- #1

Lelan Thara

- 59

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Hi folks - I've recently joined here to see if people who are more knowledgeable than me can help me understand some physics issues I have struggled with for a long time.

My current question is a pretty basic one about how it is possible for a photon to have no mass.

We have the famous equation, "E = mc squared" My math knowledge is very limited, but from what I know - if I assign the value "0" to m, and multiply 0 by c squared, the answer for E should be zero.

Yet a photon possesses energy, and is said to have no mass.

I can see 3 possibilities:

- "E = mc squared" is not a standard algebra equation, and assigning the value "0" to m doesn't result in E being zero.

- "E = mc squared" does not apply to photons - something that seems very unlikely to me.

- photons do, in fact, have mass, or conversely, have no energy.

Can someone help me understand this? I would be very grateful. Thanks!