3 ms·
And massless. Light follows a geodesic in GR. Also i don’t think intrinsic curvature is well explained by the ant analogy. The apparent force isn’t to stay in t
by lanstin 6y ago
And massless. Light follows a geodesic in GR. Also i don’t think intrinsic curvature is well explained by the ant analogy. The apparent force isn’t to stay in the manifold but to stay on the geodesic thru space time (which is free fall).
- nimish 6y agoYep, though massless particles must follow null geodesics specifically. Yeah, the ant analogy isn't the best, though it does show off that movement on a curved surface needs "corrections" from the movement on a flat surface (and the degree to which that occurs happens to entirely characterize curvature itself). If you force the ant to always travel on a great circle, then it might be a little more precise :)
- ars 6y agoIt's neither massive nor massless object that follow geodesics, it's objects with energy (including the mc^2 kind).
- nimish 6y agoYes, and "massive" and "massless" exhaustively covers both, with the special highlighting of massless particles which are further constrained to follow null geodesics. Massive particles don't have that limitation but they only travel time-like geodesics (as far as we know).
- ars 6y ago> with the special highlighting of massless particles which are further constrained to follow null geodesics. Only to an approximation. Photons generate gravitational fields, and the planets they travel near are attracted to the photons (not much obviously). (See: Kugelblitz) Gravity does not treat photons specially, the rules are the same as for other particles. For extra credit imagine a Kugelblitz traveling by at light speed - it's moving so fast, it doesn't have time to add any mass. Yet, mass transited inside the event horizon of this object.