Recent content by greypilgrim

But your diagrams are clearly about displacement, not pressure. Here's the two side by side for a pipe with one closed end: So just as I was saying, there should be a pressure node at the closed end. But the StackExchange explanation states that just outside the open end pressure fluctuates...

I think you are talking about nodes of displacement, while I meant a node of pressure at an open end.

Hi. Some results for "birefringence" in Google Image Search look odd to me: Aren't they wrong? Why would there be refraction if the angle of indicence is 0°?

Well one could imagine the last oscillator absorbing all energy and its amplitude diverging until destruction, but I guess in an isotropic system it will just transfer the energy back into the chain, hence reflect it. There's still this open question: I thought that an open end fixes the...

Hi. I found this intuitive explanation on StackExchange why a sound wave is reflected at the end of an open pipe. The basic idea is (better have a look at the link, there are diagrams) that when a pressure maximum travels along the pipe and leaves at the end, suddenly particles can flow away...

Hi. I used to think that the attitude indicators (artificial horizons) in airplanes were just bottom-heavy spheres swimming in a liquid in a transparent shell, like a ball compass: But apparently they use quite a complicated gyroscopic system. Why?

Shouldn't that be testable? If I have many copies of above state and perform a mutual spin (assuming it's a spin qubit) and position measurement on all of them, shouldn't I get a larger position spread for the ##\left|1\right\rangle## measurement then?

Hi. In this video of Looking Glass Universe, the host "proves" the Born rule by breaking down states into "finer" ones and then applying the principle of indifference. In the description, she bases this on papers by Deutsch, Hossenfelder, Zurek and Hardy. I have never heard of this argument so...

That's why I said "limit", not "case ##L=0##". No, but neither will a real wavefront be clipped off sharply on the sides as in this diagram. It just find it hard to believe it to be utter coincidence for those systems to follow the exact same law, but I might just have to accept that.

Seems like the same discontinuous slope emerges in the limit of the axle length going to zero. What about taking the approach via Fermat's principle, light taking the path of shortest time? Can the axle and wheels be written in Lagrangian or Hamiltonian formulation, and how would that look...

Is it just coincidence that this mechanical model leads to Snell's law as well, or is it more than just an analogy to the propagation of light?

I don't know much about how "dispersion" is used elsewhere, I used as it is in optics: Dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency. (Wikipedia) But you might be right that I think about those things the wrong way around, I'll have to think about...

Pink Floyd might not have gotten their prism exactly right, but this is the official poster of the Swiss section of the Physics Olympiad :smile:

So as far as I understand, frequency dispersion simply means that the wave speed is a function of frequency, ##c\left(f\right)## with no other constraints, so just as "dispersion" has been used from the start of this thread. So is the summation just assumed to work? But what about the problems...

I played around with the following applet: https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_all.html However, they unfortunately do not say how they model the damping, but it looks exponential to me: Then I placed a loose end at ##x=\lambda## and assumed continuity...