BandGap
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 Apr 26 comment What software programs are used to draw physics diagrams, and what are their relative merits? I used matplotlib for many graphics in my thesis. The only downside is the lack of tex output. This meant I had to import my .svg files in Inkscape to add text an then export is as tex. Apr 26 comment Software for geometrical optics I thought of raytracers when I wrote my comment since they can calculate (some) aspects of wave optics but clearly you are right. Jan 18 comment How can the 5-photon absorption coefficient be estimated? I think you are mixing two things here: The non-linear coefficients rise as powers of two, where the intensity rises by one. Simply stated this stems from the fact that polarisation depends on electric field like $P(E)=\chi^1 |E| + \chi^3 |E|^3 + ...$ and since the absorption loss $W$ depends on $W=P * E$ you get $W_5=\chi^9 |E^9|*E = \chi^9 * I^5$. Thus in essence I am interested in the $\chi^9$ coefficient for 5-photon absorption. Jan 17 comment How can the 5-photon absorption coefficient be estimated? Hmm, could you elaborate on what you mean by "leading order difference"? Jan 17 comment Withstanding charlatans: How to protect friends from buying “water structuring facilities”? This question should be expanded to "How to protect from homeopathy". The same arguments against it holds for the water people just as well. Jan 17 comment How can the 5-photon absorption coefficient be estimated? Indeed, those effects are extremely small. I want to show that this process is irrelevant in comparison to any intensities that might be produced in a lab. I could go for a rough estimate and just say that if 2 or 3-photon absorption has very small values, then 5 will certainly be neglegible. Nov 13 comment Bandgap Spacing in Photonic Crystals Also, isn't the Bragg formula used for constructive interference? If so you'd have to take d*0.5 Nov 13 comment Bandgap Spacing in Photonic Crystals What exactly is an amorphous photonic crystal? One which has no long-range order? Nov 13 comment Are a quantum mechanical system a chaotic (yet deterministic) system? Your point 1 is wrong. QM systems are deterministic. It is a statistical theory, yes, and single outcomes of an experiment might look random but an ensemble of experimental outcomes is definitely deterministic. Jun 25 comment What is your prefered toolkit / program for 3D visualisations of data? Btw: How is this not off-topic: physics.stackexchange.com/questions/11451/… ?? Oh wait, it relates to HEP. Must be valid I guess. Jun 25 comment What is your prefered toolkit / program for 3D visualisations of data? Not constructive/off topic? How can analysing ones data efficiently not be constructive? I guess I'm not thinking like a theorist here, lacking imagination. Oddly enought all the journals I read seem to show what I'm talking about. Guess people don't read Science, Nature, PRL, etc. any more. Jun 14 comment Software for geometrical optics Geometrical optics is simpler in terms of descrbing the way a light beam travels. It completely ignores such effects as diffraction or interference. Ray or wave optics handles just that ... Mar 11 comment Why is GNUplot so pervasive in Physics when there are much more modern tools? And it can be scripted nicely. The output can be TeX as well so you can incorporate is easily in papers... Mar 11 comment Could a bubble of photons make a spaceship massless? Funny for you to say that "Photons (...) [a]re just pieces of light". As Einstein said in a letter to Besso: "50 years of consciously pondering have not gotten me closer to the answer of the question 'What are quanta of light'. Today every rascal thinks he knows but he is wrong" (that's a simple translation from the originally german letter) Mar 11 comment Physics of a skateboard ollie @Mark: I'm sorry if my comment sounded harsh but still it is correct. Your notion of "then applying a downward force on the left axle" is exactly what I disagree on as stated by the cited part of my explanation. You generate no lift with just pushing down the tail (or the right part off the right axle) The force applied to the left axle will generate a rotation which simply counters the initial one. Mar 11 comment Physics of a skateboard ollie @Georg: The sketches are the same orientation as the video. The move is described not from the riders frame of reference but the viewer's. "parallel to the boards surface" means the surface on which you stand on when the board is in a resting position.