Related Experiment Video

Updated: Jun 30, 2026

Bringing the Visible Universe into Focus with Robo-AO
10:35

Bringing the Visible Universe into Focus with Robo-AO

Published on: February 12, 2013

The double quasar 0957+561: examination of the gravitational lens hypothesis using the very large array

P E Greenfield, D H Roberts, B F Burke

    Science (New York, N.Y.)
    |May 2, 1980
    PubMed

    More Related Videos

    The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry12:14

    The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry

    Published on: August 12, 2013

    Using Three-color Single-molecule FRET to Study the Correlation of Protein Interactions11:22

    Using Three-color Single-molecule FRET to Study the Correlation of Protein Interactions

    Published on: January 30, 2018

    Related Concept Videos

    Kepler's First Law of Planetary Motion01:10

    Kepler's First Law of Planetary Motion

    In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. He formulated his first two laws based on the observations of his forebears, Nikolaus Copernicus and Tycho Brahe.
    Polish astronomer Nikolaus Copernicus put forth a theory that stated a heliocentric model for the solar system. According to this heliocentric theory, all the planets, including Earth, orbit the Sun in circular orbits.
    On the other hand,...
    Schwarzschild Radius and Event Horizon01:21

    Schwarzschild Radius and Event Horizon

    No object with a finite mass can travel faster than the speed of light in a vacuum. This fact has an interesting consequence in the domain of extremely high gravitational fields.
    The minimum speed required to launch a projectile from the surface of an object to which it is gravitationally bound so that it eventually escapes the object’s gravitational field is called the escape velocity. The escape velocity is independent of the mass of the object. Merging the idea of escape velocity with the...
    Detection of Black Holes01:10

    Detection of Black Holes

    Although black holes were theoretically postulated in the 1920s, they remained outside the domain of observational astronomy until the 1970s.
    Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
    Not until the 1960s, when the first neutron...
    Space-Time Curvature and the General Theory of Relativity01:17

    Space-Time Curvature and the General Theory of Relativity

    In 1905, Albert Einstein published his special theory of relativity. According to this theory, no matter in the universe can attain a speed greater than the speed of light in a vacuum, which thus serves as the speed limit of the universe.
    This has been verified in many experiments. However, space and time are no longer absolute. Two observers moving relative to one another do not agree on the length of objects or the passage of time. The mechanics of objects based on Newton's laws of motion,...
    Gravitation Between Spherically Symmetric Masses01:14

    Gravitation Between Spherically Symmetric Masses

    The gravitational potential energy between two spherically symmetric bodies can be calculated from the masses and the distance between the bodies, assuming that the center of mass is concentrated at the respective centers of the bodies.
    Reduced Mass Coordinates: Isolated Two-body Problem01:12

    Reduced Mass Coordinates: Isolated Two-body Problem

    In classical mechanics, the two-body problem is one of the fundamental problems describing the motion of two interacting bodies under gravity or any other central force. When considering the motion of two bodies, one of the most important concepts is the reduced mass coordinates, a quantity that allows the two-body problem to be solved like a single-body problem. In these circumstances, it is assumed that a single body with reduced mass revolves around another body fixed in a position with an...