It sounds like a joke but I just want to know if shadows have mass, since shadows are formed when there is blocking of light. It forms a black pattern with no energy therefore it has no mass.
2 Answers
A shadow is a lack of light. Therefore, a shadow has no mass, for a shadow is not an object or energy. Shadows can go faster than light in certain cases because they are not objects. In the same way, a vacuum has no mass.
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$\begingroup$ Can you explain in what cases shadows can go faster than light? $\endgroup$– PraharMay 23, 2015 at 21:41
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$\begingroup$ @Prahar physics.stackexchange.com/q/63434 and youtube.com/watch?v=JTvcpdfGUtQ $\endgroup$– Jimmy360May 23, 2015 at 22:33
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$\begingroup$ @prahar I have read this stuff as if it is a violation of GR(although Jimmy has given a good justification on the stuff), in Michio Kaku's book - physicis of impossible $\endgroup$– DavidNov 20, 2020 at 13:19
Shadow is not a matter; so it does not have mass. The simple characteristics of matter are: They have mass and take up space.