- [Narrator] Since their first
devastating use back in 1945, nuclear weapons have been a
huge source of anxiety and fear across the globe. For almost a century now, we've lived in the knowledge
that our world leaders could plunge us into nuclear
war with destruction on a scale never before seen in history. But how likely really is this scenario? What was the biggest
nuclear weapon ever dropped? And how does a nuke even work anyway? Slip your hazmat suit on and
brace yourself for impact because you're about to get
hit with a fat knowledge bomb. (upbeat electronic music) Let's start with a little
history and ask the question, why were nuclear bombs ever
developed in the first place? In 1938, just a year before the
world was plunged into war, German scientist Otto Hahn
was working in a lab in Berlin when he discovered something
incredible, nuclear energy. By splitting the nucleus of an atom, the smallest unit of matter
in the known universe, Hahn realized a monumental
amount of energy was released. After word got out about his findings, US president Franklin D.
Roosevelt was worried that the Germans would use this newfound energy to develop a super weapon. So, he asked US scientists
to develop one first. When America joined World
War II in December, 1941, these efforts were doubled
and Roosevelt established the "Manhattan Project." Based in Manhattan, New York, the project was a joint effort
by the military and several hundred scientists to
weaponize nuclear energy. Just four years after its
formation, its goal was met. On the 16th of July, 1945, the US conducted the first
ever test of a nuclear bomb, code named the "Trinity Test." The bomb, containing one
kiloton of destructive power, that's the same as 1,000 tons
of conventional explosives, was dropped from a plane
over Socorro, New Mexico. The resulting explosion stunned
the US military and left the bomb site so
irradiated that even today, the area contains more than
10 times the normal level of background radiation. In other words, it was
a resounding success. Less than a month later, the US would put this
terrifying new technology to horrific use. With the war almost over, but Japan refusing to surrender, newly instated President
Harry S. Truman ordered the atomic bombing of the city of Hiroshima. When the bomb named
"Little Boy" was dropped, everything changed. The plane chosen for the mission, a B-29 Superfortress bomber
called "The Enola Gay" reached Hiroshima at 9:14 AM local time on the 6th of August, 1945. The bombardier, Thomas Ferebee, dropped the near 10,000 pound bomb. Then the pilot, Paul Tibbets, sharply turned and flew away from the city as fast as he could. 43 seconds later, "Little Boy" exploded with the force of more than 16,500 tons of TNT. The nuclear explosion instantly vaporized anyone at its center, scorched the ground around it
to temperatures hotter than 7,000 degrees Fahrenheit, and sent a shockwave that
smashed through buildings and obliterated land for miles around. It was hell on Earth. A daunting mushroom cloud
soared in the air 20,000 feet above the city, blocking
out sunlight to those below. But still, the Japanese emperor Hirohito
refused to back down. Surprised, but unperturbed, Truman ordered the
dropping of a second bomb, this time over the city of Nagasaki. This bomb named "Fat Man" was even bigger and more powerful than its predecessor. Just three days after
the bombing of Hiroshima, "Fat Man" fell from a US plane
and exploded over Nagasaki, obliterating over 2 1/2
square miles of the city. A second mushroom cloud was
thrust high into the air and radioactive rain burned down on anyone unfortunate enough to have
survived the initial blast. Yeah, you might have been
better off being vaporized than being a little further out
when the bomb went off. Those not in the immediate blast suffered all kinds of nasty maladies, like burns, internal
injuries, and blindness. And many succumbed to them. Emperor Hirohito, seeing such destruction, finally announced the country's surrender. At the cost of over
200,000 innocent lives, the allies had won the war. Perhaps unsurprisingly, the newly formed United Nations
made one of their first acts to call for the elimination
of atomic weapons, and even less unsurprisingly,
this was completely ignored. In the years following the war, the US continued testing atomic bombs and the Soviet Union, under communist rule and firmly against the American way of life, accelerated their own nuclear program. In 1949, the Soviet Union became the
second nation to successfully detonate a nuclear bomb. The Cold War had officially begun. Two nations with wildly
conflicting belief systems, both harboring the most powerful weapons mankind had ever seen. What could possibly go wrong? You know where you can't go wrong, though. Hitting those like and
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almost every single day. Anyway, back to blowing stuff up. In 1952, 3 years after the Soviet Union's first successful nuclear test and with Cold War tensions
rising ever higher, the US took nuclear weaponry
to a whole new level by detonating the first ever hydrogen bomb. Can you guess how much more
powerful this hydrogen bomb was than the OG atom bombs? 10 times? 100 times? Nope, it was 1,000 times more
powerful than the bomb dropped on Hiroshima or when
obliterating an entire city just isn't enough. When the bomb exploded over
a remote Pacific island, it did so with the monumental force of 10.4 megatons of TNT. That's over 10 million tons of this stuff. The colossal blast made a
fireball at least four miles wide that by expert estimates
shone brighter than 1,000 suns and the heat was felt by observers standing as far as 30 miles away. But the Soviets were hot on the US's tail. And if you thought what
you just saw was big, strap yourselves in because
you've seen nothing yet. Let's put things into
perspective for a moment. The bomb dropped on
Hiroshima was 15 kilotons, the first hydrogen bomb was 10 megatons, but nine years later in 1961, the Soviets tested a hydrogen bomb that was an unbelievable 57 megatons. That's 3,800 times the power of the bomb that destroyed Hiroshima. The absolute behemoth of a weapon was called the "Tsar
Bomba" and measured in at 26 feet long as well as
weighing 27 metric tons, about six times the weight of "Little Boy" and over twice the length. The monstrous super weapon
was so big that it didn't even fit inside a plane and had to
be carried underneath instead. You've gotta feel for the poor pilot. He and his crew were
only given a 50/50 chance of surviving the test. On October 30th, 1961, the plane carrying the bomb took off and flew towards the test site, an island in the Arctic
Ocean named Novaya Zemlya. Once over the island, the crew released the payload
and got the hell out of there as fast as they could. To give them more time, the enormous explosive had
been fitted with a parachute to slow its descent. Even so, when it detonated, the blast was so powerful
that its shockwave slammed into the plane, sending it plummeting over 3,000 feet. (man speaking in foreign language) Luckily, the pilot recovered control, but the explosion annihilated
everything within 22 miles and created a massive mushroom
cloud over 37 miles high. The bomber's crew, still hurdling away as fast as they could, watched as the beautiful,
terrifying plume pierced the sky where they'd been mere moments before. (narrator shivering) In reality, the test was nothing
more than Soviet Premier Nikita Khrushchev flexing
his military muscle to show the US who was boss. But the bomb itself, while
undoubtedly impressive, was impractical and wasn't as effective as dropping several smaller bombs, so no attempt by either side was ever made to make one bigger. Even today, the "Tsar Bomba" remains the biggest nuclear weapon ever created and used, though I came pretty close to topping it after last night's curry. Despite no single bomb ever matching the "Tsar Bomba's" power,
between 1945 and 1980, a combined total of 510
megatons of explosives were detonated around the
world in nuclear tests. That's 170 times more blast power than was used in the
whole of World War II. And though easily the
two biggest culprits, it wasn't just the US and Soviet
Union that were responsible for the barrage of blasts. By 1980, the UK, France, and China
had all waded into the fray with their own tests, albeit on a far smaller scale. With five nations all
blowing the living daylights out of any barren patch
of land they could find, you might expect there to be some environmental consequences, right? Well, we can't be sure just
how much radioactive material has been flung up into the atmosphere from the decades of testing, but we know it's a lot, like a lot, a lot. And what goes up must come down. Throughout the Cold War, one of the Soviet's favorite
nuclear test sites was a patch of land in Semipalatinsk,
Kazakhstan called "The Polygon." Even today, this area is one
of the most radioactive places in the whole world. It's been hit with about
450 nuclear explosions. And with every single one, masses of radioactive dust and dirt were thrown into the air
and carried across the neighboring communities as toxic fallout. A test in 1956 resulted
in over 600 residents of the city of Ust-Kamenogorsk being rushed to hospital
with radiation sickness, and they were 250 miles away. Now, trust me, you don't want
to get radiation sickness. If you're ever subjected to
a strong dose of radiation, the symptoms can be severe
and quick to set in. The invisible rays penetrate your body so they don't just damage your
skin, but also your insides. The cells that make your hair die off, causing you to lose it, your disease fighting
white blood cells die too, crippling your immune system, even your very DNA is attacked, causing it to break and mutate. You'll feel sick, weak, and disoriented. Even if you survive the
initial dose of radiation, years later, you're more likely to develop
life threatening illnesses like leukemia or cancer. That's exactly what happened
with the many residents of Ust-Kamenogorsk. But the tests didn't just
affect one generation of people. Because DNA mutations are often passed on, pregnant women at the time were
more likely to give birth to children with learning difficulties
or physical impairments. Overall, the tests in Semipalatinsk alone are estimated to have affected over 350,000 people
across three generations. Geez. But what actually is it that
makes these monstrous weapons so preposterously powerful? How did we go from conventional
bombs to colossal weapons of mass destruction in the
space of just a few years? To find out, we need to return
to our German scientist, Otto Hahn, back in 1938. You see, he didn't just
discover nuclear energy, he discovered something
called nuclear fission and it's the entire reason that we're now capable of our own Armageddon. Okay, so here's the sitch. Everything in the
universe is made of atoms. You, me, the chair you're sat on, even your gran's false teeth. They're so small, you can't
even see them with a microscope, but they're everywhere. Inside every atom is a nucleus containing a load of protons,
which are positively charged, and neutrons, which have no charge. These are bound together
tightly to the nucleus, which takes a great deal of energy to keep together because naturally, things that have the same
charge repel one another. Think about magnets. If you try to push two magnets together, positive to positive, there's resistance. If you let go of those magnets,
they'd spring backwards, releasing kinetic energy as they did so. It's the same principle here. The protons are held
together by a powerful force, but if that force is broken, all the energy being
contained by it is released. This process is called nuclear fission and it's the principle
behind both the Hiroshima and Nagasaki atom bombs. To instigate fission, a neutron is fired at
the nucleus of an atom. When it hits the nucleus,
it smashes it apart, forming two smaller nuclei and releasing energy in the form of heat. At the same time, some neutrons are flung
from the nuclei entirely and go on to hit other atoms, splitting their nuclei and
creating a chain reaction. In this way, a massive amount
of heat energy is produced that increases exponentially
in just a fraction of a second and it's all reliant on
reactions in the nucleus. Nucleus, nuclear, get it? It's the basic process that
powers all nuclear weapons and most nuclear power
plants use it to generate electricity, too. However, just to throw
a spanner in the works, there is another way of
creating nuclear energy, called nuclear fusion. This is much more powerful than fission and is used to power hydrogen bombs. Here, instead of splitting atoms apart, they're fused together. Fusion only works with
small atoms, like hydrogen, the nucleus of which
contains just one proton. Naturally, two hydrogen
atoms repel one another because they're both positively charged, but if the force
repelling them is overcome and they're impelled to
fuse with one another, creating a bigger atom and releasing a huge amount of energy in the process. So, how do you overcome the powerful force repelling the atoms
and fuse them together? Well, you need to compress
them into a small a space as you can so they're
more likely to collide and blast them with an
absolute butt ton of heat. This way, they're not only
closer to one another, but the heat makes them move faster. And when I say a butt ton of heat, I mean at least 180
million degrees Fahrenheit. Spicy. And for comparison, that's almost seven times
hotter than the sun, which also runs off nuclear fusion. Because of the immense gravitational pressures at the sun's core, about 200 billion times greater than the atmospheric pressure here on Earth, atoms are crushed so close
together that it doesn't need to be so hot for fusion to occur. On Earth, however, we need to make up for
the lack of pressure by ramping up the heat. And you know what generates a lot of heat? Yeah, nuclear fission. Therefore, hydrogen bombs, otherwise known as thermonuclear weapons, explode using the heat
from a fission reaction to kickstart a more
powerful fusion reaction. In other words, when a
hydrogen bomb goes off, it burns seven times hotter than the sun. Whoo. Okay, if you're with me so far, give yourself a pat on the back. Now we know the basic
reaction powering the bombs, but how do the bombs
themselves actually work? Let's start with the fuel inside them, which is either uranium-235
or plutonium-239. These are both radioactive metals, meaning their atoms have unstable nuclei. An unstable nucleus has too many neutrons or protons inside it and will eject them to try and become stable. This is called radioactive decay and it produces energy
in the form of radiation. Atoms with unstable nuclei
are also easier to split with nuclear fission, hence why they're used in nuclear weapons. Now, "Little Boy's"
design was very simple. The bomb had two separate
pieces of uranium-235 inside it, the plug and the target. Upon detonation, several thousand pounds
of conventional explosive was set off inside the shell, which fired the plug down a
barrel and onto the target. The two pieces of uranium smash together, compressing the atoms close enough to instigate a fission reaction, which grew in power exponentially
until it exploded out from the bomb's shell in a fearsome fireball. All nuclear weapons produce this fireball. Then it expands so fast that
in a one megaton hydrogen bomb, which is far more powerful
than "Little Boy" was, it can reach 440 feet across
in less than a millisecond. You see, "Little Boy" was
actually pretty inefficient, which is why nobody ever made any bigger, more powerful versions of the weapon. "Fat Man," the bomb dropped on Nagasaki, had a very different design. Instead of uranium-235, "Fat Man" was powered by plutonium-239. However, the plutonium-239
used had trace amounts of plutonium-240 in it. This is a different kind of
plutonium, called an isotope. Plutonium-240 has a higher
fission rate than plutonium-239, which means if the same gun-type design as "Little Boy" was used, it would've begun fission
before the two masses of plutonium had been brought together. This would've made it so inefficient, it wouldn't have been worth using, so another design was thought up. For "Fat Man," one plutonium sphere was held
in the center of the bomb. Around this, a layer
of uranium was placed. This layer of uranium held the
plutonium in place and helped reflect neutrons back to the core, improving the efficiency
of the fission reaction. Blocks of conventional explosives
were then precisely placed around this to produce
a symmetrical implosion when activated, which would
compress the plutonium sphere. Once compressed, a device
inside the plutonium was crushed and injected neutrons into
the radioactive metal, kickstarting the fission reaction
and setting off the nuke. But there's one more thing
that needed to be considered for both bombs, how the detonation would be
triggered in the first place. Impact with the ground
would've done the trick, but the ground would also
have absorbed a lot of the explosion and limited its radius. Instead, for maximum
destructive potential, the bombs had to be detonated in the air. To do this, both were equipped
with specialized circuitry that could detect their
height from the ground and detonate at just the right moment. As well as affecting more area, an aerial explosion sends out
a shockwave that smashes into the ground, rebounds, and then combines with the initial blast to form an even bigger shockwave. So the cruise of the
planes dropping the bombs really had to skedaddle fast. Well, in the modern world, we don't have to drop
these deadly destroyers from planes anymore. We can fire them straight into the air on automated missiles. Ballistic missiles are
about 20 times faster than traditional bombers and can
carry hydrogen-powered nuclear warheads far deadlier than the
atom bombs dropped on Japan. Luckily, we've also got some pretty nifty anti-missile defense systems. So which countries have nukes today? Any guesses who has the most? Because of how secretive
the world's governments are about their nuclear stockpiles, we can't be 100% sure
on the exact figures, but as of 2021 estimates, Russia has the most nukes
with a world-ending 6,255. Hot on their heels in second place, we have the USA with a considerable 5,550. The other seven nuclear-capable
nations have a lot less, with North Korea owning the least, somewhere between 40 and 50. And though 40 nukes
doesn't sound like much compared to over 6,000, that's still enough
firepower to completely wipe New York City off
the map and then some. Which makes me wonder, what would it be like if
the unthinkable happened and the world really did descend into full blown nuclear warfare? As a global community, we're currently sat on over
13,000 nuclear warheads. However, this number
is a little misleading. Due to disarmament efforts, only 3,000 to 4,000 are actually active and the rest are decommissioned. This is relatively low compared with 1986, when the total number of
active warheads hit a whopping world high of 70,300. Of course, 4,000 nuclear
missiles could still do a pretty hefty amount of damage. If even a 10th of them found their target, the loss of human life
would be catastrophic, and not just from the
explosions and radiation, from huge firestorms, too. Yeah, as if nuclear
weapons weren't bad enough. At Hiroshima, all the
individual fires caused by the explosion amalgamated into one
terrible tempest of flames. Hot air rose and created
burning hurricane strength wind that turned inward towards
the fire and fanned it. This made it rage even harder, destroying everything
in its path for almost 4 1/2 square miles before
eventually dying out. One apocalyptic theory
called "Nuclear Winter" claims that if enough bombs went off, thousands of these furious
firestorms would burn their way across the globe, kicking up hundreds of millions of tons of smoke and ash as they did so. This would form a thick belt of particles, encircling the Northern atmosphere, plunging our world into darkness. Lack of sunlight would
cause dramatic falls in temperatures and destroy
much of Earth's vegetation and animal life. With crops failing, animals dying, and cities and infrastructure destroyed, surviving humans would be left in a cold, irradiated wasteland and
the dark clouds could remain for a whole decade. In other words, it wouldn't be very fun. Hold on, though. Before you go and spend your
life savings on a fallout shelter and 1,000 tins of beans, you should know that we're
probably not heading toward Armageddon any times soon. Mankind has possessed the
power to destroy itself since the end of World War II. Despite this, no nuclear
weapon has ever been used outside of a test since 1945. Why? Well, nuclear warfare
doesn't benefit anyone. If one country launches a
nuclear attack on another, the defending country is likely to launch a counter nuclear attack in response and both parties would
be sent to their doom, but we call this mutually
assured destruction and it's not ideal. This worked pretty well during
the Cold War, but today, it's a bit more complex. With countries around the world developing blisteringly
fast hypersonic missiles, conventional defense systems
just won't cut it anymore. Not only do hypersonic missiles fly faster than a mile a second, they're also more maneuverable than their ballistic counterparts, making them supremely
tough to defend against. Even so, mutually assured
destruction still applies. The US, Russia, and China are
all developing the technology alongside a number of other countries. Because of this, ironically, an attack is far less likely than if just one country had the power. Okay, I know that's not the
most comforting thing to hear, but hey, weapons of mass
destruction aren't very comforting. I guess that's why you never see any cuddly nuke toys in kid stores. Anyway, the modern world
is much more focused on using nuclear energy
for constructive uses than the destructive. In fact, about 10% of
the world's electricity is now nuclear, and that's a good thing. It doesn't pollute the
atmosphere and it's about 10 million times more efficient
than burning fossil fuels. Nuclear research has also helped doctors in the fight against cancer, allowing them to predict the
amount of radiation needed to kill tumors without
damaging healthy cells. We even use radiation to kill
harmful bacteria on our food. So it's not all doom and gloom. And thanks to nuclear technology, we're actually taking some steps towards creating a better world. Let's just hope we don't blow
that world into smithereens before we get there, right? So, what do you think of all this? Would we be better off if we'd never discovered nuclear energy? Or has the threat of nuclear weaponry actually prevented another
global scale conflict? Let me know down in the comments below and thanks for watching.
