A Mach cone is created when something travels faster than the waves it's emitting - this often happens when a plane is travelling faster than the speed of sound, producing an ultra-loud boom. But not many people know light can do the same.

So how exactly do you create a 'photonic boom'? At first thought, it seems ludicrous that light could also have a Mach cone. After all, nothing can travel faster than the speed of light in a vacuum – about 300,000 kilometres per second.

But light can be slowed down, and as such it can slip faster though some material than others. Which is how the team were able to create the photonic Mach cone.

In this experiment, a team of researchers led by optical engineer Jinyang Liang from Washington University created a channel between two plates of silicone rubber and powdered aluminium oxide. They filled the gap with a dry-ice fog, and then fired a 7 picosecond laser pulse which scattered off the suspended particles.