4 ms·

So 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 t

by g82918 7y ago

So 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.

eesmith 7y ago
https://iopscience.iop.org/article/10.3847/1538-4357/aae5f7/pdf 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).
- fergbrain 7y ago
  > “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?
  - g82918 7y ago
    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.
    - eesmith 7y ago
      I missed this the first time - https://en.wikipedia.org/wiki/Variable_speed_of_light 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.

by g82918 7y ago

eesmith 7y ago

https://iopscience.iop.org/article/10.3847/1538-4357/aae5f7/pdf 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).

fergbrain 7y ago
> “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?
- g82918 7y ago
  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.
  - eesmith 7y ago
    I missed this the first time - https://en.wikipedia.org/wiki/Variable_speed_of_light 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.