Einstein's general relativity question says that the curvature of spacetime depends on the energy tensor. Does this mean that light by itself, i.e. massless but containing energy, can cause gravity? Yes, 100%. This is part of the principle of equivalence that Einstein used to inspire himself to invent general relativity. Everything with mass or energy or existence causes gravity. So yes, it not only can, but it absolutely does, and that's super important.
Welcome to the July 2023 Ask Me Anything episode of Mindscape! These monthly excursions are funded by Patreon supporters (who are also the ones asking the questions). We take questions asked by Patreons, whittle them down to a more manageable number -- based primarily on whether I have anything interesting to say about them, not whether the questions themselves are good -- and sometimes group them together if they are about a similar topic.
We're experimenting with a new benefit for Patreon supporters: short video (or audio-only) reflections by me on the podcast that just happened. If you've been wondering whether to join up, this could be the time.
Blog post with questions and transcript: https://www.preposterousuniverse.com/podcast/2023/07/03/ama-july-2023/
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