I will note that this is the case for conventional fiber-optic cable. The newer hollow-core fiber cables transmit light at nearly c. As far as I know hollow-core has not seen wide-spread use, but it will be interesting if trans-continental connections switch over.
Any stretch of fibre you replace with hollow core fibre will see latency reduced to two thirds of what it was before. (It would be half if the speed of light in it were double what it is in normal fibre, but it's only 50% faster).
You say sans routing latencies, but these are very much significant for intercontinental communication:
I get 6ms ping to AWS eu-central, which is less than 100km by air from me. I get 114ms to AWS us-east-1, which is roughly 6500km. Now 6500km / (2/3 * c) = ~32ms. So if there were a fibre running in a straight line, time in the fibre would be 32ms. Of course it isn't running in a straight line, so let's say 50ms are pure "light traveling through fibre". Switching all of that to hollow-core would cut that to 33ms, so that's a savings of 17ms or roughly 15% of my total latency.
This is still a very nice savings, but very far off from cutting latency in half.
(Also, it's a single hop from my company network to DE-CIX, one of the largest internet exchanges in the world, so I feel confident saying my results aren't skewed by a bad uplink.)
That's a great point, I was curious so I looked it up. Google offered the following:
"The speed of light in air is about 299,705 kilometers per second, or 2.99705 × 10^8 meters per second. This is almost as fast as light travels in a vacuum, slowing down by only three ten-thousandths of the speed of light."
So seems like the speed of light in atmosphere is still a lot faster than fiber.
I will note that this is the case for conventional fiber-optic cable. The newer hollow-core fiber cables transmit light at nearly c. As far as I know hollow-core has not seen wide-spread use, but it will be interesting if trans-continental connections switch over.
Will adopting the new cables everywhere mean nearly halving latency all across the board? Sans routing latencies.
This would be huge for realtime gaming across continents.
Any stretch of fibre you replace with hollow core fibre will see latency reduced to two thirds of what it was before. (It would be half if the speed of light in it were double what it is in normal fibre, but it's only 50% faster).
You say sans routing latencies, but these are very much significant for intercontinental communication:
I get 6ms ping to AWS eu-central, which is less than 100km by air from me. I get 114ms to AWS us-east-1, which is roughly 6500km. Now 6500km / (2/3 * c) = ~32ms. So if there were a fibre running in a straight line, time in the fibre would be 32ms. Of course it isn't running in a straight line, so let's say 50ms are pure "light traveling through fibre". Switching all of that to hollow-core would cut that to 33ms, so that's a savings of 17ms or roughly 15% of my total latency.
This is still a very nice savings, but very far off from cutting latency in half.
(Also, it's a single hop from my company network to DE-CIX, one of the largest internet exchanges in the world, so I feel confident saying my results aren't skewed by a bad uplink.)
The area between a starlink receiver on the ground and a satellite isn’t a vacuum
That's a great point, I was curious so I looked it up. Google offered the following:
"The speed of light in air is about 299,705 kilometers per second, or 2.99705 × 10^8 meters per second. This is almost as fast as light travels in a vacuum, slowing down by only three ten-thousandths of the speed of light."
So seems like the speed of light in atmosphere is still a lot faster than fiber.
The speed of light in air is 99.97% of that in a vacuum, vs about 2/3 of c through fiber.
Is attenuation in a vacuum also better?
yes, glass has a non zero amount of absorption which is why Erbium amplification is required.