One line across the globe

A line across the Pacific

Let's pull back from the glass thread. First you see the cable, then the sea floor, and finally the whole Earth. The glass thread you just saw is one line across the floor of the Pacific Ocean, from Busan to Oregon in the United States. Along the route in this picture, it is about 9,200 km long. Light crosses it in about 45 ms.

Why?Light travels about 300,000 km in one second. Inside glass it slows down to about 200,000 km per second. Even so, it crosses nearly half the world in less than 0.05 seconds.

Learn moreReal cables go around undersea mountains and deep trenches, so they are longer than the route in the picture. Several cables connect Korea and the US, and some pass through Japan. The route in the picture is simplified.

Time

10 ms → 22 ms

Simplified route · light in glass at about 200,000 km per second