1,171 reputation
411
bio website marty-green.blogspot.com
location Canada
age
visits member for 3 years, 5 months
seen 35 mins ago

Aug
31
answered How can area be a vector?
Aug
30
answered Embrace Physics
Aug
24
comment Does a photon interfere only with itself?
Robert, perhaps you will post this as a fresh question, because questions that appear in the comment field do not seem to attract much attention here. I for one would be happy to post an answer.
Aug
21
comment Why does light change direction when it travels through glass?
Looking it up on Wikipedia, it appears to me that Fermat's Principle is indeed nothing more than the rule that light gets from A to B in the least amount of time. This doesn't explain why. If anything, Huygen's principle appears to be more in line with what I have called an explanation with a mechanism. Either way, I still do not know what further insights are gained from QED; and I am not aware of any corrections to classical trajectories are obtainable by a more complete QED treatment. If you are able to correct me on this I would be interested.
Aug
18
revised Tracking photon color in Bell experiments
added 350 characters in body; edited tags
Aug
18
comment Tracking photon color in Bell experiments
This is a really good answer to a question I put up a few weeks ago. It raises more question in my mind which I think I will place as an edit to my original question, because otherwise it will tend to languish unnoticed if we try to discuss it in the comment field.
Aug
18
accepted Tracking photon color in Bell experiments
Aug
18
comment Introducing emf of a chemical cell as a hint towards quantum mechanics
Slaviks, I'll give you some points for your answer to my question on color tracking. You'll be creating all the tags you want before long.
Aug
18
comment Why does light change direction when it travels through glass?
Marek has me second-guessing my explanation somewhat, but only to the degree that I failed to clearly link the calculation method to the least-time outcome. I still think I could have done this entirely within a classical framework, so I don't see what additional insights would be gained from a QED treatment. As for the comparison of my method with Snell's Law or Fermat's Principle, I disagree. These are just calculational methods that give the right answer without any reason. My explanation actually provides a mechanism.
Aug
17
answered Why does light change direction when it travels through glass?
Aug
17
comment Spring oscillations and waves
Great pictures. I might add that if you take the original mass on a spring, replace the spring with one whose stiffness is exactly half, put the mass in the middle of the spring instead of the end, and then fasten a string of these units together end to end, you get the case shown in the very first diagram above. You only get standing waves at that frequency; to get travelling waves, you have to go lower down in the pictures and drive the system at a much lower frequency it approximates a continuous medium.
Aug
17
comment Why do Bell tests give perfect correlations?
I wouldn't ask you to edit your answer; you've made your case and ideally we should be able to argue it out. Unfortunately, for reasons I don't really understand, the structure of this forum does not really lend itself to good discussions. Any takers our there?
Aug
17
comment Why do Bell tests give perfect correlations?
Contrary to Slaviks' opinion, I believe Roger was right on the money when he identified the 100% correlation as the deepest part of the quantum mystery of entanglement. The detailed Bell arguments about polarizers at 22.5 degrees are terribly clever but completely miss the essential point: the perfect correlations with polarizers aligned were already hugely problematic from a classical wave perspective. Carl and Lagerbaer both correctly identify key aspects of this, especially Carl's explicit demonstration that the singlet state maps to itself when rotated 90 degrees.
Aug
17
awarded  Critic
Aug
16
awarded  Revival
Aug
14
answered Are these two quantum systems distinguishable?
Aug
13
comment In quantum mechanics, given certain energy spectrum can one generate the corresponding potential?
I started to post the opinion that David is right; but I am starting to think he is wrong, for a bizarre reason. The spectra would indeed be identical, if we are talking about the spectrum that you can measure experimentally. No experiment measures the absolute value of the ground state frequency; only the differences. But there is a problem: the half-potential includes only waveforms with odd parity, and when placed in superposition with each other, they will radiate very weakly, if at all. It is not totally obvious to me that there will even be a measurable spectrum.
Aug
12
comment How does one build up intuition in physics?
I would have thought the intuitive thing to do with this integral would be to start by setting x_0 = 0 and p_0 = 1.
Aug
9
comment Why photons transfer to electrons perpendicular momentum?
@Hans I'm sorry I didn't see this post when it first went up, or I would have asked you: why are the spin currents more important than the alternating charge layers? The charge layers are static but so are the current layers, so neither interacts with the incoming e-m wave until they are set in motion to some degree. If you are interested in explaining this, let me know and I will post it as a separate question.
Aug
6
comment How is a spherical electromagnetic wave emitted from an antenna described in terms of photons?
"If the frequency and angular momentum of the photon is known, its position - direction in which it propagates - is completely unknown". Surely Lubos wrote this in haste. The relevant uncertainties for this problem are the initial position of the "photon", presumed to be completely known, and its final momentum, presumed to be completely unknown. In fact it's a little more suttle: even for a fixed initial position, we can specify one axis along which the momentum is known to be zero; but that's as much as I can say in 600 characters or less.