Another neat hack for estimating lower limits on latency is that light travels roughly 1 foot in a nanosecond. So if two servers are in a room 100 feet apart,

Another neat hack for estimating lower limits on latency is that light travels roughly 1 foot in a nanosecond. So if two servers are in a room 100 feet apart, the time it takes for them to communicate cannot be lower than 100 ns.