TL;DR Summary

I'm confused about the meaning of the recent discrepancy in the measurements of the universe's expansion rate in the context of the accelerated expansion of the universe, demonstrated in 1998.

Hi! Obviously my understanding is at a pretty elementary level, but nevertheless I'm puzzled by the reaction of astronomers and astrophysicists to the discrepancy in the measurements of the expansion of the early universe based on the Cosmic Microwave Background, and the measurements of its expansion rate today, based on current measurements. According to articles I've read, the current expansion rate-- 9% faster than predicted from the CMB-- is being borne out to greater and greater degrees of certainty with each new study. But no mention is made in any of those articles of the accelerated expansion of the universe due to dark energy, discovered in 1998.

So am I to conclude that this 9% discrepancy is occurring despite taking into account the accelerating effects of dark energy? Please clarify!

 

[Orodruin]

Yes. The energy content of the Universe is taken into account.

 

[Bandersnatch]

But no mention is made in any of those articles of the accelerated expansion of the universe due to dark energy, discovered in 1998.

So am I to conclude that this 9% discrepancy is occurring despite taking into account the accelerating effects of dark energy?

Take note of the name of the researcher leading the studies measuring the discrepancy. One can assume he remembers what he got his Nobel prize for.

 

[alantheastronomer]

Summary: I'm confused about the meaning of the recent discrepancy in the measurements of the universe's expansion rate in the context of the accelerated expansion of the universe, demonstrated in 1998.

Hi! Obviously my understanding is at a pretty elementary level, but nevertheless I'm puzzled by the reaction of astronomers and astrophysicists to the discrepancy in the measurements of the expansion of the early universe based on the Cosmic Microwave Background, and the measurements of its expansion rate today, based on current measurements. According to articles I've read, the current expansion rate-- 9% faster than predicted from the CMB-- is being borne out to greater and greater degrees of certainty with each new study. But no mention is made in any of those articles of the accelerated expansion of the universe due to dark energy, discovered in 1998.

So am I to conclude that this 9% discrepancy is occurring despite taking into account the accelerating effects of dark energy? Please clarify!

The current expansion rate was determined by the same researchers who discovered the accelerating expansion. They reduced the degree of uncertainty in their previous measurements of the present day expansion rate by using measurements of binary stars in the Large Megallanic Cloud to better calibrate the Cepheid variable period-luminosity relationship. They had already determined that the present day Hubble constant is 74km/sec/Mpc, this just confirms that measurement as being just that more certain.
What I'm wondering, along with you, is, has that accelerated expansion been taken into account in the calculation done using the Planck measurements of the CMB to find a present day expansion rate of 68km/sec/Mpc? Does anyone here know how that calculation was done?

 

[HankDorsett]

The closest I've came was Finding articles regarding computer models.

Let's see if someone else may remember a study like this. Until then, I have another question. do we use the rate of Universe expansion to help calculate the age of the universe? If it does, would this change the age of our universe?

 

[berkeman]

Until then, I have another question.

You should probably start a new thread with your new question. Be sure to post links to the reading you have been doing about that question -- you may even be able to answer that question yourself by finding some good links...

 

[HankDorsett]

You should probably start a new thread with your new question. Be sure to post links to the reading you have been doing about that question -- you may even be able to answer that question yourself by finding some good links...

I apologize, I meant to respond to another post.

 

[Auston Louis]

The current expansion rate was determined by the same researchers who discovered the accelerating expansion. They reduced the degree of uncertainty in their previous measurements of the present day expansion rate by using measurements of binary stars in the Large Megallanic Cloud to better calibrate the Cepheid variable period-luminosity relationship. They had already determined that the present day Hubble constant is 74km/sec/Mpc, this just confirms that measurement as being just that more certain.
What I'm wondering, along with you, is, has that accelerated expansion been taken into account in the calculation done using the Planck measurements of the CMB to find a present day expansion rate of 68km/sec/Mpc? Does anyone here know how that calculation was done?

Just wondering if the study in the International Journal of Modern Physics by Eric Lerner from Lawrenceville Plasma Physics, Renato Falomo of the Astronomical Observatory in Italy and Riccardo Scarlatti from the Institute of Astrophysics in Spain that the surface brightness of the near and far galaxies are identical, which is consistent with what would be expected from ordinary geometry if the universe were not expanding, has had any influence on the current expanding universe hypothesis?

 

[alantheastronomer]

Just wondering if the study...that the surface brightness of the near and far galaxies are identical...has had any influence on the current expanding universe hypothesis?

No, no it hasn't. That's because Peebles has determined from those acoustic oscillations in the microwave background radiation for whose prediction he won the Nobel prize, that the universe was still flat at the time the radiation was produced. That means there is no change in the curvature to alter surface brightness over time...and that the size of the universe has been vastly underestimated! There's a new wrinkle in this saga, however. Wendy Friedman, a researcher specializing in the construction of the cosmological distance ladder, much to her surprise found, using a different technique to measure distances to nearby galaxies, a value for the Hubble constant of 70km/sec/Mpc, much closer to the value of 68km/sec/Mpc found using the CMB method than the value of 74km/sec/Mpc found by Adam Reiss using nearby Cepheid variables. Her method used the brightness of stars at the tip of the giant branch, stars just beginning to undergo helium fusion in their cores, which are remarkably consistent in the infrared. There was no overlap however, in the galaxies used in her's and Reiss's studies, so we can't be sure where their measurements begin to disagree.

 

[PeterDonis]

That means there is no change in the curvature to alter surface brightness over time...and that the size of the universe has been vastly underestimated!

Reference, please?

 

[alantheastronomer]

Reference, please?

That would be the aforementioned paper by Lerner et.al. which finds no change in the surface brightness of galaxies over cosmological distances, contrary to what the authors expected if the universe was curved and expanding, leading them to conclude that the universe is flat, static, and did not originate in a "big bang". But their observations are actually supported by the CMB observations, which means they overestimated the curvature of the universe and underestimated the size of the universe.

 

[PeterDonis]

That would be the aforementioned paper by Lerner et.al.

Does anyone happen to have an actual link to this paper?

 

[alantheastronomer]

Oops sorry, I can only access the abstract, but here's a link to a later paper;https://arxiv.org/ftp/arxiv/papers/1803/1803.08382.pdf

 

[Vanadium 50]

Eric Lerner from Lawrenceville Plasma Physics

You mean The Big Bang Never Happened Eric Lerner?
The plasma cosmology (a banned topic on PF) Eric Lerner?
The conspiracy theorist Eric Lerner?
That Eric Lerner?

 

[berkeman]

You mean The Big Bang Never Happened Eric Lerner?
The plasma cosmology (a banned topic on PF) Eric Lerner?
The conspiracy theorist Eric Lerner?
That Eric Lerner?

That seems like a good way to tie off this thread.