The reconciliation of general relativity and quantum mechanics ... of strontium atoms vertically in grids of laser light.

By measuring the tiny shifts of oscillation frequency in these ultra-precise clocks, researchers are able to explore the influences of Einstein's theory of relativity on quantum systems.

This is no ordinary clock — it's a highly precise instrument built to put Einstein’s theories of special and general relativity to the test. ACES will measure time with unmatched accuracy ...