We take it for granted that gravity pulls things towards the Earth. But in reality this is just one of many explanations. And they are all equally made up.
The kilogram is the last international measurement standard that relies on a precisely crafted physical object. This standard-bearer will soon be replaced by space-age measurements based on physical constants.
Nearly two years ago, LIGO opened up a new window onto the cosmos when they discovered gravitational waves. But what has happened since and how could it change our understanding of space, time, and gravity?
The model used to measure the mass of particles such as protons and neutrons has been used by physicists for almost 50 years. Now Tomas Brauner and his research collaborators discovered that two terms in the model’s equation were missing.