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A duck walks into a bar. Animal control is promptly called and the duck is released into a near by park.


Apr
14
comment Does anyone take the Wightman axioms seriously?
"The question sounds like this, for a classical physicist: Does anyone...". That should read: The question sounds (to an here not further specified referent, probably you mean yourself) like the following question sounds like to a classical physicist: Does anyone..."
Apr
13
revised Lie algebra and Lie group about quantum harmonic oscillator
he lied to us.
Apr
13
suggested suggested edit on Lie algebra and Lie group about quantum harmonic oscillator
Apr
13
awarded  Enlightened
Apr
13
awarded  Nice Answer
Apr
10
comment Is $\langle k \vert k_1k_2\rangle=0$
Have you tried writing down the bracket with the annihilation/procreation operators in full, and permuted them inside the vacuum state according to the commutator rule?
Apr
9
comment Feynman propagators for scalar fields
Off-topic remark: I'd add $\left|_{J_1=0}\right.$ right after the operator. Btw. to force a good height of |, that reads "\left|_{J_1=0}\right."
Apr
4
comment Where do $L_+$ and $L_-$ live, if not in $\mathfrak{so(3)}$?
@user35952: My points is, e.g., if you study the multiplication of the number $7$ by the number $5$ in $\mathbb N$, there is no reason to write this as $7\mapsto(1-2i)\,7\,\overline{(1-2i)}$, if you think that's useful.
Apr
4
comment Where do $L_+$ and $L_-$ live, if not in $\mathfrak{so(3)}$?
I might be misunderstanding something here, so let me raise a point: Without judging if the operators do or do not lie in the algebra, why does your question arise anyway? In my ear, it sounds similar to "I want to study the properties of consecutive derivatives and people use abstract algebra to do it. How is that justified?" Why not? If you study how $a\mapsto\mathrm{e}^{i\phi}a$ affects elements of $\mathbb C$, is there a reason you would you restrict your study by demanding not to use complex conjugation on $\mathbb C$?
Apr
2
comment What are the spaces over spacetime points in which a field takes its values? Is it always the same?
What is the b-boundary approach? What objects are added to the frame bundle? And at those new fibers the direct sum of frame bundle and that new object then?
Apr
1
revised Does QED provide a closed form for Coulomb logarithms?
added 59 characters in body
Mar
31
asked What are the spaces over spacetime points in which a field takes its values? Is it always the same?
Mar
31
comment Why do we require manifolds to be a topological space?
What is $U$? Anyway, the Wikipedia article Metric space says in the fourth section how every metric space induces a topology. / The work I liked to is a little long. The main idea is to use topoi, which are frameworks which encompass the set paradigm, but generally don't need to play the same game/follow the same logical rules. This is related. And just for curiosity, lets me mention that the discussion in this question reminded me of Exotic R4.
Mar
31
comment Why do we require manifolds to be a topological space?
Just two comments: a) Doesn't a metric induce a topology anyway? If you want to have conventional spacetime, there will necessarily be some topology. b) There are doing physics in topoi, e.g. this, in which the notion of openness is a little broader (but not for manifolds, it doesn't start out with spacetime.)
Mar
30
comment Why is the Gibbs Free Energy $F-HM$?
@ChickenGod: You can use $\mathrm dV_1=-\mathrm dV_2$ to show equilibration of the intensive variables $P_1,P_2$, but it's not, I think, relevant in the proof to show that $T\mathrm dS\ge \delta Q = \mathrm d(U-\frac{\partial U}{\partial q}\cdot q)$, were $q$ is $V, M, \dots$.
Mar
28
comment Why is the Gibbs Free Energy $F-HM$?
@ChickenGod: I don't know what the first half of your response has to do with the question at the end, or what you set $E_2=TS_2$ for, but let me ask you something in return: How does "$V$" in the derivation of the extremal conditions for the various potential single out that it has to do with volume. If you have a proof for $V$ and $P$, why doesn't it work if you use the other $M$ and $H$ in their place instead?
Mar
27
comment Homogeneity of space implies linearity of Lorentz transformations
"some reference"... do you have little more background on what your thoughts on this are? Have you le asked this before somewhere?
Mar
27
comment S. Weinberg, “The Quantum theory of fields: Foundations” (1995), Eq. 9.2.15
Final value theorem.
Mar
26
comment Attraction and repulsion of charge?
@JohnRennie: Well, the question has 3 electromagnetism tags. Yes, I start with the point of view that there is the experimental observation that there are repelling objects and non-repelling objects.
Mar
26
comment Attraction and repulsion of charge?
@JohnRennie: I don't know how you can justify using quantum field theory other than by that it works, which is the same argument that I use. I agree that a quantum field theory explanation has great appeal. It also has the merit that it explains it in terms of some other structures which relate to many other things, which I don't do. Not sure how I'd classify "fundamental" though. Maybe by "part of current research", then it works.