The 13,800-year-old archaeological site points to an ancient cultural connection spanning the Bering Land Bridge.

In September 1976 physicist Masao Doi, then working at Tokyo Metropolitan University, published two groundbreaking papers. The work – published in Journal of Physics A – cast classical stochastic many-body problems in the mathematical language samiliar to that of quantum-field theory (9 1465 and 9 1479).

Although this happened at a time when theoretical field methods in statistical mechanics were getting into full swing, this gem of deep scientific insight remained hidden for many years.

Indeed, it was reinvented several times, most notably in 1980 by Peter Grassberger and Martin Scheunert from the University of Wuppertal, who also highlighted the many applications for the theory.

Following conversations with Grassberger at a meeting organised by the Centre Européen de Calcul Atomique et Moléculaire in September 1985, Luca Peliti from the University of Rome went about putting Doi’s theory into a path integral formalism, thus making it amenable to renormalisation.

That same year he published a letter on the renormalisation group treatment of a reaction-diffusion process, using the framework that was named Doi-Peliti field theory (J. Phys. France 46 1469).

The works by Doi and Peliti quickly became viewed as fundamental building blocks to calculate not only asymptotics but also systematic approximations of observables in reaction-diffusion processes.

Theoretical physicist John Cardy from the University of Oxford, used Doi-Peliti theory as a work-horse for reaction-diffusion processes.

In the 2000s, Cardy and colleagues produced not only a string of renormalisation group treatments of reaction-diffusion processes, but also reviews and tutorials at different levels of technicality, which made Doi-Peliti field theory accessible to many of us.

Key insights

In 2018 Doi became chief scientist at the Wenzhou Institute of the University of Chinese Academy of Sciences and was well-known for his work in polymer and soft-matter physics.

Yet when my former PhD student Ziluo Zhang joined the Wenzhou Institute as a postdoc in 2023, he found that Doi was unaware that the field theory bears his name and the many developments since its inception.

Indeed, Doi and Peliti had never met until a meeting from 22 to 25 September at the University of Cambridge that celebrated Doi and Peliti’s work.

“[It was ]the first time that I attend a conference which has my name on it,” noted Doi.

Funded by the Wildcard programme of the German Carl Zeiss Foundation, the meeting featured talks on historic developments and the many achievements and challenges of the Doi-Peliti framework.

In a relaxed atmosphere, some of the key players explained how their insights came about.

Doi-Peliti field theory is a brilliant concept conceived by brilliant minds. One might be tempted to speculate how many more theories have been spun off and developed that are attributed – or even unattributed – to the pair without them ever knowing.

• An upcoming special issue of Journal of Physics A will be dedicated to the Doi-Peliti field theory.

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The facts are simple enough.

Abdus Salam shared the 1979 Nobel Prize in Physics with Sheldon Glashow and Steven Weinberg for “their contributions to the theory of the unified weak and electromagnetic interaction between elementary particles, including, inter alia, the prediction of the weak neutral current”.

What Salam had done was to incorporate the Higgs mechanism – co-discovered by his colleague at Imperial College London Tom Kibble – into electroweak theory, which unifies the electromagnetic and weak forces.

As the Imperial theorist Claudia de Rham said in a 2024 interview with Physics World, Salam’s work “changed the way we see the world by underlining the importance of symmetry and by showing how some forces – which may appear different – are actually linked”.

But Salam, who died in 1996 after suffering from a cruel neurodegnerative disease, did more than unify the weak and electromagnetic interactions. He also became the first – and so far the only – person from Pakistan to win a science-related Nobel prize, yet for a long time remained overlooked in his homeland.

Great minds

Salam was born on 29 January 1926 in the Punjabi city of Jhang in what was then British India. A child genius, he studied mathematics at Government College, Lahore, completing his master’s degree in 1946 with record marks (getting 765/850 or 90%).

Later that year Salam moved to the UK after winning a scholarship to study at St John’s College, Cambridge, studying initially mathematics and then physics, gaining a double first-class honours in 1949.

Back home, India was in turmoil, with a growing demand for independence from the British, and the Muslims seeking a homeland for themselves.

As a Muslim himself, Salam would no doubt have celebrated when Pakistan was created during the partition of India, with the country coming into existence at the stroke of midnight (0.00 a.m.) on 14 August 1947.

After completing his PhD in quantum electrodynamics at Cambridge in 1951, Salam returned to Pakistan, taking up a teaching post at Government College, keen to establish a research base in the fledgling country. But lacking journals, colleagues or any proper scientific infrastructure in Pakistan, Salam realized he would have to go abroad again.

“Either I must leave my country or leave physics,” he said. “And with great anguish I choose to leave my country.”

In 1954 Salam went back to Cambridge for three years before appointed a professor of applied mathematics at Imperial in 1957. He later switched to Imperial’s physics department, where he set up a renowned theoretical-physics group that he led for much of the rest of his life.

In 1964 Salam also founded the International Centre for Theoretical Physics (ICTP) in Trieste, Italy, to help support physicists from developing nations.

Home at heart

But Pakistan was always in his heart. Salam served for 13 years as presidential science adviser in Pakistan and in the 1970s also played a slighly murky role in the country’s nuclear-weapons programme.

Upon winning a Nobel prize in 1979, Pakistan had existed for only 32 years, meaning it, along with Austria, is the joint 13th quickest nation to win a Nobel Prize in Physics, according to our Physics World infographic.

At the official Nobel banquet in Stockholm on 10 December 1979, Salam thanked the Nobel Foundation and the Royal Swedish Academy of Sciences. “Pakistan,” he declared, “is deeply indebted to you for this.”

Yet back home, little was made of Salam’s impressive award. Most Pakistanis are Sunnis but Salam was an Ahmadi, part of a minor Islamic movement founded in the late 19th century by the religious leader Mirzā Ghulām Ahmad (1835–1908).

Such was the opposition in Pakistan to the Ahmadis that in 1974 the country’s parliament declared them non-Muslims – heretics essentially – and the constitution was altered to reflect that fact.

Pakistan’s decision to outcast the Ahmadis profoundly affected Salam. As he wrote in his diary: “Declared non Muslim. Cannot cope.” Having previously been largely a “cultural Muslim”, Salam now saw his religious beliefs re-awakened.

Belatedly, Pakistan did offer some formal recognition in the form of a two rupee stamp in 1998, but it is surprising the country has not done much more. In 2016 Physics World reported that then Pakistani prime minister Nawaz Sharif was going to rename the National Centre for Physics at Quaid-i-Azam University in Islamabad as the Professor Abdus Salam Centre for Physics – but, as far as I can tell, that has not taken place.

Imperial, in contrast, renamed its main library in honour of Salam in 2023 and this year has been celebrating the centenary of his birth. The ICTP was also renamed after him in 1997.

A few years ago Zakir Thaver and Omar Vandal produced a wonderful documentary film called Salam: the First ****** Nobel Laureate. Directed by the physicist Anand Kamalakar, it explores in detail the strange relationship between Salam and Pakistan, which surely should have done more to honour its greatest physicist.

I can’t imagine other countries doing so little for their first Nobel prize winners as Pakistan has for Salam.

The post Abdus Salam: Pakistan’s first (and so far only) physics Nobel prize-winner appeared first on Physics World.

Back when I used to commute to Physics World’s Bristol, UK offices every day, I heard a lot of excuses explanations for why my train was delayed. Missing crew members. Road vehicles colliding with bridges. Even, on one memorable occasion, a herd of cows blocking the tracks.

One explanation I never heard, though, was the one proposed for a train that supposedly left the south-west English city of Exeter at 10.05 p.m. on 18 October 1841. According to an anonymous correspondent in Nature some 30 years later, this 10.05 train was delayed by 16 minutes because of “a very intense magnetic disturbance” that made it “impossible to ascertain if the line was clear”. This disturbance, the correspondent argued, was due to “the magnetic and auroral storms that have of late excited some attention and discussion in these pages”.

Such storms are now known as space weather, and in 2013 Trey Cade, a physicist who leads the Space Weather Research Lab at Baylor University in the US, made an intriguing suggestion: was this supposed 1841 delay the first recorded example of space weather affecting human technology?

An auroral detective story

According to the latest research, the answer is firmly in line with Betteridge’s law, which states that any headline that ends in a question mark can be answered by the word “no”. Although space weather was (and is) capable of delaying trains, it couldn’t have delayed the 10.05 from Exeter in 1841 for a very simple reason: the railway line in that part of England didn’t open until 1846.

That, however, raises a further question. Assuming Nature’s correspondent wasn’t making up the story of the aurora-delayed train, was he perhaps misremembering the date of a different, later storm?

To find out, a broad group of experts led by Lancaster University’s Jim Wild, and including personnel from the British Geological Survey, Natural Resources Canada, Nature, RMIT University in Australia and STFC RAL Space in the UK as well as Cade himself – dug into the data. By combining evidence from railway timetables, historical newspapers, records of solar observations, reports of aurorae and digitized geomagnetic records, they concluded that Nature’s correspondent – whom they tentatively identified as an electrical engineer called Nathaniel John Holmes – was probably thinking of a storm that took place on 18 October 1848, not 1841.

Having debunked the 1841 hypothesis, the authors of the new research, which is published in Space Weather, say that the earliest known example of space weather impacting human technology is now an incident involving telegraph systems on England’s Midland Railway in March 1847. If that still sounds rather early, Wild says that’s the point. “Society has been experiencing the effects of space weather on technology for almost as long as electrical technologies have existed,” he says. “The technologies affected have evolved from railway telegraphs to satellites…but the challenge remains the same: understanding the risk and ensuring society is resilient to its impacts.”

Raising awareness

According to Lasse Clausen, who studies space weather at the University of Oslo, Norway, but was not involved in the 10.05 from Exeter study, the biggest barrier to this understanding is a shortage of data about what’s going on in the Earth’s ionosphere, where space weather occurs. Although our ability to detect space weather has improved since the 1840s, he says that when it comes to predicting it, we’re roughly where conventional weather forecasting was in the 1920s. “Essentially, we can look out the window and say whether it’s raining or not,” he says.

Changing that will require additional funding, and for that, Clausen thinks raising awareness is essential. “The ionosphere is useful, but it’s not very sexy,” he tells me. The new study, he adds, is “a nice piece of detective work” that “firmly belongs in the ‘awareness raising’ category”.

The post Did space weather delay a train in 1841? appeared first on Physics World.

One does not simply walk into the Trinity test site. Although the radioactivity from the world’s first atomic explosion has mostly dissipated over the past 81 years, the gates to this real-life Mordor are still guarded by military police, and the US Army continues to use it as a missile range.

Members of the public are allowed in just once a year, on the third Saturday in October, between 8 a.m. and 3.30 p.m. Apart from these tightly controlled “open house” events, the site where Manhattan Project participants gathered on 16 July 1945 to witness the dawn of the nuclear age is strictly off-limits.

For fans of atomic history who lack the time, money or inclination to visit this inhospitable corner of New Mexico during its annual open house, Trinity: an Illustrated History of the World’s First Atomic Test is the next best thing. In some respects, this coffee-table-sized book by Emily Seyl and her colleagues at the Los Alamos National Laboratory’s National Security Research Center (NSRC) may even be better.

As the book makes clear, there is not much to see at Trinity nowadays. A few dilapidated buildings; a commemorative obelisk; a fragment of a half-million-pound steel tank – these are all that remain of the once-bustling site where the first atomic device, known as the Gadget, was assembled and tested.

Trinity’s great achievement is to turn back the clock and make both the site and the individuals who worked there come alive. Using more than 200 photos from the test’s official archive and other sources, Seyl and her colleagues have created an important public record of a period that is fast receding from living memory and a place that is still veiled in secrecy. The result is a book that is by turns illuminating, beautiful and disturbing.

A fresh look at familiar history

Let’s start with the illuminating part. As an undergraduate intern at Los Alamos, I read Richard Rhodes’ seminal book The Making of the Atomic Bomb. Since then, I’ve read (and occasionally reviewed for this magazine) numerous other works of atomic history, from Ray Monk’s 800-page biography of the Manhattan Project’s scientific leader, J Robert Oppenheimer, to Denise Kiernan’s The Girls of Atomic City and Kate Brown’s Plutopia, both of which focus on less well-known figures.

Even so, once I got past Trinity’s introduction – which takes just six pages to cover Lise Meitner and Otto Frisch’s 1938 realizations about nuclear fission; the start of the Second World War; Enrico Fermi’s demonstration of the first nuclear chain reaction; and the launch of the Manhattan Project to weaponize these discoveries and thereby secure an Allied victory – I was into material new to me.

That steel tank, for example. Its name is Jumbo, it cost $12m in 1940s money, and it was originally designed to withstand the conventional explosives that imploded the Gadget’s plutonium core. If the explosives worked, but the chain reaction didn’t (a definite possibility – hence the need to test the Gadget’s design before deploying it in a bomb), the idea was that Jumbo would prevent plutonium from spraying all over the site.

So far, so sensible. In early 1944, Manhattan Project engineers duly drew up specifications for a containment vessel. An Ohio-based manufacturer, Babcock & Wilcox, agreed to build it, though for security reasons no-one told them what this mysterious “accumulator” was for. The finished Jumbo was then transported, under wraps, to New Mexico by heavy-duty freight train, offloaded onto a specially built carriage and wheeled to a location 800 yards from the intended ground zero.

Which is where it stayed. By the time it arrived in spring 1945, scientists working at the Manhattan Project’s nerve centre in Los Alamos, nine hours’ drive north of Trinity, had grown confident enough in the Gadget that Jumbo was deemed surplus to requirements, more likely to confuse diagnostic tests than to provide any useful safety function.

The fact that technicians had spent days hauling Jumbo across the desert is an excellent example of how the Manhattan Project combined herculean effort and ingenious engineering with tremendous cost and institutionally stupid bureaucracy

The fact that their technician colleagues had spent days hauling it across the desert is thus an excellent example of how the Manhattan Project combined herculean effort and ingenious engineering with tremendous cost and institutionally stupid bureaucracy. Despite this, I do not recall reading about Jumbo before. It’s to Seyl’s credit that she and her NSRC managers granted this potentially embarrassing episode so many pages of gorgeous black-and-white photos.

Because make no mistake, Trinity is gorgeous. I love the New Mexico desert, but you don’t need to be a fan of this austere landscape to appreciate these photographs of the people who toiled there and the machines they built. Though Oppenheimer and other well-known physicists appear in several photos, much of the book focuses on the contributions of relative unknowns such as Jack Aeby, a technician in the Army’s Special Engineer Detachment.

This organization existed to divert soldiers with technical training away from battlefields and into atomic grunt work, and Aeby, an amateur photographer, asked his group leader (the physicist Emilio Segrè) if he could document the explosion with his personal camera. Due to technical problems with the official Kodak cameras, Aeby’s snapshot is now the only decent colour image we have of the Trinity test.

My favourite photo in the book is of a chemist called Donald Hornig. As the inventor of the X unit – a heavy-duty switch that triggered the Gadget’s detonators – Hornig had the unenviable job of arming this switch a few hours before the test, with a summer lightning storm flickering all around him. He thus became the last person to see the Gadget intact, and his expression as he slumps next to it is hard to read. Is he smiling? Proud? Or merely exhausted and wishing the photographer would leave him alone?

The final pages of Trinity depict events that followed the test, including the atomic bombings of Hiroshima and Nagasaki. Only five photos are known to exist of the immediate aftermath in Hiroshima, and the book reproduces three of them. Taken by Yoshito Matsushige, a staff photographer at the regional newspaper Chugoku Shimbun, they are far more disturbing for what they don’t show than for what they do. Although Matsushige later explained that he felt a professional duty to document the bombing, he found himself unable to press the shutter on most of what he witnessed. It was simply too horrible.

Beauty and horror make an unsettling combination. Despite Trinity’s quality, it is hard to see it appealing to a broad audience; in one of the book’s two forewords, Jim Eckles, who used to work in the missile range’s public affairs office, suggests it will “make a great memento for visitors to the site”. This unambitious statement is probably correct, but I hope that some physicists – weaponeers, disarmament campaigners and everyone in between – will also find space for it on their shelves. Our atomic age may yet end with a whimper, but it began with a bang, and it is worth remembering that bang in all its complicated majesty.

• 2026 University of Chicago Press $39.00/£32.00hb 344pp

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