Monday, 25 February 2013

Knowledge is a subset of belief

The following article recently created some confusion in certain forums. One should always avoid talking about over 100% efficiencies in a popular science article. Their LED produces 69 pW worth of photons while consuming only 30 pW of power, it also cools itself down in the process. Even those who are somewhat familiar with thermodynamics didn't seem to clearly point out what is the source of this extra energy which allows the led to cool at the same time and produce more photons than would be otherwise possible.

The simple answer is of course that this device is a kind of heat pump. The "heat" flux between which the device pumps energy and extracts the excess is that between the temperature of the device and its surroundings and the space into which it radiates its photons. The space is cold and the device is warm. They even heat it up artificially. It is offering a path between the cold space and a warm device in the form of a photon, a path which doesn't normally exist. This effect would be impossible should there be an energy balance between the space and the device, such as leaving photons would be equal to incoming photons. Obviously this is not the case.


"If one neglects to take into account the gravitational attraction of a single electron on the other side of the observable universe, then after just 50 collisions on average per molecule, the calculated positions of particles would be completely different than if one did correctly account for that electron."