3 ms·

Remember, the speed of light in fiber optic cables is ~1.47x slower than its speed in a vacuum, which means an equatorial transit is 0.2s instead. This differen

Remember, the speed of light in fiber optic cables is ~1.47x slower than its speed in a vacuum, which means an equatorial transit is 0.2s instead. This difference is significant enough that some High Frequency Trading firms have used microwave links to reduce latency from Chicago to New York from 7.5ms to 5ms. https://arstechnica.com/information-technology/2016/11/private-microwave-networks-financial-hft/ https://arstechnica.com/information-technology/2016/11/priva...

hwillis 4y ago
Well. Significantly more than that due to latency from switches etc and also because of the fact that there's so little land along the equator, meaning there's only one cable that travels roughly equatorially. It's from Fortaleza, Brazil to Kribi, Cameroon: https://www.submarinecablemap.com/ https://www.submarinecablemap.com/ If you set up a bunch of good first-surface mirrors, I'm pretty sure you could get to pretty much the speed of light. You'd have to put them pretty high up in the air to avoid hitting things (a problem for cables as well, obviously) but putting the beam 2km in the air would still only lengthen the path by 4pi km, or .03%. I have always found it very neat that the propagation speed of a light wave in glass is roughly the same as electrical waves in a coaxial cable. Both are shockingly slow compared to air/vacuum, but for completely different reasons. In both cases the advantages in signal integrity are immense.
- metadat 4y ago
  Discussed just 1 month ago: https://news.ycombinator.com/item?id=33110478 https://news.ycombinator.com/item?id=33110478 (175 points, 162 comments)
- whatshisface 4y ago
  They're both light waves, and it's for the same reasons (the medium/waveguide stores and releases energy).
  - hwillis 4y ago
    one would usually consider a waveguide and a medium to be very different, but good job! You've managed to be condescending while also remaining completely opaque to anyone who does not already completely understand both cases.

hwillis 4y ago

Well. Significantly more than that due to latency from switches etc and also because of the fact that there's so little land along the equator, meaning there's only one cable that travels roughly equatorially. It's from Fortaleza, Brazil to Kribi, Cameroon: https://www.submarinecablemap.com/ https://www.submarinecablemap.com/ If you set up a bunch of good first-surface mirrors, I'm pretty sure you could get to pretty much the speed of light. You'd have to put them pretty high up in the air to avoid hitting things (a problem for cables as well, obviously) but putting the beam 2km in the air would still only lengthen the path by 4pi km, or .03%. I have always found it very neat that the propagation speed of a light wave in glass is roughly the same as electrical waves in a coaxial cable. Both are shockingly slow compared to air/vacuum, but for completely different reasons. In both cases the advantages in signal integrity are immense.

metadat 4y ago
Discussed just 1 month ago: https://news.ycombinator.com/item?id=33110478 https://news.ycombinator.com/item?id=33110478 (175 points, 162 comments)
whatshisface 4y ago
They're both light waves, and it's for the same reasons (the medium/waveguide stores and releases energy).
- hwillis 4y ago
  one would usually consider a waveguide and a medium to be very different, but good job! You've managed to be condescending while also remaining completely opaque to anyone who does not already completely understand both cases.