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Comment by hyperhello | Hacker News Reader

So submarine cables were limited to 0.67c and now aren’t? Can this really work?

For submarine cables there are two things here. The first is lower attenuation which allows for fewer amplifiers along the route making it overall cheaper. The second is lower latency. There have been cases where high frequency trading people went wireless to get lower latency because of the higher propagation speed of EM-waves in air. For really long distances you can go theoretically use satellite links to get lower latency than a submarine cable even if the total distance increases.

Someday, someone is finally going to work out how to do comms with neutrinos (which can pass directly through the Earth and come out the other side) and make so much money...

They are not, for the thing that would make neutrinos useful for communications is also the thing that makes them useless for communications. In order to use them for comms you'd need to produce such a huge number of neutrinos, and/or in a very colimated beam, that one shudders to think of how one might produce them!

I suspect it may be possible using neutrino-antineutrino annihilation if there's a good way to produce streams of both types of particles, but... physics isn't my field.

I think you could moderate a large nuclear fission reactor (on the edge of criticality) to produce detectable differences in neutrino rate on the other side of the world. KamLAND and a few other experiments detected multi-GW reactor anti neutrinos at 1000km[0] and so presumably tens of GW (easily [if perhaps not safely?] achievable briefly in current reactors) should be detectable over 8000km.

[0] https://www.sciencedirect.com/science/article/pii/S173857331...

> So submarine cables were limited to 0.67c and now aren’t?

I think it’s more like in the future they might not be. It’s anyone’s guess how mass production and deployment of this might look.

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