You’ll also note that two of the so-called chemical reactions are properly classified as being in the physics videos (Meissner effect and breathing helium/sulphur hexafluoride). Ha! Take that, chemistry. You’re down to a top 8! (Without even arguing that floating a boat of air of the sulphur hexafluoride is a physics effect as well)
(Note the flash photography during the musical tesla coil video. Gee, I wonder if that helps?)
via The Great Beyond, which adds two Feynman drumming videos to the list. Wait, that’s twelve! Twelve videos! (A, ha, ha, ha. I love to count science videos!)
Oooooh. It displays six whole digits past the decimal. Down to the microsecond. (can you sense the sarcasm?) It’s a display. Just because it reads that many digits doesn’t mean the measurement actually has that precision.
I’ve wanted to get a display that went to the picosecond for the lab, but have it flash 12:00:00.000000000000 the whole time. Add it to the list of my unadopted suggestions.
“I see no progress in this industry. These clocks are no faster than the ones they made a hundred years ago.” — Henry Ford
I’ve inadvertently (and advertently) been doing some experimentation with polarized light lately. Liquid Crystal Displays (LCD) typically emit linearly polarized light, and most decent sunglasses act as polarizing filters. This can cause some problems, if you happen to have some gadget whose display is inconveniently set to emit light with horizontal polarization — since reflected light tends to become polarized parallel to the surface from which it reflects, sunglasses are made to filter that light. But it also makes it tough to read any LCD that is oriented to emit that polarization.
There are ways around this, though. I’ve noticed that my iPod screen (unlike my GPS receiver and watch) doesn’t go black at any orientation of my sunglasses, though I do get some shifting rainbows on the screen. Here are two orthogonal orientations of a linear polarizer:
Let’s say, for the sake of argument, that you needed to move a heavy piece of equipment you’re helping to build. And you have the constraints of not wanting to tip it, and the course you need to navigate has some spots with less than 10 cm of overhead space. (This ignores one doorway that’s actually 10 cm too low — yes, we’ve done the equivalent of having built a boat in our basement. The solution there will either be slapping Daffy Duck with a frying pan in the shape of the equipment and having him run through the door, or a sawzall.) You need a smooth ride, because it’s an expensive, somewhat delicate trinket representing a several dollars and a few person-years of labor.
I tried designing a cart, but couldn’t meet all of the constraints — anything low enough would tend to bottom out on the incline (oh, that’s right, the path isn’t level the whole way. Is that a problem? I need this soon.) One day I was stressing and kvetching about it in front of the right person, who suggested air bearings/air casters. The heretofore unconnected link between the physics and the application clicked, and I knew that was the answer. Float the sucker on air. A small industrial blower and lots of small holes.
Here’s a demo of the system with a dummy load. There are also some lead blocks there, too. (cue rimshot). 160 kg for the optical table, lead and support structure, and another 110 kg or so for me.
(if you want a soundtrack, turn on a vacuum cleaner. Any “Ishmael” wisecracks about my pasty-white legs will be subject to retaliatory editing) Continue reading →
