Davy_Jones Posted September 1, 2021 Share Posted September 1, 2021 (edited) This question is for the physicists mainly, I suppose, though there may also be a philosophical element to it. (Mods may wish to relocate the thread as appropriate). I ask as an interested layman. We're routinely told--by scientists--that there are four fundamental forces of nature, one of which is gravity. This is so commonly heard that I assume quotations are unnecessary. Gravity construed as a force seems entirely unproblematic under the erstwhile Newtonian paradigm. But times have moved on . . . Much of the lay reading I've done in this area seems to suggest that general relativity--if read literally--treats gravity not as a force at all; rather, it is to be identified with the curvature/geometry of spacetime. Here are a few examples: Quote As far as we are able to judge at present, the general theory of relativity can be conceived only as a field theory. It could not have developed if one had held onto the view that the real world consists of material points which move under the influence of forces acting between them. - Einstein, "The Meaning of Relativity" Quote By 25 November 1915, Einstein had the final equations. Matter and energy were intimately linked with the geometery of space-time. Planets orbit Suns because the geometry of space-time around these massive bodies is curved, just as two drivers starting at the Earth's equator going north gradually approach each other because the Earth's surface is curved. There is no "force" pulling them toward each other. Einstein showed that a similar, albeit more complex kind of geometrical curvature can explain gravity. - Jeffrey Crelinsten, "Einstein's Jury", p88 Quote Light, and all other physical phenomena, must travel on locally curved paths in gravity. This point strongly motivates the idea that gravity is an aspect of geometry and does not belong in the menagerie of forces! - John B. Kogut, "Special Relativity, Electrodynamics, and General Relativity", p198 Would it be accurate to say that contemporary physicists continue to speak of gravity as if it were a force, even though (assuming Einstein got it right) it is not . . . perhaps out of deference to their scientific forebears, or to engender a sense of continuity? Anyway, the question in short: Is gravity a force or not? (In layperson's terms, insofar as possible) Interested to hear any comments. Thanks! Edited September 1, 2021 by Davy_Jones 1 Link to comment Share on other sites More sharing options...
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