00:00Mankind had never seen anything like it. When it was unleashed on people in an effort to stop a war,
00:05all people saw was a blinding light followed by complete darkness and destruction. It was August 6, 1945. It was
00:14the most powerful weapon ever created by mankind. Its shockwave turned everything in a one mile radius into rubble. It
00:21unleashed energy and radiation that killed 140,000 people in the industrial city of Hiroshima, Japan.
00:28As powerful as this bomb was, mankind has since invented a weapon that is hundreds of times more powerful. Today
00:36we have thermonuclear weapons, also called the hydrogen bomb. To give you an idea of its power, if the original
00:42Hiroshima bomb was dropped in New York City, it would destroy everything in a one mile radius. But if a
00:49hydrogen bomb was dropped there, heaven forbid, it would not just destroy everything in a one mile radius, it would
00:55make into rubble. Everything in a
00:5810 mile radius. This would be a total calamity. The world now has over 10,000 such bombs, capable of
01:06easily destroying every single person on our planet many times over. What makes these weapons so powerful? How do they
01:14actually work? That's coming up, right now.
01:22The bomb on Hiroshima released an energy equivalent of 15,000 tons of TNT. The first hydrogen bomb released the
01:29energy equivalent of 10 million tons of TNT. While the atomic bomb, like the one that was dropped on Hiroshima,
01:37worked on the principles of releasing energy through the splitting of atoms, also called fission. See my video on that.
01:43A hydrogen bomb does something that releases even more energy, and that is, it fuses atoms together. Fusion is even
01:51more powerful than fission. It is the same process that powers our sun. And when fission is combined with fusion
01:58in a hydrogen bomb, it creates energy orders of magnitude higher than fission alone, making the hydrogen bomb hundreds to
02:05thousands of times more powerful than atomic bombs.
02:08How does fusion work? The fusion portion of the bomb creates energy by combining two isotopes of hydrogen, called deuterium
02:17and tritium, to create helium.
02:19Unlike a natural hydrogen bomb that is made of one electron orbiting around one proton, these isotopes have extra neutrons
02:28in their nuclei. A large amount of energy is released when these two isotopes fuse together to form helium.
02:34Because a helium atom has much less energy than these two isotopes combined. This excess energy is released. One of
02:43the main problems with creating the hydrogen bomb was obtaining the tritium.
02:47Scientists found that they could generate this on the spot, inside the hydrogen bomb, with a compound combining lithium and
02:54deuterium. The result was a dry, solid, stable powder called lithium deuteride.
02:59So this is what most hydrogen bombs today use as their fuel. But how does the process of fusion actually
03:06occur?
03:07Ordinarily, the nuclei of two atoms cannot be combined because these nuclei have strong positive electrical charges and repel each
03:14other.
03:15This is why scientists chose hydrogen as the best candidate for fusion because it has only one proton, and thus
03:21would have less electrical charge than atoms with multiple protons in their nuclei.
03:26But if the nuclei repel each other, how do they fuse? It turns out that if you increase the temperature
03:31by millions of degrees, it is possible to combine nuclei together.
03:35As the temperature increases, the atoms speed up. But an extraordinary increase in speed of the atoms is needed in
03:42order to give them a chance to overcome their natural repulsion.
03:45The temperatures needed are astronomical, higher than even that at the center of our sun, 100 million degrees Celsius.
03:54The center of the sun is 15 million degrees Celsius.
03:57At this temperature, the isotopes become a form of matter called plasma.
04:01This is when the electrons orbiting the nuclei are stripped away from the nucleus, and the nuclei in electrons are
04:07floating around freely in a kind of high temperature soup.
04:10At this temperature, the nuclei can get very close to each other, and when they get as close as 1
04:15times 10 to the negative 15 meters apart,
04:17then the strong nuclear force, which is present only at very close distances and is responsible for keeping protons and
04:24neutrons glued together,
04:26takes over and binds the protons and neutrons together to form a helium nucleus and a free neutron.
04:32But how is a temperature of 100 million degrees achieved?
04:36This is where the fission or atomic bomb inside the hydrogen bomb enclosure comes in.
04:42The purpose of the fission bomb is to provide the energy needed to heat up the fusion reaction to this
04:47100 million degrees.
04:49So how do they work together?
04:50A hydrogen bomb is actually three bombs in one.
04:53It contains an ordinary chemical bomb, a fission bomb like the one dropped on Nagasaki, and a fusion bomb.
04:59All three work in concert.
05:02The chemical bomb initiates the fission bomb, which initiates the fusion bomb.
05:06To understand how the fission and fusion bombs work together, it's important to understand how the bomb is put together.
05:13In a ballistic missile, the bomb is usually located at the top, inside the cone portion of the missile.
05:19Here is where the hydrogen bomb vessel sits.
05:22The casing of the bomb is lined with beryllium.
05:25This acts as a mirror to reflect the neutrons back into the casing rather than allowing them to escape the
05:31vessel.
05:32A small atomic bomb is located at the top of the casing.
05:35It's shaped like a sphere.
05:36The top of the sphere contains conventional chemical explosives surrounding a sphere of beryllium mirror casing,
05:43inside of which is a smaller uranium or plutonium sphere about 4 to 6 inches in diameter.
05:49Below this atomic bomb is the hydrogen or fusion bomb.
05:53It consists of a cylinder made of uranium.
05:56The fuel for the fusion reaction, lithium deuteride, sits inside the cylinder.
06:01And at the core of the cylinder sits a rod of plutonium.
06:04In between the fission and fusion bombs is an encasing made of styrofoam.
06:09And here is how it all works together.
06:11First, the fission bomb is detonated by exploding conventional chemical bombs in sequence.
06:17This forces the sphere of plutonium 239 or uranium 235 to implode on itself.
06:23The implosion or compression of this material creates a critical mass,
06:28which results in a chained reaction of neutrons splitting atoms apart
06:32and creating more neutrons, which split more atoms apart.
06:35The chained reaction results in an atomic explosion.
06:39This fission explosion creates high energy gamma rays and x-rays,
06:42which heat up the styrofoam and turns it into plasma.
06:45This plasma reflects off the beryllium-lined walls and focuses its energy on the fusion cylinder.
06:52These x-rays travel at the speed of light, so they can reach the hydrogen fuel sooner
06:56than the physical shock wave from the atomic bomb.
07:00This is important because if the shock wave reached there first,
07:03then the fusion bomb would be blown apart before it could create fusion reactions.
07:08The heat and pressure of the plasma compresses the fusion cylinder,
07:11causing the lithium deuteride to react. This releases tritium.
07:16The tritium and deuterium fuse to form helium and more neutrons.
07:20The neutrons cause the uranium casing and plutonium rod to undergo more fission reactions.
07:25This causes more pressure on the lithium deuteride, not only from the outside in,
07:31but also from the inside out. This produces more fusion and releases more neutrons,
07:37which causes more fission. This positive feedback loop of fission, fusion, fission,
07:43fusion reactions goes back and forth until a huge explosion occurs, ripping everything apart.
07:48Amazingly, all these events happen in only about 600 billionths of a second.
07:54550 billionths of a second for the fission bomb implosion, and 50 billionths of a second for the fusion bomb.
08:00The result in this immense explosion with a 10 million ton yield,
08:05700 times more powerful than the Hiroshima bomb.
08:08And where does all this energy actually come from?
08:11Well, if you could weigh all the atoms of the fuel before the explosion,
08:16and all the atoms released after the fusion,
08:18the sum of all atoms after the explosion would be less than the sum of all the atoms before the
08:24explosion.
08:25This difference in mass is converted to energy using Einstein's famous equation, E equals MC squared.
08:32And exactly how much mass is converted to energy?
08:35To give you an idea, the bomb dropped on Hiroshima converted 700 milligrams of mass into energy,
08:41about one third the mass of a US penny.
08:44The total uranium used was 55 pounds.
08:48A hydrogen bomb, however, converts about a kilogram, or two pounds of mass, to pure energy.
08:54But in order to convert this much, you have to start with about 140 kilos, or 300 pounds of hydrogen
09:00fuel.
09:00Only six countries have such bombs.
09:03China, France, India, Russia, the United Kingdom, and the United States.
09:08Almost all the nuclear weapons deployed today are hydrogen bombs,
09:11because they are much smaller and lighter,
09:13and so can be deployed in intercontinental ballistic missiles.
09:17These things don't just kill, they annihilate.
09:20We humans have become quite efficient at it.
09:24Arvin Ash here.
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09:38See you in the next video.
09:39Bye.
09:40Bye.
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