Scientists have created a new class of laser beam that appears to violate long-held laws of light physics. These new beams, which the team calls “spacetime wave packets,” follow different rules of refraction, which could lead to new communication technologies.
Light travels at different speeds through different media, slowing down in denser materials. It’s a phenomenon that’s best summed up in a basic, middle-school science experiment: if you place a spoon in a glass of water, the spoon will appear to be broken at the water’s surface. That’s because the light is travelling slower through the water than the air, and the light rays bend as they enter the water – a phenomenon known as Snell’s Law.
But the new laser beams don’t follow this basic law of light. And it’s not just Snell’s Law either – the team says they also ignore Fermat’s Principle, which says that light always takes the shortest possible path.
“This new class of laser beams has unique properties that are not shared by common laser beams,” says Ayman Abouraddy, principal investigator of the study. “Spacetime wave packets can be arranged to behave in the usual manner, to not change speed at all, or even to anomalously speed up in denser materials. As such, these pulses of light can arrive at different points in space at the same time.”