• TotallynotJessica@lemmy.world
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    8 months ago

    No. I’m not going to pretend to understand the math, but the reality has more to do with other forces resisting the pull of gravity. Gravity simply says that you’re pulled towards the center of the earth, but the other fundamental forces are necessary to explain why you don’t get there. Various repulsive forces resist the pull of gravity, like the fact that certain particles resist occupying the same space. The reason you’re basically being accelerated upwards is because the repulsive forces keeping the earth from collapsing into a singularity keep you from being at rest. When you’re on the surface of a planet and not in free fall, you experience the feeling of weight, because you’re not truly at rest.

    The way to picture it is space constantly falling inward towards the net source of gravity. If you’re in free fall towards a planet’s surface, you’re actually at rest in relativistic terms. However, because the mass of the planet warps spacetime, you staying at the same spot in space results in you and the source of gravity reaching eachother at some point in time. Neither you or the other object are actually being pulled together by a force, the way both you and the object warp spacetime results in you occupying the same point in space at a future point in time without anything changing your momentum.

    When you’re experiencing the sensation of weight, that isn’t really some force of gravity, but an illusion originating from the forces that keep the ground from giving way beneath you, combined with inertia.

      • TotallynotJessica@lemmy.world
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        8 months ago

        A free body diagram uses classical physics, but the effects that we see in classical mechanics come out of deeper truths in relativistic mechanics. Part of it is the speed of light which is the same for everyone, no matter how fast you move. No matter how fast you travel, light always moves at a specific speed.

        Time dilates depending on where you are or how fast you travel compared to others, observers can’t agree which event preceded another, and objects in orbit around a planet travel in a straight line. A free body diagram uses the assumptions of a flat plane where parallel lines never intersect, but relativity explains the apparent force of gravity using curvature on that plane. In curved space, the sum of all angles on a triangle are not necessarily 180°. It’s not just more complicated, it fundamentally throws out one of the foundational geometric postulates. However, it is the second most verified theory in all of physics.

        • fkn@lemmy.worldM
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          8 months ago

          And the wonderful thing about it is we know it is incomplete, because relativity math stops working at the quantum level. Quantum math and relatively math used to be incompatible… The standard model of physics unifies the two(or is it “is unifying” still?), but with that some truly mind-boggling math came out of it. String theory, m theory, multi universe theories… experiments that show macro objects that should respect relativity math behaving according to quantum math… And we are just at the beginning of understanding the implications of what some of the math suggests.