Ask Ethan: How can we better measure G, the gravitational constant?

"Our physical universe, to the best of our understanding, can only be made sense of because it always obeys the same fundamental laws: everywhere and at all times. It isn't just the underlying laws of nature that apply to all physical systems, but a series of fundamental constants as well. Chief among these constants are h, Planck's constant that governs quantum physics, c, the speed of light in a vacuum that's the same for all observers,"

"Even though Newton introduced G in the late 1600s, it wasn't until 1798 that we were first able to measure it. 200 years later, we realized that many of our claimed refinements were in error, and that our uncertainties were still quite large. Even today, in 2025, G remains one of the least well-known fundamental constants, as the current figure still has a 0.0022% uncertainty on it, while h and c are now defined exactly."

Fundamental physical laws and constants such as h, c, and G underlie the behavior of all physical systems. Planck's constant h and the speed of light c are now defined exactly, while the gravitational constant G remains poorly known. G was introduced by Newton and first measured in 1798, but subsequent claimed refinements produced significant disagreements and persistent uncertainties. As of 2025, G carries an uncertainty of about 0.0022%. Measurements on Earth are notoriously difficult and inconsistent beyond quoted uncertainties. Measuring G from space is theoretically possible and could offer advantages, but practical and technical challenges make near-term space-based precision improvements unlikely.

Read at Big Think