Comment by Optimal_Persona | Hacker News Reader

Comment by Optimal_Persona | Hacker News Reader

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Optimal_Persona

I am not a physicist, astronomer, mathematician or anything like that. But as a lifelong musician who's learned a thing or two about acoustics, I am familiar with the topology of a space affecting the perception AND measurement of vibrations produced within it.

Example - take a speaker with good bass response, play something through it holding it above the floor in the center of the room, then on the floor in the center of the room, then where the floor meets a wall, and finally in a corner where 2 walls meet the floor. You will perceive (and measure) a 3dB increase of low-frequency for each of the boundaries at that position. This is a trick I've used as a DJ to fill rooms with sound from very small speakers.

Is there any way that the topology of the universe/higher dimensions could affect measurements of things like dark matter, etc.? Again probably a very naive question as I know not all modes of vibration are identical.

You may know the reason why but for those that don’t… Bernoulli’s Principle, think thumb over a garden hose. The effect is most pronounced with low frequencies but occurs at all frequencies. We perceive loudness as an increase in pressure.

I’ve not heard it described that way before; I would love to hear more of what you mean by this. The way I learned it in my upper level acoustics courses in college was image sources: hard surfaces are effectively mirrors for sound, so just like you see a copy of an object in an actual mirror, you hear a copy of the speaker coming as if from inside the wall. With three surfaces meeting in the corner, you effectively get 8 sound sources instead of just one. For low frequencies these virtual sources constructively interfere and make louder sound. Of course, this is just a more intuitive way of thinking of the effects of boundary conditions to a partial differential equation.

Light reflectors (e.g., for bikes) are also made out of many little corners to reflect the light to its source.

For sound, it should be the same with a corner of a room, it ~doubles the sound in the vicinity of the corner, hence a ~3dB increase

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