7 ms·
But gravity isn't really a force. In the same way that inertia is not really a force. It's just an artifact of the coordinate system being curved.
by jenadine 4y ago
But gravity isn't really a force. In the same way that inertia is not really a force. It's just an artifact of the coordinate system being curved.
- deanCommie 4y agoBut WHY is the coordinate system curved?
- jenadine 4y agoBecause of mass. But WHAT is mass?
- drsnow 4y agoA measure of a particle's energy as pertains to the spacetime curvature it induces
- irrational 4y agoWikipedia says “the property of "mass" is a manifestation of potential energy transferred to fundamental particles when they interact ("couple") with the Higgs field, which had contained that mass in the form of energy.”
- ars 4y agoEnergy, not mass. Photons also curve space in this way. Mass is just one kind of energy.
- dghughes 4y agoWell for anything curved there is more tension in the middle compared to the ends. Maybe it's the same thing.
- ars 4y agoBy that definition electrical attraction is also not a force, because a charged particle will curve in an electrical field.
- jenadine 4y agoMaybe indeed electromagnetic charges curves space time as well, is there a theory for that? According to general relativity, in absence of forces, an object follow a geodesic in space-time. Which we approximate to an uniform motion in straight line for high school physics. But masses "curve" the space time, so there are no straight line. If there was no intramolecular forces to keep the apple on the tree, it would follow a geodesic that would make it fall towards earth. The same way that if the seat was not applying a force to my back, I would be pushed backwards in an accelerating car.
- BlackFly 4y agoKaluza-Klein theory is a geometric unification of general relativity and electromagnetism. A description of electricity as a curvature of a fifth dimension. https://en.m.wikipedia.org https://en.m.wikipedia.org /wiki/Kaluza%E2%80%93Klein_theory If I recall correctly, the description of charged matter is somewhat problematic.
- nextaccountic 4y ago> Maybe indeed electromagnetic charges curves space time as well, is there a theory for that? There is https://en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory https://en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory
- vbezhenar 4y agoElectromagnetic field has some energy. Energy and mass are equivalent (e=mc2). So electromagnetic field curves space time.
- chao- 4y agoA key difference is that we have identified a force-carrying particle for the electromagnetic force (photon), whereas we have not been able to prove a force-carrying particle for the effect we observe as gravity.
- kazinator 4y agoIf it moves the needle of a weight scale or force meter, it's a force.
- jenadine 4y agoI think that's a fair definition of a force. But I'd say that the force that eventually moves the needle is not gravity, but the one that the table applies to the scale to prevent it from going down.
- raattgift 4y agoIt's hard to better than Don Koks on this point <https://math.ucr.edu/home/baez/physics/General/Weight/whatIsWeight.html https://math.ucr.edu/home/baez/physics/General/Weight/whatIs...> ("What is weight?", Usenet Physics FAQ, 2014). The contact camp agrees with you. I'm in the contact camp: a scale or balance blocks the freely falling motion of the weighed item. Or, by equivalence, the weighing apparatus (and anything supporting it, be it the whole planet Earth or a rocket engine) imparts an acceleration (i.e., applies a force) on the weighed item, so the latter cannot be in geodesic motion.
- kazinator 4y agoThe free-body diagram of the object has to show two balanced forces: the scale pushing on it, and gravity pulling on it. The net force is zero. When forces balance, they may balance to zero so the object in question doesn't move; but there is compression or tension in it. The scale measures that stress. If you remove either gravity or the restraining support (floor, table, ...) the stress goes away. Force is defined as mass times acceleration: F = ma. A body falling due to gravity experiences a force because it has mass and is accelerating. That's how force is defined.
- jenadine 4y agoThere are some "real" physical force that do not depend on the reference frame and are caused by some law of nature. And there are pseudo-forces that are just a mathematical artifact of a non inertial référence frame. Gravity is a pseudo force. https://en.wikipedia.org/wiki/Fictitious_force https://en.wikipedia.org/wiki/Fictitious_force
- BlackFly 4y agoTo me, this is the real answer. Gravity is not a force, it is a constraint on the shape of the universe. It is geometry.