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> When bootstrapping, physicists determine how elementary particles with different amounts of “spin,” or intrinsic angular momentum, can consistently behave. In
by tus88 7y ago
> When bootstrapping, physicists determine how elementary particles with different amounts of “spin,” or intrinsic angular momentum, can consistently behave. In doing this, they rediscover the four fundamental forces that shape the universe.
They have derived gravity through quantum mechanics? What rock have I been living under?
- namirez 7y ago> They have derived gravity through quantum mechanics? Sort of! The problem is that the solutions of the existing quantum field theories are not renormalizable so infinities arise in the solutions. The whole point of quantum gravity is to find realizable solutions.
- qubex 7y agoAsymptotically safe quantum gravity may not be a dead end, incidentally.
- mcaruso 7y agoNot a physicist by any means, but from the article it talks about gravity in the context of the graviton (as one plausible solution to the problem mentioned). Which is still hypothetical, so it's not like they've proven gravity from first principle or anything.
- nsomaru 7y agoAs a layman reading this, it’s funny. Because I do not need gravity proven to me from first principles ;)
- maxnoe 7y agoProven is the wrong word. You cannot prove a theory. Deriving a description of gravity from first principles would be more appropriate
- hprotagonist 7y ago*an empirical theory. I can certainly prove things about, say, addition.
- solarist 7y agoif you mean you can prove 2+2==4, it's actually tautology: | | + | | == | | | |
- hprotagonist 7y agono like, "addition is closed over the integers" is something you can show to be True (for all members of an infinite set, no less -- so it's not empirical.)
- deleted 7y ago[deleted]
- bsder 7y agoAnd yet, funnily enough, your phone needs a more thorough understanding of gravity than you do. The GPS system must correct for relativistic effects that cause the atomic clocks to shift relative to ground.
- orbifold 7y agoThere is a nice derivation of Newton’s law from quantum field theory in Zee‘s book „Quantum Field theory in a nutshell“. You can also arrive at Einstein’s field equations by deriving the beta function of bosonic string theory and (2-2 scattering to be precise) and requiring that it is constant.
- Iwan-Zotow 7y agoFeynman lectures on Gravitation, 1962
- tus88 7y agoThanks.
- Iwan-Zotow 7y agoBasically, Feynman starts with microscopic approach. We want to describe interaction where each piece of mass/energy is attracted to each other. So lets introduce a boson (whole number spin - 0, 1, 2, ...) to carry interaction. Then he talks about spin properties, rejects spin-1 boson (aka photon), somehow rejects spin-0 boson (I don't remember arguments) and start building microscopic theory of interacting via spin-2 massless bosons. Because they carry energy there is a self-interaction. He builds interaction rules, Feynman diagrams, and then goes to classical limit, where he derives macroscopic classic GR from microscopic quantum interactions. That's what I remember from reading this book. Apparently he did it on the fly, lots of errors in derivations which were noted and corrected in footnotes. Nevertheless, very entertaining approach...