Recent content by EnigmaticField

I have the similar experience of being prolongedly delayed in publication. Nevertheless, I encounter it as a master graduate preparing for applying for PhD programs, rather than a registered student. After graduation, I keep having difficulty in getting a paid position as I got my MSc in pure...

I did research on theoretical formulations in general relativity during my MSc studies. I look forward to pursuing PhD and have searched many universities and some research institutes for suitable research themes, but haven't found many research groups undertaking research consistent with my...

Do you want to work on Loop Quantum Gravity? I have searched universities in Germany and only found FAU has professors working on it. But they have not had open PhD position pronouncement at least since 2013, when I found them. Also, when I wrote e-mails to them, they never replied me. So do you...

Since the first day I learned the torsion I keep having the question how a nonvanishing torsion is likely to occur because based on the definition formula of the torsion, it looks like the torsion always vanishes. I have come back to think about this question a couple of times after my first...

Thank you for your enlightening me. I probably have been disentangled from my puzzle. I think your statement can be understood by the following diagram. I previously thought wrong about the lit part of the moon so deduced wrong.

We are experiencing a regular series of the Aldebaran occultations by the moon now. I read this in the article http://www.skyandtelescope.com/observing/moon-covers-bright-star-aldebaran/. What puzzle me are the advancing directions of the occultations across the moon described in the article...

Why is the vanishing torsion (the invariance of the infinitesimal translation of the vielbein field up to the contribution from a Lorentz gauge transformation) a manifestation of the principle of equivalence? I have long understood that the vanishing curvature means the parallel transport is...

I wonder, given a manifold which has spin structures so that we can construct a spinor bundle on it, whether any spinor field on the bundle satisfies the Dirac equation. I don't think the answer is yes, because if that's the case, the Dirac equation is an identity, instead of an equation which...

This paper, at first glance, looks very intriguing, but as I read it in detail, I found it is so hard to understand its derivations because it uses the technique of differential topology, of which I don't have systematical knowledge. I'm not sure why the paper keeps stressing that set...

Not true. My original question is to ask why \bar{\psi}\gamma^\mu\psi is timelike. When I inquired this, I didn't think of invoking that \bar{\psi}\gamma^\mu\psi is involved with a Noether current though I have ever read about the latter in several different places. Some time ago I asked my...

Really? That \bar{\psi}\gamma^\mu\psi is timelike can be proved directly by using the Dirac equation? I can't see this after some trials. I can only see the Dirac equation \mathrm{i}\gamma^\nu\frac{\partial\bar{\psi}}{\partial x^\nu}+\mathrm{m}\bar{\psi}=0...

I recently got a clue to my question. Is that because the Noether current of the Dirac Lagrangian \mathcal{L}=\frac{\mathrm{i}}{2}[\bar{\psi}\gamma^\nu\partial_\nu\psi-\partial_\nu\bar{\psi}\gamma^\nu\psi]-\mathrm{m}\bar{\psi}\psi under a U(1) gauge transformation is...

I consider whenever a special term is coined for the purpose of referring to a class of things differing from their original counterparts in a certain way, the original counterparts are automatically assigned some contrast term when confusion is likely to occur or emphasis is intended. For...

I heard (somebody told me and I also read from some paper) that a polar vector whose components are parameterized by the Dirac spinor \bar\psi\gamma^\mu\psi must be a timelike vector. Why is so? I think a general polar vector can either be timelike or spacelike, isn't it? Is that because a...

Really? I doubt this considerably. In high school, I was pretty good at physics but I was not so good at math exams. I had no problems understanding math textbooks by self-studying but seldom did well in math exams. I usually self-studied math in high school because I couldn't understand what...