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bio website marty-green.blogspot.com
location Canada
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visits member for 3 years, 3 months
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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/…
Jul
14
comment How can molecule of a few angstroms absorb visible light of a few hundred nanometers?
You made that animation? That is excellent and really needed on the internet. I used to be able to find some pretty good three-dimensional animations of the hydrogen orbitals in superposition, but I can't find them anymore. So your animation, which clearly shows the basic idea, is really useful.
Jul
14
answered How can molecule of a few angstroms absorb visible light of a few hundred nanometers?
Jul
2
awarded  Curious
Jun
14
comment Nodes in wave functions outside of the classical turning point
Yeah, it's a little hard to find because it's not listed as the Potential Well in the Table of Contents. Section 16-6, "Quantized Energy Levels".
Jun
13
answered Nodes in wave functions outside of the classical turning point
Jun
11
comment What is predicted to happen for electron beams in the Stern-Gerlach experiment?
But I didn't make any claims about the results of numerical experiments.
Jun
11
comment What is predicted to happen for electron beams in the Stern-Gerlach experiment?
You didn't read my blog posting, did you?
Jun
11
comment What is predicted to happen for electron beams in the Stern-Gerlach experiment?
Okay, you can get two dots if you use a numerical computation. I meant you can't get two dots if you try to do the actual experiment.
Jun
2
comment Can nuclear transmutation be observed in real time?
You didn't read my essay, did you?
Jun
2
comment Can nuclear transmutation be observed in real time?
People talk about doing the double slit experiment "one electron at a time", but all they mean is that the beam intensity is so low that the detection events are far apart. There is still no machine that shoots out single electrons at will. I talk about this in an essay I posted a few years ago on the FQXI site: "There Are No Pea-Shooters For Photons". fqxi.org/data/essay-contest-files/…
Jun
2
answered Can nuclear transmutation be observed in real time?
May
29
suggested suggested edit on Applications of Calculus 2 to Physics
May
28
answered Quantum mechanics: How do the atoms in an electronic circuit enter a smaller orbit on the filament of an incandescent light bulb?
May
27
comment Intuition/derivation behind the probability current definition
I pity the fool who thinks he can out-umlaut the Germans.
May
25
comment Interesting relationship between diffraction and Heisenberg's Uncertainty Principle?
you are so right. I don't know what their problem is.