Ernest Walton: The pioneering physicist whose work links Oppenheimer to Trinity

Meet the Trinity alumnus and Nobel Prize Laureate who first split the atom

As Christopher Nolan’s Oppenheimer becomes a perpetual cinematic success, we feel obliged to remind ourselves of those who had been smashing atoms (an essential aspect of the nuclear process) far before the film’s titular theoretical physicist, J. Robert Oppenheimer. Often associated with the marvellous “Apples and Atoms” sculpture that lies just outside College’s physics building, Ernest Walton – Irish physicist of the highest calibre – was the first, alongside his Cambridge fellow John Cockroft, to split the atom.

Before his stay at Cambridge, Ernest’s reputation was synonymous with intellectual praise; having attended the Methodist College in Belfast and subsequently having received a scholarship to read mathematics and experimental sciences at Trinity College Dublin, Walton was renowned for his excellence in science and mathematics (the hitherto distinction between the two is a product of philosophical and methodological principles).

Upon leaving the country to pursue his academics at Cavendish Laboratory in Cambridge, Ernest was fortunate enough to study under the tuition of Ernest Rutherford, discoverer of the atom’s nuclear structure – amongst other things. Their first name wasn’t all they had in common: Rutherford’s sheer thirst for experimentalism was very much conducive to his pupil’s atomic discoveries, the influence of which was said to have played a crucial role in Walton’s scientific development.

Under Rutherford’s guidance, Cockroft and Walton had the bright idea to bombard lithium with high-speed protons, which split the nucleus, producing a nuclear reaction. More specifically, lithium particles, arranged in a crystal lattice and containing a relatively low atomic number, were shot with protons accelerated via the usage of an electrical field. This electrical field was the product of a rather genius contraption: the heaping together of spare parts, woods, and nails. Upon impact, a strong repulsive arose because of the force emitted by the positive charges within both the protons and the lithium nuclei. Following this, the emitted protons needed enough force to overcome what is termed the Coulomb barrier (simply, an electrical ‘barrier’ created by the inner repulsion of particles within the nucleus). Of course, the protons needed sufficient energy to overcome this ‘barrier’. When they received this energy, they then got close enough to interact with the nucleus. The high-energy collision between the accelerated protons and the lithium nuclei thereafter led to the disintegration of the lithium nuclei. This disintegration caused the lithium nuclei to break apart into smaller fragments, releasing various subatomic particles. The nuclear disintegration of lithium nuclei resulted in the creation of helium nuclei (alpha particles) and other particles as byproducts: all-in-all, daring and ingenious.

As the scientific process goes, numerous laboratories stood on these three giants’ shoulders, adding to their work. Within this global flood of experiments, another fellow Ernest Lawrence – equally as destined for scientific greatness – was inspired to build a cyclotron, a cyclical accelerator capable of reaching tremendous speeds. Lawrence was central to the Manhattan Project, under which the first nuclear bombs were produced, as was his cyclotron, which other scientists on the team were using to discover which of the other elements were capable of undergoing nuclear fission.

For all this tremendous success, Walton won a Nobel Prize in Physics in 1951 for the “transmutation of the atomic nuclei by artificially accelerated atomic particles”, after which he elected to lecture at Trinity College Dublin and was positioned on numerous national governmental committees – most notably the Royal Irish Academy and the Royal Dublin Society. Unfortunately, Walton passed away in 1995 after presenting his Nobel Prize medal to Trinity at the age of 91. Questionably shaped sculpture aside, Walton’s impact on the scientific community has been recognised through the placement of a plaque in Walton Park, in his birthplace of Dungarvan, numerous honorary doctorates, and the erection of two university buildings under his name in his alma mater and Waterford Institute of Technology.

Perhaps the physicist at the centre of the next blockbuster biopic could have shared the same lecture halls as we do?

Sébastien Laymond

Sébastien Laymond is the Editor of the 'SciTech' column for Trinity News, and is currently in his Junior Sophister Year reading law.