Glossary
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Absolute motion: Motion that exists, undeniably, without reference to anything else. The relativity principle denies the possibility of absolute motion.
Big Bang: The explosive event that began the expansion of the universe.
Black hole: An object so small yet so massive that escape speed exceeds the speed of light. General relativity predicts the possibility of black holes, and modern astrophysics has essentially confirmed their existence.
Color force: The very strong force that acts between quarks, binding them together to form hadrons and mesons.
Compton effect: An interaction between a photon and an electron, in which the photon scatters off the electron, as in a collision between billiard balls, and comes off with less energy. The effect provides a convincing demonstration of the quantization of light energy.
Copenhagen interpretation of quantum physics: The standard view of the meaning of quantum physics, which states that it makes no sense to talk about quantities, such as the precise velocity and position of a particle, that cannot even in principle be measured simultaneously.
Cosmic microwave background: "Fossil" radiation from the time 500,000 years after the Big Bang, when atoms formed and the universe became transparent.
Dark matter: Matter in the cosmos that is undetectable because it doesn't glow. Dark matter, some of it in the form of as-yet-undiscovered exotic particles, is thought to comprise most of the universe.
Electromagnetic wave: A structure consisting of electric and magnetic fields in which each kind of field generates the other to keep the structure propagating through empty space at the speed of light, c. Electromagnetic waves include radio and TV signals, infrared radiation, visible light, ultraviolet light, x rays, and gamma waves.
Electroweak force: One of the three fundamental forces now identified, the electroweak force subsumes electromagnetism and the weak nuclear force.
Elsewhere: A region of spacetime that is neither past nor future. The elsewhere of a given event consists of those other events that cannot influence or be influenced by the given event - namely, those events that are far enough away in space that not even light can travel between them and the given event.
Escape speed: The speed needed to escape to infinitely great distance from a gravitating object. For Earth, escape speed from the surface is about 7 miles per second; for a black hole, escape speed exceeds the speed of light.
Ether: A hypothetical substance, proposed by nineteenth century physicists and thought to be the medium in which electromagnetic waves were disturbances.
Event horizon: A spherical surface surrounding a black hole and marking the "point of no return" from which nothing can escape.
Field: A way of describing interacting objects that avoids action at a distance. In the field view, one object creates a field that pervades space; a second object responds to the field in its immediate vicinity. Examples include the electric field, the magnetic field, and the gravitational field.
General theory of relativity: Einstein's generalization of special relativity that makes all observers, whatever their sates of motion, essentially equivalent. Because of the equivalence principle, general relativity is necessarily a theory about gravity.
Geodesic: The shortest path in a curved geometry, like a great circle on Earth's surface. Objects that move freely follow geodesics in the curved spacetime of general relativity.
Gravitational lensing: An effect caused by the general relativistic bending of light, whereby light from a distant astrophysical object is bent by an intervening massive object to produce multiple and/or distorted images.
Gravitational time dilation: The slowing of time in regions of intense gravity (large spacetime curvature).
Gravitational waves: Literally, "ripples" in the fabric of spacetime. They propagate at the speed of light and result in transient distortions in space and time.
Gravity: According to Newton, an attractive force that acts between all matter in the universe. According to Einstein, a geometrical property of spacetime (spacetime curvature) that results in the straightest paths not being Euclidean straight lines.
Hadron: A "heavy" particle, made up of three quarks. Protons and neutrons are the most well known hadrons.
Heisenberg uncertainty principle: The statement that one cannot simultaneously measure both the position and velocity (actually, momentum) of a particle with arbitrary precision.
Interference: A wave phenomenon, whereby two waves at the same place simply add together to make a composite wave. When both waves reinforce, the interference is said to be constructive and results in a stronger wave. When the waves tend to cancel each other, the interference is destructive. Interference is useful in precision optical measurements, including the Michelson-Morley experiment.
Length contraction: The phenomenon whereby an object or distance is shortest in a reference frame in which the object or the endpoints of the distance are at rest. Also called the Lorentz contraction and Lorentz-Fitzgerald contraction.
Lepton: Collective name for the light particles electron, muon, tau, and their associated neutrinos.
Mass-energy equivalence: The statement, embodied in Einstein's equation E=mc2 , that matter and energy are interchangeable.
Maxwell's equations: The four equations that govern all electromagnetic phenomena described by classical physics. It was Maxwell in the 1860s who completed the full set of equations and went on to show how they predict the existence of electromagnetic waves. Maxwell's equations are fully consistent with special relativity.
Mechanics: The branch of physics dealing with the study of motion.
Meson: A particle made up of two quarks (actually, a quark and an antiquark).
Michelson-Morley experiment: An 1880s experiment designed to detect Earth's motion through the ether. The experiment failed to detect such motion paving the way for the abandonment of the ether concept and the advent of relativity.
Neutrino:. An elusive particle with very small mass that arises in weak nuclear reactions.
Neutron star: An astrophysical object that arises at the end of the lifetime of certain massive stars. A typical neutron star has the mass of several Suns crammed into a ball with a diameter about that of a city.
Photoelectric effect: The ejection of electrons from a metal by the influence of light incident on the metal.
Photon: The quantum of electromagnetic radiation. For radiation of frequency f, the quantum of energy is E=hf.
Plank's constant: A fundamental constant of nature, designated h, that sets the basic scale of quantization. If h were zero, classical physics would be correct; h being nonzero is what necessitates quantum physics.
Principle of Complementarity: Bohr's statement that wave and particle aspects of nature are complementary and can never both be true simultaneously.
Principle of Equivalence: The statement that the effects of gravity and acceleration are indistinguishable in a sufficiently small reference frame. The principle of equivalence is at the heart of general relativity's identification of gravity with the geometry of spacetime.
Principle of Galilean Relativity: The statement that the laws of motion are the same in all uniformly moving frames of reference; equivalently, such statements as "I am moving" or "I am at rest" are meaningless unless "moving" and "rest" are relative to some other object or reference frame.
Principle of Rotational Relativity: This is the fundamental premise of the theory of vibrational relativity theory. It is the rotational velocity equivalent to Einstein's principle of special relativity, which deals with the relativity of linear velocity. The principle of rotational relativity states: "Within an 'otherwise massless universe', or in circumstances which closely resemble such a universe (e.g. the hydrogen atom) the laws of physics remain the same for all observers in uniform angular relative motion."
Principle of Special Relativity: (a.k.a. Einstein's relativity principle). "The law's of physics (both the mechanical laws of motion and Maxwell's laws of electromagnetism) remain the same for all observers in uniform linear motion".
Quanta: A fundamental particle, building block of protons and neutrons, as well as all other hadrons and mesons. There are six different quarks, two in each f the three families of matter.
Quark: A fundamental particle, building block of protons and neutrons, as well as all other hadrons and mesons. There are six different quarks, tow in each of he three families of matter.
Relativistic invariant: A quantity that has a value that is the same in all frames of reference. The spacetime interval is one example of a relativistic invariant.
Relativity principle: (a.k.a. Einstein's principle of special relativity). A statement that only relative motion is significant, that is, the law's of physics remain the same for all observers in uniform [linear] motion. The principle of Galilean relativity is a special case, applicable only to the laws of motion. Einstein's principle of special relativity covers all of physics but is limited to the case of uniform motion.
Spacetime: The four-dimensional continuum in which the events of the universe take place. According to relativity, spacetime breaks down into space and time in different ways for different observers.
Spacetime curvature: The geometrical property of spacetime that causes its geometry to differ from ordinary Euclidean geometry. The curvature is caused by the presence of massive objects, and other objects naturally follow the straightest possible paths in curved spacetime. This is the essence of general relativity's description of gravity.
Spacetime interval: A four-dimensional "distance" in spacetime. Unlike intervals of time or distance, which are different for observers in relative motion, the spacetime interval between two events has the same value for all observers.
Special theory of relativity: Einstein's statement that the laws of physics are the same for all observers in uniform [linear] motion.
String theory: A description of physical reality in which the fundamental entities are not particles but tiny string-like loops. Different oscillations of the loops correspond to what we now consider different "elementary" particles. Sting theory is a leading candidate for a "theory of everything".
Time dilation: In special relativity, the phenomenon whereby the time measured by a uniformly moving clock present at two events is shorter than that measured by separate clocks located at the two events. In general relativity, the phenomenon of time running slower in a region of stronger gravity (greater spacetime curvature).
Ultraviolet catastrophe: The absurd prediction of classical physics that a hot glowing object should emit an infinite amount of energy in the short-wavelength region of the electromagnetic spectrum.
Universal gravitation: The concept, originated by Newton, that every piece of matter in the universe attracts every other piece.
Vibrational relativity theory: A third "Einsteinian" theory after special and general relativity which is founded upon the "principle of rotational relativity" which asserts that within an "otherwise massless universe", or in circumstances which closely resemble an "otherwise massless universe" (e.g. the hydrogen atom) the laws of physics remain the same for all observers in uniform angular motion. Vibrational relativity theory achieves an integration between general relativity theory and quantum mechanics, a key objective toward the goal of a unified theory of physics.
Wave packet: A construction made from waves of different frequencies that results in a localized wave disturbance.
White dwarf: A collapsed star with approximately the mass of the Sun crammed into the size of the Earth.
Wormhole: A hypothetical "tunnel" linking otherwise distant regions of spacetime.
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Copyright (c) 2003 Kenneth A. Miller, MD www.vibrationalrelativity.info
Modification of these materials in any way without my permission is prohibited.