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bio website marty-green.blogspot.com
location Canada
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visits member for 3 years, 8 months
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Dec
15
comment How does a Wavefunction collapse?
Let's remember your starting position. Here is what you said: "You can measure the energy eigenstate of a hydrogen atom by measuring the magnetic moment of the atom, which will depend on the angular momentum of the electronic state, the energy of the electron, and the alignment of the electron's spin."
Dec
10
comment How does a Wavefunction collapse?
Oh come on. They both have zero orbital energy. And dont' try to squirm out of it by invoking the fine structure constant.
Dec
10
comment How does a Wavefunction collapse?
@jerrySchirmer no you can't measure the energy of a hydrogen atom by measuring its spin state. The 1s and 2s states have the same spin, so a hydrogen atom with a spin of 1/2 can be in any superposition of the 1s and 2s states.
Dec
10
comment How does a Wavefunction collapse?
Anna, downvoting my answer doesn't mean that you're right and I'm wrong.
Dec
9
comment How does a Wavefunction collapse?
The density matrix is related but it's not exactly my territory. I would refer you to this interesting discussion where the people who understand density matrices show that you cannot distinguish between a system where 50% of the atoms are in an excited state versus a system where all the atoms are in a 50-50 superposition of states: physics.stackexchange.com/questions/8049/…
Dec
9
comment How does the hydrogen atom know which frequencies it can emit photons at?
@Lalinsky good answer. You are the only one who is remotely correct on this question. The other answers are all such nonsense.
Dec
8
comment Simple real-life examples of Fermi's golden rule?
@JamalS Thanks for doing my latex! I don't know how I'm supposed to be smart enough to do quantum mechanics if I'm too dumb to do latex.
Dec
7
comment How far back can you trace a photon?
Oh come on now. Does your potassium atom make an audible click when it absorbs a photon from the distant star?
Dec
7
comment How far back can you trace a photon?
Then your argument is with Richard Feynmann, not me. I more or less quoted what he calls "Proposition A" (Vol. 3, chapter 1-5 in the Feynmann Lectures)...the very proposition which he concludes is false. According to Feynmann, it is simply not true that the photon must have passed through either one slit or the other.
Dec
7
comment How far back can you trace a photon?
You start by saying you are going to "keep it simple" but then you throw in so many extraneous complications that your answer is all but incomprehensible. Let me list the things you bring up that have nothing to do with the question: the motion of the star relative to the earth, the expansion of space, existence of gravitational "wells" (?), the redshift, the blueshift, and the standard model. And why do you have a second potassium atom...and why do you think there are potassium atoms inside the detector? And how do you "see" an absorption line with a photomultiplier?
Dec
7
comment How far back can you trace a photon?
If there is no energy spread out, then the energy must be concentrated. And in your "standard quantum mechanics", we have local conservation of energy, which means the energy must be somewhere. So you're saying the photon existed from the moment it left the potassium atom. I suppose you're saying if it encountered a double slit along the way, it must have passed through either one or the other of the slits.
Dec
7
comment How far back can you trace a photon?
It seems like I'm saying it didn't become a photon until it entered the detector, and you're saying it was a photon from the moment it left the potassium atom.
Nov
12
comment Solar vs lunar gravity: inverse square law
The force you caluculate for the sun is much greater. I'm just not sure it's a force you can actually FEEL.
Aug
29
comment How can I stand on the ground? EM or/and Pauli?
Yes, you're right about that. I think what I meant was that it's not exactly the same s-orbital as the hydrogen atom. It's a different shape, because the electrons push each other apart. But regardless, I'm still don't know why I'm the only guy who thinks Heisenberg is more important than Pauli when it comes to stopping us from falling through the floor.
Aug
27
comment How can blackbody radition be explained by quantization?
Yes, it is funny what you can learn when you apply the mathematics to a hypothetical case. I'm glad you agree.
Jul
15
comment How can molecule of a few angstroms absorb visible light of a few hundred nanometers?
The theoretical result whereby the absorption cross-section of a small classical antenna is on the order of the wavelength squared is a not-so-well-known classical result that nevertheless appears in such textbooks as Kraus (from the 1930's) and you can verify it on Wikipedia. It is normally derived by pure mathematics; however, on my website I give a physical picture of why it makes sense: see marty-green.blogspot.ca/2011/10/crystal-radio.html
Jul
15
comment How can molecule of a few angstroms absorb visible light of a few hundred nanometers?
I've wondered what might be possible with very small antennas using piezo-electrics, but not because of the dielectric constant. My thinking was that if the capacitive element had a mechanical oscillation in tune with the electrical frequency, you wouldn't need huge inductors to tune the antenna. But then I don't suppose it would have to be piezo-electric...just any old dielectric that was highly tuned to the right mechanical frequency could work. Maybe that's what they are doing with ceramic chips?
Jul
14
comment How can molecule of a few angstroms absorb visible light of a few hundred nanometers?
This is not a bad answer, but it is unnecessary to talk about "lossy" components in understanding the classical antenna. We can imagine everything made of superconducting wires; and then, as user21748 correctly notes, it is not so much the absorption cross-section which goes down as you make the antenna smaller, but the bandwidth. And to be technically correct, it is not exponential but cubic: that is, if you make your ideal lossless antenna half as big, your Q factor (wL/R) and with it your bandwidth goes by a factor of 8.
Jul
14
comment How can molecule of a few angstroms absorb visible light of a few hundred nanometers?
@leftaroundabout: Not unless you have a microphone that is super-sensitive to low B-flat but rejects low A and low B. Which is what the atom does.
Jul
14
comment How can molecule of a few angstroms absorb visible light of a few hundred nanometers?
I don't know anywhere you'll find the analysis except on my blog. I used to think that Jaynes and Scully "semi-classical" school represented my ideas, but it turns out they don't. Did you check out the link on Crystal Radio that I posted in my answer? I go into more detail on the comparision between the Copenhagen calculation and the semi-classical analysis in a series of articles starting with this one: marty-green.blogspot.ca/2012/02/…