Undergrad The Power of QM and QFT

[bhobba]

We often see discussions about what QM and QFT mean, but hardly anything on just how fundamental they are to much of physics. To rectify that, see the following;
https://www.cambridge.org/engage/ap...maxwell-s-equations-from-first-principles.pdf

'Somewhat magically, if one then applies local gauge invariance to the Dirac Lagrangian, a field appears, and from this field it is possible to derive Maxwell’s Equations (and therefore all of ElectroMagnetism).'


Thanks
Bill

 

[mad mathematician]

Well you have two options Quantum vs Classical. Now infinities are all over physics (classical and quantum), the self energy of an electron is known to diverge to infinity.

So from a classical logic stand it's obvious you can infer CFT (Classical Field Theories) from QFT, from logical contradiction you can infer whatever you like.... a dead and alive cats and kets that wear bras.
(sorry, that's my sense of humour, not everyone get it).

 

[pines-demon]

We often see discussions about what QM and QFT mean, but hardly anything on just how fundamental they are to much of physics. To rectify that, see the following;
https://www.cambridge.org/engage/ap...maxwell-s-equations-from-first-principles.pdf

'Somewhat magically, if one then applies local gauge invariance to the Dirac Lagrangian, a field appears, and from this field it is possible to derive Maxwell’s Equations (and therefore all of ElectroMagnetism).'


Thanks
Bill

Isn’t that how we justify the whole Standard Model Lagrangian? What’s new here?

 

[bhobba]

a dead and alive cats and kets that wear bras.
(sorry, that's my sense of humour, not everyone get it).

I get it.

Thanks
Bill

 

[bhobba]

What’s new here?

Nothing,

It's for those that do not know about it, especially at the I level here or those in later undergraduate years.

Thanks
Bill