In my neck of the woods, the longest wavelengths you can reliably produce at a usefully high intensity and usefully short pulses is something like three microns
@EmilioPisanty yeah that might work. am wondering if anyone has tried to measure "photon arrival times" at very high resolution for very long wavelengths
@EmilioPisanty long story but basically some bell experiments in late 1990s used timers and did the correlations on a computer instead of in the hardware. (weihs) wonder about other technologies/ experiments etc...
@EmilioPisanty just trying to understand what kinds of general physics experiments have been done in the area of measuring photon timing wrt very long wavelengths and very high time resolution on the detection.
@vzn He's saying that you should be more careful in specifying what you're asking for. Of course no one has done any experiments on the matter at the million kilometer scale: we don't have the receivers.
@JohnRennie Right. So at about 0.20 when blue becomes 0 red color predominates. And this is before the constructive interference of blue at 0.4. So my guess was correct that red is the color which appears closest to the central white ?
@EmilioPisanty it seems like most laser/ coherent EM experiments are with short wavelengths. so am just wondering how long the wavelengths are that have been studied.
@anonymous your calculation is wrong. It isn't immediately obvious to me what you've done wrong but it's clearly wrong as the limits of $cos^2$ are zero and one. Also your two waves have the same periodicity.
@JohnRennie I believe you because you know what to look for in checking the resulting figures. But I can't tell you how many times students have told be that when they weren't even in the same ballpark as the right procedure.
@dmckee if you're calculating two waves with different periodicities and the graph shows them to have the same periodicity that should be a clue there's a mistake :-)
@EmilioPisanty so that helps me formulate the question. what are the longest wavelengths where single photons can be detected. & think that is not much different than the original question :|
@vzn ... in the sense that as far as the relativity+causality considerations go, you need to be able to guarantee the measurement will happen exclusively in some time window for each branch.
If you want to go into what time within that window, that's a whole different kettle of fish
doesn't necessarily mean that that's what they're doing
but anyway, if your question is "if I have a coherent state for a single pulsed mode which spans a time window $[0,T]$, is there something useful I can say about the distribution of PMT clicks on the detector?"
@DanielSank my deal? I just came back from a small vacation with my girl, and now I'm catching up with manga updates I missed while trying not to sulk for failing an exam. And also thought I might waste some time here as well :)
what exactly do you mean? I'm currently on my bachelor's thesis, and it's almost finished. Still no idea about a master thesis though, although I'll probably want it to be in the same field, which is computational astrophysics
@vzn (also why do you see the light as it moves in another direction...?)
@vzn So the professor I work with/for has this particle/fluid simulation code called ramses (see bitbucket.org/rteyssie/ramses ). A relatively new feature was a clump finding algorithm that works on the fly, and my task was to implement a particle unbinding algorithm.
The code advances the (dark matter) particles in time and space, and the clumpfinder finds clumps based on the density field of the particles. My job was to find out whether each particle in a clump is energetically bound to it.
@Mladen huh, interesting, (dark matter is a Big Deal™ these days...) dont know about "dark matter particles"... there are no conjectured particles wrt dark matter are there?
@Mladen ps guest spkr chat slot still open, see we discussed it few mos ago, plz let me know on that, hope you get the courage unlike anyone else these days :) :P
Apparently assigning noninteracting particles to dark matter explains some effects other theories couldn't, and I've mostly seen it from the simulation side, where everything is usually simplified. So.... I'm absolutely clueless.
@Mladen there are some nearly-radical new theories eg Verlinde "emergent gravity", have been citing him lately. my own theory is dark matter is spacetime distortions =D ... re "absolutely clueless"... Hawking recently says "dark matter is just a name for something we dont understand"
@dmckee lol have you guys for that :P ps are your students still doing any experiments lately? would be interesting to hear about them, & plz let me know if any are interested in something really wild/ exotic :P
@Mladen iirc @KyleKanos used to do lots of this type of work, have you met him?
@Mladen I tried working with Ramses once. I could understand what was actually being done to make it work on some of the side physics (e.g., heat losses), so I gave up on it & went with another code.
But I did supernova remnant evolution as part of my dissertation
@KyleKanos I can imagine. It's not documented very well, I spent hours trying to figure it out. Still don't know how most of the code works. But yeah, it can also work without DM. Apparently it can handle " self-gravitating, magnetised, compressible, radiative fluid flows. ", but I've worked with DM exclusively so far.
@KyleKanos I didn't intend to imply that is was special, but I couldn't compare it to other codes for lack of knowledge. I just happened to work on it with the original author for my bachelors thesis, that's how it came up.
