Incoming links: Meh
What does it mean that photons are force carriers for electromagnetism? Updated 2025-01-01 +Created 1970-01-01
TODO find/create decent answer.
I think the best answer is something along:
- local symmetries of the Lagrangian imply conserved currents. gives conserved charges.
- OK now. We want a local symmetry. And we also want:Given all of that, the most obvious and direct thing we reach a guess at the quantum electrodynamics Lagrangian is Video "Deriving the qED Lagrangian by Dietterich Labs (2018)"
- Dirac equation: quantum relativistic Newton's laws that specify what forces do to the fields
- electromagnetism: specifies what causes forces based on currents. But not what it does to masses.
A basic non-precise intuition is that a good model of reality is that electrons do not "interact with one another directly via the electromagnetic field".
A better model happens to be the quantum field theory view that the electromagnetic field interacts with the photon field but not directly with itself, and then the photon field interacts with parts of the electromagnetic field further away.
The more precise statement is that the photon field is a gauge field of the electromagnetic force under local U(1) symmetry, which is described by a Lie group. TODO understand.
This idea was first applied in general relativity, where Einstein understood that the "force of gravity" can be understood just in terms of symmetry and curvature of space. This was later applied o quantum electrodynamics and the entire Standard Model.
From Video "Lorenzo Sadun on the "Yang-Mills and Mass Gap" Millennium problem":
- www.youtube.com/watch?v=pCQ9GIqpGBI&t=1663s mentions this idea first came about from Hermann Weyl.
- youtu.be/pCQ9GIqpGBI?t=2827 mentions that in that case the curvature is given by the electromagnetic tensor.
Bibliography:
- www.youtube.com/watch?v=qtf6U3FfDNQ Symmetry and Quantum Electrodynamics (The Standard Model Part 1) by ZAP Physics (2021)
- www.youtube.com/watch?v=OQF7kkWjVWM The Symmetry and Simplicity of the Laws of Nature and the Higgs Boson by Juan Maldacena (2012). Meh, also too basic.
Ciro Santilli publishes videos of this not-so-common visual programming experiments on his YouTube channel occasionally: www.youtube.com/c/CiroSantilli. Ciro should however not be lazy and also upload each video produced to Wikimedia Commons, since YouTube does not offer a download option even for videos marked with a Creative Commons license: www.quora.com/Can-I-download-Creative-Commons-licensed-YouTube-videos-to-edit-them-and-use-them/answer/Tarmo-Toikkanen!
This is also where Ciro's downtime converged to in his early 30's, since he long lost patience for stupid video games and television series.
Ciro developed one interesting technique: while scrolling through YouTube's useless recommendations, when he understands what a channel is about, he either immediately:This helps to keep this feed clean of boring stuff he already knows about. There is unfortunately an infinite amount of useless videos out there however on the topics of:and no matter how much you say you don't want to hear about them, YouTube juts keeps on sending more.
- subscribes if it is amazing and then "Don't recommend channel"
- otherwise just "Don't recommend channel" immediately
- sports
- music, mostly idiotic top of the charts
- news and political commentary
- food
- programming tutorials. Meh, got Stack Overflow.
- stuff that is not in English, and notably languages that Ciro does not even speak!
- motorcycles
- ASMR
- cute animals
- gaming and movie commentary. Ciro is interested only in a very specific number of video games
- nature life, e.g. hiking, cycling, or living in isolation, this Ciro enjoys
- science for kids (popular science)
Things Ciro hates about YouTube:
- you can't follow or ignore a subject, only indirectly tell the algorithm about that. Once you click a popular cat video, you will be forced to watch cat videos for all eternity.
Likely FFmpeg is the backend of YouTube.
Bought by Google in 2006.
YouTube: From Concept to Hypergrowth Jawed Karim (2006)
Source. YouTube co-founder explains that the key enabling technology for YouTube was the addition of video capabilities to Macromedia Flash 7.