1,476 reputation
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bio website marty-green.blogspot.com
location Canada
age
visits member for 4 years, 3 months
seen 2 hours ago

Jul
20
comment What's wrong with this argument that aerodynamic lift really does rely on Bernoulli?
@Dunlavey And yes, I've been a big fan of the John Denker website since I first saw it about ten years ago.
Jul
20
comment What's wrong with this argument that aerodynamic lift really does rely on Bernoulli?
The wing pushes air down because of the angle of attack. But I don't know any way to calculate exactly HOW MUCH air gets pushed down, either from the angle of attack or by some kind of Bernoulli's Principle analysis. But assuming that the wing is actually functioning properly (not stalling or anything like that) I think you'd get a pretty good estimate by multiplying the effective cross section by the velocity of the airplane.
Mar
30
comment Why do lines in atomic spectra have thickness? (Bohr's Model)
Thanks for the edit, Noah. And thanks for my first lesson in LATEX. Now I know that the code for 10^(-8) is DOLLARSIGN\ 10^{-8}DOLLARSIGN (with actual $'s instead of DOLLARSIGN).
Mar
21
comment Can quantum fluctuation happen outside space-time?
It's easy to make fun of an outsider who asks this kind of question. But it seems to me that serious physicists are responsible for the claim that "the big bang was the result of some kind of quantum fluctuation". If that's the kind of statement that legitimate physics deals with, then I really don't see what's wrong with the question. Because it's about as meaningful as the statement which inspired it.
Mar
20
comment How wrong are the classical Maxwell's equations (as compared to QED)?
Thanks, @FraSchelle. What is especially baffling is that more than 100 years into the new paradigm that is quantum physics, I am still considered a kook on the internet for drawing attention to these obvious and readily verifiable truths.
Mar
11
comment How wrong are the classical Maxwell's equations (as compared to QED)?
You didn't answer my question, Jerry. Am I right about the black body radiation, the atomic spectra, and the laser?
Mar
11
comment How wrong are the classical Maxwell's equations (as compared to QED)?
Oh come on. You get the wrong answer when you apply Maxwell's Equations to orbiting electron because you're using the wrong model for the hydrogen atom. There's nothing wrong with Maxwell's Equations. When you apply them to the Schroedinger atom instead of the incorrect Bohr atom, you get the right answer for the spectral lines and the linewidths.
Mar
11
comment How wrong are the classical Maxwell's equations (as compared to QED)?
I think in the first paragraph where I said you don't need to quantize the energy, I meant the e-m field energy. You still get discrete energy levels in the mechanical system when you solve the Schroedinger equation. Those states have stationary charge distributions. But any system in a superposition of those discrete states will have an oscillating charge density, and that oscillating charge emits and aborbs radiation strictly according to classical antenna theory.
Mar
10
comment How wrong are the classical Maxwell's equations (as compared to QED)?
So are you agreeing that I'm right about the black body spectrum, the atomic spectra, and the laser?
Feb
18
comment Calculate the approximate number of conduction electrons
I agreed with Sofia that JohnRennie's comment was a good answer...it helped ME understand how to do the question. I actually thought he put too much detail in the actual answer which he subsequently posted. I think he could have literally put his comment down as an answer, because it's a homework question and it points the way to the solution.
Jan
19
comment Some applications of the Einstein-Podolsky-Rosen (EPR) paradox?
You should know that I suffer from a low-level personality disorder which compels me to disagree with authority figures. Recently a Provincial Court judge has upheld the University of Winnipeg's decision to bar me from the campus because of my "single-minded determinedness to demonstrate that (my) point of view is the superior one". You can read the full decision here (quoted passage from paragraphs 46-50): canlii.org/en/mb/mbpc/doc/2014/2014mbpc42/2014mbpc42.html
Jan
18
comment Some applications of the Einstein-Podolsky-Rosen (EPR) paradox?
But your professional physicists DID get it wrong. They show the particles shotting out of the block along opposite trajectories, towards distant detectors. You already pointed out that they should have had submicroscopic detectors in the interstitial spaces between the uranium atoms (!). That's not what they're showing in their picture.
Jan
16
comment Some applications of the Einstein-Podolsky-Rosen (EPR) paradox?
And yes, I think physicists are extremely sloppy in this kind of thing. Like the authors of that paper you referred me to who used exactly my setup of an example of producing entangled pairs. It only works for isolated atoms, not a block. They forgot to take into account the momentum absorbed by the uranium sample.
Jan
16
comment Some applications of the Einstein-Podolsky-Rosen (EPR) paradox?
I appreciate your interest in my opinion, but I don't think I could have been more clear in my last statement: you should be suspicious of highly contrived measurement proposals. Surely you've read Feynmann's story of how people proposed different methods of measuring which slit the electron went through (he was drawing on the extended correspondence between Bohr and Einstein on this question) only to show that all such efforts were ultimately frustrated by the uncertainty principle.
Jan
14
comment Physical meaning of linear combination of possible states in infinite well
And don't forget that all the states you mix together have a time component...they are multiplied by exp(jwt), where w depends on the energy level. So the pattern is changing with time as the relative phases move with respect to one another.
Jan
14
comment Physical meaning of linear combination of possible states in infinite well
The amplitudes don't remain fixed in time. You need to think about the simple example I gave where you mix just the the ground function and the first excited state. Since the electron is bouncing back and forth, it is radiating. So it loses energy. The amplitude "drains" from the excited state to the ground state until eventually it stops moving. It's the exact same thing that happens to a hydrogen atom in a superposition of the ground (1s) state and first excited (2p) state.
Jan
13
comment Physical meaning of linear combination of possible states in infinite well
You're assuming you add them all in phase at the middle of the box and with equal amplitudes. Yes, you get a wave packet at that instant but I don't think it holds together...I think it explosed all over the box. I'm not sure it's all that easy to get coherent packets that stick together, like the ones you can create in the harmonic oscillator potential.
Jan
11
comment Some applications of the Einstein-Podolsky-Rosen (EPR) paradox?
In general, it's a good idea to be suspicious if you find yourself going to extreme lengths to justify how something might be measurable.
Jan
11
comment Some applications of the Einstein-Podolsky-Rosen (EPR) paradox?
@hypnosifl I'm not sure that the very problematical measurement system you propose actually meets the condition of being executable even "in principle". But if it is, you're saying that if you had a properly isolated block of uranium emitting a continuous flux of alpha particles...that you wouldn't be able to set up a double-slit system and measure a diffraction pattern? I don't think that's right. I think you would get a diffraction pattern.
Jan
11
comment Some applications of the Einstein-Podolsky-Rosen (EPR) paradox?
If you have only one uranium atom, then when it decays, the momentum of the thorium must be equal and opposite to the momentum of the alpha particle. If there's a block or uranium, no such restriction. The momentum is divided three ways, so measuring the alph particle tells you nothing about the momentum of the thorium atom.