Hacker Newsnew | past | comments | ask | show | jobs | submitlogin

I take your point, but I think the author's main point was that because objects in free-fall merely follow spacetime geodesics, it makes calling gravity a "force" a little bogus, at least compared to the other forces. Tidal effects don't change that; tidal effects mean the spacetime curvature "over here" is different than the spacetime curvature "over there", which means the principle of equivalence isn't true in a global sense. But objects still follow spacetime geodesics, which is a concept that's hard to reconcile with the notion of a "force."


That "perspective" can be extended to other forces. E.g.: one could say that an electron taking a complex spiralling path through a magnetic field on Earth is merely following a "gravity+EM geodesic" and is actually in free fall the whole time.




Consider applying for YC's Summer 2026 batch! Applications are open till May 4

Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: