Re: Approximately 300,000 km/s With Respect To What?

Mikko <mikko.levanto@iki.fi> wrote:

On 2024-07-12 09:55:27 +0000, J. J. Lodder said:
 

Mikko <mikko.levanto@iki.fi> wrote:
 

On 2024-07-11 19:58:02 +0000, amirjf nin said:
 

Approximately 300,000 km/s with respect to what?

 
Whenever the speec of something is measured it is measured with respect
to someting else. The report should make clear what is the reference that
is considered stationary. Usually it is the instruments used in the
measurement, and usually but not always they are at rest with restpect to
Earth surface at the place of the measurement.

 
You really need to have a look at what and how is actually measured,
instead of elaborating your own ideas of measurement.

 
Yes, that is a correct interpretation of my words. Of course, what and
how is not alwasys the same so you need to look at thar separately for
each measurement.

The first electromagnetic measurement of the 'speed of light',
by Weber and Kohlrausch, didn't involve any velocity at all.
They pointed the way for Maxwell.

Maxwell's equations [1] likewise have a   c  in them
but no velocity,

Jan

[1] In Heaviside-Lorentz units for example.