A proof of the constancy of the velocity of light (1913)
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A proof of the constancy of the velocity of light (1913)
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Re: A proof of the constancy of the velocity of light (1913)
#2So this is interesting. But it doesn't deal well with the idea that the speed of light may be variable across time. Not a particularly mainstream theory but the idea that the speed of light depends on time is kind of fun at least to consider.
Re: A proof of the constancy of the velocity of light (1913)
#3It's interesting how succinct this is. How come this didn't appear before being postulated in Einstein's theory of special relativity, given that there was a 16 year gap between this and the Michelson-Morley experiment?
Re: A proof of the constancy of the velocity of light (1913)
#4So this is interesting. But it doesn't deal well with the idea that the speed of light may be variable across time. Not a particularly mainstream theory but the idea that the speed of light depends on time is kind of fun at least to consider.
https://iopscience.iop.org/article/10.3847/1538-4357/aae5f7/... says:
> On the other hand,during the past 2 decades great attention has been paid to the theories with varying speed of light (VSL), in which the speed of light might be dynamical and could have been varying in the past. ...
> The measurement of c in the distant universe is an almost completely uncharted territory. Recently, with the angular diameter distances measured for intermediate-luminosity quasars extending to high redshifts, Cao et al.(2017a) performed the first measurement of the speed of light referring to the redshift baseline z = 1.70. The result was in very good agreement with the value of c obtained on Earth(i.e.,at z = 0).
Re: A proof of the constancy of the velocity of light (1913)
#5So this is interesting. But it doesn't deal well with the idea that the speed of light may be variable across time. Not a particularly mainstream theory but the idea that the speed of light depends on time is kind of fun at least to consider.
https://iopscience.iop.org/article/10.3847/1538-4357/aae5f7/... says: > On the other hand,during the past 2 decades great attention has been paid to the theories with varying speed of light (VSL), in which the speed of light might be dynamical and could have been varying in the past. ... > The measurement of c in the distant universe is an almost completely uncharted territory. Recently, with the angular diameter dis…
> “It is worth recalling that Ellis & Uzan (2005) gave a sobering review of serious conceptual problems one faces while trying to change the status of c in physics. In particular, they stressed that it is usually not consistent to allow a constant to vary in an equation that has been derived from a variational principle under the hypothesis of this quantity being constant. Therefore, one needs to go back to the Lagrangian and derive new equations after having replaced the constant by a dynamical field.”
The math is a bit out of my depth...did they go back to the Lagrangian and derive new equations after having replaced the constant by a dynamical field?
Re: A proof of the constancy of the velocity of light (1913)
#6Earlier quoted context omitted.
https://iopscience.iop.org/article/10.3847/1538-4357/aae5f7/... says: > On the other hand,during the past 2 decades great attention has been paid to the theories with varying speed of light (VSL), in which the speed of light might be dynamical and could have been varying in the past. ... > The measurement of c in the distant universe is an almost completely uncharted territory. Recently, with the angular diameter dis…
> “It is worth recalling that Ellis & Uzan (2005) gave a sobering review of serious conceptual problems one faces while trying to change the status of c in physics. In particular, they stressed that it is usually not consistent to allow a constant to vary in an equation that has been derived from a variational principle under the hypothesis of this quantity being constant. Therefore, one needs to go back to the Lagra…
People have at least once though the citation escapes me, it was 2006ish. And it could be found in agreement with observation. Not that I believe in it.
Re: A proof of the constancy of the velocity of light (1913)
#7It's interesting how succinct this is. How come this didn't appear before being postulated in Einstein's theory of special relativity, given that there was a 16 year gap between this and the Michelson-Morley experiment?
One idea is that there weren't many double stars so the evidence was weak.
Re: A proof of the constancy of the velocity of light (1913)
#8Earlier quoted context omitted.
> “It is worth recalling that Ellis & Uzan (2005) gave a sobering review of serious conceptual problems one faces while trying to change the status of c in physics. In particular, they stressed that it is usually not consistent to allow a constant to vary in an equation that has been derived from a variational principle under the hypothesis of this quantity being constant. Therefore, one needs to go back to the Lagra…
People have at least once though the citation escapes me, it was 2006ish. And it could be found in agreement with observation. Not that I believe in it.
I missed this the first time - https://en.wikipedia.org/wiki/Variable_speed_of_light (I used Google Scholar to find that first reference).
There are about a dozen references in the 2006ish timeframe.
Re: A proof of the constancy of the velocity of light (1913)
#9Can someone please explain the argument in easier terms?
I am stuck here itself:
>> Then from the law of motion of the star we can derive an equation: >> u=f(t-t0)
The function 'f' is not specified. What is it and how is it derived from the laws of motion?
Also, what really is tau-0? It is the time at which light from a stationary star at the same distance would have reached the observer, or alternatively is the time under Lorentz/Einstein's theory. However, what meaning is that holding in the said argument.
Re: A proof of the constancy of the velocity of light (1913)
#10Can someone please explain the argument in easier terms? I am stuck here itself: >> Then from the law of motion of the star we can derive an equation: >> u=f(t-t0) The function 'f' is not specified. What is it and how is it derived from the laws of motion? Also, what really is tau-0? It is the time at which light from a stationary star at the same distance would have reached the observer, or alternatively is the time…
Might be completely out of my depth here, but I think that just means "the motion of the star is a function of something that changes over time".
I'd naively assume it's of its relative position over time, but again, I'm likely out of my depth.