How do you know what time it is right now? One good way to find out is to check with the time standard at the US Naval Observatory. You can always go to that website but it is also the time standard used by GPS, which transmits the time information as part of position determination. How about your cell phone? That time generally comes from the USNO. You could set your local network to use the USNO Network Time Protocol (NTP) servers or do it yourself and pull it directly from GPS for your network. How exactly is that time measured? One second at a time, as shown in this great video from The Atlantic interviewing Dr. Demetrios Matsakis, Chief Scientist for USNO’s Time Services:
