4:24 AM
2

So it seems like that Einstein returned to the concept of aether, but from the point of view of a general relativistic framework. https://mathshistory.st-andrews.ac.uk/Extras/Einstein_ether/ This is often overlooked by modern theoretical physicists. Does the introduction of this aether from a gen...

16 hours later…
8:13 PM
2

Sometimes, I see this called the Dirac Hamiltonian: $$\hat{H} =\vec{\mathbf{\alpha}}\cdot\hat{\vec{p}} + \mathbf{\beta}m ;$$ but, if we take the Dirac Lagrangian density, obtain the corresponding Hamiltonian density via Legendre transforming and integrate, we get --- if I'm not mistaken --- \ha...