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

Hi, I am a string theorist and a publicist.


Jul
22
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"
Jul
22
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".
Jul
22
comment About Shor's error correcting algorithm
Hi @user6818, you mean equation 4.3 not 4.2, right? The barred-c is different because it is an element of a smaller Hilbert space than the broader Hilbert space into which the right hand side vectors belong. Therefore it's an "encoding transformation", as explained in the text around the equation. Do you read the paper as well or are you just taking equations out of the context?
Jul
22
awarded  electromagnetism
Jul
21
awarded  Good Answer
Jul
21
answered About Shor's error correcting algorithm
Jul
21
comment Why do some hand dryers blow hot air?
LOL, it is not true that the hair dryer throws droplets just like if you shake your hand. Most of the water from the hair evaporates, one H2O molecule after another - evaporation doesn't require one to reach boiling point - and a higher temperature surely increases the evaporation rate, doesn't it? The relative humidity of the air decreases which encourages the hot air to absorb more H2O molecules.
Jul
21
revised One question about sextupole
added 197 characters in body
Jul
21
answered One question about sextupole
Jul
21
awarded  Good Answer
Jul
21
answered My basis set isn't orthonormal?
Jul
20
awarded  Nice Answer
Jul
20
awarded  Enlightened
Jul
20
awarded  Nice Answer
Jul
20
answered The physical definition of work seems paradoxical
Jul
20
comment Coleman-Weinberg potential: resum at 2 loops?
Bechira, in all the cases, one simply writes down all the Feynman diagrams with the appropriate external lines containing the allowed vertices. If the insertions are zero, they're either guaranteed to vanish, or assumed to be subtracted in a different way before you write down the action for the quantum part.
Jul
20
comment Lagrangian description of Brownian motion?
These are interesting research projects, I think, not questions about established science. ;-)
Jul
20
comment Is Red-Shift experiment correct?
Yes, I would. I think that the "magic" words make it sound more controversial than it actually is but the beef is right.
Jul
20
awarded  visible-light
Jul
19
comment Mathematical formalism to include wave and particle perspectives of light
It's called "quantum field theory".