In the sci-fi epic Dune, characters carry a portable force field that protects them from speeding projectiles. Could we make one of these for real?
In the Dune universe, a Holtzman shield is a portable force field capable of protecting an individual soldier in battle. Created by a generator worn on the belt, the shield is able to deflect speeding projectiles away from the wearer, although slow-moving objects, such as a knife in hand-to-hand combat, can penetrate the barrier.
Force fields like this are a tall order in the real world. There are four known fundamental forces of nature – gravity, electromagnetism, and the strong and weak nuclear forces that exist within atomic nuclei.
Of these, gravity is too weak to be useful as a localized force field – it takes all the gravity produced by our planet, the Earth, to stick our relatively puny bodies to its surface. On the other hand, the nuclear forces can be strong but, as the name suggests, they are confined within the minuscule cores of atoms.
Physicist Prof Jim Al-Khalili, of the University of Surrey, thinks it may one day be possible to build a force field based on electromagnetism. It’s certainly a stronger force than gravity, with a longer range than the nuclear forces. However, it only exerts its influence on bodies that are electrically charged. So the first job upon detecting an incoming projectile would be to charge it up.
This could be done, Al-Khalili believes, by bombarding the object with a beam of positrons. These are particles of antimatter, of equal mass to the electrons that orbit around the outside of atoms, but with an opposite electrical charge. When positrons and electrons come together they totally annihilate one another. He speculates that this effect could be exploited to charge up an inbound projectile so it can be deflected.
“You can use positrons to destroy electrons in the target,” he says. “And if you destroy enough of them then the target becomes positively charged. Then you can whack on an electric or magnetic field to deflect it.”
Although plausible, this is still most likely a technology reserved for the far future – indeed, it’s probably just as well that the action in Dune doesn’t take place for another 20,000 years.
One concept that is being developed now is electric armour for battle tanks. Ordinarily, a tank relies on hefty steel plates to deflect incoming bombs, missiles and gunfire.
But the new idea means switching the thick armour for two thinner metal plates separated by an insulating layer. The plates are electrified from a power source so they act like a high-power capacitor, able to store up a huge electrical charge because of the insulator between them.
“When a metal projectile penetrates the outer layer and impacts on the second, it closes the circuit and allows a massive amount of power and energy to be dumped into the projectile,” says James Bingham, a military analyst. “This destroys the projectile or offsets its kinetic energy and penetrative effects sufficiently to mitigate its destructive impact.”
This makes for armour that’s highly effective and much lighter than usual, giving armoured vehicles greater speed and manoeuvrability. Electric armour is currently under development at the UK’s Defence Science and Technology Laboratory.