I wonder what it would take to get it further towards the speed-of-light limit. 2 ms for, say, 3 km is 1500 km/s, or around 0.75% the speed of light in fiber (

I wonder what it would take to get it further towards the speed-of-light limit. 2 ms for, say, 3 km is 1500 km/s, or around 0.75% the speed of light in fiber (~200,000 km/s). I wonder what the bottleneck is.