There are elements of the electromagnetic force that I ponder upon that is currently untested, setting up thought a experiment that is testable within the universe.
The speed of change of the electromagnetic force over a distance has not been measured, we have a measure for the speed of light, we have also a measure for the speed of electricity through a wire, which is the speed of sound depending on the material, like the speed of sound is as electrons are pushed through a material and repel each other with a force direction, but it would be an interesting to test the speed of a magnetic field.
To test this a coil is set up with direct current running through the coil with a switch to change direction of the electrical current through the coil, a manually controlled alternating current.
Multiple magnetic detectors are placed at an even distance away from the coil, when the direct current changes with the time distance between the coils and the magnetic detectors, a speed can determined.
The more detectors set up the more detailed the information, another possible testable element of magnetic field is to see if it directly effecting the magnetic field from afar from the coil almost instantly or ripples in a slower wave, with multiple detectors set in align to the coil as well as away from the coil, it is possible to gather much better data to the nature of the magnetic field from the source of an electrical current.
With no presumption on the possible result, the statistics of the result would speak for itself when tested, to compare to current scientific models and theories.