# Satellite Laser-Ranging as a Probe of Fundamental Physics

## TL;DR

This paper demonstrates the use of satellite laser-ranging to test the weak equivalence principle with unprecedented precision, confirming it to about one part in a billion using laser-ranged satellites.

## Contribution

It provides the first high-precision test of the weak equivalence principle at new ranges and with new materials using satellite laser-ranging.

## Key findings

- Confirmed the weak equivalence principle to approximately one part in a billion.
- Achieved testing at previously untested ranges and with new satellite materials.
- Supports the validity of General Relativity in Earth's gravitational field.

## Abstract

Satellite laser-ranging is successfully used in space geodesy, geodynamics and Earth sciences; and to test fundamental physics and specific features of General Relativity. We present a confirmation to approximately one part in a billion of the fundamental weak equivalence principle (uniqueness of free fall) in the Earth's gravitational field, obtained with three laser-ranged satellites, at previously untested range and with previously untested materials. The weak equivalence principle is at the foundation of General Relativity and of most gravitational theories.