White holes share a great deal of properties with black holes such as being completely characterized by rotation, mass and charge, even they have a Hawking temperature. However, I am not able to argue if they bend light in their surroundings in their proximities in a similar way a black hole does. Is there any idea of why it should or not do it?
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2 Answers
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Light follows the curvature of spacetime. A white hole curve spacetime. More accurately: a white hole is a form of curved spacetime, just like a black hole is a form of curved spacetime. So yes, a white hole would bend light.
Disclaimer: This answer should be regarded as an illustration of classical general relativity. This answer does not presume that white holes actually exist in the real world, and it does not presume that classical general relativity is always a good approximation.
answered Jun 20, 2021 at 20:40
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A white hole is the time reversal of a black hole. Take any light trajectory in a black hole spacetime, and time reverse it, and you have the light trajectory in the white hole spacetime.
answered Jun 22, 2021 at 19:36
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$\begingroup$ I was under the perhaps false impression that white holes had opposite sign of scalar curvature, so light rays bend away from the horizon. Hadn't realised that time reversal and curvature reversal are actually mutually incompatible $\endgroup$– lurscherCommented Jun 22, 2021 at 19:46
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$\begingroup$ @lurscher The “scalar curvature” term typically refers to the Ricci scalar, which is exactly zero everywhere in the black or white hole spacetime. There is also the Kretschmann scalar, but it defines tidal forces only, which have hardly anything to do with the bending of light. $\endgroup$ Commented Jun 22, 2021 at 20:24
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1$\begingroup$ @lurscher: You may be implicitly conflating white holes with negative-mass Schwarzschild solutions. However, they are not the same thing. $\endgroup$ Commented Jun 22, 2021 at 20:44