Does Electricity travel at the Speed of Light?

[andrew s]

To have an independent meter would over specify the system of units unless you dropped c or the hyperfine frequency.  It's just a matter of choice given our current understanding of physics which "things" appear to be constants of nature.

I don't know of a candidate for length.

Regards Andrew 

Edited February 2, 2022 by andrew s

[Kev M]

It is difficult to define length, as any measured object  exists in at least 2 different places in spacetime.

 

Consider two places A & B separated by a distance.

To measure this distance you have to put your ruler at A and then it takes a certain time to move your focus to B to read the measurement.

Currently the fastest time we can move our focus from A to B is the speed of light.

 

Obviously if A & B are moving relative to each other or to ourselves then results will vary.

 

However if we are happy to take both the speed of light and time as being universal constants then the metre can be accurately defined.