Recent content by feld

In QED, 'electron self energy' to first order results from an electron emitting and reabsorbing a photon. But surely the emitted photon can be absorbed by any other electron in the universe, not just the emitting electron? Indeed it makes no sense to say the photon is absorbed by the same...

After discussing SU(2) and orthogonal rotations in 3-space, ryder discusses SL(2,ℂ) and lorentz transformations in spacetime. The rotation operators are stated as ##J_i =\sigma_i/2## and the boost generators ##K_i= -i\sigma_i/2##. This is standard theory, and correct, but the only justification...

I think ryder is trying to justify the use of dirac matrices. Once he 'explains' that the SU(2) matrices describe rotations in 3-space, he then introduces imaginary angles to describe boosts. It is known from special relativity that boosts are rotations through an imaginary angle. However, with...

I have been reading the same section in ryder's book recently. Ryder identifies h with H. Clearly both H and h are traceless, so the identification is OK so far. Ryder states that h is hermitian, but this is assuming x, y, z are real. However it may readily be checked that H is not hermitian...

tom.stoer, I am talking about the worldwide "community" of professional physicists, engaged in the pursuit of a unified "theory" of quantum theory and general relativity. I hope this is a clear enough definition. I am expressing concern about the speculative turn that fundamental physics...

ThudanBlunder, If I understand your post correctly, you are saying that the physics community is struggling to develop a consistent theory of matter because of: (1) its propensity for inventing mathematical theories that are devoid of physical reality; (2) dysfunction in the system...