Who was Robert Oppenheimer, portrayed in film – 07/20/2023 – Science

The trajectory of the New York physicist Robert Oppenheimer (1904-1967) and the history of the development of the first atomic bombs is the most emblematic example the difficulty of predicting the effects of a new technology, as shown in the film “Oppenheimer”, by director Christopher Nolan.

The team led by Oppenheimer saw their work as something that could defeat Nazi Germany once and for all and maybe even end wars forever, without imagining that the first explosion in the Japanese city of Hiroshima would be just the beginning of an arms race capable of leading human civilization to extinction.

The behavior of the two superpowers of the 20th century (the USA and the Soviet Union) also made clear the difficulty of “putting the genie back in the bottle” when scientific and technological advances are no longer exclusive to a single laboratory or country. Although the military use of bombs has not reappeared, the development and production of these weapons has continued to advance. And there is no sign that the complete abandonment of nuclear weapons is likely to happen any time soon.

The process that triggered the Manhattan Project, a billionaire effort led by Oppenheimer that would culminate in the atomic bombing of Japan in 1945, shows how science and politics, in this field of studies, walked together all along.

The first clear experimental evidence that it would be possible to fragment the nucleus of atoms and produce a chain reaction capable of multiplying the phenomenon came to light between 1938 and 1939. This process, the so-called nuclear fission, is at the base of virtually all weapons of this type to date. The detail is that the crucial discoveries about the mechanism happened in Germany, shortly before the regime of Adolf Hitler unleashed the Second World War.

In the pre-war years, the Nazi regime was already marginalizing, persecuting and imprisoning scientists of Jewish origin or belonging to the left of the political spectrum. These researchers, many of whom took refuge in the US or the UK, began to be incorporated into the war effort of the enemies of Hitler’s Germany. Aware that the Nazis could use nuclear fission to produce very powerful bombs, they began to advocate that the Americans come out ahead of this race.

This was the subject of a letter signed by the greatest scientist of the time, the German Jew Albert Einstein, and written by the Hungarian Jew Leo Szilard, in August 1939. The two physicists addressed the message to the US President, Franklin Roosevelt, warning him about the possibility of building this type of weapon, advising the government to invest in research on the subject and warning Roosevelt that Germany could also embark on this path.

Roosevelt determined the start of relatively modest studies on the subject, but the initiative took about two years to take off for good. That’s because the US would only officially enter World War II when attacked by Japan (Germany’s ally) at the end of 1941. Soon after, Hitler declared war on the Americans.

Given this, and with the support of its British allies and many refugee scientists, the US would end up investing the equivalent of the current US$ 25 billion (R$ 120 billion) in the Manhattan Project. Oppenheimer, then a professor at the University of California at Berkeley, was chosen to lead the scientific arm of the project. He was not considered one of the greatest physics geniuses of his generation – he would never win the Nobel Prize, for example – but he had the broadest interests and the greatest interdisciplinary ability, in addition to being highly respected by his peers. This allowed him to master every aspect of bomb construction, from theoretical physics to the design of each device.

Furthermore, both Oppenheimer and many of his collaborators were left-wing and saw the bomb as the great opportunity to defeat Hitler once and for all. “We didn’t want to lose a single day, a single week. And there was no doubt that losing a month would be a calamity”, summarized Isidor Rabi, who would win the Nobel Prize in Physics in 1944.

In addition to encyclopedic knowledge, Oppenheimer’s charisma would have been a key ingredient for success. “Los Alamos [laboratório do projeto criado no deserto] it could have worked without him, but certainly only with a lot more effort, less enthusiasm and less speed. He was a leader”, summed up physicist Hans Bethe, another member of the team that would end up winning the Nobel Prize.

Oppie, as the project coordinator was known, argued that the destructive effect of the bomb would cause such amazement in the public that wars would become unthinkable after its detonation — an idea that had already been proposed by the science fiction writer HG Wells and by the inventor Thomas Edison when the weapon was still just a theoretical possibility.

Even with Germany defeated before the devices were ready, he said it made sense to use the weapons to force Japan — who were still up against the Americans — to surrender unconditionally. He even helped plan the positioning of the plane that would drop the bomb on Hiroshima so that the damage caused was as much as possible.

After the attack, however, Oppenheimer’s position changed considerably—although he was still ambivalent. On the one hand, in a meeting with President Harry Truman (who succeeded Roosevelt after his death), the physicist declared: “I feel like I have blood on my hands” (after the conversation, Truman reportedly banned Oppenheimer from appearing again at the White House, calling him a “crybaby”).

After the war, Oppie continued to serve on a number of US government advisory bodies. His initial objective was to create an international treaty that completely barred the construction of new atomic weapons, without success. He was also defeated by a former subordinate, Edward Teller, who convinced the US government to fund the creation of the first hydrogen bombs. They worked on the basis of nuclear fusion (essentially the same source of energy as the Sun) and had a destructive power thousands of times greater than those of Hiroshima.

With a few years delay and with the help of spies who had participated in the Manhattan Project, the Soviet Union developed its own bombs, starting a race to accumulate atomic weapons. “We may be compared to two scorpions in a bottle, each capable of killing the other, but at the risk of sacrificing its own life,” Oppenheimer wrote about this process in 1953. Still, he thought that tactical nuclear bombs—that is, of relatively modest size—could still have some military use.

The association with the left —involving, for example, contributions to the American Communist Party— would eventually cause Oppenheimer to lose the access he had to national security bodies in Washington. He died in 1967, without witnessing discoveries that would end up burying once and for all, at least in the minds of most of the public, any legitimacy of a nuclear conflict.

This process was consolidated in the early 1980s, thanks in part to the discoveries of a former participant in the Manhattan Project. At that time, Luis Alvarez (also a nobelist) proposed that the impact of a meteorite on Earth 66 million years ago would have exterminated the dinosaurs by causing global darkness (thanks to the impact debris suspended in the atmosphere).

Partly inspired by these data, a team that included astrophysicist and science popularizer Carl Sagan formulated the idea of ​​a “nuclear winter”, which would be the inevitable result of such a war between the US and the Soviet Union. Nuclear winter would be very similar to the end of the dinosaurs. The thesis became popular and stimulated disarmament efforts in which Americans and Soviets committed to significantly reducing their arsenals.