For half a century, global positioning rested upon microwave-frequency atomic clocks ticking aboard satellites orbiting twenty thousand kilometers overhead. While transformative, those systems remain vulnerable to orbital drift and ground-station jamming.
The advent of optical lattice atomic clocks—measuring transitions in strontium atoms interrogated by coherent laser light at optical rather than microwave frequencies—delivers a thousand-fold leap in timing resolution.
“We are measuring time so precisely that elevating the instrument by two centimeters registers gravitational time dilation from Earth’s mass.”
