Without Einstein, your sat-nav would be kilometres wrong.
Without Einstein, your sat-nav would be kilometres wrong — every single day. Here's why. GPS works by timing signals from satellites that carry extraordinarily precise atomic clocks. The problem is that those clocks don't tick at the same rate as clocks on the ground. Einstein showed that speed and gravity both affect how fast time passes. Up in orbit, away from Earth's gravitational pull, the satellites' clocks run very slightly fast compared to ours. Leave that gap uncorrected and your phone's position drifts by several kilometres within twenty-four hours. So engineers baked Einstein's equations directly into every GPS receiver. The mathematics of relativity runs quietly in the background every time you navigate somewhere. Physics that once seemed impossibly abstract is now the reason you don't miss your turn-off. Follow Deep Field Vault for more of the universe hiding in plain sight.