5 ms·
No it isn't. The speed of light in SR is not really about light. It's just a good way to explain things. You can calculate the speed of light from other phys
by jlokier 5y ago
No it isn't. The speed of light in SR is not really about light. It's just a good way to explain things.
You can calculate the speed of light from other physical, measurable constants without using light (the permittivity and permeability of free space). Those you can measure with inductors and capacitors. So because those measurable physical behaviours are invariant in all reference frames under SR, it follows that the speed of light is also invariant.
- javajosh 5y agoc is defined. https://physics.nist.gov/cgi-bin/cuu/Value?c https://physics.nist.gov/cgi-bin/cuu/Value?c You don't have to measure c, or calculate it. The causal chain goes the other way - we assume c is invariant and define capacitance and inductance in terms of it (c, that is).
- a1369209993 5y agoNo, the meter is defined (as c times a certain number of seconds).
- javajosh 5y agoNo, the meter is defined in terms of c and the hyperfine transition frequency of Cs-133 is defined https://physics.nist.gov/cgi-bin/cuu/Value?nucs https://physics.nist.gov/cgi-bin/cuu/Value?nucs. If that link isn't good enough, you can check out the SI Mises en pratique on the subject: https://www.bipm.org/en/publications/mises-en-pratique https://www.bipm.org/en/publications/mises-en-pratique Edit: I'm totally this guy right now https://xkcd.com/386/ https://xkcd.com/386/
- a1369209993 5y ago> the meter is defined in terms of c That is what I just said: the meter is defined in terms of c, not vice versa.
- javajosh 5y agoI think you are confused. I suggest you read up on this stuff. It's really fascinating, but you're not using the words right. Cheers, and good night.