The great circle distance between SF and Amsterdam is about 5,450 miles. A round trip is 10,900 miles. At the speed of light, that's 58.5 milliseconds. So in theory, infinitely efficient computers (and some sort of light-in-a-vacuum wire) and networking equipment could knock 60% off that time, but no more.
However, I suspect one big problem is that there are a number of hops between the Netherlands and San Francisco. I suspect there's not a fiber line that goes right through Idaho to Greenland, then, Scotland, and then the Netherlands. I'm curious what the actual route is be and how many miles are involved.
Okay, so 80ms of light speed travel, or about 120ms assuming today's fiber optic medium, so that only leaves maybe 30ms of potential improvement. Sounds very believable, thanks!
Yeah, but the faster speed of light through vacuum can still be enough to make up for the longer path.
Back-of-the-envelope calculation: at an altitude of 550km and minimum elevation of 25 degrees above the horizon, a single Starlink hop could cover a maximum of 1880km of distance along the earth's surface, with a ground-satellite-ground length of 2068km.
So the total distance traveled through space is about 10% farther, but the signal goes 50% faster than through fiber, which is enough to cut your round-trip time from about 19ms to 14ms (plus any extra latency introduced by routers). That's nothing to sneeze at.
The 3rd parent was suggesting hollow core fiber, which I _think_ is supposed to reduce the distance travelled to near fiber length through band gap effects i.e eliminating the extra distance travelled in regular fiber core due to total internal reflection, hence the lower latency. Light still travels about 2/3 the speed in silica core compared to in a vacuum, so it would make the fastest possible speed 2*10^8 m/s (per meter of actual fiber)
So in order for LEO satellites to compete, the total distance from A to B must be less than 1.5 times the equivalent of hollow core fiber on the ground.
Oh god I have to do trig! So finding the ratio of the the horizontal (ground) to vertical (altitude) when the hypotenuse is 1.5 * the horizontal =
(1.5**2-1)**0.5 = 1.118033988749895.
i.e 1:1.11 half-ground:altitude
550 / 1.118033988749895 * 2 = 984km
i.e A single hop Satellite at 550km altitude would beat a straight line (ignoring curvature, bored through the ground) hollow core fiber at 984km (I _think_ :P). Realistically you can probably lower the distance since we don't actually get straight line A-B fiber, but that's still quite a long minimum distance.
Disclaimer: there are too many assumptions and approximations in here, it's just for fun.
[edit]
whoops, hollow core is supposed to be almost speed of light, so actually it's not much of a competition any more in the idealised case.
Direct point to point conduits carrying fiber would reduce latency to a worst case of 21ms, but requires a fiber that doesn't melt at core temps (around 5200C).
No. The deepest we've ever sent anything is a little over 12Km; the crust's minimum thickness is about 40Km, and the diameter of the Earth is about 12700Km.
