World News

I kinda hate to say this, because I hate Musk, but this is pretty much what Starlink does. It uses lasers to transfer data from satellite to satellite (or it's supposed to, not sure if it actually works yet or is just vaporware). Because of their low orbit, the latency isn't too bad. Not as good as a fiber link of course, but still usable. It's probably the best alternative we currently have to underwater fiber links. Because it's somewhat above the atmosphere in orbit, it sidesteps a lot of issues with laser data transfers.

However I still think Starlink is insanely stupid, it costs so much money and it needs so many launches all the time to keep up with decay. I'm sure it only exists to keep SpaceX afloat, it's the biggest customer aside from the US government subsidies. There is no way it can ever be made profitable and even if it could, we shouldn't because it's so wasteful.

To be clear: Starlink isn't designed to work as a replacement to fiber cables, it dumps all data to ground based equipment as soon as possible and uses the same network as we all do. But they could in principle be used as a replacement with poor latency and poor throughput, but in a disaster kind of situation.

Atmosphere and could still be disturbed or intercepted with an airplane.

earth is round

Point to point communication is already pretty well served by microwave links, no?

In addition to the curvature of the Earth as mentioned by @[email protected], there is also atmospheric dispersion (implied by @[email protected] answer) and... geological movement.

Land moves slowly due to geological faults, thermal expansion, the gravitational influence of the Moon, ground vibrations (such as those caused by cars and trucks rolling over the ground), among other reasons. This is not a short-term problem for fiber optic cables (because fiber optic cables have some extra length to compensate if the distance becomes slightly longer or shorter), but it is a problem for lasers, because they need to be precisely aimed at a receiver area.

Just micrometers (less than 1 mm) of displacement are enough to mess with the phase of the light. In fact, this is a well-known phenomenon and has been well-exploited in optical interferometry experiments (such as LIGO, which observes small fluctuations in alignment to detect gravitational waves).

Air movement (wind and convection currents) also provokes slight light displacement, enough for laser misalignment.

I just learned about this: https://en.m.wikipedia.org/wiki/Optical_telegraph

Your idea worked for a long time and in France where they had a well established system it took awhile for electric telegraph to win over it.

Many of the problems they had lasers would also face, including atmosphere, and I'm curious if people could intercept the signal without being detected, which was certainly a big issue for them.

Fibre optic glass is much more transparent than air, as I understand it. A laser can have much lower power and reach farther through a cable. The cable 'bounces' the signal through optical refraction, so it doesn't need to be aimed precisely.

Well, this was a power cable this time, not a communication cable.

As for your idea, atmospheric distortion makes lasers not viable beyond a certain distance. Even on a crystal clear day the light would be too distorted/spread out to be useful beyond a few miles. The cables use fiber optic, which mitigates the distortion problem, but still requires repeaters to boost the signal every 100 kilometers or so.

Stupid: somewhat (isn't this just direct satellite communications?)

applicable: absolutely not since Estlink is not about communication but power transfer,

Hilarious: yup