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Comment by nabla9 | Hacker News Reader

You would have to map out the cables to do that.

Light in fiber optic cable travels roughly 70% of the speed of light ~210,000 km/s Earth's circumferences is ~40,000 kilometers. Direct route from the other side of Earth to another would be roughly 100 milliseconds, round trip 200 ms.

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It’s pretty trivial to do this, any big fiber company will provide you with Google Earth KMZ files (protected by NDA) when considering a purchase. This is absolutely necessary when designing a redundant network or if you want lower latency.

Since light travels at 100% the speed of light in a vacuum (by definition), I have wondered if latency over far distances could be improved by sending the data through a constellation of satellites in low earth orbit instead. Though I suspect the set of tradeoffs here (much lower throughput, much higher cost, more jitter in the latency due to satellites constantly moving around relative to the terrestrial surface) probably wouldn't make this worth it for a slight decrease in latency for any use case.

I am pretty sure this was one of the advertised strength of Starlink. Technically the journey is a bit longer, but because you can rely on the full speed of light you still come out ahead.

In the past we just had line of sight microwave links all over the US instead.

I think it's just too damn expensive for your average webapp to cut out ten milliseconds from backend latency.

Yes. There are companies that sell microwave links over radio relay towers to various high frequency traders.

Hollow core fiber (HCF) is designed to substantially reduce the latency of normal fiber while maintaining equivalent bandwidth. It's been deployed quite a bit for low latency trading applications within a metro area, but might find more uses in reducing long-haul interconnect latency.

Absolutely! The distance to LEO satellites (like spacex or kuiper) is low enough that you would beat latency of fiber paths once the destination is far enough.

Cable mapping would be nice but 100ms is a meaningfully long amount of time to make straight-line comparison worthwhile

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