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From: hertz778@gmail.com (rhertz)
Newsgroups: sci.physics.relativity
Subject: Re: Gravitational red-shifting in the biggest star. What are the real
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Date: Sun, 29 Sep 2024 17:05:40 +0000
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On Sun, 29 Sep 2024 13:57:22 +0000, J. J. Lodder wrote:

> Paul.B.Andersen <relativity@paulba.no> wrote:
>
>> Den 28.09.2024 04:34, skrev rhertz:
>>> This link illustrates a bit:
>>>
>>> https://en.wikipedia.org/wiki/Gravitational_redshift
>>>
>>> Using the most common formula from that link: "To first approximation,
>>> gravitational redshift is proportional to the difference in
>>> gravitational potential divided by the speed of light squared"
>>>
>>> ?f/f = ??/? = z = GM/c? (1/R - 1/r) = ?(R)/c? - ?(r)/c?
>>
>>   ??/? = GM/Rc?  observed at infinity  (r -> ∞)
>>
>> https://www.space.com/41290-biggest-star.html
>>>
>>> G = 6.6743E?11 m^3 kg^?1 s^?2
>>> M = 5E+09 x 1.989E+30 Kg = 9.945E+39 Kg
>>> R = 1,700 x 634,000 Km = 1,077,800,000,000 m
>>>
>>>
>>> ?(R)/c? = 6,842,736.59
>>
>>  From whence did you get the idiotic idea that the mass
>> of UY Scuti was 5 billion solar masses? :-D
>>
>> M = 30 solar masses =  5.967e31 kg
>> R = 696340e3?1700 m = 57868e6 m
>> c = 299792458 m/s
>>
>> ??/? = GM/Rc? = 7.65e-7
>>
>> Which is less than the red shift from the Sun.
>>
>>>
>>> In comparison, ?(RSun)/c? = 0.000002327
>>
>> M = 1.989E+30 kg
>> R = 696340e3 m
>>
>> ??/? = GM/Rc? = 2.12e-6
>>
>>
>>
>>>
>>> WHAT IS WRONG WITH MY CALCULATIONS, BASED ON THE WIKI LINK?
>>
>> Now you know.
>
> He is looking for trouble where none exists.
> Even for neutron stars you get a nice finite gravitational redshift,
> which is 'easily' observable. For example:
> <https://pubmed.ncbi.nlm.nih.gov/12422210/>
>
> They find a redshift value of z = 0.35 ,
> which is consistent with standard neutron star models,
> (but not with some exotic ones)
>
> Jan
>
> (such a large gravitational redshift dwarfs any possible Doppler shift)

/////////////////////////////////////////////////////////////////////


You forgot to read this, don't you? I posted it two posts above.

.............................


In 2021, Mediavilla (IAC, Spain) & Jiménez-Vicente (UGR, Spain) were
able to use measurements of the gravitational redshift in quasars up to
cosmological redshift of z ≈ 3 to confirm the predictions of Einstein's
equivalence principle and the lack of cosmological evolution within
13%.[28]


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