Warped Passages - Lisa Randall [227]
general relativity The theory of gravity that describes the gravitational field due to any source of matter and energy, including that stored by the gravitational field itself, in any frame of reference; general relativity encapsulates the gravitational field in the curvature of spacetime.
generation Each of the three sets of the full complement of particle types (left-and right-handed charged lepton, up-type quark, down-type quark and left-handed neutrino).
geodesic In space, the shortest path between two points; in spacetime, the path a free-falling observer (one with no forces acting on him) would follow.
GeV (gigaelectronvolt) A unit of energy equal to one billion eV.
gluon The elementary particle that communicates the strong force.
Grand Unified Theory (GUT) A proposed theory in which the three known nongravitational forces fuse into a single force at high energy.
gravitational lensing The splitting of light into multiple images as it bends around a massive object.
gravitino The superpartner of the graviton.
graviton The particle that communicates the force of gravity.
hadron A strongly bound object with constituent quarks and/or gluons.
handedness The direction of spin, to the left or to the right.
heterotic string theory A version of string theory in which the oscillation modes that travel clockwise are different from the modes that travel counterclockwise.
hierarchy problem The question of the weakness of gravity or, equivalently, of why the Planck scale mass that characterizes gravity’s strength is sixteen orders of magnitude greater than the weak scale mass associated with the weak force.
Higgs field The field that participates in the Higgs mechanism, that is responsible for breaking the symmetry associated with the electroweak force.
Higgs mechanism The spontaneous breaking of the electroweak symmetry that allows gauge bosons and other elementary particles to acquire mass.
Hořava-Witten theory The strongly coupled heterotic string version of string theory, or equivalently (by duality) a version of string theory with two branes that are separated by an eleventh dimension in which the two branes house the forces of the heterotic string.
horizon A region beyond which nothing can escape.
hypercube A generalization of a cube to more than three dimensions.
inertial frame of reference A reference frame that moves at fixed velocity with respect to a fixed reference frame, such as the one at rest.
intermediate (internal) particles Virtual particles whose exchange mediates interactions among other particles.
internal symmetry A symmetry in which physical laws do not change for a set of transformations that does not change the geometric position of particles, but only some internal properties or labels.
intrinsic spin (spin) A number that characterizes how a particle behaves—as if it were spinning. Spin can take integer or half-integer values.
inverse square law The rule that describes those forces whose strength decreases with separation as the square of the distance between them; classical gravitational and electric forces obey inverse square laws.
ion A charged bound state of a nucleus and electrons; an atom with too few or too many electrons.
jet An energetic cluster of strongly interacting particles surrounding an energetic quark or gluon that moves in a particular direction.
Kaluza-Klein (KK) mode A four-dimensional particles with a higher-dimensional origin; KK modes are distinguished by their extra-dimensional momenta.
kinetic energy Energy due to motion.
lepton An elementary fermionic particle that does not experience the strong force.
LHC (Large Hadron Collider) A high-energy particle collider that will bang together 7 TeV proton beams and produce particles with mass up to a few TeV.
local interaction An interaction between adjacent or coincident objects.
localized gravity A high concentration of the gravitational field in a particular region of space; gravity appears to be lower-dimensional since it isn’t diluted into an extra