4 ms·
May I ask: how sensitive? Sensitive enough to, say, detect the movement of something moving at a known frequency on the other side of the planet? Are we on th
by fho 3y ago
May I ask: how sensitive?
Sensitive enough to, say, detect the movement of something moving at a known frequency on the other side of the planet?
Are we on the edge of gravitation based communication channels?
- white_dragon88 3y agoI would imagine that there is is an insane amount of gravitational noise from things like the planet’s asymmetry and events occurring all the way from the core to the crust, the ocean… to cut through that noise you need one big thumper.
- martopix 3y agoThe most obvious source of noise seems to me the fact that the submarine is moving and has therefore nonzero accelerations all the time
- andromeduck 3y agoMost obvious would be the phase of the moon.
- fho 3y agoThing is, you don't have to cut through the noise these days. Low energy/low bandwidth radio communication routinely sends messages below the noise floor. Depends on you application, but if you only send some bits of information ("stocks just crashed") having a big thumper with a very known impact profile is sufficient.
- hwillis 3y agoLocal surface gravity varies by up to a ten-thousandth, about .001 m/s: https://en.wikipedia.org/wiki/Gal_(unit) https://en.wikipedia.org/wiki/Gal_(unit) Sensitive detectors can measure differences in hundreds of millionths (10^-8 parts) or around .1 um/s^2. A 1 million tonne mass on the other side of the earth will create a TOTAL acceleration of 4*10^-16. Changes in that will not be detectable.
- fho 3y agoAh yes ... That's some orders of magnitude too much :-)
- Rygian 3y agoI would wonder how massive the thing on the other side of the planet has to be, in order to be detectable. The more mass necessary, the more energy you'll need to send messages. Unless the detection is extremely accurate, you would be better off spending that energy in electromagnetic radiation that bounces off the atmosphere.
- failbuffer 3y agoFor the most part yes, but for market arbitrage, the milliseconds saved by communicating thru the planet might be worth figuring out how to oscillate an extremely large weight very rapidly.
- roywiggins 3y agoMaybe easier to use neutrinos? It has, technically, already been done at short range: https://physicsworld.com/a/neutrino-based-communication-is-a-first/ https://physicsworld.com/a/neutrino-based-communication-is-a...
- georgeecollins 3y agoIt's apparently extremely sensitive. Check this out: https://www.jpl.nasa.gov/missions/cold-atom-laboratory-cal https://www.jpl.nasa.gov/missions/cold-atom-laboratory-cal