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seen 15 hours ago

Apr
14
answered CMB curly B-modes and dark matter
Apr
2
accepted Are there any musical instruments which use resonance tubes with two closed ends?
Apr
2
comment Are there any musical instruments which use resonance tubes with two closed ends?
Well, as I mentioned about percussion instruments I was thinking of instruments that can be roughly modeled as closed-closed resonance tubes, which the Ocarina cannot. But, I would say this class of flute is the closet I will get.
Apr
2
comment Are there any musical instruments which use resonance tubes with two closed ends?
I was not thinking of percussion instruments because of the overtones are not pure - not that they are pure on wind instruments either, but the vibrating heads on percussion instruments have a very complex set of oscillations so modeling them as closed tubes wouldn't make sense.
Apr
1
comment Are there any musical instruments which use resonance tubes with two closed ends?
A beer bottle is a closed-open instrument, so is not what I'm looking for. (not that familiar with Ocarina but I think that is also closed-open). I guess "air pocket" is pretty accurate - I would accept an instrument with other holes to make the notes as long as the ends were closed, I think. That seems like the same level of complication as suggesting that a Clarinet is "just a half-open tube."
Mar
31
asked Are there any musical instruments which use resonance tubes with two closed ends?
Feb
23
accepted Sterile Neutrinos and Supersymmetry
Feb
21
asked Sterile Neutrinos and Supersymmetry
Jan
28
awarded  Enthusiast
Jan
18
accepted Can a compass be used in a submarine?
Jan
17
revised Can a compass be used in a submarine?
I added in the information from his other answer which I consider to be required for me to mark this as correct. If the edits are accepted I will mark as the answer.
Jan
17
suggested suggested edit on Can a compass be used in a submarine?
Jan
17
awarded  Yearling
Jan
17
comment Can a compass be used in a submarine?
Sure that makes sense, as a way to model the distortion. That $H_m$ probably has a pretty complicated dependence right? Like it must depend on both the location and orientation of the submarine?
Jan
9
comment Compatibility conditions of spinors and Riemannian Metrics
Yeah the wikipedia site mostly focuses on the topological restrictions - the vanishing of the Steifel-Whitney class - for a manifold to admit spin structures. But Montesinos worked on the opposite question - is there a spin structure which can be compatible with all the metrics? We get obstructions in both cases, but it seems like they should not be related.
Jan
9
comment Compatibility conditions of spinors and Riemannian Metrics
Yeah exactly, I'm thinking there are some topological restrictions but I don't understand the metric stuff.
Jan
9
asked Compatibility conditions of spinors and Riemannian Metrics
Jan
7
comment Can a compass be used in a submarine?
@Kyle ok so there is some kind of effect in submarines which shields the magnetic field of the Earth - maybe they have a significant amount of conducting material inside them?
Jan
7
asked Can a compass be used in a submarine?
Jan
6
comment Beam focused through lens at an angle
In the thin lens approximation, each of the rays from my picture below can be thought of a collimated beam. The rules for ray tracing would apply. If the thin lens approximation is violated, I'd image there could be significant distortion of the beam due to the geometric effects.