Relativity and Quantum Mechanics

I posted the following reply to this interesting article on Ars Technica: A “no math” (but seven-part) guide to modern quantum mechanics I thought it might be fun to also publish it here.

I think a lot of quantum "weirdness" can be better understood when people take into account the relativistic effects of fast moving particles.

When something approaches the speed of light, most people are aware of the time distortion effects (from our perspective the clock of an accelerated object seems to slow down), but many forget there is also an accompanying spacial distortion as well (i.e. the length of "a meter" measured by an accelerated object is much longer than a meter if measured in our perspective).

In the case of a photon (in a vacuum) there would both be "no time" between an emission point and an absorption point, and "no space," as the time and spacial distortions become infinite at the speed of light. Particles going very close to the speed of light will have "very small time" and "very small distances" between emission and absorption.

An additional feature of relativity is that the universe must agree that both the photon's "point of view" and our point of view is a valid and true description of time and space events. From the photon's POV there is almost no space in between the the laser and the wall, yet from our POV there is space in between, but both observers must agree on what happens.

So while from our perspective it appears the photons are interfering with each other, from the photon's point of view the paths it can travel are limited to those that won't interfere with any other similar photons traveling a similar path in the universe. This ensures that the result (the pattern on the wall) makes sense from both the "fact" that there is a lot of space between emission and absorption (our POV) and the that there is almost no space between emission and absorption (the photon's POV).

The reasons that the photon's path is limited when moving through the two slits are complex and involve wave mechanics, but it may be sufficient to understand that the single photon MUST travel in a way that appears to us to involve time and space, but to the photon involves "allowed" and "not allowed" paths and probability distributions, and BOTH must agree.

(BTW, the only way we can "see" the interference pattern caused by single particles going "through both slits" is that we create an artificial image where we compare numerous particles to each other. There is no way to detect the interference pattern if we only examine a single particle.)