/sci/ - Science & Math

something about relativity requires microcontinuity and some aspects of quantam physics are discrete
GR predicts every particle would become a tiny black hole
quantam physics barely worries about time dilation and does the math assuming time is static
look it up idk much

>>10221131
well in high-energy physics basically if you try and stick a term like the einstein-hilbert action into the standard model lagrangian, then it’s not renormalizable and you get infinity for all your answers. so normal QFT methods just can’t be used to quantize general relativity

>>10221131
>entanglement/action at a distance
I don't know Quantum Field Theory, but I think it resolves this issue somehow, since QFT takes both special relativity and quantum mechanics into account. My understanding is that special relativity works just fine with quantum mechanics, and it is only general relativity (Einstein's description of gravity) which contradicts it.

Sorry I can't give a complete answer to your question.

Quantum Field Theory says you should promote the metric from General Relativity to an operator. Easier said than done.

The big problem everyone talks about from this is the apparent nonrenormalizability of quantum gravity. The babby explanation of what nonrenormalizability means is you have an infinite number of coefficients in your theory that you need an infinite number of measurements to solve for. This makes it kinda difficult to make predictions. I think a lot of people believe that there might be some way to rescue renormalizability by being really careful and clever.

I think there's also conceptual issues with field operators on a quantum spacetime. Field operators are functions of spacetime coordinates (that's what it means to be a field). This is straightforward enough for a fixed spacetime. But when your spacetime depends on where matter is, i.e. what the quantum state is, it's not immediately clear what's going on with your field operators.

I'm not a quantum gravity expert, or even a GR expert. But this is what I've picked up on in my studies.

>>10221156
>GR predicts every particle would become a tiny black hole
Actually, no. I used to believe this, but I looked it up and it turns out that for particles with spin, there is a minimum mass for forming a black hole. And it just so happens that all fundamental particles except the Higgs boson have non-zero spin.

>>10221131
The quantization of GR to get a quantum graviton
The interaction between two stars from string theory or other quantum gravity models

>>10221156
>quantam physics are discrete
Fuck off Bill Nye.

I'm suspicious of entanglement as a problem of imagination or axioms. As I've read it, the states immediately after entanglement are related, but that's not surprising. Given a collision which resulted in matter/antimatter, if you found you had a proton, you wouldn't be surprised the opposite particle was an electron.

I have a harder time finding any subsequent interaction exists, which really makes me think it's just a feature of a wave function that it can be "oriented", and a pair (or in fact, any set) of particles has opposite "orientation".

Einstein himself did a founding experiment in Quantum Mechanics which he never accepted: the photovoltaic effect. In continuous physics, electron orbits are ballistic and levels don't exist. In quantum mechanics, properties arise to lock electrons to orbital levels with some quantum noise. When you shine photons on an atom or molecule, only photons which can correspond to the orbital energy +/- noise are absorbable. A photon which is too energy or not energetic enough has near no effect no the atom, whereas classical mechanics says all photons should impart some energy. Photovoltaic effect shows not only are certain photons absorbable, that an electron displaced has a characteristic energy it gains, corresponding to the photon absorbed (which can be directly described an energy exchange in units of electron-volts, or work done by/on moving an electron through one volt of potential). As normal electricity is measured as work done by electrons, electron volts corresponding 1:1 with voltage, so if an electron performs one electron-volt of work, you produced one volt of potential (with the current of one electron).

Photovoltaic is so damn basic, but at the time we just didn't have decent materials, but photonics dominates everything these days. If Einstein lived long enough, he'd be kinda annoyed because he wouldn't be able to explain computers, lasers, LEDs, solar panels, etc.

>>10221419
>Given a collision which resulted in matter/antimatter, if you found you had a proton, you wouldn't be surprised the opposite particle was an electron.
>matter/antimatter
>proton
>electron
Uhh....

>>10221424
You know what I meant.

>>10221419
It's not so easy to explain away entanglement. You use an example like matter/antimatter where (seemingly) there's an obvious choice of the two basis states, the matter state and the antimatter state. For two electrons in a singlet configuration, you have the freedom to perform measurements along two arbitrary axes. It's only if you measure both along the same axis that you reduce to the "obvious" case where they have opposite results.

>>10221447
Did you mean positrons instead of protons?