D Black holes, by definition, cannot be observed directly. It is the 'point of no return' of the black hole anything closer than this point will not be able to escape the gravitational force of the black hole. It is the center of the black hole, a place of infinite density where the known laws of physics cannot describe the conditions.Į. There are no binary black holes-each one is isolated.ĭ.

An object can become a black hole only once, and a black hole cannot evolve into anything else.Ĭ. It is the edge of the black hole, where one could leave the observable universe.ī. 30 billion km D What do we mean by the singularity of a black hole?Ī. ingularity A What is the Schwarzschild radius of a 10 solar mass black hole?Į. B The boundary from within which light cannot escape from a black hole is called the black hole's _.ĭ. An object that is completely black in colour. An object that sucks in all the light from stars that are near it.ĭ. A place from which the escape velocity exceeds the speed of light.Ĭ. A funnel-shaped, bottomless pit in the universe.ī. C Which of the following best describes a black hole?Ī. Newton's theory of gravity is now known to be false, and we were previously misled to think it was true by measurement errors. Newton's theory of gravity is an approximation to general relativity that works when gravity is relatively weak, but breaks down when gravity is strong.ĭ. Newton's theory of gravity and general relativity give the same answers, but the former tells us to think of gravity as a force and the latter tells us to think of gravity as curvature of spacetime.Ĭ. General relativity applies at the subatomic level, but Newton's theory of gravity does not.ī. A Which of the following correctly describes the relationship between Newton's theory of gravity and general relativity?Ī. It is the place where time begins to slow down as you approach a black hole. It is the 'bottomless pit' of the black hole.ĭ. It is the boundary within which events in the black hole cannot influence events in the outside universe.ī. B What do we mean by the event horizon of a black hole?Ī. Spacetime would become flatter (less curved) at Earth's orbit.ĭ. Spacetime would become more curved at Earth's orbit.Ĭ.

The structure of spacetime would stay the same.ī. How would the structure of spacetime change at the distance of Earth's orbit?Ī. D Imagine that the Sun gained mass without changing its radius. Earth would be sucked into the black hole.ĭ.

Earth's orbit would move farther from the Sun.Ĭ. Earth's orbit would change from elliptical to unbound.ī. A Imagine that the Sun could be turned into a black hole without changing its mass. The acceleration is the same everywhere along the orbit. where spacetime has the least curvature.Ĭ. where spacetime has the most curvature.ī. Where does an object on an elliptical orbit experience the greatest acceleration?Ī. a curved rubber sheet B Rank the objects based on the strength of the gravitational force that would be felt by a spacecraft traveling at a distance of 10 AU from the center of each of the objects, from weakest to strongest.īlack Hole All are the same at that distance. the combination of time and the three dimensions of space.Ĭ. a picture taken with a poorly made telescope, so that a single large object appears as four fuzzy dots. four images of a single background galaxy, created by the gravitational lens of a massive foreground galaxy or cluster.ĭ.

a large galaxy with four central masses that glow brightly.Ĭ. four galaxies that are nearly identical because they were born at about the same time.ī. Figure S3.20a in the text shows a photograph that appears to show four identical galaxies arranged as a cross.

Light following a curved space