Warped Passages - Lisa Randall [228]
locally localized gravity A theory in which four-dimensional gravity is not experienced everywhere, but only in the region of space where the probability function of the particle acting like a four-dimensional graviton is concentrated.
longitudinal polarization Wave oscillation along the direction of motion.
M-theory A hypothesized all-embracing theory that unifies all known versions of ten-dimensional string theory and eleven-dimensional supergravity.
matrix theory A ten-dimensional quantum-mechanical theory that might be equivalent to string theory.
mediate To communicate a particle’s influence (by an intermediate particle).
metric A quantity or quantities that establish the measurement scale that determines physical distances and angles.
model A candidate theory.
molecule A bound state of two or more atoms in which electrons are shared between them.
multiverse A hypothetical generalization of a universe containing regions that don’t interact or interact only extremely weakly.
muon A short-lived, heavier version of the electron.
neutral object An object that is immune to a force; neutral objects have net charge equal to zero.
neutrino A fundamental elementary particle that interacts only via the weak force.
neutron An ingredient of the atomic nucleus in which two down quarks and an up quark are tightly bound to each other.
Newton’s gravitational constant The overall coefficient that determines the strength of gravitational attraction in Newton’s law of gravity; it is inversely proportional to the square of the Planck scale mass.
Newton’s gravitational force law The classical law of gravity that says that the strength of gravity between two massive objects is proportional to their masses and inversely proportional to the square of their separation.
nucleon A proton or neutron.
nucleus The hard, dense central component of an atom.
old quantum theory The predecessor to quantum mechanics that postulated quantization rules but didn’t systematically determine them or describe the evolution of a quantum state through time.
open string A string with two ends.
p-brane A solution to Einstein’s equations that expands infinitely far in some spatial directions, but in the remaining dimensions acts as a black hole, trapping objects that come too close.
particle accelerator A high-energy physics facility that accelerates particles to high energy.
particle collider A high-energy accelerator that smashes together particles to create enormous amounts of energy.
particle physics The study of the most elementary building blocks of matter.
Pauli exclusion principle The statement that two identical fermions cannot occupy the same position.
perturbation A small modification to a known theory.
perturbation theory When the theory you are interested in is distinguished from a solvable (usually non-interacting) theory by a small parameter (which could be a small interaction strength, for example), perturbation theory allows you to extrapolate from the solvable theory to the theory of interest through a systematic expansion in that small parameter. The results are expressed as power expansions in the corresponding parameter, usually the coupling constant.
photino The superpartner of the photon.
photon The elementary particle that communicates the electromagnetic force; the quantum of light.
Planck scale energy The energy at which gravity becomes a strong force and quantum-mechanical contributions need to be taken into account.
Planck scale length The length scale at which gravity is strong and quantum effects must be included in gravitational predictions.
Planck’s constant A quantum-mechanical quantity that relates energy to frequency and momentum to wavelength.
polarization The direction of oscillation of a wave.
positron The positively charged antiparticle of the electron.
potential energy Stored energy that can be released as kinetic energy.
probability function The square of the absolute value of the wavefunction that determines the probability of finding a particle at a given location.
projection