Next time you're wandering through a vast parking lot, looking for your car, there's a weird strategy you can try: hold your remote unlocking device up to your head.
It might sound pretty crazy, but it will actually extend the device's range a bit — perhaps causing your car to light up, letting you more easily find it.
We were skeptical too, but a few physicists have actually conducted some experiments that prove it's true.
This video, by Professor Roger Bowley of the UK's University of Nottingham, explains how this weird trick works.
Holding the device up to your head means that its signal — electromagnetic waves of a particular frequency — passes through a large number of water molecules, contained in your brain. As these waves pass through, they pull the positive charges present in the water (the hydrogen ions) in one direction, and the negative charges (the oxygen ions) in the other.
"In effect, you've got the protons being pulled upward, then downward, then upward, then downward, because of the oscillating electric field," Bowley says. "That means they're behaving rather like a radio aerial [antenna] — as they go up and down, they're radiating energy."
That energy is radiated at the same frequency as the original signal, so it can combine with it to extend its range a bit further before it dissipates. As a result, in the video, Bowley can walk outside the normal range of his device, hold it up to his head, and get his car to unlock.
He demonstrates that it's the water in his brain that's crucial by walking even farther from his car and holding the device up to a jug of water — and again, successfully unlocking it.