Quantum Theory Cannot Hurt You_ A Guide to the Universe - Marcus Chown [80]
MASS A measure of the amount of matter in a body. Mass is the most concentrated form of energy. A single gram contains the same amount of energy as 100,000 tonnes of dynamite.
MAXWELL’S EQUATIONS OF ELECTROMAGNETISM The handful of elegant equations, written down by James Clerk Maxwell in1868, that neatly summarise all electrical and magnetic phenomena. The equations reveal that light is an electromagnetic wave.
MILKY WAY Our galaxy.
MOLECULE Collection of atoms glued together by electromagnetic forces. One atom, carbon, can link with itself and other atoms to make a huge number of molecules. For this reason, chemists divide molecules into “organic”—those based on carbon—and “inorganic”—the rest.
MOMENTUM The momentum of a body is a measure of how much effort is required to stop it. For instance, an oil tanker, even though it may be going at only a few kilometres an hour, is far harder to stop than a Formula 1 racing car going 200 kilometres per hour. The oil tanker is said to have more momentum.
MOMENTUM, CONSERVATION OF Principle that momentum can never be created or destroyed.
MULTIVERSE Hypothetical enlargement of the cosmos in which our Universe turns out to be one among an enormous number of separate and distinct universes. Most universes are dead and uninteresting. Only in a tiny subset do the laws of physics promote the emergence of stars, planets, and life.
MUON Short-lived subatomic particle that behaves like a heavy version of the electron.
NEUTRINO Neutral subatomic particle with a very small mass that travels very close to the speed of light. Neutrinos, of which there are three kinds, hardly ever interact with matter. However, when created in huge numbers, they can blow a star apart in a supernova.
NEUTRON One of the two main building blocks of the atomic nucleus at the centre of atoms. Neutrons have essentially the same mass as protons but carry no electrical charge. They are unstable outside of a nucleus and disintegrate in about 10 minutes.
NEUTRON STAR A star that has shrunk under its own gravity to such an extent that most of its material has been compressed into neutrons. Typically, such a star is only 20 to 30 kilometres across. A sugar cube of neutron star stuff would weigh as much as the entire human race.
NEWTON’S UNIVERSAL LAW OF GRAVITY The idea that all bodies pull on each other across space with a force that depends on the product of their individual masses and the inverse square of their distance apart. In other words, if the distance between the bodies is doubled, the force becomes four times weaker; if it is tripled, nine times weaker; and so on. Newton’s theory of gravity is perfectly good for everyday applications but turns out to be an approximation. Einstein provided an improvement in the general theory of relativity.
NONLOCALITY The spooky ability of objects subject to quantum theory to continue to “know” about each other’s state even when separated by a large distance.
NUCLEAR ENERGY The excess energy released when one atomic nucleus changes into another atomic nucleus.
NUCLEAR FUSION The welding together of two light nuclei to make a heavier nucleus, a process that results in the liberation of nuclear binding energy. The most important fusion process for human beings is the gluing together of hydrogen nuclei to make helium in the core of the Sun since its by-product is sunlight.
NUCLEAR REACTION Any process that converts one type of atomic nucleus into another type of atomic nucleus.
NUCLEON Umbrella term used for protons and neutrons, the two building blocks of the atomic nucleus.
NUCLEUS See Atomic Nucleus.
PARTICLE ACCELERATOR Giant machine, often in the shape of