# How accurate can a clock be?

Atomic clocks now agree to within a second over many millions of years, and newer optical clocks do better. At that level a clock notices a height difference of a few centimetres, which links timekeeping to gravity. verify

Connects to:
- [Clocks](https://mapideas.org/i/ti_clocks)
- [Time and motion](https://mapideas.org/i/ti_relativity)

Sources:
- [Wikipedia: Optical lattice clock](https://en.wikipedia.org/wiki/Optical_lattice_clock)

Source: https://mapideas.org/i/q_time_clock · open on the map: https://mapideas.org/#q_time_clock