Speed of Light(c)

My mind keeps boggling around this question is speed of light really a constant or not?

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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}`	$\boxed{123}$

Comments

Please do give a proof of physical although mathematical is prefered!

Neerad Nandan - 7 years, 7 months ago

You may read Brief History of Time and clarify your doubts

Dinesh Chavan - 7 years, 7 months ago

the speed of light is constant, although light's speed varies depending on where it is. e.g. Light travels at the speed of light in a vacuum but if it travels through glass, it slows down as much as one-third of its usual speed. The speed of light is about 2 996 000 m/s but light's speed depends on where it is. try not to be confused. (Think of speed of light instead as the speed of radio)

Sharky Kesa - 7 years, 7 months ago

i've read many books on relativity but i didin't find any satisfactory answers, here "satisfactory" means mathematical proof!i've read dover books on relativity and einstein's original abstract

Neerad Nandan - 7 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}`	$\boxed{123}$