Timeline for Is there a fundamental reason why gravitational mass is the same as inertial mass?
Current License: CC BY-SA 3.0
11 events
| when toggle format | what | by | license | comment | |
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| Nov 24, 2018 at 16:25 | comment | added | Zo the Relativist | @F.Jatpil: sure, but when I'm calcluating my motion near the Earth, the Earth's mass (properly, the reduced mass of me and the Earth) doesn't drop out of the equation, it sits there, hidden in the value of $g$. It's only MY mass that cancels out. | |
| Nov 23, 2018 at 16:40 | comment | added | F. Jatpil | Well, maybe you are right, I need to think about that. | |
| Nov 23, 2018 at 16:21 | comment | added | F. Jatpil | Mass appears twice: 1)acceleration formula, F=m1*a, where F can be EM 2)Einsteins eqs(m2). Nothing forces two masses to be the same. First is related to acceleration,second to curvature. It is a mystery,why they are same. Gravity contains the idea of inertia when saying: bodies move on geodesics. But talk about how bodies curve spacetime. Electon and neutrino could have some ratio for inertial mass and a different one for "space-curving" mass. What prevents me to put into Einstein eqs different numbers than I mesure in acceleration experiment? I can do it,such theory is not self-contradictory. | |
| Nov 23, 2018 at 14:35 | comment | added | Zo the Relativist | The idea is that in E&M, you have $F = q E$, but in gravity, you have $F = m g$. The "weirdness" is that that $m$ in the second equation is inertial mass. GR handles this by moving to a metric theory, and saying that that second force is, inherently, a ficticious illusion of geodesic motion differing from naïve straight-line motion | |
| Nov 23, 2018 at 14:33 | comment | added | Zo the Relativist | @F.Jatpil: how spacetime gets curved has nothing to do with the equivalence principle. The eqivlance pinciple is about the motion of charged particles in an already extant gravitational field. | |
| Nov 22, 2018 at 17:27 | comment | added | F. Jatpil | I do not get it. You say that there is no relation between spacetime curvature and mass distribution? I do not know why you mention gravitational force, I did not mention it. Yes, ST is curved, but how, randomly? Before Enisten we did not understand why the same mass appers in acceleraton formula and newton gravity formula. Now I might ask why the same mass appears in Einstein theory and acceleration formula (acceleration when other forces, e.g. EM, are involed). | |
| Nov 22, 2018 at 15:42 | comment | added | Zo the Relativist | @F.Jatpil: there is no space-time curving constant. That's the whole point. There is no gravitational force in geodesic motion, there are just geodesics. Spacetime is curved, and that's that. The mass of a test particle is irrelevant, because there is never a point where $F = ma$ is invoked. | |
| Nov 20, 2018 at 20:15 | comment | added | F. Jatpil | But why is inertial mass equal to the space-time curving constant? It is the same problem with different labels. | |
| Feb 2, 2017 at 16:43 | comment | added | Zo the Relativist | @VineetMenon: historically, we certainly knew about the equivalence first. But the logical flow of dependency is not equivalent to our historical knowledge ==> a universe that obeys GR will obey the equivalaence principle for free. | |
| Oct 22, 2011 at 5:14 | comment | added | Vineet Menon | wasn't the equivalence which came first??? | |
| May 1, 2011 at 4:40 | history | answered | Zo the Relativist | CC BY-SA 3.0 |