Vijay Shankar Sharma
Textbook physics terms. Not a BFUT reinterpretation. 371 terms. Textbook meanings only.
11 terms. Page 1 of 1.
astro · intro
A massive, gravitationally bound system containing stars, stellar remnants, interstellar gas and dust, and dark matter, ranging from a few million to trillions of stars. Galaxies come in several broad shapes, including spiral, elliptical, and irregular, and they often cluster together into groups, clusters, and larger superclusters connected by vast cosmic filaments. The Milky Way, home to our solar system, is a large barred spiral galaxy.
em · intro
The highest-energy, shortest-wavelength form of electromagnetic radiation, produced by extremely energetic processes such as radioactive decay, nuclear reactions, and violent astrophysical events like supernovae and black hole mergers. Gamma rays carry enough energy to damage biological tissue and are blocked effectively by thick shielding such as lead or several meters of concrete. Astronomers study gamma rays from space using orbiting telescopes, since Earth's atmosphere absorbs them before they reach the ground.
relativity · intro
Albert Einstein's theory of gravity, published in 1915, which describes gravity not as a force acting between masses but as the curvature of spacetime caused by the presence of mass and energy. Objects move along the straightest possible paths, called geodesics, through this curved spacetime. General relativity successfully predicts phenomena including the bending of light by massive objects, the precession of Mercury's orbit, gravitational time dilation, and gravitational waves.
relativity · intermediate
The shortest, or straightest possible, path between two points on a curved surface or in curved spacetime. On a flat plane, geodesics are straight lines, while on a curved surface like the surface of a sphere, they are great circles. In general relativity, objects moving under gravity alone follow geodesics through curved spacetime, which is why planets orbit stars without any force actively pulling them inward in the traditional sense.
particle · intermediate
The elementary particle that mediates the strong nuclear force, binding quarks together to form protons, neutrons, and other hadrons. Unlike photons, which carry no electric charge themselves, gluons carry the color charge associated with the strong force, allowing them to interact directly with each other, which makes the mathematics of the strong force considerably more complex. There are eight distinct types of gluon in the Standard Model.
mechanics · intro
A region of space surrounding a mass in which another mass would experience a gravitational force, described as the gravitational force per unit mass at each point. Near Earth's surface, the gravitational field has a nearly constant strength of about 9.8 newtons per kilogram, directed downward. In general relativity, the gravitational field is reinterpreted as the curvature of spacetime rather than a force field in the Newtonian sense.
relativity · intermediate
The bending of light from a distant object as it passes near a massive foreground object, such as a galaxy or galaxy cluster, caused by the curvature of spacetime predicted by general relativity. This bending can magnify, distort, or even multiply the image of the background object into arcs or rings. Gravitational lensing is a key tool for astronomers to map the distribution of both visible and dark matter in the universe.
mechanics · intro
The energy an object possesses because of its position within a gravitational field, relative to some reference point, typically increasing as the object moves farther from the source of gravity. Near Earth's surface, it is often approximated as mass multiplied by gravitational acceleration multiplied by height, though the full expression accounts for how gravity weakens with distance. This energy converts into kinetic energy as an object falls.
relativity · intermediate
A ripple in the curvature of spacetime that propagates outward at the speed of light, produced by accelerating massive objects, particularly extreme events like the merger of two black holes or neutron stars. Predicted by Einstein's general relativity in 1916, gravitational waves were first directly detected in 2015 by the LIGO observatory, opening a new way of observing the universe beyond traditional electromagnetic telescopes.
mechanics · intro
The fundamental attractive force between any two objects with mass, responsible for holding planets in orbit, giving objects weight near Earth's surface, and shaping the large-scale structure of the universe. In Newtonian physics, gravity is described as a force proportional to the product of two masses and inversely proportional to the square of the distance between them. In general relativity, gravity instead arises from the curvature of spacetime caused by mass and energy.
waves · intermediate
The speed at which the overall shape, or envelope, of a wave packet made up of multiple overlapping waves travels through space, which can differ from the speed of the individual wave crests within it, known as the phase velocity. Group velocity is the speed at which energy and information are actually transmitted by a wave packet. In some unusual materials, group velocity can even exceed or become negative relative to phase velocity without violating the fundamental speed limit for information.