One of the most iconic sequences in all of movie history comes from the original Star Wars film, where the Galactic Empire brings Princess Leia to her home planet, Alderaan, and threatens her with the destruction of her world using their “superlaser” unless she reveals the secret location of the rebel base. She (lyingly) reveals it, and then they give the order to fire anyway, destroying the entire Earth-sized world in a single shot.
While it’s an excellent plot point to showcase the ruthlessness and cruelty of the Galactic Empire, it might seem unrealistic that a simple laser — even a superlaser — could cause that level of destruction with a single blast. But if we wanted to destroy an Earth-sized world with a single blast, in seconds, and still have enough energy to send huge fragments of the planet hurtling through space at incredible speeds, the laws of physics provide us with a fantastic solution. Let’s look at what it would take, first.
The Earth is an extremely massive object, totaling around 6 × 10^24 kilograms of matter, from our surface down to our core. The force of gravity holding us together is tremendous, and if we wanted to literally destroy the planet, we’ve not only got to overcome that force, we need to impart enough energy to the planet in the right fashion to overcome that gravitational binding energy. The amount of that energy, by the way, which we’d have to exceed to blow it apart, is an astounding 2.24 × 10^32 Joules, or 224,000,000,000,000,000,000,000,000,000,000 Joules of energy.
But the secret of the Sun’s energy is the very key to making aliteral doomsday weapon such as this. The Sun, you see, gets its power by converting matter into energy via Einstein’s E = mc^2. By fusing hydrogen into helium, about 0.7% of every hydrogen atom’s mass gets converted into pure energy, a process that converts the equivalent of 4,300,000 metric tons of matter into energy each second. Still, relying on a nuclear fusion reaction is a fool’s game, as you might have guessed just by looking at the size of the Sun.
When you release that much energy at once, it causing tremendous heating and expansion, and so if you try to ignite that reaction on board the Death Star, it’s going to need to contain a million times more energy than the Sun can at any given time. That’s a bad idea, and if you foolishly did build your Death Star this way, you wouldn’t need a well-piloted X-Wing (or Millennium Falcon) to blow it up; it would spontaneously do so on its own.
But there’s a very, very good idea that’s even more efficient than nuclear fusion: taking advantage of the properties of matter itself. You see, a planet’s core is extremely dense and packed with matter: the m in E = mc^2. If we could somehow spontaneously turn that mass into pure energy — even just 2.5 trillion tons of that mass — that would release enough energy to destroy the entire world, exactly as we wished.
Luckily for us, there’s a straightforward way to turn matter into pure energy: collide it with an equal amount of antimatter, converting the mass of both into energy via Einstein’s E = mc^2.
Instead of storing energy on the Death Star itself, or creating energy to be spontaneously released towards the target planet, you can simply create-and-carry the antimatter mass you need with you. If 2.5 trillion tons of mass needs to be converted into energy in the planet’s core in order to destroy it, then bringing half that mass in antimatter, delivering it to the planet’s core and simply letting it collide with the existing matter will do the job for you.
1.25 trillion tons of mass might seem like a lot, but in reality, that’s only the size of a modest asteroid.
Of the asteroids shown above, the asteroid 5535 Annefrank is closest in mass to what we’d need, at just a few km in size along each axis. If we could make (and contain) a solid “chunk” of antimatter like this, keep it on board our Death Star, carve a path to the planet’s core (which an actual lasercould do) and deliver this antimatter to it, it’d be the perfect way to literally destroy the Earth, Alderaan, or whatever planet we chose.
It’s not even technically impossible; we’ve already created antimatter atoms in the lab, with antiproton for nuclei and positrons in place of electrons. If we could bind these anti-atoms together in a lattice — either as metallic (anti)hydrogenor with heavier anti-atoms that spontaneously bind together (add some anti-carbon and you can construct an anti-diamond!) — all you’d have to do is isolate it in a vacuum and you’d be able to transport it anywhere.
The Death Star may have begun as a symbol of imperialism, military power and hubris run amok, but thanks to our understanding of physics, it’s only a resourceful mad scientist away from becoming a reality. The power of science literally holds the secret, if we choose to make it so, to destroying an entire world.
Ethan Siegel is the writer and founder of Starts With A Bang, a NASA columnist and professor at Lewis & Clark College. Follow him on Twitter, Facebook, Google+, and support hisPatreon.
Source: forbes.com
