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243165
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location Greece
age 75
visits member for 4 years, 5 months
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Retired experimental particle physicist.

The picture is a fayum . It looks like aunts and cousins of mine :).


1d
comment Does measurement change the evolution of wave function?
Eveni if it can it be the same hamiltonian, when the boundary conditions for the particle under consideration have changed, your famous "collapse", that particle/instance of the psi probability distribution has been changed and a new psi is needed for the specific particle. see the example in my answer
1d
answered Does measurement change the evolution of wave function?
1d
revised How does a photon leave trace of its polarization state in a photon detector but not trace of which direction it came in?
completed answer
1d
answered How does a photon leave trace of its polarization state in a photon detector but not trace of which direction it came in?
1d
comment Do virtual particles actually physically exist?
@innisfree Too long ago, at some graduate level course. I am not talking of vertices but of the propagator which has the pole and is the source of the virtual particle meme.
1d
comment Do virtual particles actually physically exist?
@innisfree the virtual particle is the one that does not obey it, because it is within an integral. After the integration the input and output real particles obey the conservation rules. If the virtual obeyed it, it would not be off mass shell.
1d
reviewed Approve Do virtual particles actually physically exist?
1d
comment Cleaning a dirty jar
Really, best cleaning comes from having in the water some harder floating stuff, like newspaper. Used to clean wine bottles this way. Just shaking water is little use. It needs something dense to transfer momentum and then the amount of water is irrelevant.
1d
comment Particle annihilation - mathematical description, equations governing it?
As Kylle says, there exists a one to one correspondance of Feynman diagrams with rules and formulae, integrals that give crossections for the interactions described pictorially. its.caltech.edu/~matilde/FeyAlgGeomShort.pdf and people.sc.fsu.edu/~dduke/devoto-duke-84.pdf
2d
revised Is quantum entanglement functionally equivalent to a measurement?
added link
Jun
30
answered Is quantum entanglement functionally equivalent to a measurement?
Jun
30
answered Can a photon have little to no energy and/or speed?
Jun
29
comment Particle annihilation - mathematical description, equations governing it?
please look at physics.stackexchange.com/q/190463 where I have recently answered the same question
Jun
29
comment A confusion regarding a paragraph in The Feynman Lectures
I have the impression that one should add a little weight on the left pan to get it started to lift the right pan, as we look at the page. If we take a bit off the left the right will sink , not lift. It is probably a confusion between left and right.
Jun
29
comment How is quantum superposition different from mixed state?
particle A from particle N will control whether the superposition of the individual wave functions is entangled/coherent or not. If it is coherent, it is called mixed. If it is incoherent it is just a superposition of independent wavefunctions which is the classical limit.
Jun
29
comment How is quantum superposition different from mixed state?
In my view a pure state is a state with a single wave function solution of the boundary conditions. This is feasible with few particles entering the equation . From then on one has to use approximations. One type of approximation is to assume all the external interactions to the system under consideration can be replaced by a potential . Then again one can have a pure solution, to approximate the situation. Mixed solutions come when one takes individual wave functions representing the particles and approximates the solution of the total state with the density matrix. Here the "distance" of
Jun
29
comment In atomic bomb tests under ground, where does the volume of the rocks go?
The point to stress is the "vapor turned to liquid lava" . Lava cools to a very dense state, much denser than the original soil. This will have the smallest volume for the matter in the hole, and that is why cavities that turn into craters can form.
Jun
29
revised How is quantum superposition different from mixed state?
clarification after comment by OP
Jun
28
comment How is quantum superposition different from mixed state?
@user36790 above was for your question. I edited my answer and changed it because it was confusing the issues
Jun
28
revised How is quantum superposition different from mixed state?
corrected mistake