This artful illustration of Einstein, some of his equations, and a rendering of a surreal clock helps us conceptualize the differing passage of time experienced by people in different locations and moving at different rates. Although time dilation had been measured for subatomic particles previously, it wasn’t until ~50 years ago that it was measured for an actual clock. (Credit: pasja1000/pixabay)

Einstein was right. Flying clocks around the world in opposite directions proved it.

Time isn’t the same for everyone, even on Earth. Flying around the world gave Einstein the ultimate test. No one is immune from relativity.

In 1905, our conception of how the Universe changed forever when Einstein put forth his special theory of relativity. Prior to Einstein, scientists were able to describe every “point” in the Universe with the use of just four coordinates: three spatial positions for each of the three dimensions, plus a time to indicate which moment any particular event occurred. All of this changed when Einstein had the fundamental realization that every single observer in the Universe, dependent on their motion and location, each had a unique perspective on where and when every event in the Universe would have occurred.

Whenever one observer moves through the Universe relative to another, the observer-in-motion will experience time dilation: where their clocks run slower relative to the observer-at-rest. Based on this, Einstein suggested that we could make use of two clocks to put this to the test: one at the equator, which speeds around the Earth at approximately 1670 km/hr (1038 mph), and one at the Earth’s poles, which is at rest as the Earth rotates about its…