4 ms·
The French definition of the meter can also be described as "such that the distance from the equator to the North Pole, through Paris, is 10,000 km." This is a
by troymc 2y ago
The French definition of the meter can also be described as "such that the distance from the equator to the North Pole, through Paris, is 10,000 km." This is a handy number to know!
It means, for example, that the circumference of the Earth is four times as big, or 40,000 km (roughly speaking; I know that the Earth is smooshed due to its rotation etc.). And then to estimate the diameter, you just divide that by pi:
40,000 km / 3.14159... ~= 12,732 km
and half that is the radius of the Earth:
r_Earth ~= 6366 km
- troymc 2y agoOne use case is to estimate the minimum latency for communications between two points on opposite sides of the Earth, which would be how long it takes light to travel halfway around the Earth: = 20,000 km / (speed of light) ~= 66.7 milliseconds
- whatshisface 2y agoNot quite the minimum. :-) Beams of neutrinos can be sent through the Earth and detected on the other side. https://www.livescience.com/19075-neutrino-particle-communications-message.html https://www.livescience.com/19075-neutrino-particle-communic...
- troymc 2y agoThis is true. Using a neutrino beam, the minimum latency would be approximately: (diameter of Earth) / (speed of light) ~= 42.5 milliseconds Some high-frequency traders might actually be able to justify the investment needed to enable such low-latency communications! Come to think of it, you could also use gravitational waves...
- gunian 2y agothe earth is flat everyone knows that it's how our lord and savior jesus christ made it