Relativity says that light always moves in a straight line through empty space, and always at the same speed in a vacuum, no matter what your observation point.
它指出光在真空中走直线，且在真空中光速恒定，不论你的观测点如何。
2
For high-speed and low-drive -power light, modulation, the advantages of the use of asymmetric strip line was shown.
It is applied for the special line with steep gradient and small radius of curvature. This tourist car which runs with light load and low speed has high safe ty performance.