Of course air flow does not have to be supersonic to create density variations; subsonic wind tunnels can be equipped with schlieren optics as well. HVAC as you’ve never seen it before.

Since electricity prefers to travel through lower density air, the spark moves in that direction. The ultrasound pulses move this hotter, lower-density air around, which in turn guides the ...

The James Webb Space Telescope may have detected life-associated gas in the atmosphere of a far-off planet. The news is being greeted with both enthusiasm and skepticism.