Length contraction

Length contraction is the reduction in an object's measured length along its direction of motion relative to an observer, compared with its length in the object's rest frame.

Lorentz transformation: A set of equations relating space and time coordinates measured in inertial reference frames moving at constant relative velocity. Its transformation of spatial coordinates produces the change in measured length.
Barn and ladder paradox: A thought experiment about whether a fast-moving ladder can fit momentarily inside a shorter barn. Relativity of simultaneity resolves the apparent conflict between the barn's and ladder's length measurements.
Time dilation: The relativistic difference in elapsed time measured between events by observers in relative motion. It is the temporal counterpart to length contraction in comparisons between inertial frames.
Relativistic beaming: The concentration of radiation into a narrow forward direction from a source moving at relativistic speed. It affects observations of jets whose source-frame dimensions and observer-frame appearance differ.
Proper length: The length of an object measured in the inertial frame in which the object is at rest. It is the rest-frame length against which a contracted measurement is compared.
Bertozzi experiment: A 1964 experiment in which electron pulses were accelerated through a known distance and their speeds and energies measured. Its relativistic electron measurements are consistent with the high-speed regime where length contraction becomes substantial.
Terrell rotation: The apparent rotation of a rapidly moving three-dimensional object caused by differences in light-travel time. It distinguishes optical appearance from the length obtained by simultaneous position measurements.
Relativistic jet: A narrow outflow of plasma emitted by an astrophysical object at a speed close to light. Length and timing transformations matter when interpreting compact, rapidly moving jet regions.
Relativity of simultaneity: The principle that spatially separated events simultaneous in one inertial frame need not be simultaneous in another. A moving object's endpoints must be measured simultaneously, and simultaneity differs between frames.
Muon: An elementary particle similar to the electron but heavier and unstable. Earth-frame descriptions of atmospheric muons use contracted atmospheric distances to explain their detected arrival.

Linked from 9 pages