= Quantum field theory
{tag=Ciro Santilli's fetishes}
= QFT
{c}
{synonym}
{title2}
Theoretical framework on which quantum field theories are based, theories based on framework include:
* <quantum electrodynamics>
* <quantum chromodynamics>
so basically the entire <Standard Model>
The basic idea is that there is a field for each particle particle type.
E.g. in QED, one for the <electron> and one for the <photon>: https://physics.stackexchange.com/questions/166709/are-electron-fields-and-photon-fields-part-of-the-same-field-in-qed[].
And then those fields interact with some <Lagrangian>.
One way to look at QFT is to split it into two parts:
* deriving the Lagrangians of the <Standard Model>: <why do symmetries such as SU(3), SU(2) and U(1) matter in particle physics?s>. This is the easier part, since the lagrangians themselves can be understood with not very advanced mathematics, and derived beautifully from symmetry constraints
* the qantization of fields. This is the hard part <Ciro Santilli> is unable to understand, TODO <mathematical formulation of quantum field theory>.
Then interwined with those two is the part "OK, how to solve the equations, if they are solvable at all", which is an open problem: <Yang-Mills existence and mass gap>.
There appear to be two main equivalent formulations of quantum field theory:
* <second quantization>
* <path integral formulation>
\Video[https://www.youtube.com/watch?v=MmG2ah5Df4g]
{title=Quantum Field Theory visualized by <ScienceClic> English (2020)}
{description=
Gives one piece of possibly OK intuition: quantum theories kind of model all possible evolutions of the system at the same time, but with different probabilities. QFT is no different in that aspect.
* https://youtu.be/MmG2ah5Df4g?t=209 describes how the <spin number of a field> is directly related to how much you have to rotate an element to reach the original position
* https://youtu.be/MmG2ah5Df4g?t=480 explains which particles are modelled by which spin number
}
\Video[https://youtu.be/zNVQfWC_evg]
{title=Quantum Fields: The Real Building Blocks of the Universe by <David Tong> (2017)}
{description=
Boring, does not give anything except the usual blabla everyone knows from Googling:
* https://youtu.be/zNVQfWC_evg?t=1335 shows https://www.youtube.com/watch?v=9TJe1Pr5c9Q from <quantum field theory simulations>
* https://youtu.be/zNVQfWC_evg?t=1522 alludes to the <Birch and Swinnerton-Dyer conjecture>
}
\Video[https://www.youtube.com/watch?v=QPAxzr6ihu8]
{title=Quantum Field Theory: What is a particle? by <Physics Explained> (2021)}
{description=Gives some high level analogies between high level principles of <non-relativistic quantum mechanics> and <special relativity> in to suggest that there is a minimum quanta of a relativistic quantum field.}