That's a very good point. I had never thought about the difficulty of communicating with sub-- it makes sense that it's really hard though, with such a large volume of water. https://en.m.wikipedia.org/wiki/Communication_with_submarines

Agreed, why drill a difficult hole when you could build a Dyson sphere? My main point was just considering what level of technology it would require to actually accomplish the feat.

It is possible though that some unexpected mechanism would make it more feasible than expected, and communication straight through the planet would have some serious benefits. Especially if it was a straight hole, and light was sent directly through it, without even using a fiber optic cable.

Interesting discussion of neutrino communication: https://physics.stackexchange.com/questions/199606/is-neutrino-based-communication-possible

Plus the inner core is a 1500 mile diameter sphere of a solid iron alloy.

At some point it'll probably be possible, but I'd imagine that's pretty far future territory.

I wonder at what point in the future it will be even possible? Probanly quite a long time. Right now, even if the entire GDP of earth was funneled into it, I'm sure they wouldn't be able to do it.

Simply because of light traveling slower in fiber optics than a vacuum?

If you cut straight through the earth, that would. Change the equation.