Can light travel at the speed of light?


‘Befuddlement’ by Mayank Chhaya

Light is made up of photons which have been so far assumed to be massless and hence eternally stable. It turns out that photons might, just might, have mass. That in turn means that they would eventually die and decay into smaller particles which, in turn, can travel faster than light. Since nothing is supposed to travel faster than light, what do we do?

A new study by particle physicist Julian Heeck, who is a Ph.D. student at the Max Planck Institute for Nuclear Physics at Heidelberg, Germany, suggests that photons might have mass. As a consequence, they could decay into even lighter elementary particles. The institute’s official press announcement puts it thus: “Photons, the quantum of electromagnetic radiation, usually assumed to be massless. But simple extensions of the theory allow a nonzero rest mass*

The existence of mass in anything is also a condition to decay and eventual death. Heeck’s study has found that photons may have a lifetime of a billion billion years. It has been helpfully pointed out that a billion billion years may seem like an eternity to us earthly creatures but for a photon traveling at the speed of light it feels like only three years.

Let me spare you all the dense physics that invariably attends such findings and instead entertain you a bit with my own speculative interpretation. Not being a serious anything has unshackled me from the responsibilities of a serious mind. So I can speculate and wonder the way I please in these columns.

Heeck has been quoted by Scientific American’s Claire Ely as saying that in case photons do have some mass and therefore limited lifetimes, “the notion of light-speed obviously wouldn’t make much sense anymore." "There would still be an absolute limit on velocities, but the photons would have to obey that law, too, and travel below the speed of light,” he says.

That comment has set off speculation in me which would be either profoundly brilliant or irredeemably foolish. My money is on the latter but then I already told you that not being a serious anything has unshackled me from the responsibilities of a serious mind. So here goes.

If light is made up of photons and if photons have mass, then are we now finding that given that photons might have mass, no matter how incomprehensibly tiny, light cannot travel at the speed of light?

A smarter mind would say what Heeck is saying which is that the idea of the speed of light being a universal limit becomes redundant. I, on the other hand, am stuck on the paradox that light, as we know it, cannot travel at the speed of light if photons have any rest mass at all.

Science at the particle level has a way of becoming one epic befuddlement. There are two ways to approach it. One is to feel emotionally frustrated,  frequently vent it and ultimately give up. The other, which I prefer, is to experience that epic befuddlement. Every time I enter the realm of epic befuddlement I think of my long overdue bills and become hurtfully clear about what’s what.

* Mass, in fact, is rest mass which means mass when a photon or any other particle is stationary. It is not practically possible to determine the mass of stationary particles at that level. Hence scientists do so when they are in motion.


About chutiumsulfate

South Asians can infer from my name what I am. View all posts by chutiumsulfate

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