What’s beyond the standard model?

Filling holes in the standard model

In 1897, JJ Thomson discovered the first fundamental particle, the electron, using nothing more than glass vacuum tubes and wires. More than 100 years later, physicists are still discovering new parts of the Standard Model.

The standard model is a predictive framework that does two things. First, it explains what the basic particles of matter are. It’s things like electrons and quarks that make up protons and neutrons. Second, it predicts how these particles of matter interact with each other using “messenger particles.” These are called bosons – they include photons and the famous Higgs boson – and they communicate the fundamental forces of nature. The Higgs boson was not discovered until 2012 after decades of work at CERN, the huge particle collider in Europe.

The Standard Model is incredibly good at predicting many aspects of how the world works, but it has some shortcomings.

Notably, it does not include any description of gravity. While Einstein’s theory General relativity describes how gravity works, physicists have not yet discovered a particle transmitting the force of gravity. A true “theory of everything” would do everything the Standard Model can do, but also include messenger particles that communicate how gravity interacts with other particles.

Another thing the Standard Model can’t do is explain why a particle has a certain mass – physicists have to measure the mass of particles directly using experiments. Only after experiments have given physicists these exact masses can they be used for predictions. The better the measurements, the better the predictions that can be made.

Recently, physicists from a CERN team measured the strength with which the Higgs boson feels. Another CERN team also measured the mass of the Higgs boson more precisely than ever. And finally, there has also been progress in measuring the mass of neutrinos. Physicists know that neutrinos have a mass greater than zero but less than the currently detectable amount. A team in Germany continued to refine techniques that could allow them to measure neutrino mass directly.

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