“I am become death, the destroyer of worlds.” The fear of the atomic bomb was felt not only by the citizens who feared enduring its wrath but also by the inventor himself, Robert J. Oppenheimer. With its debut in his 1965 interview, the quote reflects not only the fear of the wrong force holding the atomic bomb but also of the idea that the atomic bomb could set off a sudden atmospheric chain reaction, causing the earth itself to incinerate. This fear is also portrayed in the recent film “Oppenheimer,” which is based on the life story of Robert J. Oppenheimer before, during, and after the Manhattan Project. In the movie, there is an especially memorable scene in which the portrayal of theoretical physicist Edward Teller claims that there is a 3 in one million chance that the world could be incinerated via the ignition of the nitrogen in the atmosphere and oceans. After this tense moment and the initial hesitation of continuing with the Trinity test, the probability is never mentioned again. So was Teller right? Do we still face the slight probability of atmospheric incineration? Thankfully, after further calculation, it’s been determined that this method of mass extinction is not a matter of slim probability; it’s an impossibility.
Post Trinity test, a declassified 1946 Manhattan Report dives into detail proving the impossibility of a thermonuclear reaction caused by an atomic bomb of the size they were dealing with. The report analyzes atmospheric nitrogen as the subject of ignition due to the instability of its nuclei, the reactions of which yield much more energy in the form of gamma rays. On the basis that there is an ignition point of the atmosphere (10 MeV temperature), the high reactivity would need to surpass that point such that “…the thermonuclear reaction may be propagated to all parts of the atmosphere” (Konopinski et al, 1946), setting off a chain reaction. Despite the energy release via nitrogen reactions, the earth’s atmosphere is transparent to the radiation emitted by them: it cannot absorb or reemit these radiation frequencies. The energy instead escapes into other systems, causing the temperature to restabilize and fail to propagate further reactions. However, the best models of the time first considered the energy produced via the nitrogen reaction to go towards the establishment of the temperature required for atmospheric ignition. Using these more conservative models for the sake of establishing a broader safety net, the Stephan-Boltzmann law – which claims that the hotter an object is the faster it cools – affirms the impossibility of such atmospheric detonation. The size of the bomb they were dealing with would only have about 1% of the energy it released be absorbed as heat by the atmosphere. The rest would dissipate as light, kinetic energy, or escape into space (Konopinski et al, 1946). This ultimately renders a nuclear chain reaction impossible; exponentially more fission material is needed to reach atmospheric ignition. For the technology at the time, there just simply was not enough bomb to generate the required energy.
All science, however, is subject to change over time. This was the core argument of a contradictory article written almost 30 years after the initial Trinity tests and the publication of the 1946 report. The article reopens the previously debunked fallacy, arguing it’s not very possible that “…those who were instrumental in developing fusion devices (1948 to 1958) ever seriously considered the ultimate potential or the unexpected results of fusion explosions that were a 1,000 times as powerful as the fission device of 1945″ (Dudley, 1975). The current scope of today’s technology is beyond what would have been fathomed 80 years ago, including the ability to alter the rate of radioactive decay and half-lives, rendering the energy yield of fusion devices difficult to predict. This argument, however, is weak and extremely flawed as it is based on the idea of Murphy’s Law – that anything can go amiss – and maintains almost no mathematical basis. This short-sighted view and misconception was concisely rebuked less than a year later in a much more scientifically sound article. As in the 1946 report, the article looks into the unstable “…collision between two nuclei of N14 because N14 is a nucleus of relatively high energy content” (Bethe, 1976). The energy produced in the reaction that Bethe looks into (eq 1 below) surpasses the Coulomb barrier required for the reaction to occur with little difficulty and is the same process looked at by Konopinski et al.
N14 + N14 = Mg24 + He4 + 17.7 MeV eq 1
Unsurprisingly, Bethe comes up with similar results to those of Konopinski et al, finding that the energy produced by the reaction is only a minute fraction go the energy lost via physical processes such as the rapid dispersion of the energy in the form of radiation (which, as stated before, our atmosphere is transparent to), heating of the atomic nuclei, etc. The main principle is that “The air cannot be heated as hot as the weapon” (Bethe, 1976). For the atmosphere to ignite, the atomic bombs of modern scale would have to be of an entirely different design such that they could reach the required temperature for ignition; these temperatures are so high that it’s nearly impossible to create a bomb that possesses such qualities.
The profound fear associated with the atomic bomb, articulated by Robert J. Oppenheimer’s chilling words, has left an indelible mark on history. This fear extended beyond the devastation it could unleash upon humanity to include the apprehension that it might trigger an unthinkable catastrophe—igniting the Earth’s atmosphere. The portrayal of this fear, as depicted in the recent film “Oppenheimer,” highlighted a pivotal moment when theoretical physicist Edward Teller suggested a slim probability of atmospheric incineration. However, this fear was ultimately disproved via rigorous scientific analysis and understanding. Including the contradiction of these calculations in the film would take away the tension from the generally uninformed audience. While technological advancements have been made since the early days of nuclear weapons development, the fundamental principles of physics governing these devices and the behavior of our atmosphere remain unchanged. We live to see another day without nuclear damnation.
Sources:
Bethe, H. A. “Ultimate catastrophe?” Bulletin of the Atomic Scientists, vol. 32, no. 6, 1976, pp. 36–37, https://doi.org/10.1080/00963402.1976.11455623.
Dudley, H. C. “The Ultimate Catastrophe.” Bulletin of the Atomic Scientists, vol. 31, no. 9, 1975, pp. 21–24, https://doi.org/10.1080/00963402.1975.11458293.
Teller, Edward, et al. 1946, Ignition of the Atmosphere With Nuclear Bombs.
