Lecture #5 - Black Hole Theory

Escape Speed

The speed required for a projectile to break free from an object’s gravity.

Escape speed depends on ____ and ______.

The mass of the object you’re trying to escape from, and your distance, r, from the center of mass.

Black Hole

Region of space where matter is so densely compacted that you’d have to move faster than the speed of light to escape its gravity.

Event Horizon

Distance from the center at which the escape speed equals the speed of light.

Singularity

The center of the black hole, where density is equivalent to infinity.

Schwarzschild Radius

Distance from the singularity to the event horizon. Depends exclusively on the mass of the object the black hole was formed from.

Microscopic Black Holes

Hypothetical objects that could be produced during particularly energetic particle collisions. No evidence that they exist.

Stellar Mass Black Holes

Have masses in the range of five to tens of solar masses. Form when very massive stars die explosively in supernovae. Probably tens of millions of these in our own galaxy.

Intermediate Mass Black Holes

Have masses that range between 100 to 100,000 solar masses. May form from the collision of smaller objects, or originated in the early universe. Evidence they exist mainly comes from gravitational waves.

Supermassive Black Holes

Often have masses in the millions or billions of solar masses. Reside at the hearts of most large galaxies — still trying to work out how they formed. May be stellar mass black holes that grew, or formed through direct collapse.

Tidal Force

A difference in gravity between two points that can lead to the destruction of objects due to the force acted upon them.

Tidal Disruption Events

Huge flares of high-energy x-rays that are emitted as stars and other objects are shredded upon close approach to a black hole.