I Relevant/irrelevant clocks for experimental tests of relativity

[vanhees71]

My interest is to find if we have any relevant clock for experimental tests of relativity in which the electromagnetic force (and its force carrier, the photon) is not involved in any way in the clock functioning or at least in generating the events measured by the clock. Gluons were suggested in the other discussion. Do we have a clock using gluons? After a short search I find that maybe the forthcoming nuclear clock would possibly use gluons.

How do you want to use gluons for anything? Gluons are not asymptotic free states due to confinement and thus cannot be handled as, e.g., photons.

Regarding the muons, what is the speed of the force carrier involved in their decay? It is lower/different than c?

Thank you all for your interest and replies.

Muons decay due to the weak interaction, $\mu^- \rightarrow \mu_{\nu}+\mathrm{e}^- + \bar{\nu}_{\mathrm{e}}$, i.e., their lifetime is governed by the weak interaction.

The universality of the "speed of light" as a "limiting speed" of relativistic spacetime descriptions is an assumption, which can be tested. With highest accuracy the relativistic spacetime model has been confirmed in all experiments/astronomical observations so far.

 

[vanhees71]

And since the OP asked about fundamental forces, the fundamental force governing these transitions is the strong interaction, not the eletromagnetic interaction. The strong interaction force carriers, gluons, are massless, at least in the theory, but we can't observe them directly so we have no way of actually measuring their mass.

The envisaged Th clock is based on an electromagnetic transition ($\gamma$ decay). The reason, why all accurate clocks are using quantum optics is just, because you can handle these systems related to the electromagnetic interaction (atoms, molecules, astomic nuclei, solid-state quantum dots, Josephson junctions, ...) with the highest accuracy.

As you say yourself there are no free gluons or something like gluon coherent states you could use to build any type of clock.

 

[Nugatory]

This thread has reached the point of diminishing returns and is closed.

As with all thread closures we can reopen it if there is something more to say (PM any mentor) but further discussion of whether relativistic effects have never been been observed outside of electromagnetic interactions is not needed.