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Comment by oh_sigh | Hacker News Reader

Slightly on topic, but could Elon turn starlink into a giant arbitrage opportunity? Once satellite - satellite laser links are up, it could be the quickest link between say NYC and Tokyo

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Check out the analysis at https://discovery.ucl.ac.uk/id/eprint/10062262/

Yes, that might happen. Sounds weird, because the path is longer, but light is 50% slower in glass fibers than in vacuum.

Sure, there’s an arb opportunity there, until I get my Manhattan-Marunouchi neutrino beam up and running.

The Earth is concave. Don't transpacific cables travel less distance?

Yeah I'm pretty sure cables will always beat satellites over the same distance. One interesting idea I heard was to string stationary drones that would relay microwaves across the ocean, similar to what was done with the relay towers between Chicago and New York.

Light travels at ~0.8C through fiber optics, whereas it travels at very close to C through the atmosphere and C in space.

You need to make up for the extra ~200 miles going up and down, as well as the extra curvature of the satellites orbital shell vs the ground. But, it is doable, assuming you can relay the signal fast enough from satellite to satellite. Fiber optics needs to also be boosted on long routes, I'm not sure how that affects latency. But at the very least, speed of light up/over/down is faster than .8C for 7000 miles around the earth

Getting your fiber to go straight (in the great circle sense) from point A to point B can be quite challenging given the presence of mountains, water, and people or countries that control the land in the way.

For what it’s worth, hollow core fiber is available now, although at least the one vendor I found is very very expensive. I haven’t found an entirely clear answer as to the group velocity in hollow core fiber (it’s not in the data sheets), but it ought to be pretty fast. (The group velocity in vacuum-filled waveguide is not the speed of light in a vacuum — it’s slower.)

Right now, the fastest path from Chicago to London is to bounce radio signals off the ionosphere, which lands them in Lithuania, and then microwave back to London.

Wow, are there HFT firms doing this? How reliable is it?

Yes; speed is in bits: https://www.wsj.com/amp/articles/high-frequency-traders-eye-...

No just HFTs use microwave. Most big DC players (e. g. Equinix) provide access to a MW antenna, as well a dedicated links to PBs and exchanges PoP.

You have outdated information. Mine is correct. If you are talking about the Auora-NJ path, then that's microwaves. I'm talking about Auora-Europe.

https://www.linkedin.com/posts/stefanschlamp_cme-eurex-micro...

Do you mean convex?

Also, light in fiber moves significantly slower than light in a vacuum (or even air). HFT has been utilizing that fact for a while now.

The distance in altitude does increase the length, but not by enough to negate the effect of the faster speed.

The speed of light in vacuum is faster than in fiber optic cable, although presumably there are already microwave signaling networks like someone else mentioned

> presumably there are already microwave signaling networks

Across the pacific ocean?

No, Starlink would not be faster than a terrestrial fiber connection

Short wave radio being relayed via satellites could be.

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