Photo credit: Mike Walker
At first glance, this foil boat may really look like it’s magically suspended in mid-air, but the secret is sulfur hexafluoride. This gas is “typically used as a spark suppressant in high-voltage equipment — an invisible gas that’s nearly five times as dense as air — making it ideal for a demonstration of this phenomenon.” Video demonstration after the break.
After allowing SF6 to slowly fill an aquarium, I slid off the cover, leaving a pool of invisible gas that would stay put for several minutes. When I set a lightweight tinfoil boat on top of the tank, it floated on what appeared to be nothing at all.