Comments by "Lepi Doptera" (@lepidoptera9337) on "Gravity is not a force. But what does that mean?" video.

  1. It is not getting "bigger" because spacetime is falling inwards "at the same rate". Imagine swimming in a river... you have to swim against the flow just to stay still relative to the banks of the river.
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  2. How much do I have to drink to start seeing gravitons? :-)
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  3. Because that's the "natural motion" in general relativity. With gravity the simple rectangular coordinate grid of your teenage years goes out the window and you have to learn some fairly heavy math called "differential geometry" to catch up with reality. Nature really didn't make this one easy for us. Not one bit.
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  4.  @keppela1  Physics is a description of observed reality. What we observe is that without gravitating bodies close by two objects are moving in a linear fashion relative to each other (as long as there are no forces acting between them). With a gravitating body they don't even do that. That's it. That's "all" physics has to describe. If that's not enough for you I can only offer you poetry, philosophy or religion as outlets. Science doesn't care about anything else but the description of the linear (without gravity) and non-linear (with gravity) motion. But since I am neither in the literature, philosophy or the theology departments I can't tell you what those other guys will be saying about the situation. Physics, OTOH, got its part all covered with Einstein's equations. ;-)
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  5.  @keppela1  Yes, you can look out the window and you will get a totally wrong impression about the world. Don't worry. That's pretty much what happened to everybody before physicists figured out how it really works. That's why we are the smartest of the smart, after all. :-)
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  6.  @keppela1  I always hated fluid mechanics, so I will never try to explain to you how smoke blows. ;-)
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  7. No, it isn't true because the electric force depends on an electric charge, which is not related to mass.
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  8. Not unless you are standing on something. ;-)
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  9. It doesn't behave like a force. It didn't do that even in Newton's time. Newton's third law does not apply to it, for instance, (at least not without some serious fudging) and physicists were always aware of that. The definition of "force" works very nicely for contact forces, but it has serious problems for fields and it completely breaks down for metric effects like gravity.
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  10. Yes, gravity is a little more complicated than high school science wants you to believe. That's why we don't stop teaching science at the high school level. It is YOU who stopped learning at the high school level. If that makes YOU uneasy, then YOU have to go back to school. ;-)
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  11. This has nothing to do with theory. Gravity simply doesn't behave like all other forces do.
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  12. A number of such models have been proposed over the years. The problem is that without measurements at new scales we are still stuck with the macroscopic theory we already have.
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  13. Nature doesn't know anything about coordinates. Your feet can feel the building beneath you and then suddenly they stop felling it. What's your problem here? ;-)
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  14. That is the right question. It may or it may not have quantum properties. That does not necessarily mean, though, that it is classical. We may simply not have thought of a third alternative, yet.
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  15. You are correct. There are no Newtonian center of mass forces acting, but there will be tidal forces which are causing the existence of the Roche limit even in weak gravity. In the current theory we are always contracting physics to one point and its tangent space, which is an approximation that oversimplifies the actual physics of finite size objects. We can, of course, calculate the correct magnitudes of these tidal forces even in that approximation.
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  16. Here, let me give you attention. ;-)
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  17. You don't. :-)
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  18. I doubt she cares. ;-)
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  19. That gravity is a force is a lie of mercy, otherwise you would not have passed science class in high school. :-)
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