As far as I know, if something is mass less, it travels with speed of light and if it has mass, it cannot reach the speed of light.
According to De Broglie's equation, photons do have mass but yet they travel at the speed of light in electromagnetic radiations.

2 Answers

Vinayak Agrawal ·

The question you are asking in the comment is my question!!

Sayan Sinha ·

Photons have mass when they travel at the speed of light. Their rest mass is zero. So, considering that apply the formula m0/sqrt(1-(v2/c2) and you will find that it comes to 0/0. This means at the speed of light, photons can have any mass whatsoever, ranging from 0 to infinity (since 0/0 has infinite answers).


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