Speed of light a laser beam is swept quickly across a distant object, the spot of light can move faster than "c", although the initial movement of the spot is delayed because of the time it takes light to get to the distant object at the speed "c". However, the only physical entities that are moving are the laser and its emitted light, which travels at the speed "c" from the laser to the various positions of the spot. Similarly, a shadow projected onto a distant object can be made to move faster than "c", after a delay in time. In neither case
Speed of light second, these measurements of small fractions of a second must be very precise. The Lunar Laser Ranging Experiment, radar astronomy and the Deep Space Network determine distances to the Moon, planets and spacecraft, respectively, by measuring round-trip transit times. The speed of light has become important in high-frequency trading, where traders seek to gain minute advantages by delivering their trades to exchanges fractions of a second ahead of other traders. For example, traders have been switching to microwave communications between trading hubs, because of the advantage which microwaves travelling at near to the speed of light in air, have over