Future Martian colonists will need a new relativistic clock (opens in new tab)

We think of atomic clocks as the definitive timekeepers. They are famous for being accurate down to the picosecond. Unfortunately, they are still subject to general relativity, so if you put them on a different planet, they will track time slightly faster or slower than on Earth, depending on the planet's gravity. In Mars' case, an atomic clock on its surface is sitting in a slightly shallower gravity well, meaning that time moves slightly faster there. Therefore, as we begin to expand our te...