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Ready for Oppenheimer? Know Atom Bomb science to know Christopher Nolan’s movie


Christopher Nolan’s historical drama Oppenheimer just hit the theatres and has received tremendous applause from critics and cine-goers alike.

Matt Damon as Gen. Leslie Groves, left, and Cillian Murphy as J. Robert Oppenheimer in a scene from "Oppenheimer."(Universal Pictures via AP)
Matt Damon as Gen. Leslie Groves, left, and Cillian Murphy as J. Robert Oppenheimer in a scene from “Oppenheimer.”(Universal Pictures via AP)

Nolan, the critically acclaimed filmmaker behind Interstellar, Inception, and Dunkirk, is famous for creating movies that leave us thinking long after we leave the theatre. The Cillian Murphy starrer is no exception, as it keeps audiences wondering and captivated, but in addition, it also comes with heavy scientific terms.

But don’t worry, we’ve got your back! We’ll explain some of the science so you offer some relaxation to the mind and focus on the cinematic experience.

Oppenheimer and the Manhattan project

The movie is about J. Robert Oppenheimer, a famous American physicist known as the father of atom physics. He led the Manhattan Project, which created the atomic bombs that were dropped on Japan’s Hiroshima and Nagasaki on August 6 and 9, 1945 respectively, resulting in the loss of around 2 lakh lives, and leaving many with permanent injuries and deformities for years to come.

Atom bomb science easily explained!

An atomic bomb works by releasing an enormous amount of energy through a process called nuclear fission. But what exactly is nuclear fission? The science is easily explained here! Borrowing words from Danish physicist Neils Bohr, another great mind who was part of the Manhattan Project, “Young man, let me explain to you about something new and exciting in physics,” let’s try to understand the science.

Everything in our world, including ourselves, is composed of minuscule particles known as atoms. At the core of an atom lies the nucleus, a small but dense region containing electrically positive protons and electrically neutral neutrons. Surrounding the nucleus are even smaller particles called electrons.

To visualise an atom, think of it as a tiny solar system, with the nucleus representing the sun, comprising neutrons and protons, while electrons orbit around it like planets.

Scientists over time discovered that when a neutron collides with the nucleus of certain fissionable materials, it destabilises the nucleus, causing it to split into two smaller nuclei. The newly released neutrons then go on to collide with other nearby atoms, leading to a chain reaction of further splitting. This cascading effect results in an exponential number of atoms undergoing fission.

Atom bomb and relation with Albert Einstein

During nuclear fission, the total mass of the resulting fragments is slightly less than the mass of the original nucleus. This “missing mass” gets converted into an enormous amount of energy, as described by Albert Einstein’s famous equation E=mc^2 (you may choose to master this equation later!).

Einstein’s equation, however, just explains the release of energy and not how the bomb is made. His only act had been to write to President Franklin Roosevelt suggesting that the United States research atomic weapons before the Germans harnessed this deadly technology. However, later he regretted it. In an interview with Newsweek magazine, he said that “Had I known that the Germans would not succeed in developing an atomic bomb, I would have done nothing.”

Atomic bombs require special material

Practical nuclear fission requires specific elements, such as a particular variety of uranium (scientifically called isotope), called uranium-235 (in the atomic bombs dropped on Hiroshima and Nagasaki, the fission materials used were uranium-235 and plutonium-239).

“When a uranium-235 atom absorbs a neutron and fissions into two new atoms, it releases three new neutrons and some binding energy. Two neutrons do not continue the reaction because they are lost or absorbed by a uranium-238 atom. However, one neutron does collide with an atom of uranium-235, which then fissions and releases two neutrons and some binding energy. Both of those neutrons collide with uranium-235 atoms, each of which fission and release between one and three neutrons, and so on. This causes a nuclear chain reaction,” explains Atomic Heritage Foundation.

How conventional bombs are different from atomic bombs?

Conventional bombs (e.g., TNT, RDX, C4) use chemical reactions and not nuclear fission. In a chemical reaction, electrons (the planets surrounding the sun as per our analogy) rearrange between atoms or molecules, forming new chemical bonds and creating different chemical compounds in the process of releasing energy.

On the other hand, in nuclear fission, the nucleus splits into smaller nuclei.

About 64 kilograms of highly-enriched uranium was used in the nuclear bomb dropped over Hiroshima, and as per World Nuclear Association, it was equivalent to 16,000 tonnes of TNT.

So, before you watch Oppenheimer, remember these simple scientific details to enjoy the movie even more. Enjoy Christopher Nolan’s fascinating cinematic experience!


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