Particle physics experiments

The Matter of Everything by Suzie Sheehy review – 12 experiences that changed the world | science and nature books

In 1895, German physicist Wilhelm Röntgen noticed that a phosphor-coated screen emitted green light when exposed to a cathode ray tube. He quickly realized that he had found a new invisible ray. Asked what he thought when he saw this green light, he replied: “I didn’t think about it. I investigated. In fact, he spent seven weeks investigating, locked in his lab and only came out when his wife, Anna, insisted that he eat something. He rewarded her concern for her welfare by using the unknown rays to make an image of her hand on a photographic plate. This proved that they could travel through skin and flesh: the plate revealed his bones and his wedding ring. When she saw the image, she was appalled saying, “I saw my death!

In his notebook, Röntgen used a letter to designate the unknown rays: “x-rays”. As Sheehy puts it, it’s “probably the best unintentional branding in the history of physics.” Within a year of its discovery, X-rays were being used to find shrapnel in the bodies of soldiers on the battlefield.

The question of how cathode ray tubes emit X-rays led to the fundamental discovery in 1897 of the electron – the first subatomic particle. Atoms were no longer considered the smallest indivisible entity in nature. Indeed, the next century would reveal a whole catalog of particles, completely transforming our understanding of matter.

The key question for Australian physicist Suzie Sheehy is: “What is matter and how does it interact to create everything around us, including ourselves? She describes her work, in which she tries to answer this question by studying the tiniest constituents of nature and the forces that govern them, as “one of the most impressive, complex and creative adventures humans have ever undertaken”.

His specialty is accelerator physics, a field that deploys some of the greatest machines ever invented to manipulate matter on a small scale. An esoteric realm, you might think, that has little to do with our daily lives. But as it shows, particle physics has radically changed the way we live over the past century. Your nearest hospital almost certainly has a particle accelerator, your smartphone relies on quantum mechanics, and Tim Berners-Lee invented the World Wide Web to help scientists share the vast amounts of data produced by particle experiments.

Sheehy is not a theoretician, a modern-day Einstein creating speculative hypotheses about the nature of reality. Rather, she is an experimental physicist who designs equipment that pushes the boundaries of current technology and generates new data and questions. It is a demanding job that requires curiosity, passion and tenacity.

In her book – which is often complex but never less than fascinating – she uses 12 experiments to show how particle physics has shaped our understanding of the world we live in. It begins with the discovery of Röntgen, before moving on to the first experiments showing that the atom was composed mainly of empty space, with a dense nucleus surrounded by electrons, and until the creation of the first particle accelerators in the years 1930.

After the success of the top-secret Manhattan Project to build an atomic bomb during World War II, physicists took a large-scale, collaborative approach. This was the beginning of Big Science. Gone are the days when solitary researchers like Röntgen worked in their laboratories – physics was now about gigantic, expensive machines, designed by groups of experimental scientists, maintained by specialist engineers and operated by dedicated staff. The results were interpreted by teams of researchers around the world. These methods produced a deluge of new particles, from pions to positrons.

The quest culminates – for now at least – with CERN’s Large Hadron Collider, a 27 km circular proton collider, 100 meters underground near Geneva. It took two and a half decades to build, overseen by Welsh physicist Lyndon Evans, affectionately known as “Evans the Atom”.

Sheehy, who worked at CERN, guides the reader through this triumph of engineering and scientific cooperation, “one of the greatest experiments ever built”. Described as the largest machine on Earth, it is so sensitive that it must be corrected for incredibly small effects, such as the movement of the earth’s crust due to the sun and moon, or the passage of high-speed trains – anything that disrupts the proton orbit.

A proton is a million million times smaller than a grain of sand. The LHC “delivers two beams of hundreds of billions of protons at 99.999999% of the speed of light, focuses them to less than the width of a hair, and then collides them”. Its task was to detect a unique and very elusive particle: the Higgs boson, predicted in 1964. This goal was achieved in 2012, thanks to the collaboration of half of the world’s 13,000 particle physicists, and by s drawing on the resources of 110 countries.

Ultimately, as Sheehy tells us, physics isn’t just about researching how the Universe works: “Physics is about people.” His journey through the history of particle physics reveals the extraordinary ingenuity of experimental scientists and their selfless dedication to answering the big questions about matter and the universe. It’s a field that has brought enormous benefits to mankind, from new medical imaging technologies to cancer treatments. But ultimately, it just might be an example of physicists working together to solve problems that will prove most valuable to us all, at a time when the world is facing unprecedented challenges. As Sheehy says, “There is nothing more powerful than humans coming together in a collaborative effort.”

The Matter of Everything: Twelve Experiments that Changed Our World is published by Bloomsbury (£20). To support the Guardian and the Observer, order your copy from Delivery charges may apply.