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bio website motls.blogspot.com
location Czech Republic
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visits member for 4 years, 5 months
seen 15 hours ago

Hi, I am a string theorist and a publicist.


May
14
awarded  Nice Answer
May
14
revised Polchinski Equation (7.2.4)
edited body
May
14
comment Polchinski Equation (7.2.4)
Absolutely! Do you understand my - perhaps too concise - answer? It's been years since I was calculating it, so I slightly blindly parroted myself. ;-)
May
14
revised Polchinski Equation (7.2.4)
added 259 characters in body
May
14
answered Polchinski Equation (7.2.4)
May
12
comment $su(1,1) \cong su(2)$?
It's actually possible, @kaiser. Could someone please settle this question? For example by an explicit form of the matrices in terms of Pauli matrices etc. It isn't quite needed to explain why the groups are different but it would be nice to fix errors in "redundant" formulae, too.
May
12
revised $su(1,1) \cong su(2)$?
added 145 characters in body
May
11
comment $su(1,1) \cong su(2)$?
@childofsaturn - no, SU and SO are never the same. $SU(m,n)$ is pseudounitary, i.e. complex matrices with $\det M=1$ obeying $MGM^\dagger=M$ where $G$ is diagonal with $m$ times $+1$ and $n$ times $-1$. $SU(1,1)$ ends up isomorphic to $SL(2,R)$ or also $SO(2,1)$.
May
11
answered $su(1,1) \cong su(2)$?
May
11
comment Quantum Entanglement - What's the big deal?
The only Bell whom you may find in the history of quantum computing - the page above - is the Bell in "Bell Labs", and please be aware that his name was Alexander Graham Bell, not John Bell or what was the name of your "hero".
May
11
comment Quantum Entanglement - What's the big deal?
Terry, good to hear you. Bell's contribution to quantum computing was zero - i.e. vastly smaller than the string theorists' contributions. Quantum computing's links with string theory is actually a hot subject. Quantum computers are based on the regular quantum mechanics known from 1925, especially Pauli's insights about spin, and it started as an applied physics or engineering discipline in 1970 when quantum codes began to be constructed. Feel free to search through the timeline of quantum computing en.wikipedia.org/wiki/Timeline_of_quantum_computing
May
10
comment How many fundamental fields / constraints are in Maxwell's Equations?
What do you exactly want to know about them? "What about" isn't a well-defined question. I said that the auxiliary components are needed for the Lorentz-invariant dynamic of the spin-one field. They are needed for the most general situations. If you pick some less clever, special, e.g. static, situations only, you may become unable to prove what I proved (or sketched a proof) above. But that doesn't mean that my proof has a problem.
May
8
awarded  Good Answer
May
5
comment Basic question about superspace, Grassmann numbers and world sheet supersymmetry
In that case, $\theta$ and $\bar\theta$ must be treated together and be equivalent to $\theta_A$ with different components $A$. It's still true that the derivative of $\theta$ bilinear is $\theta$ linear.
May
4
comment Do light and sound waves have mass
I assure you that phonons are exactly as real as photons, they are conceptually the very same thing, obey the same quantization rules, form a Hilbert space isomorphic to a Fock space, and their behavior is described by quantum field theories. Sound is a vibration of the underlying material, and in the same way, light is a vibration of the electromagnetic field. They only differ by the substance that vibrates and the elementary degrees of freedom. The case of light only differs by the substance's being simpler or more fundamental/elementary -fields that exist even in the vacuum.
May
4
awarded  Nice Answer
May
2
comment Basic question about superspace, Grassmann numbers and world sheet supersymmetry
Dear @leastaction, thanks for reading. Concerning $\bar\theta\theta$, I believe that there is a mistake in your formula. It seems like a chiral superfield that only depends on $\bar \theta$, look at the $\psi$ term, so that should be written as an argument on the left hand side and the last $B$ term should actually be $\bar\theta\bar\theta$, and that's meant to represent $\epsilon_{AB}\bar \theta^A\bar\theta^B$, perhaps with a factor of $1/2$ or $i/2$ or whatever is their convention. But these chiral fields should only contain $\theta$ or only $\bar\theta$.
May
2
comment entanglement status of late hawking radiation in AMPS thought experiment
Dear @ChrisHanney, the whole radiation you can see at +infinity results by unitary transformation from the initial state, so it's the same information "transformed". I wouldn't call it "entanglement". One isn't entangled with his own future. The early and late Hawking radiation also come after each other but for them, their entanglement makes sense because different directions generically make an early Hawking particle and a late Hawking particle spacelike-separated. So it makes sense to talk about them as existing at the same moment, and they are entangled.
May
2
answered Basic question about superspace, Grassmann numbers and world sheet supersymmetry
May
1
answered entanglement status of late hawking radiation in AMPS thought experiment