Oppenheimer is in fashion. Directed by Christopher Nolan, the film put this American-German theoretical physicist at the center of the discussion. The biography “American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer” by Kai Bird and Martin J. Sherwin details the key role he played in the role. Leader of the Manhattan Project. Nolan’s film does just that, but highlights another key contribution of this scientist.

And Oppenheimer wasn’t just fascinated by quantum physics; He was also passionate about astrophysics and particle physics. In fact, these three branches of physics are actually intertwined. In any case, this scientist was involved in very relevant contributions beyond the Manhattan Project and the atomic bomb. One of them is known as the ‘Born-Oppenheimer approach’ and was developed by German physicists Max Born and Oppenheimer in 1927 while Oppenheimer was completing his studies at the University of Göttingen (Germany).

This approach is often used in the field of quantum chemistry to speed up the computation of the properties of some molecules. Oppenheimer also participated in the initial prediction of the tunneling effect, contributed to the field of quantum field theory, and along with the American physicist Melba Phillips “The Oppenheimer-Phillips process”, among other related contributions. Roughly, this process describes the fusion reaction that occurs under certain conditions between a neutron and the nucleus of an isotope that turns into a heavier element.

Oppenheimer and black holes

Julius Robert Oppenheimer is one of the fathers of black hole physics. In the late 1920s, he taught at the California Institute of Technology (Caltech) and the University of California, Berkeley, while completing his education at some of Europe’s top universities and embarking on a teaching career in the United States. According to the biographers, the way he approached the lessons aroused an irresistible appeal to some of his students, prompting them to delve into some of the great mysteries of science. One of them was black holes.

In 1939, Oppenheimer and Russian-Canadian physicist George Michael Volkoff predicted the existence of neutron stars. Using the Pauli exclusion principle, previous work by Lev Landau and Richard Chace Tolman allowed them to formulate the following formula: “The Tolman-Oppenheimer-Volkoff limit”. This calculation is essentially the same as the ‘Chandrasekhar limit’ for white dwarfs, for neutron stars. Second, it explains what a star’s mass limit is, so that instead of ending its days as a white dwarf, it does so as a neutron star: 1.44 solar masses.

However, the ‘Tolman-Oppenheimer-Volkoff limit’ describes what mass limit a non-rotating neutron star must exceed in order to collapse into a quark star or black hole. Solving this calculation with precision is extremely complex because the equations of state that describe the behavior of degenerate matter have not yet been fully defined. Even so, Oppenheimer and Volkoff got a fairly accurate estimate, and it was refined decades later to between 2.01 and 2.17 solar masses.

Black holes aroused an irrepressible fascination for Oppenheimer at a time when physicists knew almost nothing about them. It is important that many scientists do not overlook this. initially denied its existence although it is an indispensable consequence of the general theory of relativity and especially of Einstein’s field equations. The rest is history.

Currently, thousands of astrophysicists conduct their research in the field of black holes. One of the most famous Spanish theoretical physicists on this subject is certainly José Luis F. Barbón, doctor of physics and researcher at CSIC. I had the opportunity to speak with him to prepare my paper on time travel physics, and he is definitely one of the theoretical physicists worth following closely.

Cover Image: Universal

On Xataka: Nolan has revealed his plans after ‘Oppenheimer’ and he doesn’t have a TV series or superhero in his plans, maybe a surprise.