Caleb Garling, writing for the SF Chronicle:
On New Year’s Eve researchers at the University of Tokyo and Nagoya Institute of Technology released videos that highlighted exactly what the group had accomplished in a paper submitted earlier in the month.
They set up two sets of parallel speakers, pointing at each other — a sound geyser from north, south, east and west. The ultrasonic waves are opposite in phase as they pass each other — this creates a little pocket inside the waves. The force generated by the speakers cancel, and after accounting for gravity, keeps the object suspended.
Wow, watch the embedded video. Amazing!