Figure 1
Illustration: Alan Stonebraker

Figure 1: Atom interferometers can measure daily changes in the local gravitational acceleration (purple arrows) on Earth arising from violations of the laws of relativity. Positions of the Sun indicate the passage of the day, while the orientations of the purple arrow indicate the corresponding direction of the acceleration. The precise way in which the acceleration varies in direction and magnitude over time can be used to determine a set of coefficients whose nonzero values would indicate Lorentz violation. Inset: The local gravitational acceleration is obtained by measuring the difference in phase between the matter waves of cesium atoms moving in the gravitational field.