Have you ever wondered what the destructive power of humanity is? Today we will talk about the history and physics behind bombs, explore what is currently the deadliest bomb, and how many of them are scattered around the world. Could we really self-destruct with this technology? At the end of the episode, I will reveal what you can do to prevent the next detonation.
As a physicist and data scientist, bombs are a topic that both fascinates and terrifies me. In recent months, I have been studying the mechanisms of the deadliest bombs that exist, and the ways in which they actually kill people. I have also analyzed the most recent data on which countries possess these bombs, and what their destructive power is. So now I’m going to share with you everything I’ve learned.
To begin, let’s understand how we got here: Let’s briefly review the explosive history of bombs.
An explosive history
The first ever bombs were invented sometime in the 9th century in China, where gunpowder was discovered. Gunpowder spread around the world, becoming the fundamental compound in most of the world’s firearms, including cannons, grenades, and mines.
The great successor of gunpowder in the military realm was dynamite, invented at the end of the 19th century by the Swedish engineer, Alfred Nobel (yes, the Nobel Prize guy), and its main component was nitroglycerin. This chemical compound was very destructive, but also very unstable. In fact, Alfred Nobel’s brother accidentally died whilst experimenting with nitroglycerin.
For this reason, shortly thereafter, explosive weapons started being made using a much more stable compound, trinitrotoluene, or TNT. And this compound would end up being used as the standard way to measure the explosive power of a bomb.
For example, the GBU-43/B bomb, called the “mother of all bombs”, has a destructive power of “11 tons”. This means that it is capable of destroying as much as an explosion of 11 tons of TNT. In fact, this bomb is the most destructive explosive device used in combat… Not counting, of course, nuclear bombs.
“A short time ago, an American airplane dropped one bomb on Hiroshima.” This was announced by President Truman.
Indeed, on August 6th, 1945, the world witnessed an unprecedented level of destruction. A single bomb, dropped by an American bomber on the Japanese city of Hiroshima, caused an explosion equivalent to about 15 kilotons, that is, 15 thousand tons of TNT.
Three days later, another bomb equivalent to about 20 kilotons was dropped on the city of Nagasaki. This would go down in history as the most destructive bomb ever used in combat.
To give us an idea, if the same bomb was dropped today in the center of Madrid, in one second all the buildings and human beings within a radius of about one kilometer would be completely destroyed. People would suffer third-degree burns in a radius of more than 2 kilometers, as well as injuries and other significant material damage in a radius of almost 5 kilometers. And many of the survivors would end up dying slowly and painfully within a month, from the effects of the radiation. In total, there could be more than 130 thousand deaths, and more than 300 thousand left injured.
So, let us hope that the Nagasaki bomb keeps holding that record, given that, as I will explain shortly, there are even more powerful nuclear bombs out there somewhere today.
Much more powerful.
How does a conventional bomb work?
Before we get into nuclear bombs, let me first explain how a conventional bomb works. What a typical bomb does is to release a large amount of energy generated via chemical reactions. In the case of dynamite, the reaction is the following:
4 C₃ H₅ N₃ O₉ → 6 N₂ + 10 H₂ O + 12 CO₂ + O₂
That is, we convert 4 molecules of solid or liquid nitroglycerin into several molecules of nitrogen, water, carbon dioxide, and oxygen. And those high-temperature gases produced at the end of the reaction quickly increase in volume, causing a pressure wave that travels faster than sound. This chemical reaction is an example of a detonation.
In short, what the bomb does is it breaks the strong bonds between the atoms of the nitroglycerin molecule, releasing energy. But, if you look closely, the reaction begins and ends with the same number of atoms of each element: 12 of carbon, 20 of hydrogen, 12 of nitrogen, and 36 of oxygen. That is, the atoms themselves never change. Each atom remains untouched, since the force that protects its internal structure, its nucleus, is much greater.
And that’s where nuclear bombs come into play: they unleash the powerful energy that binds the particles within the atomic nucleus together.
How does a nuclear bomb work?
Most people will have first heard the name Oppenheimer because of the spectacular movie that this year won 7 Oscars.
But I learned about Oppenheimer many years ago, in the early days of my physics career. Then I encountered him again when I started my master’s in nuclear physics. And once more I came across him when I began my PhD on black holes. Indeed, Robert Oppenheimer made fundamental discoveries in several different areas of physics.
Of course, Oppenheimer is also known for being one of the creators of the nuclear bomb. What he and his team achieved was to release the brutal energy that supports the structure of the atomic nucleus.
There are two possible ways to extract that energy:
- Split heavy nuclei to produce smaller ones. This is what’s known as “nuclear fission”.
- The reverse process, which is joining small nuclei to create heavier ones. This is called “nuclear fusion”.
For historical reasons, a bomb that produces energy from nuclear fission, such as those used on Hiroshima and Nagasaki, is called an “atomic bomb.” And a bomb that produces energy mainly from nuclear fusion is called a “thermonuclear bomb”, or also a “hydrogen bomb” or “H-bomb”. Terminology aside, both the atomic bomb and the thermonuclear bomb are still nuclear bombs. Let’s briefly go over the physics of each kind.
How does an atomic bomb work?
An atom is made up of a nucleus of protons and neutrons, and a series of electrons floating around it, as in this figure. Of course, electrons are not green balls, nor are protons red, nor is the scale of these balls correct. But the model helps us to understand it better.
The specific element that the atom belongs to depends on how many protons there are in the nucleus. For example, the hydrogen atom has just one proton in its nucleus. Helium has two protons, and lithium has three.
Now, the nucleus can also vary in its number of neutrons. And, depending on how many neutrons there are, it will become one isotope or another. For example, the three most common isotopes of hydrogen are protium (with one proton and zero neutrons), deuterium (with one proton and one neutron), and tritium (with one proton and two neutrons).
While protium and deuterium are stable isotopes, and can last for billions of years floating through space without anything happening to them, tritium, over the course of several years, usually disintegrates naturally. In other words, one tiny extra neutron can convert a peaceful isotope into a much less stable one.
Uranium U-235 (with 92 protons and 143 neutrons), when bombarded with a neutron, produces the much less stable U-236, which breaks into two other smaller nuclei. The most common result is a krypton nucleus and a barium nucleus:
This process, in which a larger nucleus splits into two, is an example of nuclear fission.
If you look closely, we start and end the reaction with the same number of protons and neutrons. However, if you were to add up the total mass we had at the beginning and compare it to the mass at the end of the process, you would realize that they are not the same. Some mass is lost along the way. That excess mass is released in the form of energy, which is explained by the most famous equation in the world, E = m c².
Now, the energy produced during the fission of a single uranium nucleus is very small, so you need to repeat this process many times. Luckily (if you want to destroy a city), one of those 3 neutrons left over at the end can combine with another U-235 nucleus, releasing another 3 neutrons, and so on, generating more and more energy in a chain reaction.
If you keep the number of uranium nuclei that become fissioned each time under control, you can use that resulting energy to heat water, and with the steam, you can spin a turbine and generate electricity. This is how a nuclear power plant works, in simplified terms.
On the other hand, if you allow more and more nuclei to be fissioned during the chain reaction, you can release a huge amount of energy in a very short time. And destroy an entire city like Hiroshima. This is precisely what an atomic bomb does.
How does a thermonuclear bomb work?
I have just explained that splitting a nucleus as heavy as the one inside uranium is relatively easy. However, not all nuclei are equally “fissionable.” If you wanted to fission lighter nuclei, you would need more energy.
This is applicable until we reach nickel and iron, which are the most stable nuclei. From here on, it’s the other way around. To obtain energy from lighter nuclei, instead of breaking them in two, it’s actually better to do the opposite and join them.
This process, in which two light nuclei, such as deuterium and tritium, join together to form a heavier one, such as helium, is called nuclear fusion.
Fusion is capable of releasing a much greater amount of energy than fission. Unfortunately, we still do not have the right technology to be able to generate this energy in a controlled manner. Instead, what we have managed to do is to create the most destructive weapon in the world: the thermonuclear bomb, also called the hydrogen bomb, or H-bomb.
In fact, a thermonuclear bomb contains a small atomic bomb inside, which generates the temperature and pressure necessary to allow hydrogen fusion to occur. And this combination of fission and fusion has a destructive power thousands of times greater than the atomic bomb.
You see, while the bombs detonated in Hiroshima and Nagasaki were capable of killing about 200 thousand people, a thermonuclear bomb could kill millions.
“I have become Death. The destroyer of the worlds.” – J. Robert Oppenheimer.
How does a bomb kill?
I have just explained in general terms how a bomb works. And I’ve mentioned that, obviously, a bomb is capable of killing many people. But what’s not so obvious is how exactly a bomb kills its victims.
Shock wave
As I said before, a detonation provokes a pressure wave that travels faster than sound. This is what’s called a shock wave.
But the speed of sound is different when traveling through the air compared with traveling through a solid medium. As it crosses your body, the shock wave causes enormous pressure differences in the body’s cavities, damaging your ears, eyes, lungs, brain, and other organs. And this type of damage can easily cause death, either immediately or a short while later.
In movies, we’re used to seeing how explosions can cause people to go flying through the air. That’s why we usually think that it’s falling onto the ground, or hitting a wall, that hurts us the most. And of course, this type of damage is also possible. However, if a bomb is so powerful that it’s capable of lifting you off the ground, the shock wave will most likely have already caused irreversible internal damage to your lungs and other organs.
Fragmentation
The explosion of a bomb pushes out small pieces of solid material, for example, from the casing of the bomb itself, and also causes glass and other surrounding debris to become projectiles. These pieces flying at high speed can penetrate the body or cause amputations.
In fact, fragmentation wounds are the most common cause of death among explosion victims.
High temperature
The heat generated in an explosion can cause burns and fires.
In the case of a nuclear bomb, temperatures reach unimaginable extremes. To get an idea, the temperature of the sun is about 5000º C on its surface. And inside the hottest part of the sun, its core, temperatures can reach 15 million degrees Celsius.
Well, you might find it hard to believe that, for a few moments, a nuclear explosion can reach temperatures of the order of one hundred million degrees Celsius. Yes, several times hotter than the sun.
So anyone who happens to be near the explosion would be vaporized immediately.
Toxic exposure
Some bombs release chemical compounds that can be poisonous or even lethal when we breathe them in, when they come into contact with the skin, or indirectly by contaminating the water that we then drink. There are even bombs designed not to destroy, but to poison, as is the case of the so-called chemical bombs.
Chemical weapons, as well as biological weapons, are an excellent example of both human creativity and human cruelty. One of the pioneers in chemical weapons design was Fritz Haber, the man who killed millions of people and saved billions (about whom Veritasium created a very interesting video). And as an example of biological weapons being used in combat, we have the Imperial Japanese Army, which in 1940 “bombed” the Chinese city of Ningbo…with fleas infected with bubonic plague.
But if we have to pick the bomb capable of causing the greatest number of casualties from toxic exposure, again, the nuclear bomb wins by a long shot.
A lot of radioactive material is produced in a nuclear explosion. The heat causes a large amount of this material to rise into the atmosphere. And when it cools, it falls back to the earth in an area that can be very large, depending on the wind and weather conditions. This is what is called nuclear fallout.
It can last for days, months, or even years. People and animals can become infected by coming into direct contact with these particles, or indirectly, by consuming water and food produced in areas affected by radioactive fallout.
A high radiation exposure can even alter our very DNA, causing all kinds of scary side effects (which I prefer not to mention), including death.
Indirect damages
In addition to all the factors I have mentioned, bombs also have other indirect ways of killing us. For example, from the collapse of buildings damaged during the explosion. In addition, a nuclear bomb would also damage electronic devices and communication systems in a large area surrounding the explosion, including medical equipment in hospitals.
But of all the indirect ways a bomb can kill, there is one that is especially dangerous: hunger.
Nuclear winter
A nuclear bomb detonated over a flammable target, such as a city or a forest, can lift a huge amount of ash, which may reach the stratosphere. This cloud could spread out over the planet, blocking sunlight, and causing temperatures to drop drastically. The atmospheric changes would also affect agriculture. And when agriculture fails, widespread hunger follows. This is what is called a nuclear winter.
Of course, a single bomb is not capable of producing such a significant effect on the atmosphere. In fact, we have already detonated more than 2000 nuclear bombs (all but two in nuclear tests) and there has been no nuclear winter. But these bombs were detonated over a period of 80 years, and not all the bombs had the same destructive power.
Things would get serious very quickly if various, very powerful bombs were detonated at the same time, in different parts of the world. That is, if a nuclear war broke out.
What’s more, a nuclear war between two countries would not only affect millions of people in those countries. With a nuclear winter, most victims would actually be from the rest of the world.
For example, according to a recent study, a nuclear war between India and Pakistan could claim the lives of up to 2 billion people due to famine. And a war between the United States and Russia could kill more than 5 billion, including almost the entire population of the US, Russia, China… and Europe.
No one knows for sure the true consequences of a nuclear winter, and its impact may have been overestimated. But, in the worst-case scenario, it could lead to irreversible social collapse, or even the extinction of humanity.
Still, this scenario would only be possible if many nuclear bombs were detonated in a short time. Is something like this even possible?
How many nuclear bombs exist?
If one country decided to detonate a nuclear bomb against another today, the situation would be very different compared with 1945. It wouldn’t be like what happened in Hiroshima and Nagasaki, when only the United States had access to that technology. No, today at least nine countries have nuclear bombs.
Of course, no one knows exactly how many bombs each country has, and not all bombs are equally powerful. But it is estimated that, in 2023, Russia had about 4,500 and the United States about 3,700 operational bombs.
Of all these nuclear warheads, both Russia and the United States each have about 1700 bombs ready to be launched at any moment. In other words, on any given day, the president of one of these two countries could be urgently transferred to a high-security bunker: the launch of an enemy nuclear missile has been detected and the president has about 12 minutes to decide whether to launch a counterattack. If they don’t, once that fraction of time has elapsed, all their country’s bombs may have already been destroyed by the enemy.
Allow me to iterate this detail: in just a few minutes, a small handful of people have the power to condemn the rest of the world to a horrible death.
Now, obviously, not all the bombs would be dropped at the same time. Still, we can estimate how many bombs could be dropped in a first attack, and the destructive power they would have together. According to this estimate, we can see that we have managed to achieve a terrifying total power of destruction: more than 15 thousand megatons. That is, a million Hiroshimas.
With an arsenal of this caliber, more than 40% of the world’s urban land could be destroyed in a first attack, which could also lead to a nuclear winter.
If you’re feeling incredulous, let me show you how much nuclear technology has developed. The most destructive weapon in history was detonated by the Soviet Union in a test in 1961: The Tsar Bomba, a thermonuclear bomb of at least 50 megatons.
The shock wave was such that it destroyed buildings hundreds of kilometers away.
Can you imagine what a bomb like this detonated in the center of a city like Madrid would do? If we run a simulation, we can see that… basically, Madrid would cease to exist. And its entire population.
What’s more, and although it may sound like science fiction, thermonuclear bombs have already been dropped in Spain. That’s right, three! – each one as powerful as 1 megaton. If you don’t believe me, you can watch this other video in which I explain how, when, and where. And I can tell you the “why” right now: by accident. Luckily, those three bombs were not activated. But this wasn’t the only time that accidents like this have occurred.
We have already been on the brink of several nuclear wars
It is often said that when several opposing powers possess nuclear weapons, a stable balance is achieved. No one dares to launch the first attack, since the response would ensure mutual destruction. And therefore nuclear weapons serve to maintain peace.
In fact, it could be said that the bombs detonated in Hiroshima and Nagasaki were crucial in bringing about the end of World War II.
What many people don’t know is that nuclear bombs have also been on the verge of starting other world wars, and we have barely managed to escape each time.
At least 13 incidents have been documented in which one country was about to use nuclear bombs against another, either by accident or deliberately.
One such incident occurred off the coast of Cuba in 1962, when an isolated Soviet submarine nearly fired a nuclear torpedo at the United States. Luckily, one person opposed it, Vasily Arkhipov.
And a similar incident occurred in 1983, when Stanislav Petrov detected a signal that appeared to be an attack by several American missiles against Soviet territory. Luckily, Petrov did not make the announcement, thinking that it was most likely a false alarm. And indeed, it would later become clear that there was no attack to begin with.
Thanks to these decisions made by Arkhipov and Petrov, the world did not witness a large-scale nuclear war. And that’s why they have been dubbed “the men who saved the world”.
Apart from these 13, no one knows how many other similar incidents have occurred and have not even been documented. What is undoubtedly clear is that the world would be a very different place now if incidents like this had gone wrong.
The risk from nuclear weapons is not just the chance that a president with a very bad temper decides to invade another country. At any moment, there could be a misunderstanding, a false alarm, or an accident, and through sheer bad luck, an intercontinental bombing ensues that destroys billions of lives.
Sure, the nuclear arsenal keeps us in balance. But it is an unstable balance.
So, in such a fragile and dangerous situation, is there anything we can do?
What can we do to avoid a nuclear war?
The only way to survive this unstable balance in the long term is to reduce the nuclear arsenal.
And now finally, after so much pessimism and horror, I am going to give you a couple of pieces of good news.
The United Nations has been writing treaties for years with the aim of achieving the disarmament of all nuclear powers. And every year, more and more countries are stepping up to sign these treaties.
As I mentioned before, humanity has reached its maximum self-destruct power with about 15 thousand megatons. We reached this historic milestone at the beginning of the 80’s. In fact, in 1986 (the year I was born), there were more nuclear warheads in the world than ever before, more than 70 thousand. With an arsenal of that caliber, a total area of more than 800 thousand square kilometers could have been destroyed in a first attack. Put another way, that’s one and a half Spains.
Since then, both the number of bombs and their total destructive power have been decreasing. In 2010, the area that could be destroyed in a first attack dropped to about 130 thousand square kilometers. So, about one and a half Andalusias.
The number of nuclear tests has also been declining since its peak during the Cold War. In the last two decades, the only country that has carried out these tests is North Korea. And the last one they performed was in 2017.
Different governments, international organizations, and philanthropic organizations are working to reduce the risk of nuclear war, promote international cooperation, and investigate how to feed the population in the unfortunate event of a nuclear winter. But is there anything you can do yourself?
What can you do?
If you are starting your career or thinking about changing direction, consider the following: There are several key areas in which you could work to prevent, respond to, or increase humanity’s resilience to a catastrophe. You could spend the 80,000 hours that you will dedicate throughout your career to working in organizations such as the Global Catastrophic Risk Observatory or ALLFED.
However, if you already have an established career in a totally different area, and don’t see the possibility of changing course, another way to help is by making donations to some of these institutions.
I’ll leave some links to these organizations and other useful resources in the description below.
Another thing we can all do is to fight misinformation. Social media polarizes and angers us, causing us to spread fake news, elect political leaders who don’t look out for our interests, and ultimately destroy the social cohesion that we desperately need to survive as a species. In this other video, I explain how we can deal with this problem.
To conclude, I hope I have convinced you that nuclear bombs pose a terrible threat to humanity. But, scarily they are not the only threat, let alone the worst! If this is hard for you to stomach, I invite you to watch this other episode, in which I talk about the so-called existential risks.
And finally, if you found this video valuable, I also invite you to give it a “like”, leave a comment, or subscribe to my channel. So I can have the pleasure of seeing you again, in the next episode of AltruPhysics.
