- #1

SgrA*

- 16

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In a physics textbook, they derive an expression for gravitational redshift of a photon emitted by a star at a large distance from the source by taking photon as a mass traveling up, against a gravitational potential and hence expending its electromagnetic/quantum energy. The mass of the photon is taken to be:

[itex]m = \frac{h\nu}{c^{2}}.[/itex]

According to that equation, the

*mass*of an X-ray photon of [itex]10^{21} Hz[/itex] would be about 8 times mass of an electron.

Is this treatment appropriate?

*PS*: I'm aware that the "accepted" derivation for gravitational redshift involves general relativity, but the expression derived in this text is a special case of that expression.