ASTR 1102-002 2008 Fall Semester [Slides from Lecture16] Joel E. Tohline, Alumni Professor Office: 247 Nicholson Hall [Slides from Lecture16]

Chapter 22: Black Holes

Einstein’s Theory of Relativity Special Theory of Relativity Properly describes how nature behaves when objects/observers are moving at a constant velocity relative to one another Description correct even as velocities approach the speed of light General Theory of Relativity A generalization of the special theory to include accelerations, that is, objects/observers not moving at constant velocity relative to one another Includes effects of acceleration in a gravitational field

Special Relativity Based on two basic principles: Your description of physical reality is the same regardless of the constant velocity at which you move. Regardless of your speed or direction of motion, you always measure the speed of light to be the same.

Our Normal (nonrelativistic) Understanding of Nature

Implications of Special Relativity Length contraction Time dilation

Length Contraction

Time Dilation

Implications of Special Relativity Length contraction Time dilation E = mc2 Examples: Decay of unstable particles called muons (Box 22-1 in textbook) Twin paradox (not discussed in textbook)

General Relativity Equivalence principle: The downward pull of gravity can be accurately and completely duplicated by an upward acceleration of the observer.

Tests of General Relativity Gravitational bending of light Precession of Mercury’s orbit Gravitational slowing of time and gravitational redshift Gravitational waves!  LIGO

Gravitational Bending of Light

Gravitational Bending of Light

Precession of Mercury’s Orbit

Gravitational Redshift

Black Hole

Black Hole

Rotating Black Hole

Flying Toward a Black Hole

Dropping Into a Black Hole

Sloooow Evaporation of a BH