Why does laser speed matter? Because the faster the laser, the safer for humans to touch. While a slower laser might even burn you, a femtosecond laser is firing so quickly that there’s less opportunity for it to hurt, as IEEE explains. But part of what makes Fairy Lights so interesting isn’t just that they’re safer. It’s that you can still feel them. “Shock waves are generated by plasma when a user touches the plasma voxels,” the authors write. “The user feels an impulse on the finger as if the light has physical substance.”

In other words, this is a new kind of haptic interface. One where the sensation on your skin isn’t cased by a linear actuator, like the Apple Watch uses, but rather the waves that are generated when you interact with plasma in mid-air.

[Fairy Lights; h/t Spoon & Tamago | IEEE]

Contact the author at kelsey@Gizmodo.com.