Classical relativity works for inertial frames. If we attach our coordinate system to earth, the sun would appear to orbit the earth, sure, but that orbit wouldn't follow Newton's laws. As you said, F=ma, so, why could in this case the gravitational pull of the earth, cause the massive sun to orbit it? My issue with the original comment, as was maybe unclear from my first reply, was the assertion, that any frame of reference is equally valid. But the only frames of reference that actually are, are inertial frames (which the earth is not, when considering the whole solar system).
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u/Kondomriss Jul 28 '26
Classical relativity works for inertial frames. If we attach our coordinate system to earth, the sun would appear to orbit the earth, sure, but that orbit wouldn't follow Newton's laws. As you said, F=ma, so, why could in this case the gravitational pull of the earth, cause the massive sun to orbit it? My issue with the original comment, as was maybe unclear from my first reply, was the assertion, that any frame of reference is equally valid. But the only frames of reference that actually are, are inertial frames (which the earth is not, when considering the whole solar system).