We unboxed and tested three absurdly powerful flashlights—from an $800 “handheld sun” to a suitcase-sized monster—and then took them outside to see what 40,000+ lumens actually looks like. Fans spun ...

In this video I see how fast we can get a radiometer to spin by shining the world's brightest flashlight on it. Then I talk about the real reason the Crookes radiometer spins when you shine light on ...