Mass of photon and Einstein's theory of relativity

$m=\frac {m_{0}}{\sqrt {1-\frac {v^{2}}{c^{2}}}}$

As speed of light changes in a medium, should we change the denominator also?

If we dont change the denominator, then for a photon travelling with a high fraction of speed of light in a medium (less than c), mass should be defined, but it is not.

#Mechanics

Easy Math Editor

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Comments

The speed of the photon is same regardless of the medium.

It is it's apparent speed that we observe (which is lower due to collisions with the particles of the medium).

Note: This argument holds for any mass less particle as well.

A Former Brilliant Member - 4 years, 7 months ago

The 2nd is not. Obvio the first is

Prince Loomba - 4 years, 7 months ago

As I am saying mass should be defined, which is not only in photon's case

Prince Loomba - 4 years, 7 months ago

@Prince Loomba – Mass of what? The rest mass of the photon is zero. And the above formula is consistent with the fact that the moving mass of a photon is not defined.

A Former Brilliant Member - 4 years, 7 months ago

@A Former Brilliant Member – If we change it according to refractive index, then only mass of photon will be undefined in all cases. Thats my point

Prince Loomba - 4 years, 7 months ago

I'm sorry, I don't understand what you're saying.

A Former Brilliant Member - 4 years, 7 months ago

@A Former Brilliant Member – I am saying the first point is valid for all, for all particles it should be such. But the second point is for photon specially

Prince Loomba - 4 years, 7 months ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$