“Tapestries are made by many artisans working together. The contributions of separate workers cannot be discerned in the completed work, and the loose and false threads have been covered over. So it is in our picture of particle physics.” —Sheldon Lee Glashow, 1979
Exploring the subatomic world
In 1897, J.J. Thomson and his assistant Ebenezer Everett used this delicate piece of glassware to investigate cathode rays. Scientists around Europe were debating the cause of these mysterious glowing beams, created by passing an electric current through a vacuum tube.
Thomson showed that cathode rays were made up of negatively charged particles, much smaller than atoms. The electron, as it came to be known, was the first subatomic particle to be discovered.
Thomson later won a Nobel Prize for his research on electricity in gases.
Imagining the atom
Manchester, 1911: Ernest Rutherford and his team discovered another subatomic particle, later named the ‘nucleus’. This model depicts the atomic theory of Rutherford and Niels Bohr, with rings of electrons orbiting a nucleus. This structure became the classic image of the atom in popular culture.
The particle zoo
In 1946, the V-shaped track in this cloud chamber made by George Rochester and Clifford Butler in Manchester indicated an unexpected type of particle. First called the ‘strange particle’, it’s now known as the K-meson. There are now hundreds of known particles; most are only produced fleetingly in high-energy particle accelerators or by cosmic rays.
Cloud chamber photograph of antipositron (1932-08-02) by Carl David AndersonScience Museum
When Paul Dirac predicted the existence of antimatter – a ‘mirror image’ of ordinary matter – in 1928, few scientists took him seriously. But this photograph, taken by Carl Anderson in 1932, proved him right. The faint track crossing the chamber shows a positron, the anti-particle of the electron.
All the different particles and antiparticles fit together in what’s called the Standard Model of particle physics. Here’s a handy guide from our friends Max the demon and Tangle the cat.
Hunting the Higgs
In 1964, Robert Brout, François Englert, Gerald Guralnik, Carl Richard Hagen, Tom Kibble and Peter Higgs put forward a bold new idea to explain how fundamental particles acquire mass. Higgs suggested that if they were right, a new particle should exist.
On the evening of 3 July 2012, Higgs shared this bottle of champagne with theoretical physicist John Ellis and Chris Llewellyn Smith, former director of CERN, the European particle physics laboratory. The next day, CERN announced the discovery of the particle Higgs had proposed in 1964: the Higgs boson.
Competition and collaboration
During the 20th century, particle physics was a key tool of Cold War strategy: it was a symbol of economic prowess and had applications in weapons research. But the shadow of the atomic bomb also inspired physicists to develop international research collaborations as a means of building peace.
The world’s greatest experiment
Today, with particle physics facilities requiring vast resources, Europe, the US and Russia are all among the collaborators on the Large Hadron Collider (LHC) at CERN. Around 3,000 people are based at CERN’s campus at any given time, with more than 10,000 scientists globally working on LHC data.
The Large Hadron Collider is housed in an underground tunnel 27km in circumference. It’s so huge that one of the most efficient ways to get around is by bike! This one was used by Roberto Saban, the LHC’s Head of Hardware Commissioning, during construction.
Particle physics and industry have always had close links, exchanging equipment and expertise. Thomson’s discovery gave rise to the electronics industry, sparking a consumer revolution in technology – prominent today in the devices we use to browse the World Wide Web, which was invented at CERN.
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