After years of confusion, a new study confirms the proton is tinier than once thought. That enables a test of the standard model of particle physics.

I don't know where he got this idea (surely not from the internet), but Eratosthenes estimated the radius of the Earth by looking at two shadows at two different locations on the Earth. This diagram ...

A discrepancy in the measured size of the “deuteron” increases the chance that something is amiss in our understanding of atoms. The same group that discovered a curious discrepancy in measurements of ...

Puzzling problem: Karsten Schuhmann (left) and Aldo Antognini of the Paul Scherrer Institute inspect the laser system that was used for the laser spectroscopy measurements on muonic deuterium.

With 3D printed arms of fixed measurements, the depth reading from a set of digital calipers can be used to calculate the radius of a curve. Specialized tools that focus on one particular job tend to ...

A puzzle at the heart of the atom refuses to go away. The most precise measurement yet of the proton’s radius confirms that it sometimes seems smaller than the laws of physics demand – an issue that ...