Particle physics experiments

New book about 12 experiments that changed the world dismisses the role of beautiful theory in physics

Matter of Everything tells the story of physics through experiments. Any book on the history of science intended for a general audience will, of necessity, be something of a distortion. The question is whether the distortion is useful: does it offer a new perspective on the history of physics? While there’s a lot to like about the book, I found it largely polemical and unnecessary.


Review: The Matter of Everything: 12 Experiences That Changed the World – Suzie Sheehy (Bloomsbury)


Here’s what I liked about the book: it’s extremely detailed. It takes us through 12 important experiments within physics from around the last century and a half.

Experiments range from the study of X-rays and the nature of light in the early 20th century to the early development of particle accelerators to detect and study subatomic particles throughout the 20th century, culminating in the modern era of Big Science and the use of the Large Hadron Collider to find the Higgs boson. They are described in a rigorous and accessible manner.

A technician works in the tunnel of the LHC (Large Hadron Collider) of the European Organization for Nuclear Research, CERN, in 2016.
Laurent Gillieron/AP


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Rigor and accessibility are clearly opposed, at least for a non-technical public. The book handles this compromise beautifully. Complex experiments are described in an easy to understand way.

The role these experiments play in pushing the frontiers of particle physics – the study of an ever-widening range of very small bits of reality, including those that make up matter like electrons, as well as the forces that bind them – is also well explained.

This is done without the need to take the reader through the details of some towering theories, including: the various quantum field theories within the standard model of particle physics.

Author Suzie Sheehy, an Australian physicist with academic duties at the universities of Oxford and Melbourne, also does an incredible job of explaining the wider implications of the experiments being considered. Sheehy is an expert in accelerator physics: the design and operation of particle accelerators to conduct experiments.

Particular attention is given to spin-off technologies developed during the construction of particle accelerators, including the development of magnetic resonance imaging (MRI) as well as the production of radioisotopes for use in medical imaging more generally.

The point is well made that the development of these technologies was not a goal of scientific investigation but an unpredictable by-product. A caveat underlies much of the discussion about these technologies: industry should serve science, not the other way around.

I also liked the taste of the book for the ingenuity of the inventor. For each of the 12 experiments described, a common story unfolds: there is something we want to test but we just don’t know how to do it.

Scientists have to invent new ways to deal with electricity, magnetism, etc., just to be able to carry out their experiments. The world of experimental particle physics suddenly seems familiar: scientists are do-it-yourselfers, crafting new equipment the way one might invent a new kitchen utensil on the fly with tape and a healthy dose of optimism.

A twisted story

As stated, The Matter of Everything is an inevitable distortion of the history of physics. One of the main distortions lies in the central premise of the book. The 12 experiments chosen fall within the field of particle physics. Whether by design or by accident, the history of 20th century physics is being recast as the history of particle physics.

To say that leaves a lot out is an understatement. The Standard Model of particle physics is matched, in rigor and experimental confirmation, only by the theory of general relativity.



Read more: Explainer: Einstein’s Theory of General Relativity


While the Standard Model describes the world of particles and their interactions, General Relativity describes the large-scale structure of the universe and gravity.

In the 20th century, general relativity was both motivated and ultimately confirmed by a fascinating array of experiments, from the ingenious interferometer experiments at the start of the 20th century to the detection of gravity waves in 2015.



Read more: Gravitational waves discovered: Scientists explain why it’s so important


The focus on particle physics-related experiments not only paints an odd picture of 20th century physics, but also tends to cast the Standard Model in a more favorable light. Because we now know that the standard model is somehow incomplete. The Standard Model “conflicts” with General Relativity. Both theories need to be replaced.

A more balanced account of the history of 20th century physics might have included a wider range of experiments. Of course, one book can’t cover everything. But a few remarks on what is left out should be made. Otherwise, an idiosyncratic view of the history of 20th-century physics quickly turns into a polemical account of “real” physics.

Experience and theory

Why experiments? This is a question I asked myself throughout the book. Ultimately, the answer appears to be political. The book strives to make the reader understand the importance of experimental physics. Experiments are where the action is in science. Progress can only be made by gathering empirical data.

This focus on the experimenter as a pioneer, forging their way into new scientific terrain, is at best a half-truth. The companion of the experimenter is the theoretician. Theoretical work and experimental work usually go hand in hand. Theoretical physics, however, seems to be understated throughout the book. This is puzzling, given that theories are twice as essential as experimental work.

Trajectories in a cloud chamber.
Image by Gordon Fraser/CERN, http://cerncourier.com/cws/article/cern/28742), CC BY

First, theories are generally needed to generate hypotheses for experimental testing. Many experimental works test the predictions of known theories in order to confirm them. There are, of course, cases in which an experiment is conducted and produces results that defy all known theories. But even then, it is the interplay between theory and experiment that drives science forward.

Second, theories are needed to make sense of empirical data. Some theory is usually needed to understand how a given experiment works.

One example is the Large Hadron Collider – a massive ring of electromagnets used to accelerate particles to high speeds before smashing them together, to see what they’re made of. The experiment is so complex that understanding it requires grasping a range of theories from different fields of science. Experimental data in a vacuum makes almost no sense. Theories provide context for experimental data.



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The removal of theoretical work in physics is part of the gimmick of the book. But, again, the picture this gives of 20th century physics is unrealistic. The history of 20th century physics is as much the story of a beautiful theory as it is of an ingenious experiment. Again, it’s hard not to see the emphasis on experimentation as some sort of normative statement about how science should be practiced.

lost voices

People play a big part in the matter of everything. Glorious experimental machines are set against a backdrop of tinkering and toiling scientist-inventors. This focus on people is welcome. It helps to humanize the history of 20th century physics and gives the reader the feeling that they too could contribute to science, if they wandered around the shed long enough.

That being said, the book could have said more about the scientists who are widely credited with being unfairly overlooked in the history of their field. As the book itself recognizes, there is, for example, a need to tell the story of women scientists.

Given this, I found the omission of Marie Curie and her daughter Irene striking. Marie and Irene enter and exit the book at various points, but their story is never properly told.

Marie and Irene Curie.
Wikimedia Commons


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This is especially odd given that both were involved in experimental work in particle physics and one was a Nobel laureate. In the end, the book fails to fully heed its own warning, and we are left with a history of physics with notable shortcomings. It’s a shame, because it was an opportunity to set the record straight.

Limits

Overall, The Matter of Everything suffers from serious limitations. It purports to be a history of 20th century physics but, at best, tells the story of experimental particle physics.

Theoretical work is missing, as are some of the experiments related to gravitational work in physics. The book also has significant shortcomings when it comes to the scientists themselves.

So I don’t recommend the book as a complete history of 20th century physics. But read it if you’re interested in particle accelerators and want to know why they’re so important to everyday life, not just big science.