24.8 Key Terms

24.8 Key Terms

accretion disk
the disk of gas and dust found orbiting newborn stars, as well as compact stellar remnants such as white dwarfs, neutron stars, and black holes when they are in binary systems and are sufficiently close to their binary companions to draw off material
black hole
a region in spacetime where gravity is so strong that nothing—not even light—can escape
equivalence principle
concept that a gravitational force and a suitable acceleration are indistinguishable within a sufficiently local environment
event horizon
a boundary in spacetime such that events inside the boundary can have no effect on the world outside it—that is, the boundary of the region around a black hole where the curvature of spacetime no longer provides any way out
general theory of relativity
Einstein’s theory relating gravity and the structure (geometry) of space and time
gravitational redshift
an increase in wavelength of an electromagnetic wave (light) when propagating from or near a massive object
gravitational wave
a disturbance in the curvature of spacetime caused by changes in how matter is distributed; gravitational waves propagate at (or near) the speed of light.
singularity
the point of zero volume and infinite density to which any object that becomes a black hole must collapse, according to the theory of general relativity
spacetime
system of one time and three space coordinates, with respect to which the time and place of an event can be specified

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