Using technology that even Thor -- the hammer-wielding, lightning-controlling Norse god -- would be jealous of, the U.S. Army has begun to test directing lightning with laser technology.
As directly stated on the Army website announcing successful progress and testing of this innovation "soldiers and science fiction fans, you're welcome."
The scientists and engineers at Picatinny Arsenal created the Laser-Induced Plasma Channel (LIPC) to "take out targets that conduct electricity" by harnessing the power of lightning as directed by a laser. How does a laser help? Here's how the Army explains it:
"Light travels more slowly in gases and solids than it does in a vacuum," explained [lead scientist George] Fischer. "We typically think of the speed of light in each material as constant. There is, however, a very small additional intensity-dependent factor to its speed. In air, this factor is positive, so light slows down by a tiny fraction when the light is more intense."
"If a laser puts out a pulse with modest energy, but the time is incredibly tiny, the power can be huge," Fischer continued. "During the duration of the laser pulse, it can be putting out more power than a large city needs, but the pulse only lasts for two-trillionths of a second."
"For very powerful and high intensity laser pulses, the air can act like a lens, keeping the light in a small-diameter filament," said Fischer. "We use an ultra-short-pulse laser of modest energy to make a laser beam so intense that it focuses on itself in air and stays focused in a filament."
To put the energy output in perspective, a big filament light bulb uses 100 watts. The optical amplifier output is 50 billion watts of optical power, Fischer said.
"If a laser beam is intense enough, its electro-magnetic field is strong enough to rip electrons off of air molecules, creating plasma," said Fischer. "This plasma is located along the path of the laser beam, so we can direct it wherever we want by moving a mirror."
"Air is composed of neutral molecules and is an insulator," Fischer said. When lightning from a thunderstorm leaps from cloud to ground, it behaves just as any other sources of electrical energy and follows the path of least resistance.
"The plasma channel conducts electricity way better than un-ionized air, so if we set up the laser so that the filament comes near a high voltage source, the electrical energy will travel down the filament," Fischer elaborated.
A little more simply put, Popular Science explains it this way:
In other words, just as lightning arcs from cloud to ground via the path of least resistance, a high-voltage current will find its way down this filament rather than arcing unpredictably through the air. In other words, the laser just creates the path of least resistance between the power source and the target. Laser, lightning, destruction of target--in that order.
Although the scientists were able to figure out technically how this would work, the Army stated that it wasn't without its challenges, such as the danger of the light focusing in on and destroying parts of the laser itself.
Still with some success in testing -- although refinement is still needed -- Fischer said the team "never got tired of the lightning bolts zapping our simulated [targets.]"