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Humanity was ill prepared for the potential destruction that was available through discoveries in chemistry and nuclear physics, but they were warned. Speeches by the Curies at the turn of the century warned of the potential danger of radioactivity. During World War I, Rutherford warned of the potential danger of releasing the energy of the atom. He hoped scientists would not learn how to extract atomic energy until “man was living at peace with his neighbors.” [1] Unfortunately, scientists figured out how to release the energy of the atom just as World War II began, which was exactly what Rutherford feared and seems to be a confirmation of Murphy's Law.
Figure 2‑11. The hand of Mrs. Wilhelm Roentgen: the first X-ray image, 1895. In Otto Glasser, Wilhelm Conrad Röntgen and the early history of the Roentgen rays. London, 1933. National Library of Medicine.
Radiation is any process that transmits energy through space. Ionizing radiation is radiation that is harmful to humans because it can knock electrons loose from atoms (disrupt cells). The three main types of ionizing radiation are alpha (helium nuclei), beta (electrons), and gamma (x-rays and other high-energy electromagnetic radiation transmitted by photons) radiation. Nuclear explosions and nuclear reactors emit massive quantities of alpha particles. Beta particles are high-energy electrons. They can move through the body and cause great harm. They are part of radioactive fallout from atomic weapons. Nuclear reactors also produce beta radiation. Gamma radiation is emitted from space and from radioactive elements in the earth, but the dose from natural sources on humans is extremely low. Decaying radioactive materials emit high energy gamma radiation.
It is probably appropriate that the first discovery of ionizing radiation had an eerily deathlike appearance. Roentgen made an image of his wife’s hand by placing her hand over the cathode ray tube and placing a photographic plate on the other side of her hand (Figure 2‑11).
Figure 2‑12. Fission of 235U chain reaction. Credit: FastFission. Public domain
In the 1930s. Rutherford showed that elements bombarded by alpha particles (helium nuclei with two neutrons and two protons) absorb the protons and neutrons of the alpha particles into the nucleus. The additional protons and neutrons in the nucleus changed the properties of the element. In 1933, Pierre and Irene Joliet-Curie (Marie Curie’s daughter) bombarded elements with alpha particles and made them radioactive. In 1934, Enrico Fermi, an Italian physicist, bombarded uranium with neutrons and thought that he observed new elements, which he called transuranics. German physicist Ida Noddack proposed that Fermi’s new elements were the halves of a divided uranium nucleus. She criticized Fermi for not checking for lighter elements that would have been the result of nuclear fission; however, scientists ignored her paper. It is fortunate that Fermi missed this result in 1934; otherwise, nuclear bomb research based on nuclear fission might have begun in fascist Italy in 1934. [2] Because of the persecution of the Jews by their fascist governments, Fermi and many other Jewish nuclear physicists left Italy and Germany for America and Britain in the 1930s.
Otto Hahn and Lise Meitner had been conducting uranium experiments in Germany in which they bombarded uranium with slow neutrons. They slowed the neutrons with paraffin wax (upper right corner of Figure 2-13). Meitner had to flee Germany in 1938 because she was a Jew. Hahn stayed in Germany and ran the experiment. He discovered that the byproduct was barium (141Ba in Figure 2-12).[3]
Figure 2‑13. 1938 nuclear fission experiment by Hahn, Meitner, and Strassmann. Credit: Deutsches Museum, Munich. Image by J Brew. Used here per CC BY-SA 2.0.
Hahn wrote to Meitner, “Perhaps you can suggest some fantastic explanation. We understand that it really can’t break up into barium… so try to think of some other possibility. Barium isotopes with much higher atomic weights than 137?” [4] She wrote, “Your results are very amazing. A process that works with slow neutrons and leads to barium! To me for the time being the hypothesis of such an extensive burst seems very difficult to accept, but we experienced so many surprises in nuclear physics that one cannot say without hesitation about anything: it’s impossible.”
Meitner and her nephew Otto Frisch eventually realized that the Niels Bohr model of the nucleus as a fluid drop could explain the results; the slow neutron could have deformed the nucleus and caused it to divide into two drops (Figure 2-12).[5] Frisch and Meitner then wrote a letter to the journal Nature describing fission. Hahn, but not Meitner, eventually received the Nobel Prize for the experiment.
Figure 2‑14. Fission of 235U chain reaction. Credit: FastFission. Public domain
Leo Szilard and colleagues found that nuclear fission produces excess neutrons (Figure 2-14), which confirmed that a nuclear bomb was possible. He urged his colleagues not to publish the paper because it would lead to a nuclear arms race, but they published the paper anyway in 1939. Unfortunately, this was just as World War II began, which led to the scenario that Rutherford feared—the development of nuclear weapons due to fear of an enemy gaining the technology. Einstein wrote Roosevelt and told him of the need for America to develop nuclear weapons. Hitler knew of the potential power of nuclear bombs and took control of Bohemian mines that contained uranium. Because of the fear of the German nuclear program, the American government began a massive nuclear weapons development program.
The US Manhattan Project lasted from 1942-1946. It involved 130,000 people and cost $2 billion ($25 billion in modern dollars). The project spent ninety percent of the funds on separation of isotopes in centrifuges. Natural uranium includes 0.7% 235U isotope and 99.2% 238U isotope. In order to make a bomb, scientists concentrated 235U with the centrifuges. The Manhattan Project ended with the development of uranium and plutonium bombs. The Germans never came close to producing a bomb. German scientists claimed that they intentionally sabotaged the project because they did not want Hitler to have the bomb. German atomic scientist, Carl Von Weizsäcker, became one on the leading proponents of disarmament in the last half of the 20th century.
Figure 2‑15. Number of nuclear warheads vs. time. Credit: FastFission. Public domain.
Did the US need to drop the atom bomb on Hiroshima and Nagasaki? The Japanese might have been ready to surrender because of Russian advances in Manchuria. Almost all American generals advised Truman that we did not need to drop the bomb. There is also much controversy over whether Truman should have intentionally alienated Stalin after the war and begun the development of America’s nuclear arsenal. Eisenhower built up America’s nuclear arsenal (Figure 2-15) in the 1950s to tens of thousands of nuclear warheads, and the Soviet Union even exceeded this number in the 1960s and 1970s. Finally, Reagan and Gorbachev negotiated a nuclear arms treaty in 1987 and began the reduction of nuclear warheads.
Since the 1987 treaty, the number of nuclear warheads has dropped from 30,000 on both sides to 1550. Reduction began under the Bush and Clinton presidencies. The Obama administration negotiated the New START treaty in 2010, which reduced the total number of nuclear warheads to 1,550 on both sides. It was ratified by the Senate in 2011 and expired in 2021. Trump abandoned the original 1987 treaty in 2018 and did not negotiate a new treaty to replace the New START treaty. There is no treaty in place at this time, and the US, Russia, China and other countries are upgrading their nuclear arsenals. Comparing the disastrous potential consequences to the zero potential personal, societal, or political benefit, my untrained social and political perspective is that this is the craziest human activity in world history.
Even a small-scale nuclear war between countries with few nuclear weapons could cause catastrophic environmental consequences. NASA scientists found that a nuclear war with just 1% of the current nuclear weapons arsenal in the world, for example, detonation of 1/3 of the nuclear weapons arsenals in India and Pakistan (50 bombs each) would release enough soot into the atmosphere to cause a nuclear winter and drop global temperatures by 2 0C. This would cause global famine for 5 to 10 years.
In the modern world, scientific and technological advances present civilizations with complex problems that threaten the environment and humanity. The following technologies have the potential to eliminate most, if not all, of the human population.
Chemical weapons
Biological weapons
Atomic fission and fusion, bombs and nuclear reactors
Combustion of fossil fuels – global warming
Refrigerants – deplete ozone layer
An interesting philosophical consideration is the fact that the universe is constructed such that intelligent minds can create nuclear weapons and other technologies that have the capability to destroy life on their planet. Would it be convenient for God or the multiverse to adjust the matter in the universe such that organized civilizations with scientific knowledge could not release the energy of matter in a nuclear bomb or otherwise prevent intelligent civilizations from annihilating themselves by chemical or biological warfare? By definition, anything is possible with God, but it is worth looking at the scientific information and principles related to this question.
There are two main types of nuclear weapons. (1) Fission bombs explode when sufficient fissile material is concentrated in one place. Two fissile materials are Uranium 235 and Plutonium 239. (2) Two-stage bombs rely on a fission bomb to trigger fusion of deuterium and tritium. These "hydrogen" bombs are hundreds of times more powerful than fission bombs. Another bomb type, entirely fusion bombs, are theoretically possible but do not rely on a fission explosion to trigger a fusion bomb.
Matter is energy (E = mc2). Rapid release of that energy from a few unstable elements causes nuclear explosions. There is a threshold at which elements become unstable and fissile but also persist in the universe for billions of years after formation in supernovae explosions, which is in the range of uranium and plutonium. If the strong nuclear force was slightly larger, then the unstable range might shift upward, but there would always be an unstable range. Uranium 235 is a naturally occurring fissile material.
Natural uranium is not fissile since it is primarily uranium 238. Could the universe have been designed such that natural uranium could not be converted to fissile nuclear bomb material? For example, if there was no uranium 235, then centrifuges could not enrich uranium and make it fissile. Uranium 235 does not seem necessary to the function of the earth and plate tectonics since it is less than 1% of all uranium, and the earth's internal heating is due to the combined effect of radioactive decay of uranium, thorium, and potassium, [7] and would not change significantly if there was less uranium 235.
Plutonium 239 does not exist naturally, but it is fissile (bomb material) and is a natural byproduct of non fissile uranium 238 reactions in nuclear reactors. Thus, even if there was no naturally occurring uranium 235 in the world, humans could manufacture fissile plutonium in nuclear reactors. Plutonium is atomic number 94 in the Periodic Table, and uranium is atomic number 92 in the Periodic Table. Other isotopes of plutonium are also highly radioactive. Could the universe have been adjusted such that it was impossible to manufacture plutonium or that plutonium was not fissile? It would seem to be difficult to block increasing the atomic number in uranium reactions. Any element larger than uranium is highly radioactive.
At the other end of the spectrum, it is theoretically possible to make a fusion bomb from deuterium and tritium (without a fission explosion trigger). Nobody has done this since, presumably because it is unnecessary due to the availability of plutonium.
Even if there were no naturally occurring fissile materials, the configuration of matter and energy in the universe would make it difficult for the designer of the universe, whether God or the multiverse, to completely block intelligent beings from manufacturing nuclear bombs. In addition, there are a few chemical, nuclear dirty bomb, and biological technologies that have the capability to wipe out a large fraction of the human population. In summary, it would not be convenient to design a universe that has no possibility of nuclear weapons, let alone all other biological or chemical technologies that have the potential to wipe out human life.
Unlike more "primitive" societies, civilizations have always engaged in military buildup, defensive fortifications and frequent wars. While war was always tragic, humanity quickly repopulated from the remnant population. Unlike past military technologies, nuclear weapons have the potential to destroy the entire human race. Thus, the age-old practice of military buildup followed by war is not viable with nuclear weapons. Albert Einstein stated,
“The unleashed power of the atom has changed everything but our way of thinking. Thus, we are drifting toward a catastrophe beyond comparison. We shall require a substantially new manner of thinking if mankind is to survive”
References
References
[1] Ernest Rutherford Biog., https://www.biography.com/scientist/ernest-rutherford Accessed 8/30/2020. A&E Television Networks.
[2] Jeremy Bernstein and David Cassidy, Hitler’s uranium club, the secret recordings at Farm Hall (New York: Copernicus Books, 2001), p. 6.
[3] Bernstein, Hitler’s uranium club, p. 10.
[4] Bernstein, Hitler’s uranium club, p. 10.
[5] Bernstein, Hitler’s uranium club, p. 11.
[6] Bernstein, Hitler’s Uranium Club, p. 11.
[7] Jellinek, A. M., and M. G. Jackson. "Connections between the bulk composition, geodynamics and habitability of Earth." Nature Geoscience 8, no. 8 (2015): 587-593.
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Injured civilians in Hiroshima after atomic bomb attack by United States. Public domain
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