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earth is round
Just use heavier light so it curves with the earth. Duhhh ;)
You have to be careful with that kind of thing, because too much heavy light will make a light black hole.
At this point you just put satellites in orbit to bounce the laser / maser off of, then you dont need to build big towers. Either way your communications beam will be affected by weather conditions (mostly humidity).
The sattelite beam would probably perform better in general. It has a longer path, but less of the transmission path is through the dense part of the atmosphere.
geosynchonous orbit is very high latency and thus not accaptable for most communication. Low earth is okay but now you need a lot of sattelites just so one is in view.
Has to be an extra 70+ meters higher than that because as your math shows, the straight line will intersect the curvature of the earth meaning any container ship passing would block the signal.
What is the height of the laser beam above the horizon at distance d1?
The picture and the calculator implies it is 0.
Now imagine something with non zero height is sitting at the curvature midpoint at distance d1. Container ships are 70+ meters high.
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.
Also, air is turbulent. Glass and plastic are not.
Laser communication between space and ground is achievable, but only because there's so much less atmosphere in between.
Granted, advancements in laser communication may make free space optics more effective in the future, but it's not effective right now.
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.
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.
Great point. We have some new tools since the original optical telegraph.
The original did have error correction codes to prevent man-in-the-middle attacks but the wiki page has a story about how that was defeated
Stupid: somewhat (isn't this just direct satellite communications?)
applicable: absolutely not since Estlink is not about communication but power transfer,
Hilarious: yup
Point to point communication is already pretty well served by microwave links, no?
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.