SCIENCEHACKS

Moore's Law is the observation made in 1965 by Gordon Moore, co-founder of  Intel , that the number of  transistors  per square inch on  integrated circuits  had doubled every year since the integrated circuit was invented. Moore predicted that this trend would continue for the foreseeable future. In subsequent years, the pace slowed down a bit, but data density has doubled approximately every 18 months, and this is the current definition of Moore's Law, which Moore himself has blessed. Most experts, including Moore himself, expect Moore's Law to hold true until 2020-2025. Moore’s Law was not, of course, a law of nature. It was more like an engineer’s rule of thumb, capturing the pattern Moore had discerned in the early data on microchip production. But law or no, by 1975 engineers were designing and manufacturing chips a thousand times more complex than had been possible just 10 years before-just as Moore had predicted. That year, Moore revisited his pre...

The story of quantum computers begins in 1981 with Richard Feynman, probably the most famous physicist of his time. At a conference on physics and computation at the Massachusetts Institute of Tech­nology, Feynman asked the question: Can we simulate physics on a computer? The answer was—not ex­act­ly. Or, more precisely—not all of physics. One of the branches of physics is  quantum mechanics , which studies the laws of nature on the scale of individual atoms and particles. If we try to simulate quantum mechanics on a computer, we run into a fundamental problem. The full description of quantum physics has so many variables that we cannot keep track of all of them on a computer.  If one particle can be described by two variables, then to describe the most general state of n particles, we need 2n variables. If we have 100 particles, we need 2100 variables, which is roughly 1 with 30 zeros. This number is so big that computers will never have so much me...

Quantum dots are semiconductor nanoparticles that glow a particular color after being illuminated by light. The color they glow depends on the size of the nanoparticle. When the quantum dots are illuminated by UV light, some of the electrons receive enough energy to break free from the atoms. This capability allows them to move around the nanoparticle, creating a conductance band in which electrons are free to move through a material and conduct electricity. When these electrons drop back into the outer orbit around the atom (the valence band), as illustrated in the following figure, they emit light. The color of that light depends on the energy difference between the conductance band and the valence band. What can you use quantum dots for? Optical applications So far, quantum dots have attracted most interest because of their interesting optical properties: they're being used for all sorts of applications where precise control of colored light is important. In...