The ugly, fractured reality of the cosmos deserves our attention

Emission nebula Sharpless 2-106

Not all the universe is in balance

NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Why would cosmologists, philosophers, astronomers and particle physicists gather to talk about symmetry? It sounds odd. But symmetry in a law of nature implies something extremely powerful and beloved of physicists: conservation.

It is a difficult concept though. To make life easier, consider Newton’s classical mechanics, via an experiment of throwing a ball. We get the same result in London as in Sydney, showing Newton’s ideas have “translational symmetry” – it doesn’t matter where we move the experiment.

The work of mathematician Emmy Noether, who pioneered the idea of symmetry in fundamental physics, tells us that this means momentum is conserved. Turn to the right and repeat your experiment, demonstrating rotational symmetry, which implies conservation of angular momentum. Astoundingly, your experiment being the same today as tomorrow implies energy conservation.

Other symmetries are hidden within the