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An ultra sensitive motion sensor. Intriguing. Could one derive the Earth's rotation? The motion of the solar system? By watching vibrations could it be a micr

An ultra sensitive motion sensor. Intriguing. Could one derive the Earth's rotation? The motion of the solar system? By watching vibrations could it be a microphone?

thfuran 2y ago
You don't need anything nearly so fancy for a laser microphone.
- swayvil 2y ago
  Still want one. And this vector right here.... that's the milky way's orbit about the greater magellanic cloud...
jacobp100 2y ago
No because velocity only makes sense as relative to something else. There’s no ‘fixed points’ in the universe This device will track acceleration rather than velocity
- roywiggins 2y ago
  Points on the Earth's surface are experiencing an acceleration- after all, after 12 hours their velocity has changed direction by ~180 degrees. You can detect Earth's rotation with a sufficiently large pendulum[0] or a good gyroscope. Something with enough inertia will tend to refuse to rotate with the planet, which lets you compare the two and infer the absolute rotational speed of the planet. https://en.wikipedia.org/wiki/Foucault_pendulum https://en.wikipedia.org/wiki/Foucault_pendulum
  - deleted 2y ago
    [deleted]
  - swayvil 2y ago
    I figure that all motion is curved because all motion is on space bent by gravity or whatever. So motion always involves some acceleration vectors. Is that... assful?
cooljacob204 2y ago
For the first two questions I wouldn't think so because it detects acceleration. But I also only have a high school level of physics knowledge so maybe I'm wrong.
- roywiggins 2y ago
  Anything rotating is experiencing acceleration, you can tell whether your merry-go-round is spinning or not with your eyes closed: that's the acceleration.
Majromax 2y ago
> Could one derive the Earth's rotation? Yes, existing gyroscopes are sensitive enough for that. In 1966, one of the first Soviet attempts to launch the Soyuz failed on the pad because the guidance system remained active after a scrubbed launch attempt. After a couple of hours, the Earth had rotated enough such that the guidance system thought it was off-course, triggering the still-armed launch escape system. > The motion of the solar system? This system, probably not. This class of system at lab scale, maybe eventually. It seems that the galaxy's gravitational acceleration on the solar system is on the order of 10^-10 m/s (https://www.sciencedaily.com/releases/2020/12/201203133906.htm https://www.sciencedaily.com/releases/2020/12/201203133906.h...), so about 10 pico-g. The article says that cold atom interferometers have current sensitivities in the nano-g range but could still potentially improve. > By watching vibrations could it be a microphone? With that kind of sensitivity, making it not be a microphone is probably the harder task. However, the sensitivity doesn't necessarily make it a good microphone, since detecting a small signal is useless if the signal-to-noise ratio is too low.
- red75prime 2y ago
  > that the galaxy's gravitational acceleration on the solar system is on the order of 10^-10 m/s A free falling accelerometer (that is an accelerometer that moves along a spacetime geodesic) will detect no acceleration. And the solar system "free-falls". I don't see how we can detect that.
  - Majromax 2y ago
    Good point, I retract that comment about detectability. I was too concerned with magnitudes to consider the rest of it.
  - deleted 2y ago
    [deleted]
KennyBlanken 2y ago
> Could one derive the Earth's rotation? The motion of the solar system? It's not a motion sensor; it's an acceleration sensor. That's an important distinction because the primary problem with IMUs is that they work of changes in velocity, and error in those measurements slowly accumulate - so they almost always need external references to correct for accumulated drift.

An ultra sensitive motion sensor. Intriguing. Could one derive the Earth's rotation? The motion of the solar system? By watching vibrations could it be a microphone?

thfuran 2y ago

You don't need anything nearly so fancy for a laser microphone.

swayvil 2y ago
Still want one. And this vector right here.... that's the milky way's orbit about the greater magellanic cloud...

jacobp100 2y ago

No because velocity only makes sense as relative to something else. There’s no ‘fixed points’ in the universe This device will track acceleration rather than velocity

roywiggins 2y ago
Points on the Earth's surface are experiencing an acceleration- after all, after 12 hours their velocity has changed direction by ~180 degrees. You can detect Earth's rotation with a sufficiently large pendulum[0] or a good gyroscope. Something with enough inertia will tend to refuse to rotate with the planet, which lets you compare the two and infer the absolute rotational speed of the planet. https://en.wikipedia.org/wiki/Foucault_pendulum https://en.wikipedia.org/wiki/Foucault_pendulum
- deleted 2y ago
  [deleted]
- swayvil 2y ago
  I figure that all motion is curved because all motion is on space bent by gravity or whatever. So motion always involves some acceleration vectors. Is that... assful?

cooljacob204 2y ago

For the first two questions I wouldn't think so because it detects acceleration. But I also only have a high school level of physics knowledge so maybe I'm wrong.

roywiggins 2y ago
Anything rotating is experiencing acceleration, you can tell whether your merry-go-round is spinning or not with your eyes closed: that's the acceleration.

Majromax 2y ago

> Could one derive the Earth's rotation? Yes, existing gyroscopes are sensitive enough for that. In 1966, one of the first Soviet attempts to launch the Soyuz failed on the pad because the guidance system remained active after a scrubbed launch attempt. After a couple of hours, the Earth had rotated enough such that the guidance system thought it was off-course, triggering the still-armed launch escape system. > The motion of the solar system? This system, probably not. This class of system at lab scale, maybe eventually. It seems that the galaxy's gravitational acceleration on the solar system is on the order of 10^-10 m/s (https://www.sciencedaily.com/releases/2020/12/201203133906.htm https://www.sciencedaily.com/releases/2020/12/201203133906.h...), so about 10 pico-g. The article says that cold atom interferometers have current sensitivities in the nano-g range but could still potentially improve. > By watching vibrations could it be a microphone? With that kind of sensitivity, making it not be a microphone is probably the harder task. However, the sensitivity doesn't necessarily make it a good microphone, since detecting a small signal is useless if the signal-to-noise ratio is too low.

red75prime 2y ago
> that the galaxy's gravitational acceleration on the solar system is on the order of 10^-10 m/s A free falling accelerometer (that is an accelerometer that moves along a spacetime geodesic) will detect no acceleration. And the solar system "free-falls". I don't see how we can detect that.
- Majromax 2y ago
  Good point, I retract that comment about detectability. I was too concerned with magnitudes to consider the rest of it.
- deleted 2y ago
  [deleted]

KennyBlanken 2y ago

> Could one derive the Earth's rotation? The motion of the solar system? It's not a motion sensor; it's an acceleration sensor. That's an important distinction because the primary problem with IMUs is that they work of changes in velocity, and error in those measurements slowly accumulate - so they almost always need external references to correct for accumulated drift.