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As I understand, massless particles such as gluons and photons do not experience time due to the principles of relativity.

An electron isn't sincerely an elementary particle - doesn't it exist more as a composite object that consists of electron-with-weak-hypercharge and electron-without-weak-hypercharge due to it's interaction with the Higgs field? If an electron didn't continuously absorb and emit weak hypercharge then it would travel at the speed of light and experience no time. So then, could an electron be thought of as two massless, timeless particles that oscillate between each other to create the emergent phenomena of mass, and time?

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  • $\begingroup$ What does it mean to "not experience time"? What does it mean to "absorb and emit weak hypercharge"? $\endgroup$ Nov 30, 2017 at 22:12
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    $\begingroup$ @probably_someone The spacetime interval for any photon should always be zero, so they do not experience time or distance, correct? SI = (ct)^2 - (x)^2. Which for photons always equates to 0. $\endgroup$ Nov 30, 2017 at 22:41
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    $\begingroup$ There is no valid reference frame for the motion of a photon, so I'm not sure what it means here to "experience" anything in that frame. $\endgroup$ Nov 30, 2017 at 22:42

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Your reasoning makes sense for someone who has read various popular treatments of these issues, but as is often the case the simplifications in these lead to misconceptions.

Misconception #1: "An electron isn't sincerely an elementary particle." This is not correct. The definition of an elementary particle is one which has no substructure, and an electron as far as we know does not.

Now, it is true that the the Higgs field, in a sense, alters what an electron is. Because the Higgs field couples the two chirality states together, an electron with definite energy has a different character in its presence*. But this is different than something being a composite particle. I don't know of an exact word for this difference in general, but in condensed matter one speaks of a quasiparticle or dressed particle, which is a very similar idea.

Misconception #2: If there were no massive particles, mass and time would be meaningless.

Even if the rest frame of reference for a single massless particle does not exist, the overall rest frame for a collection of more than one does. So, for example, for two photons speeding apart, it makes sense to ask where the center of mass of the two photon system is, and how the distance of each photon from this center changes with time. And for a universe full of only massless particles, it makes sense to ask things like how that universe expands with time. Therefore, even for a hypothetical universe that only involves massless excitations, one would still need the concepts of time and mass to understand it.

*Or, you could say that the electron as we know it doesn't exist without the Higgs field- the difference is semantic.

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