Why light does not have mass ?

1 Answer
Nov 21, 2017

Light is composed of photons.


We know that Light is composed of photons. Traditionally, photons are just mass less particles. Theoretically, photons have energy and momentum but no mass, and is confirmed by experiments within some extreme limitations.

Even before the discovering of lights containing photons, it was observed that light carried momentum and exerted pressure on a surface. This is not evidence that it has mass since momentum can exist without mass.

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