Hubble tension - astronomer hopeful there is no tension after Red Giant measurements

[gary]

Could it transpire that the "Hubble tension" - that nagging difference
between the two main ways of measuring the expansion rate of the
universe - be resolved after all by new measurements?

Wendy Freedman, the John and Marion Sullivan University Professor in
Astronomy and Astrophysics at the University of Chicago, is hopeful it will
after using measurements of Red Giants to calibrate the measurements of
noisy Cepheid variable data.

Story here :-
https://phys.org/news/2021-06-confli...se-debate.html

[xelasnave]

Gary
Do you think there is any chance that "they" are wrong about the universe expanding?

I know "tired light" is regarded as nonsense but really from an uninformed uneducated position it does not seem unreasonable.

Needless to say an expanding universe is the key stone of our current cosmology ... I do think the fact the difference exists must be cause for concern in the first place ...I mean it never should have been there onr could think.

Anyways maybe my question can stimulate some light discussion as one can expect when talking about something as uncomplicated as cosmology.

Alex

[gary]

Originally Posted by xelasnave

Gary
Do you think there is any chance that "they" are wrong about the universe expanding?

I know "tired light" is regarded as nonsense but really from an uninformed uneducated position it does not seem unreasonable.

Hi Alex,

With such a bulk of independent observations of different phenomena,
there is now very little chance that the theory that the universe
is expanding is wrong.

In fact that evidence is at a point that it is now seemingly insurmountably
difficult to make it fit any other model.

One of the nails in the coffin for the "tired light" theory is home-grown.

The Brian Schmidt et. al. observations of the Type 1a supernovae
where their brightening and fading as a function of time was correlated
with their redshift and hence compellingly explained by time dilation
was something he talked about one year at the South Pacific Star Party
(SPSP) up at Wiruna. Unlike the later Nobel Prize ceremony, no bow ties were
required by audience members.

Concurrently Adam Riess et. al. did their own Type 1a supernovae survey
and came up with the same results, which not only put to rest the tired
light theory, but scored them the Nobel Prize for Physics at the
same ceremony in 2011.

Unlike Brian Schmidt, sadly Adam Riess didn't get to address the
attendees of the SPSP and thus also missed out on the opportunity
of hob-nobbing with us all in the Boy Scout sausage sizzle tent
soirée afterwards.

Paper by Riess et. al :-
https://arxiv.org/pdf/0804.3595.pdf

[xelasnave]

Thanks Gary.
I find it most difficult to take in a paper such as the one you posted but in defence of "tired light" they made a claim that in a non expanding universe that there would be no observed time difference which I doubt if anyone suggesting "tired light" would propose.

However I am not on "Peer" level so its not even worth mentioning really.

Because of my background I just can not help pulling on any loose thread.

I need to read it a couple of times to make sure I get it..not that I can really as one needs a degree or two to climb in the ring...but one must admire the effort that goes into a paper such as this...but frankly it is way above my pay grade.

Notwithstanding all the work it still turns upon spectral analysis and the proposition that the Universe is expanding comes from red shift interpretation as I understand...I think another line of proof would be nice where actual distance could be measured or that we observe galaxies that disappear as they go over the edge but of course how to come up with how to do something like that I really dont know but the main difficulty would be that the time required to make the kind of measurement that could give us the approach I suggest would be enormous ...I have only guessed at what it may be but I expect maybe 100,000 years and probably ten fold that...even more...probably more.

I guess what I find difficult to accept, which is not in any way to suggest tired light is valid, is how light would not be affected in some way in its journey over the vast distances we deal with in these matters...and again to suggest any "slowing" goes against the very foundation of Special Relativity that of the uniformity of the speed of light...but again light does have different "speeds" in different mediums ... I guess when it all boils down I dont like the Big Bang Theory because so many folk cite it as suggesting there was a point of creation..even top scientists talk about BB as a start...I dont see how they come to such a conclusion as the theory deals with the evolution of the universe and talks about that evolution as starting with a hot dense state..certainly not the "nothing" that is mentioned casually and regularly... And really although folk talk about it with such certainty as if it is beyond doubt the fact is we had to put "inflation" in place to make BB work and really that theory does not stand upon any observation...

Anyways as they say it is our best theory of cosmology and explains a great deal but personally I feel an eternal universe makes more sense...and the BB theory can not show us this point where nothing was the only "thing" to exist...so even it ,BB, can not exclude an eternal universe...there are folk who speculate a cycle of big bangs but of course we will never know.
Thanks for your post as I found it and the paper most stimulating...
Alex

[bgilbert (Barry gilbert)]

G'day Alex and gary.
Don't panic Alex, tired light is still hanging on among a couple of heretics, I think I'm one of them ? I will lead with a question for gary, "what is the mean free path of a CMBR photon"? You may wish to read the link below first. https://jumpshare.com/v/lCw7nbSN6P79vNU2zObh

In essence the standard candles are dimmed by dust attenuation, this gives rise to error in using any distant light for calibration. If you believe in "photons" and the wave function of the photon, then the wave function diverges 1/r with time and distance, and collapses for each dust particle en route. The dust particle gains momentum and warms. Three new photons are created , one at a slightly lower energy and frequency from the original and two RF photons, one narrow band as a result of the dust translating, and one blackbody as a result of warm dust. Total energy is conserved by the sum of all photons plus kinetic energy of the dust equaling the energy of the original photon. If you subsccribe to classical Maxwellian wave theory, as I do, then it is even simpler to come to this conclusion. The end result, non Doppler Redshift, optical attenuation and 2.7 K local blackbody radiation from dust.

Regards
Barry

[xelasnave]

Hi Barry
Mmm the paper only suggests the light may be just a little sleepy and it seems to me a refinement of current work as opposed to giving cause to disregard it. ...Thanks for your input ..
Alex

[bgilbert (Barry gilbert)]

G'day Alex.
You may be not aware that "current work" suggests that CMBR "photons" travel 13 billion light years without a single interaction with any matter in the IGM, this is completely at odds with well established modern EM theory derived from Maxwell. There are currently about a dozen interpretations of QM? "current work" cannot reconcile QM with GR? "current work" is flummoxed by the muon anomaly. Why did it take 30+ years to solve the "Pioneer anomaly", that turned out to be a simple prediction of Maxwell's equations, new physics, extra dimensions etc. were proposed for that anomaly also? I applaud your cautious skepticism, so take no personal offence at my reply I'm simply putting my skepticism out there. One single cautious paper is not expected to overturn the bloated arrogant edifice of QM!

Kind regards
Barry

[xelasnave]

Hi Barry.

I can not be offended so dont worry on that count. I am just a mug so it is no surprise if folk talk to me as if I am.


Firstly to state the obvious...I am a lay man and although proudly I topped my last high school year in science and enjoy reading all I can, I do not have a degree in any area of science and only a casual understanding of SR GR The Standard Model and understand little of QM..like everyone else it would seem...mind you that does not prevent me having unsupported opinions.

I predicted that the Pioneer craft would slow on this very site...any craft passing thru the Heliosphere should slow but there is no observations to support that view.. maybe
nothing is said so as not to have any more anomolies...I thought that first they would appear to slow and after some time appear to speed up again...(the speed up has not been observed but why is entirely logical ..I explained it here years ago and dont care to again)..my reasoning was that I believe gravity is not a force of attraction ( and I know GR does not say it is attractive ..indeed it does not say the opposite) but works much as LeSage outlined in 1745 ..a "push" system if you like..in any event if that approach is valid then one would expect Interstellar space would in effect provide resistance...and so my prediction...however as I have no maths to quantify the degree of deceleration my prediction really does not count for zip...and they after 19 committees??? and much searching found a better reason which is entirely accepted.

AND yes I understand the idea that a photon does not encounter anything but the paper seems to adjust that doesnt it...and their travel I expect will be much much more than 13 odd billion light years (distance) ...13 billion years (approx) is the age of the universe but in the Big Bang Model of an expanding Universe early photons will necessarily travel a much greater distance than 13 billion (approx) light years (,distance).

Reconciling SR and GR with the rest is a great challenge or difficult matter but should that suggest that there is no opportunity for something in the future?

The fact is the standard model has issues but at the moment its all we have and one could hope that working on it and with it will produce more than throwing it out and calling for new ideas from the croud.

There seems to be increasing recognition that radiation pressure increases the further you go out rather than the opposite...I think dark matter, confining this speculation to galactic rotation curves, is easily attributed to gravity acting as an external force rather than an "internal" force of attraction...and I know GR sees no force but that is just how that model works and I suspect reality may be different to the model.

The interesting situation humanity faces with SR and GR is it really is impossible to present a different model I expect simply as there is too much to address let alone counter..I mean look how the Church maintains its truth even in this age of apparent enlightenment...and SR and GR and therefore all that follows will one could expect outlast the Church by 1000s of years. But it does not matter, with SR and GR, (not the Church) because the scientific method helps keep things somewhat real..

Baby steps are ok.

I would not say I am a sceptic ...others may but I am just a layman with a laymans opinion...not a big deal.
Alex