Understanding Spacetime and Relativity

What does the special theory of relativity suggest about the nature of time?

• Time is an illusion and does not exist.

• Time is absolute and the same for everyone.

• Time is relative and can vary between observers.

• Time is a constant that cannot be altered.

In a spacetime diagram, what does a sloped line represent?

• A stationary object.

• An object moving at a constant velocity.

• An object accelerating.

• An object moving faster than light.

What is the significance of the spacetime interval in relativity?

• It defines the flow of causality and is invariant across reference frames.

• It is used to calculate the speed of light.

• It measures the absolute time between events.

• It measures the distance between two points in space.

What does a hyperbolic contour on a spacetime diagram represent?

• The boundary of a black hole.

• A constant spacetime interval.

• The trajectory of a moving object.

• The path of a light beam.

What is the forward light cone in a spacetime diagram?

• The boundary of a black hole.

• The path of a photon.

• The region that represents past events.

• The region that represents future events that can be influenced.

What happens to the spacetime interval in the curved space within a black hole?

• It gets flipped automatically.

• It becomes zero.

• It remains constant.

• It becomes infinite.

What is the smallest stable orbit around a black hole called?

• Schwarzschild radius.

• Event horizon.

• Innermost stable circular orbit.

• Photon sphere.

What is one proposed solution to the mathematical singularity at the center of black holes?

• General relativity.

• Newtonian physics.

• Quantum mechanics.

• String theory and the concept of fuzzballs.

What is the effect of gravitational redshift observed near a black hole?

• Light is absorbed completely by the black hole.

• Light remains unchanged.

• Light is red-shifted as it climbs out of the gravitational well.

• Light is blue-shifted as it approaches the black hole.

What is the main reason stars are efficient at nuclear fusion?

• They have high temperatures.

• They have high densities.

• They are composed of hydrogen.

• They are located in accretion disks.