Kostik's latest activity

The narrative in #2 has now been added in LaTex.

That makes sense, I will endeavor to use LaTex in the future. Obviously it’s much faster for me to take a snapshot of my own notes (made...

@PeterDonis These are my own notes. If I have made an error, please critique it!

I think I found the (or an) answer. The relations $$\delta g^{\mu\nu} = -g^{\mu\rho}g^{\nu\sigma}\delta g_{\rho\sigma} \quad , \qquad...

From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu}...

A multi-photon absorption might happen I think under extreme conditions like a strong laser.

The photoelectric effect is essentially the observation that light below a certain frequency cannot ionize an atom, no matter how large...

Why don't you start with the familiar case that all $$x^0,x^1,x^2,x^3$$ have dimension of length. All the metric tensor components, thus...

@anuttarasammyak Excellent! This was hugely helpful. I wish Dirac had been a little less cryptic. It's not often that one consults...

@Kostic As for your question the explanation of L-L : seems a good complementary to Dirac.

@anuttarasammyak Very helpful, thanks. I should have looked there, because Dirac's book takes a lot from LL. In my copy of LL, this...

You mean, consider a coordinate change that moves the "front" surface of the hypercylinder from ##t = a## to some other value, leaving...

Apologies, I will try to dig in and understand this better. My GR knowledge is based on reading Dirac, Landau-Lifshitz Vol. 2, Weinberg...

It's certainly obvious to me, and it seems like it was obvious to MTW when they wrote their textbook. :wink: With Dirac it's often hard...

Something else bothers me here, unrelated to the discussion above. Dirac says on p. 62: "It is not possible to obtain an expression for...