Originally posted by Bosse de Nage
I'd like answers to all these questions, really, but I'll take what I can get.
I asked FabianFnas where mass comes from because as far as I can tell the answer is 'gravity' (see Ambrose Bierce quote above).
I was reading about Newton the other day and realized that I'd thought all my life that Newton 'discovered gravity' but in fact he did no suc ...[text shortened]... non fingo indeed.
Well, bring it on, if you please. How does energy do what it does?
I'm pretty sure you know this but I'll say anyway 😉
We can't go on and on and explain what we have. At some we would be doing some kind of highly speculative metaphysics. Like this: We say that gravity is experienced/mass by anything that has a mass. Then one can ask "But why does mass causes gravity?". Well in Newton's day that answer couldn't be given unless with was a fool one. Nowadays with Einten's theory one has the metric tensor and Einstein's equations of GR and if one knows how to read the equations and interpret them there is the reason why mass causes
gravity. But then of course one could ask but why these equations? And so on and so on.
But what scientists (I'm saying scientists but I'm just really thinking about physicists) do is to define the base from what they want to erect a body of knowledge. For instance: Thermodynamics. We have the four laws of thermodynamics. They are all experimentally based. There's no theoretical reason whatsoever for them to be in the form they are. Why do heat always flow (free flow) from hot bodies to cool bodies? Couldn't coolness
flow from cool bodies to hot bodies in a free flow too. From all we know yes it could. But things don't seem to happen that way. So we take that fact as a law (I think that a better name would be axiom but these terms are always being mixed up. We have laws that are axiom and laws that are theorems 😕) and from then on we build up a whole theory. We do that logically and then check if the facts that theory predicts under certain conditions do happen. If it does Yepee we have an appliable theory. Not a right theory
just a theory that can be used in the given limits it was thought up. If the facts don't correspond to the predictions than either we chose the wrong set of postulates to start with or we could have made some kind of logical mistake while constructing the theory. But ultimately what says if the postulates can be applied or not is a future verification of the theory. Metaphysical considerations can be discussed but in my view that is all that is to it. Discussion. One guy can give a coherent set of reasons for a given set of axioms and another guy another set of reasons equally coherent. For me this is metaphysics in the worst sense of the word.
So what I'm trying to say is that in trying to do science we are always limited. We can't try to grab everything fom the beginning. If so we would be always trying to justify the foundantions we are using or we would be just running around in circles.
I think you should read a lot about Newton and try to read things the man himself said. That guy is my favourite physicist. He knew a lot and he knew what the word knowledge meant.
Another thing I remembered is that Newton gave a possible reason for the existence of gravity. He believed a lot in God but he also was very analytic. For instance he knew that he hadn't proved that solar system is stable (this means that he hadn't prove that the orbits we always be the same and we don't have planets crashing down on each other) so he reasoned that maybe gravity was the way that God kept on acting on his creation in order for it not to destroy himself.