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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.


Jul
10
comment How can blackbody radition be explained by quantization?
Maybe this question relates as well.
Jul
8
comment Laplace operator's interpretation
@mcodesmart: don't worry.. it was fun!
Jul
7
comment English translation of Heisenberg's paper ``Über den anschaulichen Inhalt der quantentheoretischen Kinematik und Mechanik''
As a German speaking person, I'd like to add that I find the translation "actual content" a little debatable. It sounds harsher than "anschauliche Inhalt", which could be translated to "the content which can actually be visualized (maybe opposed to that which is formal but has not clear correspondence to something real)". In particular, "actual content" implies that the other half isn't proper content, while the German expression doesn't imply that.
Jul
2
comment Relationship between the continuity equation and the wave equation
Well, have you studied that free field theory on its own? Hint: If you define a trajectory by $x''=0$ in Newtons theory, then the kinetic energy is $\propto x'^2$ which you can also express via momenta $p\propto x'$ and by the way $p'=0$. If you're interested in $\partial^2\varphi=0$, the Lagrangian is $\propto (\partial \varphi)^2$ and now what you do is introducing the letter $J\propto\partial\varphi$.
Jun
21
comment Why does maximal entropy imply equilibrium?
Thanks for the response. Though my comment to Carl Brannens answer applies here too: In the first sentence of the question I say I consider the question from the point of view of pure thermodynamics, not arguing using the statistical physics model of it.
Jun
5
comment Is quantum gravity, ignoring geometry, the theory of a fictitious force?
@JohnRennie: "Dear President Nixon: Your tenure has witnessed the rise of the VHS tape and string theory as a promising avenue to quantum gravity. Which one do you think will be persued longer?" :)
May
28
comment The path integral and Feynman diagrams
I think there is a history of science SE site now, where this seems to fit. Then again, I don't know who frequents this boards. To get to the question, since you ask how Feynman came to his conclusions, the answer surely lies in his knowledge and for this it's crucial to have a look what he worked on before: wikipedia.org/wiki/Wheeler-Feynman absorber theory.
May
16
comment Double slit experiment and single particles. Is the wave function just a mathematical model?
I personally think that postulating a reality beyond the personal conscious 90 year lasting perception in this world is just humans seeking for stability - the concept is simple and convenient for some thoughts but often with little merit. I'm not good at discussing solutions which are consistent with that framework, but I'd also rather try to phrase the question directly with what you write in the third paragraph: "Will one single photon produce the interference pattern? Does it take many photons to build up the interference pattern?" (Unless the question has been asked before.)
May
16
comment Double slit experiment and single particles. Is the wave function just a mathematical model?
What would you say is an example for a concept within a physical theory which is more than token of a mathematical model?
May
6
comment Is the quantization of the harmonic oscillator unique?
Confirmed by some experiment for some application. One could imagine that the theory arising from a different quantization has other applications. Also that studying other quantization of the system leads to ideas for quantization of other systems. Or the new version might have some observables equal, but is overall more suitable for certain computations. Apart from these points, it's an interesting mathematical question.
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
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?
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?