Putting them on the board allows them to couple, so vibrations from each can interfere and the most efficient energy transfer is when they are in phase. I’ve read that this trick was exploited by sellers of pendulum clocks, back in the day — by hanging the clocks on one wall, they would similarly tend to synchronize. This would give the customer the impression that all of the products were high quality clocks when that was not the case, though you could not tell from the pricetag — the poor clocks were being driven by a few good ones.
(Leroy Anderson was the composer of The Syncopated Clock)
The roadway across the Golden Gate Bridge rises and falls as much as 16 feet depending on the temperature. When the sun hits the bridge, the metal expands and the bridge cables stretch. As the fog rolls in, the cables contract and the bridge goes up.
There’s also a 2-hour delay because of the thermal mass of the bridge.
To be fair, the “house” of bricks is more like a wall, and without mortar. Pigs may make houses out of straw and sticks, but they follow building codes, dammit.
How to keep food from sticking in a stainless-steel pan. The first explanation about pores biting into the food sounds hokey, but then we get to the Liedenfrost effect, which is demonstrated in the video.
The water “hovering” over the stainless steel pan like mercury happens due to the phenomenon known as the Leidenfrost effect. You can read more about it on wikipedia, but the basic idea is this: at a certain temperature known as the Leidenfrost point (roughly around 320˚F for water, but varying with surface and pressure), when the water droplet hits the hot pan, the bottom part of the water vaporizes immediately on contact. The resulting gas actually suspends the water above it and creates a pocket of water vapor that slows further heat transfer between the pan and the water. Thus it evaporates more slowly than it would at lower temperatures. At the proper temperature, a similar effect happens with the food you place in the pan, preventing the food from sticking.
NuFormer is a company in the Netherlands that specializes in outdoor advertising of a very peculiar sort — done on the faces of buildings. Real buildings are mapped and modeled in 3D, and then animations are created using those models and projected back onto the building. The result is incredibly lifelike — it nearly fools the eye — and whoever designs these animations does an amazing job of taking advantage the buildings’ nooks and crannies to make things look like they’re really happening in 3D space.
I think a larger version of this should be called the Leviatron
Neat, even with the overindulgence of “let’s enclose this in a tube to prove there are no wires.” Two things, though. 1) It’s not antigravity 2) The blurb about torque isn’t right — it’s not that the spinning exerts a torque, it’s that the spinning means there is angular momentum. You need a torque to change angular momentum, and the torque present because of the same-facing poles is not enough to flip the top. Just like gravity exerts a torque, but cannot flip the spinning top, either.
What he doesn’t explain here, however, is that there are varying degrees of wrong. Some kinds of wrong mean you abandon the theory. Other kinds of wrong mean you adjust the theory. Once can look at the scrap heap of discarded theories for examples of the former — phlogiston, for example, predicted that mass had to decrease in the process of combustion, because it was a substance released during the process. After that was shown to be wrong, the theory was discarded. There was no way to fix the problems, since it wasn’t a matter of refinement.
An example of refining a theory is found in laser cooling. When it was first proposed, the mechanism was Doppler cooling, stemming from a simple model of photon recoil in a two-level system, and was experimentally confirmed. But eventually experimenters discovered conditions where their laser-cooled atoms were colder than the Doppler limit. Atoms are not two-level systems, and there are conditions in which their structure can be exploited to cool the atoms further: polarization gradients in the laser light, giving rise to “Sisyphus” cooling, in which the energy levels of the atoms are shifted depending on their position, and it is possible to have some atoms continuing to lose energy as they scatter photons, somewhat like the mythological Sisyphus, who was cursed to continually push a rock uphill. It was this discovery and explanation that won the 1997 Nobel prize for Bill Phillips, Steven Chu and Claude Cohen-Tannoudji.
There are more of these examples, with the hallmark being that the original theory is seen to no longer have universal applicability, but is still used under the conditions in which it applies. Relativity comes immediately to mind; we still use Newton’s law of gravitation, still use the classical equations for e.g. kinetic energy and do Galilean transforms when using them doesn’t introduce appreciable error.
