Speed of light can only travel a maximum of about in a single cycle. Processors must therefore be placed close to each other to minimize communication latencies; this can cause difficulty with cooling. If clock frequencies continue to increase, the speed of light will eventually become a limiting factor for the internal design of single chips. Given that the equatorial circumference of the Earth is about and that "c" is about , the theoretical shortest time for a piece of information to travel half the globe along the surface is about 67 milliseconds. When light is travelling around the globe in an optical
Road speed limits in the United Kingdom change in the crash rate on the M6 in Cheshire or on the M1 in Northamptonshire. Although these 70mph speed limit road signs are normally not used on motorways (the National Speed Limit road sign is normally used, as it makes it more understandable for motorists their maximum speed on the type of vehicle they're using), they have been used on non-motorway special roads within the UK, and across the motorways within Scotland. Speed limit enforcement is used to check that road vehicles are complying with the speed limits. Methods used include Fixed speed cameras, Average speed cameras and also