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Free electrons can interact with EM waves (and photons), but you generally need very intense sources in order to affect unbound electrons enough to see an effect. But it is possible, and I have done it in an ultrafast laser lab.
And yes, it is based on the use of photons. I worked on a similar project, building a quantum random number generator, for a quantum computing theory group; their plan was to test some theorems. Alas, we ran out of money before we completed the project.
Potential energy would be a negative value, but the zero point is arbitrary. So this is one way to set the total energy to zero, for a given configuration.
The distance, R, treats the neutron stars as point particles - from their centers. The distance to use for the potential energy is R, the distance from the center of the system (assuming they are in an approximately circular orbit). To clear your head, use a different set of letters for your equations!
If the region has a null field, there is no electromagnetic interaction. But when even slightly misaligned, the field is no longer null everywhere, so there will be interactions.
@safesphere: Galileo, in his "Two New Sciences" shows how logic, along with observation, produces a physical theory. As a practicing experimental physicist, I setup experiments to measure an effect; lately it is quantum correlations, but most of my work has been with nanoparticles, electron beams, sensors, or ultrafast lasers. I have never used the word "ontology" in any of my work, practical or theoretical. I did not say that dark matter and dark energy exist; I said that they are being searched for. If not found, they will ultimately be junked, just like the aether, and Aristotle.
@anns: if you apply enough power, in a small enough space, the linear regime is overwhelmed by multi-photon capture, which acts just like the higher frequency multiple. This can be observed with ultrafast laser pulses.
@safesphere: cosmologists assume the existence of dark matter and dark energy due to observations of their effects. They are also searching for them ... that is, they assume that they are in fact, observable.
Also note that so-called digital signals are transmitted both through the air and via cables all the time, even on my computer as I type, and in the communication between the computer and the router. One way is using the method described above, with a series of rapid transitions; if the duration exceeds the cutoff, you have a "1". Another way is to use a voltage or light level, and just turn it on and off as the clock ticks. In practical applications there are more sophisticated techniques: en.wikipedia.org/wiki/Modulation#Digital_modulation_methods
As the energy density increases, the material will photo-dissociate. I have cut glass, ceramics, and metals with a 1 watt average power beam of ultrafast 800 nm pulses, tightly focused. One of the new hazards is reflection from the plasma surface!
