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What's the difference between inertial mass and gravitational mass?
See www.geocities.com/physics_world/mass_concept.htmOriginally posted by StephenPrivitera
What's the difference between inertial mass and gravitational mass?
Einstein discovered that there is none. This is called the equivalence of gravitational and inertial mass.Originally posted by StephenPrivitera
What's the difference between inertial mass and gravitational mass?
Well, I knew that they are numerically the same. I was wondering actually what they are supposed to measure. The only way for it to be possible that they are numerically different is if they measure different quantities. Why else would a scientist have to conduct an experiment to show they are the same?Originally posted by DavidW
Einstein discovered that there is none. This is called the equivalence of gravitational and inertial mass.
Not quite - That fact was around long before Einstein. GR does not explain the equivalence - it postulates itOriginally posted by DavidW
Einstein discovered that there is none. This is called the equivalence of gravitational and inertial mass.
Einstein postulated that there was no difference in principle, and that is what lead him to a theory of gravity based on space-time curvature. And as I brought up in another thread, we can derive the property of inertia from simple considerations of quantum mechanics and special relativity, so that if C^{2} is constant the gravitation can be associated with the energy as easily as with the inertia.Originally posted by DavidW
Einstein discovered that there is none. This is called the equivalence of gravitational and inertial mass.
What led Einstein to a theory of gravity was not curved spacetime - that was simply something that happened along the way. What guided Einstein was the Equivalence Principle which was based on the equality of gravitational and inertial mass. And this implied that the gravitational force is an inertial force. I.e. According to EinsteinOriginally posted by Tyger
Einstein postulated that there was no difference in principle, and that is what lead him to a theory of gravity based on space-time curvature. And as I brought up in another thread, we can derive the property of inertia from simple considerations of quantum mechanics and special relativity, so that if C^{2} is constant the gravitation can be associated with the energy as easily as with the inertia.
If you want the original article I got that from then read thisThat the relation of gravity to inertia was the motivation for general relativity is expressed in an article Einstein wrote which appeared in the February 17, 1921 issue of Nature [28]
Can gravitation and inertia be identical? This question leads directly to the General Theory of Relativity. Is it not possible for me to regard the earth as free from rotation, if I conceive of the centrifugal force, which acts on all bodies at rest relatively to the earth, as being a "real" gravitational field of gravitation, or part of such a field? If this idea can be carried out, then we shall have proved in very truth the identity of gravitation and inertia. For the same property which is regarded as inertia from the point of view of a system not taking part of the rotation can be interpreted as gravitation when considered with respect to a system that shares this rotation. According to Newton, this interpretation is impossible, because in Newton's theory there is no "real" field of the "Coriolis-field" type. But perhaps Newton's law of field could be replaced by another that fits in with the field which holds with respect to a "rotating" system of co-ordiantes? My conviction of the identity of inertial and gravitational mass aroused within me the feeling of absolute confidence in the correctness of this interpretation
You sure know how to start an argument, Stephen.Originally posted by StephenPrivitera
.... I would speculate that inertial mass is a measure of inertia, and gravitational mass is a measure of the quantity of matter. Then, from what is written in the footnote, I concluded that at high speeds these two quantities deviate from each other (ie, they would not be proportional). Is that correct?