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In 1982, I was standing on the deck of a Navy frigate watching the first attempt to launch a missile from the forecastle of our ship. Nearly the instant it came into sight, the missile exploded with a flash of light. A shock wave hit my body like a slap. A few seconds later, I realized that I couldn’t hear a thing.
I was lucky. My hearing returned within a couple of hours, and there was no other damage. The missile exploded due to a structural failure, but not with the full force of a bomb. For people who are near such explosions, the result can be significant injury or even death.
That’s the situation that a new patent from Boeing is intended to prevent. Despite the hype that accompanied some accounts of Dr. Brian Tillotson’s invention, this isn’t the kind of force fields or shields you saw in Star Wars and Star Trek. Instead, the Boeing scientist has developed a way to block the force of a shock wave created by an explosive device before it can hurt someone or cause damage.
The technology works by heating a small region of air to the point that it changes the speed of sound in the area being heated. This effectively redirects the shock wave (which is similar to a sound wave except that it moves faster) so that it misses the people or objects it’s protecting. Depending on the characteristics of the heated area, the result is that the intensity of the shock wave is attenuated.
“Shockwaves are a high-intensity version of sound waves, and sound waves travel faster in a hotter gas,” Tillotson explained in an email.
“Changing the shockwave’s speed lets us change its direction—just as the speed of light is different in glass than in air, and that lets glass refract (or bend) light when the light enters or leaves the glass, our shockwave refracts as it enters and leaves the hot region. It enters moving in one direction (say, toward a soldier) and it leaves moving in a different direction (missing the soldier).”
Creating that hot region of air so that it can refract the shock wave is the tricky part. For this to work, the device needs to detect an explosion and then create the hot air fast enough that it happens before the shock wave hits whatever it is that’s being protected.
The heart of Tillotson’s design is a collection of sensors that can detect the explosion through its electromagnetic radiation (this is usually a flash of light) and then act within milliseconds.
That action, as described in the patent, consists of firing a group of lasers into the region of air between the explosion and the target. The lasers create a temporary plasma region that is very hot.
Boeing Scientist Patents Force Field Tech That Blocks Shock Waves
That temporary plasma region has a convex shape, which is what refracts the shock wave and renders it harmless. The plasma channel may only last for a few tenths of a second before it dissipates.
What’s happened is that the plasma channel has briefly created a force field that prevents or weakens the damaging shock wave so that it doesn’t hurt anyone or create damage. But because of the way it works, the plasma channel can be whatever size is necessary and there’s no reason that it can’t be scaled to protect groups of people, or even buildings and vehicles.
The Boeing scientists have also developed a means of applying the same technique to other types of media, including water. In another patent, Boeing scientists have developed a means of creating a cavitation region within a region of water, making it possible to protect swimmers or even submarines from underwater explosions.
All of this sounds great, of course, but the big question is whether it will really work. Tillotson said that the enabling technology already exists, so there’s no reason it can’t be built. But he also said that there’s an easy way to test the principle.
“What we did test was the use of a convex region of gas where the speed of sound is higher than air.” Tillotson explained. “Those tests used helium balloons from a grocery store. We set off about 20 grams of PETN explosive and measured the shockwave intensity at several points. As our model predicted, the intensity dropped by about a factor of four in the area behind the helium balloon.
“Think about that—a sheet of armor would not necessarily protect you from that shockwave, but a helium balloon clearly does,” he said. Tillotson isn’t recommending sending soldiers into battle with bunches of helium balloons, but the idea would work.
He does point out that other elements of the explosion, such as shrapnel, would not be stopped, but he noted that military vehicles usually have protection against that, but not against the shock wave.
Obviously, this isn’t the magic, impermeable dome that science fiction fans expect when they think about force fields, but this is a first step. What’s better is that it helps prevent some of the most serious damage caused by explosions, which are injuries due to shock waves. Those shock waves can destroy organs within your body and kill you just as surely as the shrapnel.
Over the long run, this technology has the potential to protect against other types of damage from shock waves in a variety of situations, whether it is just the noise and concussions from construction site blasting, aircraft noise around airports or even really loud concerts. In those applications, you might not need the laser-generated plasma, but the attenuation could be critical.