We’ve seen the clips. A clear blue sky suddenly filled with a mushroom cloud of smoke and the resounding boom of the explosion. But if you’ve noticed, most of these clips are very old, often dating back many decades. Modern nuclear weapons have achieved staggering heights of destructive power. A single malfunction in the central technology controlling nuclear missile launch could launch a US nuclear attack at Shanghai, killing upwards of 30 million people – millions more than the 20 million total deaths (military and civilian) in World War 1.2
But what is it that makes nukes so devastating? How is it that a warhead just a few feet long and a few inches in diameter is capable of such mass destruction? Today, we’re going to be talking about the physics and evolution of nuclear weapons, as well as what would happen if a nuclear weapon was launched.
How do Nukes Work?
The nucleus of an atom is bound with an immense amount of energy. There are two ways that we can harness this energy: nuclear fission and nuclear fusion.
Generally, the nucleus of an atom is stable. However, the large nuclei in certain isotopes of heavy metals like uranium and plutonium make such atoms unstable. In Uranium-235 and Plutonium-239, it is possible to shoot a neutron at the nucleus and split the atom into two smaller atoms while expelling more neutrons and a tremendous amount of energy from the nucleus. The neutrons and energy can then proceed to initiate more fission reactions, creating a nearly instantaneous release of exponentially growing energy.4, 5
Nuclear fusion is the opposite of nuclear fission. Whereas fission took a single atom and broke it into two, fusion takes two very small atoms, usually hydrogen isotopes (like deuterium and tritium), at very high temperatures and fuses them into a single, larger atom (usually a helium isotope). Similar to nuclear fission, this releases a colossal amount of energy to fuel subsequent reactions. Nuclear fusion ultimately powers the earth, as the sun performs exactly this process, fusing hydrogens to create helium and releasing the energy as light and heat which then powers the earth (and us!).4, 5
The Evolution of Nuclear Weapons
As mentioned before, most clips of nuclear explosions demonstrate the earliest iterations of nuclear weapons. Over time, more sophisticated technology and engineering have created even more destructive weapons.
The Atomic Bomb
The first nuclear weapons developed used solely nuclear fission and were called atomic bombs. These were the infamous bombs used on Hiroshima and Nagasaki.4 While these are among the weakest nuclear weapons to date, do not underestimate their power. The bombs dropped on Hiroshima and Nagasaki had destructive power equivalent to 15,000 and 21,000 tons of TNT, respectively.4 For reference, a single kilogram of TNT will destroy a small car!8 Even more ridiculous is the fact that the collective 36,000 tons of TNT worth of destruction was carried out using a total of a mere two kilograms of radioactive fuel!4
The Hydrogen Bomb
Hydrogen bombs were developed and tested after World War 2 and have even greater destructive power and efficiencies than atomic bombs, using nuclear fusion to leave their mark on the world. Because of the high temperatures associated with nuclear fusion, hydrogen bombs are also called thermonuclear bombs. The first hydrogen bomb tested had the destructive power of several megatons of TNT, generated light brighter than a thousand suns, and created a heatwave felt over 50 kilometers away.4
Modern Nuclear Weapons
Today, chemical explosives, nuclear fission, and nuclear fusion are cleverly combined to engineer the most powerful and efficient nukes to date.5 Below is an image depicting the general design of modern thermonuclear warheads.
A nuclear explosion today contains two blasts: a primary and a secondary, though the time between both is negligible. Fusion, while more efficient and destructive, requires high temperatures to catalyze, which is where fission comes in. However, fission must be maintained for a period of time before high enough temperatures are reached, which means that enough radioactive fuel must be present for fission to continue for enough time. This is the idea of critical mass, which is the minimum amount of fuel to preserve nuclear fission.5
While early warheads like Hiroshima and Nagasaki had to use more radioactive fuel to achieve critical mass, modern warheads take advantage of the fact that higher density fuel results in a lower critical mass for higher efficiency. This is implemented in the “fission ‘primary’” part of the image by placing chemical explosives around a plutonium core, or “pit.” The chemical explosives compress the plutonium so that it can achieve critical mass and fission. The deuterium/tritium fuel inside of the plutonium core undergoes fusion when the plutonium begins to undergo fission, releasing neutrons into the plutonium core and thus facilitating further fission and creating an almost symbiotic relationship.5
The “fusion secondary” uses the heat from the fission primary to catalyze its reactions. The secondary creates rapidly escalating levels of energy by utilizing the symbiotic relationship between the release of neutrons from fusion and the heat produced by fission, similar to the primary. As the lithium deuteride fuel fuses, the released neutrons feed the fission of the outer and inner uranium layers, and the energy compresses the inner uranium to create even more energy. The outer uranium layer of the secondary ends up contributing more than half of the destructive energy because of the fusion and fission occurring within.5
As described above, nuclear weapons pack a real punch. But the death caused by the immediate explosion doesn’t hold a candle to the sheer level of suffering that would be caused by the radiation, infrastructure damage, starvation, climate change, geographical damage, and probable nuclear war that would follow.
The Immediate Aftermath
About 35% of the energy comes from thermal radiation, and the rest is released in the blast. Assuming a bomb with the destructive power of one megaton of TNT, fatal burns would occur within about 10 km of the blast radius. Temporary blindness can occur anywhere between 20 to 80 kilometers away depending on the time of day. The blast would drastically change air pressure and, in a 6km radius, create winds up to 255 km/hour, the force of which would be the equivalent of 180 tons of force on a two-story building. While the wind itself is survivable, fallen buildings and heat are the primary causes of death within a 10 km radius. Those in underground shelters might survive the previous two causes but would still have to worry about deoxygenation, as, for a certain distance, oxygen is sucked out of the atmosphere as inflammable objects burst into flames and flammable objects are vaporized.10
Survivors of the blast would still have to worry about radiation. If the bomb is detonated on or near the earth’s surface, the infamous mushroom cloud is created by the vaporized particles that used to be where the bomb exploded. These particles become radioactive, float into the air, eventually condense, and then return to the earth as radioactive fallout, potentially traveling hundreds of miles in the process. Radioactive fallout could return as black rain or as particles undetectable by humans. The radiation induced by the aftermath of the bomb will damage DNA and cells substantially, and while most of it can repair itself, approximately 25% of the DNA will not and create the opportunity for genetic mutations and cancer to occur anywhere between 7 days and over 20 years in the future.10
Outside the Blast Radius
Unfortunately, the nuclear warhead’s effect far extends past its immediate physical consequences, primarily because of how today’s society is structured. Globalization is and has been a hot topic for a long time, and corresponding with it is ever greater international connections, and on a more serious note, greater dependencies on these connections. Economically, an entity will sell that which they can produce best, and this leads to specialization, such as South American countries’ general dependence on the export of cash crops. This means that, even if a nuclear warhead were to be launched on a minor scale, such as a regional war between India and Pakistan (both of which have considerable nuclear arsenals), the impact of such a war would be global.
In addition, modern society is extremely dependent on electricity; without it, our technology is not much better than it was 300 years ago, before the Industrial Revolution. A nuclear blast would shut electricity down locally for an indefinite time and could cause electricity shortages in other areas as well due to the interconnectedness of the modern world.
The fires produced by the heatwave would reach outside the immediate blast radius, and current simulations predict that these fires would be so great in magnitude that they would affect global climates.11
All of this, of course, is the local and immediate effects that don’t consider the high likelihood of nuclear war breaking out following the initial warhead’s launch. Of course, the nuclear war’s direct impacts – hundreds of warheads decimating populations – will be devastating. Millions if not hundreds of millions of lives will be lost to the aforementioned dangers. However, the suffering that comes after will be what hits hardest.
While thermonuclear bombs are obviously very hot, the lasting consequence of nuclear war would not be heat. Enormous fires will ravage the land and send smoke clouds similar to how a volcano would.10 By blocking the sunlight, these clouds can reduce global temperatures by several degrees.10 Those familiar with climate change will know that this will be catastrophic. Growing seasons will diminish dramatically, much fewer crops can be grown, crop yield will drastically decrease, and ecosystems around the world will be thrown into chaos.10 Red Cross estimates that over a billion people in developing countries would face starvation, and because much of the modern world relies on global food supply chains, famines would rock the developed world as well.4 Communications would be shut down, meaning coordination of activities would be near impossible. Hospitals would shut down, limiting recovery for those injured, and the lack of communications would result in anarchic chaos. A nuclear apocalypse would result in billions of deaths and immeasurable suffering, and the recovery period would likely take centuries10.
Since the end of the Cold War, the world has socially acclimatized to the existence of nuclear weapons, and as such, nuclear war seems like something far off in the distance. However, a nuclear war could happen at any instant. The Cold War caused the US and Russia, the largest stockpilers of nuclear warheads, to have 1800 warheads at the ready, the justification of which being that they should be capable of being fired before another nuclear warhead destroys it.11 There have been several covert instances during which a nuclear attack was supposedly detected and nuclear war almost began.11 Technological issues and cyber-attacks mean that it is possible for a nuclear missile to be launched at any second. The consequences of such an event would be catastrophic, as described above, and will take us to pre-industrial times, if not even worse. It’s critical that the world continue the non-proliferation policies of nuclear weapons. We must not let a technological glitch be capable of destroying the modern world.