When U.S. President Donald Trump claimed during his inaugural address that Americans “split the atom,” a ripple of irritation spread across the globe. The statement, made to bolster the nation’s scientific prowess, drew swift rebuttals from historians, scientists, and even public officials from New Zealand.

Wait, what does New Zealand have to do with Trump’s speech? Well, it’s all tied to one of history’s most influential physicists, Ernest Rutherford.

Who split the atom? Separating fact from myth

Born in 1871 in a small South Island town in New Zealand, Rutherford came to the University of Manchester in Britain in 1907 to take up the position of Chair of Physics at the University. By this time, he had already earned a Nobel Prize in Chemistry for his work on radioactivity. This was a man of such brilliance and repute that Albert Einstein would later call him “a second Newton”.

At Manchester, Rutherford assembled one of the most stellar teams of scientists in the world. His “nuclear family” included immensely consequential physicists, such as Hans Geiger, who would go on to invent the radiation counter, Lawrence Bragg, who won the 1915 Nobel Prize for his work on X-ray crystallography, Ludwig Wittgenstein, the famous analytic philosopher, and none other than Niels Bohr, who revolutionized our understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922

Rutherford’s most famous experiment involved bombarding a thin sheet of gold foil with alpha particles. The unexpected results revealed that most of the atom’s mass resides in a dense nucleus— a particle 1,000 times smaller than the atom itself. Prior to that, the atom had been presumed to be the smallest particle in the universe. Decades later, Rutherford’s protegees would discover that the nucleus is made up of particles like protons and neutrons.

This 1911 discovery redefined atomic structure and, therefore, atomic physics. In 1919, Rutherford went a step further, successfully disintegrating the nucleus of a nitrogen atom by firing alpha particles, thereby producing oxygen atoms and free protons. This was the first artificially induced nuclear reaction.

Interestingly, Rutherford eschewed terms like “transmutation,” fearing associations with alchemy. Instead, he described his discovery as “disintegration.” He had not yet “split the atom”, but Rutherford showed a clear pathway toward this goal.

This achievement would come in 1932, at the Cavendish Laboratory in Cambridge. Under the mentorship of Rutherford, British physicists John Cockcroft and Ernest Walton built a particle accelerator capable of smashing protons into lithium atoms. What they observed was astonishing. The lithium nuclei split into two helium nuclei, releasing a flash of energy. This was the first time anyone had achieved nuclear fission in a laboratory. In doing so, they experimentally confirmed a central tenet of Einstein’s theory of relativity: mass could be converted into energy, a concept captured in the equation E=mc². The energy released in their experiment, while small, hinted at the tremendous power stored in the atom.

While Cockcroft and Walton were the first to split an atom with artificial means, other scientists also played key roles in unraveling the mysteries of the nucleus. Otto Hahn and Fritz Strassmann, for example, discovered nuclear fission in the heavy element uranium in 1938, sparking a race toward nuclear technology.

This work paved the way for the discovery of nuclear chain reactions, which would later be harnessed in both power generation and weaponry. This is where President Trump (or his speech writers) probably got confused. The first self-sustaining nuclear chain reaction in a nuclear reactor was achieved by Enrico Fermi’s team in 1942 at Chicago, followed by the Manhattan Project’s creation of the atomic bomb in 1945. These milestones were indeed the product of American technological leadership, but the original splitting of the atom occurred elsewhere.

Nick Smith, the mayor of Nelson, Rutherford’s birthplace, responded on social media with restrained incredulity: “I was a bit surprised when that honor belongs to Nelson’s most famous and favorite son.”

The backlash extended beyond New Zealand. Dr. James Sumner, a lecturer at the University of Manchester, where Rutherford performed his landmark experiments, expressed disappointment in Trump’s historical oversight. “I don’t think he [Trump] knew really what he was talking about,” Sumner said. Such misunderstandings, he noted, often stem from the mythologizing of scientific breakthroughs, reducing complex, collaborative discoveries to a single moment or figure.

While leaders may seek to simplify history for political purposes, the truth often lies in the messy, interconnected web of global contributions.

Today, Rutherford is remembered as the “father of nuclear physics.” His experiments in Manchester’s modest lab reshaped our understanding of the universe and laid the foundation for technologies that define the modern age—from nuclear medicine to power generation.

Perhaps the best way to honor his legacy is to preserve the accuracy of his story, ensuring that scientific history remains as precise as the experiments that built it.