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Hi, I am a string theorist and a publicist.


May
4
comment Magnetic susceptibility in 1/eV
At any rate, whatever you were taught, it's clear that $\chi_\perp$, defined as a coefficient in equation 2 of that paper, has the unit of inverse energy, just like they indicate. $\int d^3 x$ cancels against $abc$, one time derivative cancels against $\partial_t$, the other $\partial_t$ combined with one $\hbar$ gives one energy which has to be cancelled for $S$ to have the right dimension of the other $\hbar$. So maybe you should have already asked a different question about the previous texts such as eqn 2. $\chi_\perp$ is apparently normalized differently than you think.
May
4
comment Video lectures on graduate level Classical Electrodynamics
Biot-Savart law is in lecture 14, Malus' law is in lecture 30, EMF in lectures 10, 17, and others. But I don't think this is a graduate material. I've expanded my answer by an explanation why I think that a "graduate level classical electromagnetism" is an oxymoron.
May
4
revised Video lectures on graduate level Classical Electrodynamics
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May
4
answered Video lectures on graduate level Classical Electrodynamics
May
4
answered The vacuum as trigger
May
4
answered Do all of our discoveries of black holes in nature depend on the validity of GR?
May
3
comment Energy of unmixing
I am curious about the answers. The only meaningful nonzero result could be $\delta E = T\,\delta S$ where $T$ is the absolute temperature and $\delta S$ is the change of the entropy from mixing. However, there are many inherent subtleties. First of all, you don't mean a decrease of energy - the total energy is conserved during mixing as well as unmixing - you mean some work done by the other systems. But it's subtle what you count and what you don't. Moreover, if the molecules of 2 colors are just a bit different, I think you may always separate them for free.
May
3
answered How can something finite become infinite?
May
3
awarded  Nice Answer
May
3
answered Why do bar magnets have least attraction in its center?
May
3
reviewed Approve Why does the moon drift away from earth?
May
3
reviewed Approve Good book about elementary particles for high school students?
May
3
revised Can colliding gravitational waves create a black hole?
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May
3
comment Can colliding gravitational waves create a black hole?
Dear @John, read e.g. the first paragraph of introduction of this paper, arxiv.org/abs/1006.0718 - It refers to Thorne's conjecture and numerical tests by Choptuik and Pretorius; and other related papers. Second point: Total energies and momenta of objects including gravitational waves may be well-defined in GR and measured at infinity, as the ADM energy etc. The only problem is that one cannot canonically attribute the energy to individual regions of space via a density function.
May
3
comment Good book about elementary particles for high school students?
No prob, @yayu, but you may change the vote now if you wish.
May
3
revised Good book about elementary particles for high school students?
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May
3
answered Can colliding gravitational waves create a black hole?
May
3
answered Derivation of polytropic process equation
May
3
answered Casimir effect plate experiment
May
3
answered Good book about elementary particles for high school students?