Imagine being a physicist in 1920, the year the Institute of Physics was formed. The ordered world of classical physics was being turned upside down by a rapid succession of startling discoveries and radical ideas. Quantum theory was emerging as the most perplexing and yet most promising way of understanding the secrets of the atomic world, while Albert Einstein had stunned the scientific community with his general theory of relativity. It challenged Newton’s laws of gravity with mind-expanding concepts such as curved space–time and predicted gravitational effects such as the bending of light, the first evidence for which had just been obtained by Arthur Eddington on his eclipse expedition of 1919.

Life for physicists had been very different just 30 years earlier, when it had seemed that all the major problems in physics had been solved. Classical mechanics could reliably predict the movement of objects on Earth as well as the planets and stars; the laws of thermodynamics had been put to work in the development of steam engines; and James Clerk Maxwell’s seminal equations had unified the theories of electricity and magnetism. Such breakthroughs had made sense of much of the observable world, and most physicists thought that their only remaining tasks would be to finesse existing models and improve the accuracy of their measurement techniques.

That view was first challenged in 1895, when German physicist Wilhelm Röntgen discovered X-rays, which could pass through solid objects and the human body – beautifully demonstrating his finding with an image showing the skeletal structure of his wife’s hand. Just a year later, while working at the National Museum of Natural History in Paris, Henri Becquerel was surprised to find that the uranium salts he had locked away in a drawer emitted radiation of their own accord. The discovery inspired Marie Curie, also based in Paris at the time, to perform pioneering experiments that led her to conclude that the radiation was emitted by the uranium atom itself – in conflict with the prevailing notion that atoms were indivisible. Physicists then had to come to terms with the discovery of the electron, made by British physicist J J Thomson in 1897. Five years later the New Zealander Ernest Rutherford and others confirmed that alpha, beta and gamma radiation were emitted by the spontaneous breakdown of heavy atoms into lighter ones.

Meanwhile, theorists were developing new models to explain puzzling electromagnetic phenomena that could not be reconciled with classical theory. In 1900 German physicist Max Planck had introduced the revolutionary idea that atoms could only absorb or emit energy in discrete “quanta” to resolve the energy distribution of blackbody radiation, a concept that Einstein exploited in 1905 to show that the photoelectric effect could be explained by treating light as quantized particles. That year went down in history as Einstein’s “annus mirabilis”, during which he also published papers on Brownian motion, special relativity and the equivalence between energy and mass.

“No physicist who has reached middle age can forget the romantic interest of the 10 years following 1895,” remarked American physicist Henry Bumstead during a lecture at Yale University in 1920. Summing up the mood of the time, he recalled how “startling discoveries followed each other in rapid succession and the physical journals were awaited with an impatience not unlike the desire for newspapers in wartime. But the news was all good news, and recorded an almost unbroken series of victories”.

Those 10 remarkable years at the turn of the century were followed by further breakthroughs that underlined the need for a new approach to physics, including Rutherford’s work on defining and splitting the atomic nucleus, American Robert Millikan’s confirmation of Einstein’s photon theory of light, and British physicist William Henry Bragg’s conclusion that X-rays must also be “corpuscular” in nature. By 1920, as the horrors of the First World War began to abate, it had become clear that physicists would need to revise some of their most fundamental ideas. In his lecture that year at Yale, Bumstead noted that the laws that govern atoms may be quite different from the laws of mechanics and electrodynamics that were so familiar to physicists of the time, remarking that this would be “rather a wrench for those of us who have been nursed and reared in the old regime”. But this discomfort, he felt, was “much more than compensated for by the fascinating and apparently inexhaustible field for research and speculation which is now being opened up for our use and pleasure”.

That sense of wonder and excitement heralded a new era of modern physics. The discoveries of the past quarter century had been reported widely in the mainstream press, attracting a new generation of scientists who were keen to solve the riddles posed by atomic and quantum physics. The First World War had shown that physics could have practical benefits too. Bragg and Rutherford, for example, developed better hydrophones for detecting enemy submarines, and their research on underwater sound paved the way for Canadian physicist Robert Boyle and Paul Langevin, in France, to produce the first practical pulse-echo system based on piezoelectric transducers in 1918.

There was real concern among physicists about the attitudes towards their occupation, and younger scientists in particular were seeking an improvement in their status

No credit where credit was due

While many of the early pioneers had enough time and money to pursue their own scientific interests, the university laboratories of the time were small and poorly equipped, at least in the UK. “50 years ago physical labs were very few, and very very sparsely populated,” said Thomson in a speech in 1921. “There were few advanced students, and fewer still who intended to make physics the business of their life; and indeed that was a very reckless and dangerous thing because the only positions open to physicists in those days were a few – very few – badly paid professorships.”

By the start of the 1920s, Thomson estimated that between 800 and 1000 scientists were engaged in some sort of physics research in the UK. New laboratories had sprung up across the country for training students and providing facilities for practical work, while the Cavendish Laboratory at the University of Cambridge had become a world-renowned research centre with more than 40 graduate students working alongside senior academics. Physicists were also employed in government laboratories, as well as in a growing number of industries that were making use of advances in electronics, optics and communications.

But there was still very little recognition for physics as a distinct profession. Indeed, there was real concern among physicists about the attitudes towards their occupation, and younger scientists in particular were seeking an improvement in their status. “There was little or no recognized position for physicists,” said Richard Glazebrook in a speech to fellow physicists, shortly after retiring as the first director of the UK’s National Physical Laboratory in 1919. “Men [sic] who have done important work in physics have, in some cases, only been given an official status by being termed research chemists.”

This lack of recognition led to low wages, insecure employment prospects and scant money for experimental apparatus. Newer universities struggled to attract and retain experienced physicists, while even the most established research centres had to cope on meagre finances. George Paget Thomson – the son of J J Thomson – later recalled how, in his early days at the Cavendish Laboratory, senior academics had to rely on college fellowships worth about £250 (roughly £11,000 in today’s money) to top up their salaries. Demand also frequently outstripped supply for standard equipment such as galvanometers, pumps and even resistors.

Timeline of the Institute of Physics

1874 The Physical Society of London meets for the first time to enable scientific discussion and the demonstration of new results and techniques, followed by the first publication of the Proceedings of the Physical Society of London

1914 The first Guthrie Lecture – established to honour the founder of the Physical Society of London, Frederick Guthrie – is given by Robert Wood on “Radiation of gas molecules excited by light”

1920 The Institute of Physics (IOP) is formally incorporated as a professional society for physicists, and its Memorandum and Articles of Association are approved

1923 The Journal of Scientific Instruments is published by the IOP for the first time

1932 The Optical Society and Physical Society of London merge to form the Physical Society

1934 The first international physics conference takes place in the UK, organized jointly by the Physical Society and the Royal Society (the UK’s national academy of sciences) in conjunction with a meeting of the Union of Pure and Applied Physics

1946 The IOP establishes headquarters at 47 Belgrave Square, London

1956 The 1000th fellow of the IOP is admitted to membership, along with the 2000th associate and 1000th graduate members

1960 The Physical Society and IOP merge to create a single learned and professional society

1966 The IOP journal Physics Education is launched to enable professional development among physics teachers

1986 IOP Publishing is created as a separate business unit to manage all publishing activities

1988 Physics World is launched

1996 The IOP moves its headquarters to 76 Portland Place, London

2001 The Chartered Physicist programme is introduced to strengthen the professional recognition of qualified physicists

2018 The IOP opens new headquarters at 37 Caledonian Road, London

2020 The membership of the IOP stands at 23,000

A professional physics society

By the end of the First World War the need for a professional association for physics in the UK was becoming clear. While the Physical Society of London had been founded in 1874, its focus was to provide a forum for discussing and demonstrating new scientific results. Back then, scientists such as Maxwell and Rayleigh would not have imagined that anyone would be able to earn a living through physics, let alone that scientific research would be put to practical use by industry or the government.

Now what was needed was an organization that would boost the status of professional physicists, while also co-ordinating the activities of the Physical Society of London and smaller but related learned bodies based in the UK – notably the Optical Society and the Faraday and Röntgen societies. At a meeting in 1918, representatives from all interested parties discussed the possible activities of a proposed “Institute of Physics”, which included awarding diplomas to physicists with adequate training, registering the qualifications of members, creating a shared headquarters and library, and establishing new exhibitions and publications.

A board was formed in 1919, agreeing that Glazebrook would be the first president, and the Institute of Physics (IOP) was formally incorporated in November 1920. By then 300 physicists had joined the new organization as fellows or members. “It is a tribute to the status already acquired by the newly formed Institute that its diploma is now being required from applicants for government and other important positions requiring a knowledge of physics,” the UK newspaper The Times noted, “and the physicist is now being recognized as a member of a specific profession.”

For the next 40 years the IOP ran in parallel with the now simply named Physical Society, the former looking after professional matters with the latter continuing to focus on scientific results and discussion. Speaking at the IOP’s inaugural meeting in 1921, J J Thomson – who later that year was to become the IOP’s second president – clearly defined the scope of the new body. “This Institute is one which, like similar organizations of doctors, lawyers, engineers and chemists, has been founded to promote the interest of the profession,” he said, “to act as a bond of union, to ensure that the highest standard of efficiency is reached by those interested in it, and also to ensure a high standard of professional conduct.”

From 1920 to 2020: a century in publications

In 1920, when the Institute of Physics (IOP) was founded, physics as a distinct scientific discipline was still in its infancy. According to a 2015 survey by the physicist Albert-László Barabási and colleagues at Northeastern University in the US, only a few hundred research papers in physics were published that year, representing just 4% of all scientific publications (Nature Physics 11 791).

Since then, the research output from the physics community has grown exponentially, aside from a short pause during the Second World War. By 1950 physicists were writing around 1000 research papers every year, rising to 100,000 by 2010, and since the 1980s physics has accounted for some 22% of all scientific publications, with the IOP itself now publishing more than 85 academic journals.

The scientific literature also reveals how physics has changed from an individual, single-minded pursuit to a more collaborative endeavour. A study by US science historians Donald Deb Beaver and Richard Rosen in 1978 estimated that only 20% of physics research published in 1920 involved any sort of collaboration (Scientometrics 1 65). Today, in contrast, the average number of authors on a physics paper has risen more than in any other scientific field. According to Nature Index, for papers in the 68 journals it tracks, the average number of authors in the physical sciences more than quadrupled from nine in 2012 to 39 in 2016 – driven largely by the emergence of publications with more than a thousand co-authors.

Physics has also become more interdisciplinary. The analysis by Barabási and colleagues shows that before 1910 almost all research papers were published in core physics journals such as Physical Review and the Proceedings of the Physical Society. But 1920 saw a significant increase in research reports published by physicists in other fields, or in more general titles such as Nature and Science.

At the same time, point out Barabási and colleagues, the myriad of different subfields of physics have developed their own lexicons, methodologies and culture, with papers published in certain domains significantly more likely to cite other publications in the same subfield and not outside it. This behaviour is particularly prevalent in nuclear and particle physics.

To underline its role for representing physicists in government and industry, one of the IOP’s first major initiatives was to launch the Journal of Scientific Instruments in 1923, which is still published today as Measurement Science and Technology. Proposed by Glazebrook, the new journal aimed to deal with “methods of measurement, and the theory, construction and use of instruments as an aid to research in all branches of sciences and engineering”. There was a clear desire even then to make the journal interdisciplinary in nature, with biologists, engineers, chemists and instrument makers invited to join physicists on the scientific advisory committee.

As the IOP expanded, it created subject groups that catered for growing specialization within the field, as well as overseas and regional branches. It also issued certificates to members who were proficient in specific experimental techniques and laboratory arts, such as glass blowing, that young researchers were still routinely required to learn.

A growing community

By the end of the Second World War the IOP was increasingly working with government to help shape science policy and physics education, particularly as it was becoming clear in the post-war years that there were too few physicists to fill the growing number of vacancies in industry, academia and science teaching. Salary surveys offered guidance on the wages that new and experienced physicists could expect to earn, with the 1948 edition suggesting that graduates should be receiving £600 per annum (roughly £22,000 in 2020) by age 30, with an upper limit of around £1250 (about £46,000 now) for the most experienced and able IOP fellows.

The IOP had also assumed much of the administrative work of the Physical Society, and by 1944 the two organizations agreed to co-operate on many of their core activities, including conferences and publications. After a prolonged period of will-they-won’t-they, the two bodies merged in 1960 to create “The Institute of Physics and The Physical Society”, a cumbersome name that was subsequently shortened to “The Institute of Physics” when the IOP was awarded its Royal Charter in 1970.

Since then the combined professional body and learned society has continued to champion physics and professional physicists. The IOP has developed and supported physics education, provided advice and expertise to policymakers, encouraged innovation and growth in industry, worked internationally with other physical societies across the world, and inspired people from different backgrounds to explore the wonders of physics. Meanwhile, its commitment to disseminate scientific research has enabled its publishing business, IOP Publishing, to become a leading international publisher of research journals, ebooks and, of course, Physics World.

Among the IOP’s lesser-known achievements was the creation of a benevolent fund in 1924, seeded by a donation of £100 from Major Charles Phillips – a British physicist and a founder of the IOP – and topped up by regular contributions from members. The value of the fund had risen to more than £1m by the start of the 21st century, allowing the IOP to provide direct financial support to physicists and their families who are in need. More recently, astrophysicist Jocelyn Bell Burnell – who served as the IOP’s first woman president – donated her £2.3m winnings from the Breakthrough Prize for her work on discovering pulsars, allowing the IOP to launch last year a fund to support PhD students from under-represented groups at universities in the UK and Ireland. Looking to the future, meanwhile, the IOP has just launched a major new campaign to widen participation in physics (see box above).

The physics community of 2020 is very different from the one that existed in 1920 when the IOP was founded. It is far bigger now, of course, but thankfully also much more diverse, and the myriad of careers that physicists today pursue – from IT and engineering to finance and education – would surely have been enthusiastically welcomed by J J Thomson. “I should like, on behalf of those interested in physics,” he said, while addressing the first meeting of the IOP, “to express our obligation to those who have conceived the idea of this Institute, and who have borne the labours in connection with its initiation.” One wonders what Thomson would say were he to address the IOP’s membership today.