Can’t explosions both make and break things? Perhaps it depends whether they’re accidental or not. And are we talking about explosions in nature or man-made ones? Why don’t we dig a little deeper…
Are explosions always destructive?
First, we need to address what defines an explosion. An explosion occurs when a large amount of energy is released into a small volume of area in a very short time. This release of energy can be mechanical, chemical or nuclear. Whether the nature of the explosives is natural, like volcanoes, or man-made, like bombs, the violent burst associated with explosions makes us think of them only as a tool for destruction. But when it comes to explosions there’s more than meets the eye. When used in a controlled manner, explosives not only can be beneficial and useful but even pretty! And, if we go a little further, a particular type of explosion might be the reason that we’re all here...
Why do explosions take place?
The power of Mother Nature
First of all, not all explosions are man-made. Volcanoes are one of the most powerful representations of mother Earth’s power. As majestic as an eruption can be, they can be terribly damaging. The nature of why eruptions occur is diverse and complex. Underneath the Earth’s crust, there are layers of molten rock. Due to the high temperatures, this rock becomes a flowing substance called magma. With time, gasses are released which increases the pressure in the magma chambers until eventually, this magma pushes through to the Earth’s surface. Magma that has erupted is called lava.
How explosive an eruption is depends on the viscosity (thickness) of the magma. If the magma is thin and runny gasses can easily escape. This type is not as dangerous since this ‘runny’ lava does not flow that quickly and so you could potentially outrun it should you come near it. The situation is a lot more dangerous when the magma is thick since the gasses cannot escape until the build-up pressure make them do so violently. This type is known as an explosive volcanic eruption. It can be extremely dangerous due to pyroclastic clouds (clouds of ash and hot gas that can reach 1000°C) which have the ability to destroy everything in its path and the subsequent blankets of ash suffocate any life beneath them.
Volcanoes are not the only example of natural explosions occurring on Earth. There are other examples on Earth like geysers and hot springs. But natural explosions, on a completely different scale, can also occur in space...
There are on-going explosions happening in space in the shape of gamma-ray bursts and supernovas. Gamma-ray bursts are extremely energetic forms of electromagnetic radiation, thought to occur when a black hole is formed by a type of supernova. There are two types of supernova. The first is when a star - which is orbiting around a companion star - explodes after grabbing some material from the companion star. The second type is when the most massive stars reach the end of their life and collapse before exploding. Not all dying starts result in a supernova though. The sun, for example, does not have enough mass and instead will expand before fizzling out to become a very small star called a white dwarf.
Supernovas are, therefore, believed to play a key role in creating life on Earth since the massive stars that go supernova also create the heavy elements required for life such as oxygen, carbon and nitrogen. They do this via nuclear fusion in their cores, where the high temperatures help fuse hydrogen and helium into heavier elements. This is the scientific basis behind the phrase: “we’re all made of stardust”.
To learn more about nuclear fusion and how it differs to nuclear fission, take a look at the video below:
Man-made snap, crackle and pop!
Humans have, of course, also contributed to the destroying power of explosions, particularly in the modern age with the advancements in science and technology. In some cases, explosions were accidental as a result of a malfunction. The Hindenberg and R101 airship disasters for example in which a series of incidents led these hydrogen gas-filled structures to rapidly catch fire.
But perhaps the biggest cause of man-made explosions is the development of bombs which have featured in many wars and attacks. All bombs, along with other explosive military weapons, use an exothermic reaction (which releases heat) of an explosive material to provide a violent release of energy. In order to achieve this reaction, different techniques are used, such as the chemical reaction of explosive materials. Modern bombs have also made use of nuclear fusion (the same process that occurs in stars to create heavy elements). But all nuclear bombs use the reverse process known as nuclear fission, in which an atom decays into smaller parts releasing a large amount of energy in the process. The most infamous examples of nuclear fission bombs are the atomic bombs dropped on Hiroshima and Nagasaki, Japan at the end of the Second World War, killing and injuring thousands of people.
That said, the same principle of using an explosive device can also result in a beautiful display. Fireworks are basically a colourful missile, except that they explode in a controlled and pretty way!
What about entropy?
Given the laws of probability, things are much more likely to be disorganised than organised. Some of us might have heard of the term entropy and how it always increases. But what does entropy has to do with explosions? Well, entropy can be interpreted as the degree of disorder or randomness in a system, and explosions are an extreme example of disorder! If you want to take a deeper look at what entropy is all about take a look at the video below:
So what's the verdict?
While explosions (both natural or man-made) can result in devastation and mass loss of life, when used in a controlled manner, they can actually be beneficial. Man-made explosives can be put to good use in our everyday lives as can be seen in (refer to later resource here). And in nature, volcanic explosions provide nutrients to the surrounding soil, and some explosions in space have led to the development of life (e.g. supernova explosions). Therefore, although we should be wary of the power of explosives and, in particular, of our own contribution to their development, next time you think that explosives are always destructive, remember: we’re all here because of them!
How to make a supernova on Earth
Researchers from the University of Oxford are using the largest, most intense lasers on the planet, to for the first time, show the general public how to recreate the effects of supernovae, in a laboratory.
4 things that wouldn't exist without explosions
- A popcorn kernel (seed) is mostly made up of starch, surrounded by a strong, hard shell. When you pop a packet of these kernels in the microwave and heat them up, the starchy moisture inside also gets hot and wants to turn into steam. But the hard outer shell stops this from happening. As things get hotter and hotter, the pressure builds up and the heat starts to turn the starch into a kind of jelly. Eventually, the hard shell of the kernel gives in to the pressure and splits, which blows the starchy jelly out into the air where it cools down and hardens into the foam which we call popcorn. Yum. It definitely tastes better than it sounds.
- Car engines
- Every time you get a lift somewhere, remember that explosions (better known as combustion) are what’s helping you on your way. If you put a tiny amount of high-energy fuel (like petroleum) in a small, enclosed space and ignite it, a huge amount of energy is released in the form of expanding gas. If you can create a cycle that allows you to set off explosions like this, hundreds of times per minute, and if you can harness that energy in a useful way, then what you have is the core of a car engine. Almost all modern car engines use something called a ‘four-stroke combustion cycle’ to convert petrol into motion.
- A firework is basically just a very colourful missile, designed to explode in a very controlled - and pretty - way. And it takes several different types of explosion to make the beautiful displays we 'ooh' and 'ahh' about. There’s an initial ‘charge’ explosion, which is usually made up of tightly packed gunpowder and is designed to blast the firework up into the sky - sometimes more than 1000 feet high and at roughly the same speed as a jet fighter! Then there are the ‘effect’ explosions, made up of finer, more loosely packed explosive material often separated into different ‘stars’ which make up the small, colourful explosions from a larger firework. More specifically, gunpowder is a mix of saltpetre, sulfur and carbon (charcoal) and it's these different chemical compounds that give the different colours.
- If you're ever unlucky enough to be in a car accident, a carefully controlled explosion could save you. When a car hits something, it starts to decelerate (lose speed) very rapidly - much faster than normal braking. If it slows down fast enough, the accelerometer (an electronic chip in the car that measures acceleration and force) triggers the airbag circuit. This generates an electric current which then ignites a chemical explosive (Sodium Azide). As the explosive burns, it creates Nitrogen gas, which floods into nylon bags packed behind the steering wheel and dashboard of the car. As the bags expand they blow through their plastic coverings and inflate in front of the passenger and the driver, cushioning some of the impact from the crash and helping to reduce their injuries.
90% of Mount Rushmore was carved with dynamite!
90% of Mount Rushmore was carved with dynamite!
Take a look at the science (and the implications) behind one of the most explosive ideas in human history: the atomic bomb.
Enduring an epic explosion: 6 creatures that could survive a nuclear bomb
- It might sound like a made-up creature from Hogwarts, but it’s actually a type of fish and it can literally live anywhere. It normally hangs out in the most polluted areas of ocean where there are severe chemical spills, but it’s also the only fish to have been to space. A few mummichogs were taken to the Skylab space station in 1973 for tests and it was discovered that they could actually swim in space, as well as have babies up there (who were all born normally). Plus mummichogs have been observed adapting their own body parts to cope with new environments, so they’re all set for the post-nuclear-destruction world.
- Braconidae wasps
- The braconidae is a kind of parasitoid wasp - that means they lay their eggs inside other animals. Researchers have discovered they can withstand up to 1800 Sieverts of radiation. To put it in perspective, the UK workplace limit for how much background radiation an employee can be exposed to, is 20 thousandths of 1 Sievert. This makes Braconidae wasps one of the toughest animals alive today. Although, there’s some argument about whether or not the species would survive for long, as there wouldn’t be many other animals for them to lay their eggs in. But if this list turns out to be right, they’ll have at least five other types of creature to choose from for their egg babysitters.
- It’s not an absolute guarantee, but these little guys are pretty hardcore. They’re not harmed at all by ultraviolet radiation and can even be frozen and brought back to life. And they’re usually found in burrows or rock crevasses, which would give them some extra physical protection from nuclear radiation. Plus, they can glow in the dark. And that’s just cool.
- Otherwise known as ‘water bears’ these dudes are insane - they’re what scientists call ‘extremophiles’ because they can withstand crazy extremes that would instantly kill other creatures. They can be boiled, crushed, frozen, live in space, live without water and be brought back to life after being clinically dead for almost a decade! So they probably won’t be put off by a little thing like a nuclear bomb. They also only grow up to 1.5mm long, so are less likely to be at risk from the explosion itself.
- Fruit flies
- The common fruit fly (or Drosophila if you want to use their scientific name) can survive high doses of radiation up to around 640 sieverts, so they’re pretty likely to make it through a blast even if they’re close to the epicentre. The fact that they’re so small works in their favour too, as they have fewer cells to be affected by the radiation and a smaller surface area to absorb it.
- These creepy little scuttlers always make the guest list for the nuclear bomb after-party, but actually, they’re only a ‘maybe’. Some research was done exposing a group of cockroaches to a radiation level of 100 Sieverts and only about 10% of them survived, and most nuclear explosions would involve higher radiation levels than that now. If they were far enough from the epicentre of the explosion they might be ok, and they’ve still got a higher chance of survival than most animals - but of all the creatures on our list they’re actually the least likely to make it.
Are explosions always destructive?
Some create new life
Supernovas are believed to play a key role in creating life on Earth since the massive stars that go supernova also create the heavy elements required for life such as oxygen, carbon and nitrogen. There are two types of supernova. The first is when a star - which is orbiting around a companion star - explodes after grabbing some material from the companion star. The second type is when the most massive stars reach the end of their life and collapse before exploding. They do this via nuclear fusion in their cores, where the high temperatures help fuse hydrogen and helium into heavier elements. This is the scientific basis behind the phrase: “we’re all made of stardust”.
Explosions can kill
Bombs have featured in wars and attacks for many, many years and our developing understanding of science and technology has only served to accelerate the power of them. The nuclear bombs that were dropped on Hiroshima and Nagasaki, Japan at the end of the Second World War killed and injured thousands of people. It also destroyed people’s homes and livelihoods. Many of those affected were ordinary civilians. The damage caused continued beyond the explosion itself with the long-lasting effects of injury, grief and potential radiation poisoning. This continues to be a highly controversial historical issue with some believing that this destruction ultimately prevented further devastation that a prolonged world war would have caused. While others believe that destruction on this scale can never be justified.
Explosions can be beautiful
A firework is basically just a very colourful missile, designed to explode in a very controlled - and pretty - way. The initial ‘charge’ explosion can blast a firework more than 1000 feet high and at roughly the same speed as a jet fighter! Then the ‘effect’ explosions which are made up of finer, more loosely packed explosive material often separate into different ‘stars’. Although they are not without their dangers, fireworks can be very artistic. So when you ‘ooh’ and 'ah' next Bonfire Night, take a moment to think about the clever science behind it all. Also, 90% of Mount Rushmore was carved by dynamite and as a piece of sculpted art, it continues to impress tourists.
Explosive science can go seriously wrong
Science can be amazing but also amazingly dangerous when it goes wrong, especially when there's an explosion involved. The Hindenberg and R101 airship disasters occurred when a series of incidents (technical fault, bad weather conditions) led these hydrogen gas-filled structures to rapidly catch fire. Both resulted in many fatalities and serious injuries demonstrating the powerful impact of explosions.
They can be useful, life-saving and tasty!
Explosions have been put to a range of purposes – some which are very useful and feature in our everyday lives. Every time you get a lift somewhere, remember that explosions (better known as combustion) are what’s helping you on your way. Almost all modern car engines use something called a ‘four-stroke combustion cycle’ to convert petrol into motion. If you're ever unlucky enough to be in a car accident, a carefully controlled explosion could save you in the form of airbags. When the airbag circuit is triggered, this generates an electric current which then ignites a chemical explosive (Sodium Azide). As the explosive burns, it creates Nitrogen gas, which floods into nylon bags packed behind the steering wheel and dashboard of the car. Air bags cushion some of the impact from a crash and help reduce injuries – potentially saving many people’s lives. And last but not least, popcorn is a result of a series of mini-explosions that turn the hard kernels into the airy puffs of corn that we know and love!
Nature can be explosive
Not all explosions are man-made. Planet Earth can pack an equally as powerful and frightening punch. Volcanoes have proven this for centuries. In fact, the biggest volcanic eruption ever recorded took place in April 1815 when Indonesia’s Mount Tambora blew its top, sending molten rock 25 miles up into the air. The resulting lava flows and tsunamis killed more than 60,000 people. Don’t mess with Mother Nature!
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