97,279 reputation
7128265
bio website motls.blogspot.com
location Czech Republic
age 40
visits member for 3 years, 6 months
seen 12 hours ago

Hi, I am a string theorist and a publicist.


20h
answered Could the universe have non-vanishing net colour charge?
22h
comment Do randomness and indeterminacy in Quantum Physics mean the same?
"Quantum indeterminacy may refer to both Indeterminacy of time evolution and Indeterminacy of measurement results." - Sorry but there is only one indeterminacy. Results of measurements are the only thing that is supposed to be predicted by science - the observables meant to predict the measurements are evolving in time - so the predicted quantities are either determined or not. It is completely wrong - an artifact of classical intuition - to try to divide physics into two different processes, evolution and measurement. There is no such division in Nature. QM predicts the outcomes directly.
22h
comment Do randomness and indeterminacy in Quantum Physics mean the same?
They are really the same thing.
1d
answered Do randomness and indeterminacy in Quantum Physics mean the same?
1d
comment CPT invariance of Dirac equation
The Dirac equation is invariant under C,P,T even separately, so of course it is invariant under CPT in this form as well. However, the true general CPT invariance shouldn't be tested on one-particle equations or classical fields such as Dirac's equation. The general argument why CPT works only makes sense on the full multiparticle quantum field theory.
1d
revised Traces in different representation
added 34 characters in body
1d
revised Traces in different representation
added 34 characters in body
1d
answered Traces in different representation
1d
comment Why does smashing a TV remote load its batteries?
Ions are matter, Olin. Nuclei have to be able to migrate from one side to another, so it's clear that the room left by them will be filled by something else.
1d
comment Why does smashing a TV remote load its batteries?
Great Olin, I may agree, but isn't a paste nothing else than a viscous liquid? Moreover, alkaline (AA) batteries as well as NiMH and Lithium-ion batteries seem to contain classic liquids, don't they? At any rate, if nothing "moves" inside the battery - like in a liquid - then the battery cannot work!
1d
comment Why does a Resistor cause a potential drop?
Please don't worry about that! ;-)
1d
answered Why does a Resistor cause a potential drop?
1d
answered Which interaction violates T symmetry?
1d
answered Why does smashing a TV remote load its batteries?
2d
answered Why is it that the cathodic battery symbol in an equivalent battery circuit doesn't point in reverse for an open circuit case?
2d
comment P-N junction voltage under polarization
The things you claim don't imply that they obey a superposition principle. You could only say that they obey superposition principle if the relevant calculated quantities were linear in the voltages, e.g. for current $I(V_1+V_2)=I(V_1)+I(V_2)$. This is surely not true for semiconductors. Here, the things are nonlinear. One only adds a bias and the bias means - it is defined - as effectively reducing the voltage.
2d
revised Fierz identity for Weyl spinors in tensor currents
added 24 characters in body
2d
answered Fierz identity for Weyl spinors in tensor currents
2d
comment The physical definition of work seems paradoxical
@Addem, good to hear. Just to re-emphasize this insight. There are many forms of energy and work and many "quantities with the units of one joule". But the words denoting them are not synonyma. So energy isn't quite the same thing as work and it isn't the same thing as heat or mechanical work or something else (also, debt and profit aren't the same despite the same unit of a dollar). The energy conservation law says that the sum of several quantities of this kind are zero or equal etc. but the different terms have to be distinguished and in these contexts, "work" really means "mechanical work"
2d
comment What is the meaning of non-compactness in the context of $U(1)$ in gauge theories?
Sorry, I don't understand what your confusion could possibly be, @symanzik138. Your assertion is also correct when formulated correctly but I probably needed a different, "converse" statement. I said that an operator identity $\exp(2\pi i Q)=1$ holds if the spectrum of $Q$ is a subset of integers. If there is no non-integer, the equation holds, if there is a non-integer, it fails, therefore "iff". It's an equivalence. If there were two correct statements in maths, then they are equally correct and one cannot be "more correct" - at most, it may be "more understandable to you".