Okay since we're not going to improve the speed of light any time soon, here's my idea for speeding up CA to NL roundtrip: let's straight shot a cable through the center of the earth.
From CA you will end up off the coast of Madagaskar, and from the NL somewhere near New Zealand. You do not have to go very deep inside the earth to get straight from CA to NL.
https://idlewords.com/2007/04/the_alameda_weehawken_burrito_...