4 ms·

I'm sure this is a dumb question, but are there any conceivable use cases for a gravity-based communication system?

mikewarot 5y ago
No, but it is used for Navigation in submarines. https://en.wikipedia.org/wiki/Gravity_gradiometry#Gravity_gradiometers https://en.wikipedia.org/wiki/Gravity_gradiometry#Gravity_gr...
- FredPret 5y ago
  That is so cool
- nappy 5y ago
  This is not a communications system.
contravariant 5y ago
Well you've got a virtually unblockable signal that travels at the speed of light, but other than that there are literally no upsides. I reckon you might as well use neutrino's, they're easier to detect and easier to produce.
- loteck 5y ago
  Wouldn't neutrino communication have to be highly targeted, though? Whereas gravity could "broadcast"?
  - ArtB 5y ago
    Sounds like it would have lots of noise.
    - infogulch 5y ago
      "Sorry could you repeat that? Someone in the next town over clicked their pen and resulting change in gravity due to the ink tube offset by 1cm drowned out your signal."
- raverbashing 5y ago
  Yeah, now try to measure a very weak accelerational signal with a reasonable size (even at high frequencies) Remember how big and complicated LIGO and VIRGO are and that's to detect the loudest signals of that nature in the universe (at a very narrow frequency range)
soheil 5y ago
Gravitons [0] are the only particles that would be able to travel in higher dimensions, so yes if they do exist along with higher dimensions that you find yourself in need of communicating with then gravity would be pretty useful [1]. You do need to move around a planet or at least a moon to generate the signals though. [0] https://en.wikipedia.org/wiki/Graviton https://en.wikipedia.org/wiki/Graviton [1] https://home.cern/science/physics/extra-dimensions-gravitons-and-tiny-black-holes https://home.cern/science/physics/extra-dimensions-gravitons...
elihu 5y ago
It's not very practical. We've been able to detect gravitational waves from black holes (or maybe neutron stars? Something like that anyways...) falling into each other, so in theory we could send a message across the galaxy using non-electromagnetic means if we could deliberately cause a similar event. I'm not sure why we'd want to even if we could, though I guess "hey look at this, I can push a black hole into another one" would likely be regarded as a rather meaningful kind of message on its own to anyone with the technology to hear it.
- TheOtherHobbes 5y ago
  It's not much of a message unless you can push multiple black holes into each other in a carefully timed sequence. If you can do that, a lot of other civs are going to give you a wide berth. And some of the rest may consider you a problem.
BreakfastB0b 5y ago
It’s not dumb at all and perhaps some incredibly advanced civilisation would do exactly that. However space time is exceedingly stiff, the energies required to create measurable ripples are enormous. Targeted neutrino based communication would probably make more sense though.

No, but it is used for Navigation in submarines. https://en.wikipedia.org/wiki/Gravity_gradiometry#Gravity_gradiometers https://en.wikipedia.org/wiki/Gravity_gradiometry#Gravity_gr...

FredPret 5y ago
That is so cool
nappy 5y ago
This is not a communications system.

contravariant 5y ago

Well you've got a virtually unblockable signal that travels at the speed of light, but other than that there are literally no upsides. I reckon you might as well use neutrino's, they're easier to detect and easier to produce.

loteck 5y ago
Wouldn't neutrino communication have to be highly targeted, though? Whereas gravity could "broadcast"?
- ArtB 5y ago
  Sounds like it would have lots of noise.
  - infogulch 5y ago
    "Sorry could you repeat that? Someone in the next town over clicked their pen and resulting change in gravity due to the ink tube offset by 1cm drowned out your signal."
raverbashing 5y ago
Yeah, now try to measure a very weak accelerational signal with a reasonable size (even at high frequencies) Remember how big and complicated LIGO and VIRGO are and that's to detect the loudest signals of that nature in the universe (at a very narrow frequency range)

soheil 5y ago

Gravitons [0] are the only particles that would be able to travel in higher dimensions, so yes if they do exist along with higher dimensions that you find yourself in need of communicating with then gravity would be pretty useful [1]. You do need to move around a planet or at least a moon to generate the signals though. [0] https://en.wikipedia.org/wiki/Graviton https://en.wikipedia.org/wiki/Graviton [1] https://home.cern/science/physics/extra-dimensions-gravitons-and-tiny-black-holes https://home.cern/science/physics/extra-dimensions-gravitons...

elihu 5y ago

It's not very practical. We've been able to detect gravitational waves from black holes (or maybe neutron stars? Something like that anyways...) falling into each other, so in theory we could send a message across the galaxy using non-electromagnetic means if we could deliberately cause a similar event. I'm not sure why we'd want to even if we could, though I guess "hey look at this, I can push a black hole into another one" would likely be regarded as a rather meaningful kind of message on its own to anyone with the technology to hear it.

TheOtherHobbes 5y ago
It's not much of a message unless you can push multiple black holes into each other in a carefully timed sequence. If you can do that, a lot of other civs are going to give you a wide berth. And some of the rest may consider you a problem.

BreakfastB0b 5y ago

It’s not dumb at all and perhaps some incredibly advanced civilisation would do exactly that. However space time is exceedingly stiff, the energies required to create measurable ripples are enormous. Targeted neutrino based communication would probably make more sense though.