As quantum mechanics becomes more and more mainstream, with researchers at universities across the globe devoting time and energy to making its bizarre phenomena applicable to practical applications, I thought this a good time to take a quick gander at this strange science. Quantum mechanics certainly has a long and dignified history to it, extending back just over a hundred years to that eminent luminary, Albert Einstein, and his original ruminations on relativity. While many of his predictions came true in his lifetime, including the possibility of an atomic bomb, others had to wait nearly until the turn of the millennium before they were proven accurate.
While there continues to be a considerable disjoint between our observable world — where traditional Newtonian physics are generally accurate enough for day-to-day operations — and the world of the very… very… very small, the theories of quantum mechanics can still give us a fascinating, and more accurate description of how reality works. Among the most important of the equations developed to describe quantum activities is Werner Heisenberg’s famous “Uncertainty Principle”, an equation almost as misunderstood as Einstein’s own E=mc2:
ΔxΔp ≥ h / (4 π)
Where x is the position, p is the momentum, h is Planck’s constant and π is… π.
This formula effectively states that the more certainty you have for an atom’s position, the less certain you are about its momentum, and vice-versa. All of this comes about because of the wave-particle duality of particles. At the scales where quantum mechanics come into play, that is, at the level of atoms on down, objects do not work like solid billiard balls, but possess the characteristics of both particle and wave. Depending on how an observer (that is, the scientist or his equipment) chooses how to look at a particular atom, it can play either role.
Einstein and an associate of his, Satyendra Nath Bose, proposed that under certain scenarios, some types of particles, such as photons, could collapse into each other such that they could not be distinguished from one another. Later, Einstein took the idea a step further, and wrote a paper stating that whole atoms may be able to smoosh into other atoms to form a new state of matter altogether. As all of this would require temperatures of no more than one ten-thousandth of a degree above absolute zero, the idea of such a condensate was expected to remain just that – an idea. But a novel approach by scientists at the University of Colorado at Boulder allowed for the first such Bose-Einstein Condensate to be created and observed.
Temperature, of course, is directly related to the average speed of atoms in a material. Drs Cornell and Wieman used carefully timed and controlled laser pulses to slow the movement of rubidium atoms, and, with the assistance of magnets to pull off the most active of the atoms in the study, they were able to slow 2,000 of the atoms to almost nothing; a billionth of a degree above absolute zero. According to Heisenberg, now that the momentum (speed and direction) of these atoms was practically certain, the uncertainty of their position must be (relatively) huge! And that’s just what Cornell and Wieman found.
The two scientists squished the supercooled and ghostly rubidium atoms together into a single, giant blob, which lasted nearly ten seconds before it disintegrated.
Physics gets weirder all the time.
Wikipedia entry for Bose-Einstein Condensate
BEC Homepage at University of Colorado @ Boulder
The Disappearing Spoon by Sam Kean