The experiment involved liquid droplets merely 1 micron in diameter and the researchers used a laser beam with the input power of about 1 W that made the droplets levitate.
Gravity force on the one hand, and the laser beam pressure, on the other, forced the droplets perform curious movements similar to those of balls dancing in a juggler’s hands. LED back illumination, a microscope and a camera at 45,000 frames per second helped to record the process on video.
When one droplet is underneath the other, the electromagnetic intensity decreases and the droplet begins to fall, but soon gets back into the laser beam focus and the process repeats itself.
It may seem just like a fun physical experiment, but in fact the discovery is of great importance for science. It corroborates Johannes Kepler’s hypothesis about particle acceleration by light; it can help create a new particle accelerator as well as gain insights into the processes taking place in space.