DIY Photon Propulsion Part 2. April Fools.Follow article
The physics behind the project was explained correctly. I simply left out some important bits:
Only part of the light did hit the mirrors. Part of it was also shining on the black backside. And most of the time, the light beam was not in a right angle to the mirror's surface. So the resulting radiation pressure is probably much smaller than calculated.
I also cheated with the weight of the wheel, which is nearly 4 g (I simply set 1.8 g tara before putting the wheel onto the scale). But I've used watch bearings with jewels to reduce the friction to a minimum.
I would love to have a lab at hand, which could have lent me a vacuum pump. But even if I would have had such a pump, I would not have been able to achieve a high vacuum (HV) with only 10-3 mbar (hPa). Rotary vane pumps would get down to maybe 10-2 mbar. You would need an oil diffusion pump for HV. The sealings you would need for such HV pressures need to be much more efficient, and you would also need to dry the air with more sophisticated methods than Silicagel. But wait a moment: You could see the vacuum meter showing a perfect vacuum. Well, that was fake. I drilled a hole into the meter and used a screw to manipulate the measurement. There was no vacuum at all inside the container.
But how could the wheel turn? No, there was no motor involved, even if I was tempted to get one of these ultra-tiny 2 x 10 mm motors from Faulhaber and build it into a hidden place in my setup. But which force did turn the wheel? No light, no motor, no magnets. It was a tiny flow of fresh air. The brass strand for the upper bearing was a tube with a hole at its side where the air came out. So I built a DIY windmill!
The end of the tube was connected to a secret channel inside the base plate, and one of the electric wires was just the wire sleeve and no copper inside. This wire was connected to an air spray.
But why then did you hear me yelling for joy in the video when the wheel started turning if it was all fake? Because at that moment, I had a vision of you watching the video and believing this complete nonsense. I know... that was just my vision. In reality, you knew that it was the 1st of April and that I wanted to fool you.
Well, I knew you all needed distraction from the problems in the world right now, and bearing the heavy load is much easier with a laugh. I hope you enjoyed my joke! How about fooling your colleague? Show him the first video and find out how sceptic he is. If he believed it, you celebrate teaching him the truth. Have fun and take care!