NJ silent drones? Pfft

RESEARCHERS CREATE HOLOGRAMS ABLE TO MOVE IN THE AIR

Researchers at BYU have been able to create hologram images that actually move in the air. The breakthrough is inspired by displays seen in science fiction, and the scenes they create are described as "real," according to lead researcher Dan Smalley. Smalley notes the scenes have nothing computer-generated about them, and the images are real and can be seen from any angle in that space.

https://www.slashgear.com/researchers-create-holograms-able-to-move-in-the-air-06671761/