Physical Constants Have Remained Unchanged For 7.2 Gyr

A new paper determines from astronomy measurements that there have been no changes to the electromagnetic coupling constant (a.k.a. the fine structure constant), to the proton-electron mass ratio, or to another property of the proton called the proton g-factor, in the last 7.2 billion years. The constraints on any change in that time period are very tight.

This confirms all prior studies of this type.