58,320 reputation
481199
bio website
location New York City
age 41
visits member for 3 years, 3 months
seen Nov 25 at 17:21

I do not participate on this site any longer, except to respond to comments regarding my own text, if that text is unavailable in another form. I do not accept the political moderation atmosphere here, it is not compatible with open science. I participate at physicsoverflow.org.


Aug
13
awarded  Critic
Aug
13
comment Time in special relativity and quantum mechanics
And Dirac's approach (and Feynman's) makes time an "operator" (or equivalently an integration variable in the path integral). This answer is no more satisfying than saying "In classical mechanics, position is a function, and time is a parameter". That's true, but only if you choose to parametrize by time and not proper time. The same is true in quantum mechanics.
Aug
13
answered In quantum mechanics, given certain energy spectrum can one generate the corresponding potential?
Aug
13
answered In dimensional analysis, why the dimensionless constant is usually of order 1?
Aug
13
comment What the heck is the sigma (f0) 600?
@Timatam: you're not the only person to have this idea. This particle was delisted for a long time, meaning people concluded that it was just a made up particle, just a bump in the cross section due to pion interactions. But the experimentalists shouted that it was really there, and people who do extrapolations of experimental data to extract particles now say that have a pole. I also used to think it was made up, this is why I am confused.
Aug
13
awarded  Revival
Aug
13
comment The entropic cost of tying knots in polymers
Why do you think it's a cost, and not a benefit? There is a way of calculating this--- figure out the statistics of prime decomposition of a random closed path. But its going to be peaked at something like a given number of prime knots per length. Will you accept an answer which is negative?
Aug
13
awarded  Commentator
Aug
13
awarded  Citizen Patrol
Aug
13
comment What is the difference between complex field and two scalar fields?
@Jerry; You are confusing Dirac masses with Weyl masses. A Weyl mass is the same as a Majorana mass in 4d.
Aug
13
revised Does the Unruh effect violate Mach's principle?
specious is the right word
Aug
12
awarded  Student
Aug
12
asked What the heck is the sigma (f0) 600?
Aug
12
revised Does the Unruh effect violate Mach's principle?
clarify statement
Aug
12
comment Does the Unruh effect violate Mach's principle?
I edited the answer to make it clear the deSitter space is empty.
Aug
12
comment Does the Unruh effect violate Mach's principle?
FRW can rotate if the cosmological horizon rotates the other way. This is also true in deSitter space--- if you have a black hole in deSitter, it can rotate. It's just empty de-Sitter that can't rotate. To be clear about what "the other way" means (it isn't obvious in curved space), I mean that if you take a Nariai limit of dS-Schwartzschild (BH as large as possible), then the space-time is a cylinder (dS2 cross S2) and there is a meaningful symmetry between the two S2 horizons at the edge of the dS2. If you rotate one horizon slightly, the other rotates badkwards the same amount.
Aug
12
comment Please justify invoking logical positivism to causal patches and black hole interiors in quantum gravity!
Positivism isn't questionable, it is obvious. The arguments against is are very weak.
Aug
12
answered Logical positivism and black hole interiors
Aug
12
comment Myths in the history of Physics
Heisenberg's matrices were infinite, and it is not clear he would have recognized the matrix rule for them, because they were structured from classical Fourier coefficients, and did not have an obvious linear transformation interpretation until Schrodinger and Born gave one.
Aug
12
comment Is anti-matter matter going backwards in time?
This is interpreting "going back in time" differently than anyone else does. Going back in time, as it is usually meant, requires flipping the sign of the energy as measured along the proper time and the sign of the proper time as measured relative to coordinate time. This operation preserves the sign of the energy.