Earth Science: Quantum Mechanics – Quantum effects in our daily lives
Quantum physical effects play an essential role in modern technology: examples are lasers, electron microscopes, atomic clocks, and superconductors. They all promise very new and exciting commercial applications.
Radio-controlled clocks are popular in the home because they always give the correct time. Where do they get their time signal and why is it so precise? Many universities and research groups operate these clocks, transmitting signals over the air that are used to correctly set the time.
The signal used is generated by an atomic clock with a precision that is a direct consequence of quantum laws. These laws fix the permitted orbits (or better, the quantum conditions) of the electrons of an atom. This means that there is a fixed energy difference between two conditions of an electron, which is the same throughout the universe for all atoms of an element.
This energy difference corresponds to a frequency, and since this frequency is the reciprocal value of time, an exact measurement of the frequency provides a correspondingly exact time signal. Nowadays the best atomic clocks reach precisions of 1 :10^15 and better.
Superconductivity
When electric current flows through a wire, that wire warms up. The reason is the electric resistance of the conductor (in this case, the wire). Even with good quality copper wires, this cannot be avoided, or can it? Here a quantum effect is at work, which would be impossible to describe through conventional physics.
Quantum physics, however, shows that at very low temperatures, electrons form pairs that suffer less interference from the actions of atoms and impurities in the semiconductor and so exchange less energy with the atoms of the wire. This leads to an almost lossless conductivity in the material.
Many metals display such superconductivity, or lack of resistance, at temperatures of a few kelvins (a few degrees above absolute zero).
Ceramics
The principles of superconductivity discovered in 1911 by Heike Kamerlingh Onnes, (1853-1926), only became really interesting when the
first ceramic conductors were discovered in 1987. These conductors displayed an interesting property: upon being cooled, using liquid nitrogen, to a temperature of 100K(-279.76°F) they would become superconductive.
Modern high temperature superconductors (HTS or High-Tc) can be cooled with much less effort and their use promises higher degrees of efficiency in energy-transfer cables, transformers,
and motors.
ISSUES TO SOLVE
COMMERCIAL APPLICATIONS are impeded by the fact that high temperature semiconductor ceramic, in contrast to metal, are brittle and difficult to manufacture into wires.
However the integration of a 393-foot- (120-m) long cable into the electricity grid is currently being tested in Detroit.