- #26

bhobba

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what does it mean to say about the "classical electromagnetism" to be U(1) invariant?

Very nice thread - loved it.

Personally though I prefer the reverse - getting EM from local U(1) invariance of QM rather than asking what does it mean to be U(1) invariant.

It's even found in popular books eg Victor Stenger - The Comprehensible Cosmos - page 251 under Electromagnetism:.

https://www.amazon.com/dp/1591024242/?tag=pfamazon01-20

He covers the other stuff too (symmetry breaking and all that), again at the populist level using just a little bit of math and calculus.

This is an advanced thread, but I mention it for those not advanced but would like a gentle introduction - you just need a bit of calculus.

Thanks

Bill