Article said light year was defined using the time the Earth takes to orbit the sun. It isn't -- its defined in terms of the Julian year (365.25 days of 86400 SI seconds each). The reason for this is that the time it takes for the Earth to orbit the sun can be known only to limited accuracy, and varies over time. Thus if the light year was defined based on that, it would not be a stable nor accurate measurement. (Although arguably the amount of inaccuracy and stability would be insignificant over the distances the light year is used to measure.)
Axel removed this:
- Under normal circumstances, no material object can travel faster than the speed that light propagates in a vacuum. Particles routinely move faster than light in some media, such as the water used as coolant in nuclear reactors(see Cherenkov radiation). However, even the general light-speed rule seems to be abrograted by cases of quantum tunneling, and several laboratory experiments have suggested that light can, in some cases, move faster than the standard 299,792,458 m/s. See Theory of relativity.
Is it incorrect, or just in the wrong place? Can it be be moved to speed of light? -- Tarquin