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1d
comment Why isn't there a potential difference across a disconnected diode?
Related (possible duplicate): physics.stackexchange.com/questions/86843/…
Apr
3
comment What does a $SU(2)$ doublet really mean?
I wrote up a pretty basic explanation on wikipedia a while ago: en.wikipedia.org/w/…
Apr
3
comment Why is cold fusion considered bogus?
UPDATE (via email): Ron sees now that the Hagelstein bound forbids an incoherent reaction. This rules out the incoherent process he proposed as the explanation for the excess heat experiments, the radiation observed is too low. This points to coherent processes, and he is now exploring coherent versions of the same process, to complete Hagelstein's model, which he believes is entirely sound, and if the appropriate modes are identified, should explain the phenomenon.
Apr
2
comment Could one measure a stick to an arbitrary precision by having its length estimated by enough people?
@ParthVader : Optical illusions are a reasonable way to talk about observational bias in the context of visually estimating lengths -- which is what this question is about. But yes, observational bias comes in many forms.
Apr
1
answered Could one measure a stick to an arbitrary precision by having its length estimated by enough people?
Mar
28
comment Can a burning laser be directed through fiber optics?
If the beam is too powerful and the fiber is too long (e.g. a kilowatt traveling a kilometer), the beam will lose intensity due to stimulated Brillouin scattering. Normally there's no reason to bring a laser beam such a long distance ... except in the oil industry. foroenergy.com/technology
Mar
28
comment The value of one atomic mass unit
$1.66\times 10^{-27} = (6.02\times 10^{26})^{-1}$ :-D
Mar
28
asked Why doesn't Fermi's golden rule distinguish attraction from repulsion?
Mar
26
answered Does optical fiber preserve the angles of incoming light?
Mar
22
comment Is there a sound theoretical argument against inner-shell induced nuclear chain reactions?
For example, the question asserts that Auger deuteron emission is far more likely than Auger electron emission. Therefore, the fact that X-ray emission is likelier than electron emission, as you say, does not preclude the possibility that deuteron emission is more likely than either. You are entitled to argue that the question's assertion is wrong, but that's not what you did. You just ignored the assertion ... as if you hadn't even read the question.
Mar
22
comment Is there a sound theoretical argument against inner-shell induced nuclear chain reactions?
@DavePhD -- The muon is a postulated seed -- the main question is about the chain reaction, not the seed. The chain reaction is indeed supposed to involve fast charged alpha particles, not x-rays. The fusion chain reaction is supposed to happen in a room-temperature tabletop apparatus, not in a billion-dollar facility like NIF or ITER. (Have you heard of cold fusion? You need to look it up if you want to understand the question.) Anyway, from everything you've written, I get the strong impression that you don't understand the question being asked. You should re-read the question.
Mar
20
comment Band gaps: are they at the centre or at the edge of the Brillouin zone?
If I have a transition from the center of the first BZ, to the boundary between the second and third BZ, I would NOT describe this transition as a "band gap ... at the edge of the BZ".
Mar
20
comment Band gaps: are they at the centre or at the edge of the Brillouin zone?
You're not missing anything. What you said is correct. I have no idea what that quotation could be talking about. Need more context. Maybe it's talking about something very specific, i.e. a specific model of a specific system, rather than band gaps in general.
Mar
19
comment Is there a sound theoretical argument against inner-shell induced nuclear chain reactions?
Ron emailed me. Summary: One K-shell hole is enough energy, but the deuterons would be too far from the Pd nucleus for it to participate. So an electron would have to be the 3rd body instead. This is possible but there are some reasons to think it is less likely. About kinetics and stability: He says there is a series of micro-explosions. Maybe each explosion is centered on a region of unusually high D-density (drawn by a low electric potential), and the reaction can't engulf the whole electrode because D density is lower elsewhere, below $B/A$. There is more discussion I'm leaving out. :-P
Mar
18
awarded  Revival
Mar
18
revised Is there a sound theoretical argument against inner-shell induced nuclear chain reactions?
clarify
Mar
17
comment What is the area in Faraday's law if we have only a piece of metal moving in a magnetic field?
You should define E*...
Mar
17
comment What is the area in Faraday's law if we have only a piece of metal moving in a magnetic field?
You're describing a "homopolar generator". There is a discussion of how Faraday's law does (not) apply to homopolar generators at: en.wikipedia.org/wiki/…
Mar
17
answered Is there a sound theoretical argument against inner-shell induced nuclear chain reactions?
Mar
17
comment Is there a sound theoretical argument against inner-shell induced nuclear chain reactions?
See "The Theory of Auger Transitions" by Chattarji, p 16-19: "Physically, the perturbation causing the [Auger] transition arises from the Coulomb interaction between neighboring electrons ... We must point out here another reason for considering the [Auger] effect to be a radiationless transition rather than a conversion process..." etc. etc. The discussion is detailed and thorough. (Of course, Auger emission involves virtual photons, like any electromagnetic interaction. And there are retardation corrections etc., i.e. not exactly "electrostatic". But no real photon is involved.)