> This might as be considered a law of physics - electromagnetic energy will always travel faster, more... through a conductive medium than through air.

it actually travels faster through air (no vacuum necessary) than through fiber or copper as those transmit information at 2/3rd of the speed of light while air transmits it at 99% [1].

which is why starlink could in theory achieve better latency than a straight run of fiber optic across the world [2].

this of course doesn't mean that it's better in a mouse because of the overhead of processing such a short distance.

[1] https://archive.is/c859M [2] https://youtu.be/QEIUdMiColU?t=238