BIGGEST EXPLOSIONS

Hey, Vsauce. Michael here, and today I'm in my apartment. But when I was in Kansas with family, my dad lit off what is known as a quarter stick. But don't worry, absolutely no children were around. Okay, look, the point is that today we're going to talk about explosives.

Let's begin way down the scale with black powder, or smokeless powder, which many modern rounds use. Now, usually, smokeless powder doesn't even detonate. Instead, it deflagrates. Technically, an explosion is only a detonation when the material or the gases expelled travel faster than the speed of sound. If the explosion is subsonic, you're only dealing with a deflagration.

Now, we want a bullet's propellant to deflagrate, not detonate, because we want it to have enough power to move the bullet quickly, but not release its energy so fast as to damage the gun or ourselves. Take a look at some smokeless powder lit in the open and slow motion. It burns very strongly and quickly, but at all times, the gases it expels never exceed the speed of sound and no shock wave is produced. We're looking at deflagration here, not detonation.

To compare, this is nitroglycerin. It's so fragile, you hit it with a hammer and it detonates. Even at a slower speed, we can see that all the material immediately explodes. Consumer fireworks use black powder, gun powder, and as such, they don't have enough power to really ever be set to detonate. The same goes for that quarter stick you saw my dad light off. Those and M80s and cherry bombs are louder and often illegal, but they burn flash powder, not a high explosive like dynamite.

But that doesn't mean fireworks can't be amazing. Currently, some of the largest shells in use are 48 inches across. When exploded in the air, a 48 inch shell looks like this. Or like this. Oh yeah, when they fail to launch and burst on the ground instead, it looks like this.

But let's move on to detonations—no matter what material releases the energy—whether it's a conventional explosive or a nuclear bomb or an asteroid impact or an earthquake, they are all commonly measured by saying how much TNT you would have to detonate to get an equivalently strong explosion. To give you a sense of scale, here is the detonation of approximately 100 tons of TNT by a defense contractor disposing of explosives.

Unlike deflagrations, detonations produce a shockwave, which is just that, a wave made of areas of high pressure and low pressure. This explosion was so powerful the area of low pressure had such low pressure that water vapor in the air around it condensed momentarily, which formed this cloud. And here's a video of an explosion where the shock wave is particularly visible as it approaches and hits the cameraman.

You can also see shock condensation clouds around these explosions set off by the United States in Hawaii in 1965. The US wanted to know how nuclear attacks would affect naval ships, so they detonated an equivalent amount of TNT on an island with US ships anchored nearby. This pile contains 500 tons of TNT waiting to explode. When it does, it looks like this.

Earlier, the US tested actual nuclear weapons to see how underwater detonations might affect our ships. This underwater nuclear explosion is much larger, the equivalent of not 100 tons of TNT, not 500 tons, but 8,000 tons. For comparison, the atomic bomb dropped on Hiroshima in 1945 exploded with the energy of 15,000 tons of TNT.

The single most physically powerful device ever used by humanity was the Tsar Bomb. The Soviet Union tested it in 1961, far up north away from civilization. It was detonated two and a half miles above the surface of the earth to minimize its destruction, which was unprecedented by man. The Tsar Bomb exploded with the power equivalent to 50 million tons of TNT.

The mushroom cloud from the Tsar Bomb extended beyond our normal atmosphere into the mesosphere and dwarfed the largest clouds from US detonations. It was so large that comparatively the bombs dropped on Japan, well, they're on the graph way down there. But at the end of the day, nothing can beat supernovas, the explosion of an entire star.

While 50 million tons may sound like a lot, one supernova is estimated to give off the energy equivalent of ten octillion million tons of TNT. I leave you with a cannon developed by the US to shoot a normal little cannonball, except that it carried a nuclear warhead. I'm pretty sure you can pick these up at Bass Pro Shop, but regardless, be sure you're subscribed to Vsauce so you don't miss anything coming up, and as always, thanks for watching.