Key Concepts in Gravity, Black Holes, and Stellar Evolution

These flashcards cover key vocabulary and concepts related to gravity, black holes, stellar evolution, and cosmological phenomena, as discussed in the lecture notes.

Newton’s Law of Gravity

The force of gravity between two objects is equal to the product of their masses and the gravitational constant, divided by the square of the distance between them.

Einstein’s General Relativity

The theory that describes gravity as the curvature of spacetime caused by mass and energy, instead of a force acting at a distance.

Escape Speed

The speed required for an object to break free from another object's gravitational pull.

Event Horizon

The outer boundary of a black hole, beyond which nothing can escape the gravitational pull.

Singularity

The point at the center of a black hole where density is thought to become infinite.

Tidal Force

The difference in gravitational force experienced by an object in a varying gravitational field, such as when approaching a black hole.

Gravitational Time Dilation

The phenomenon where time runs slower in strong gravitational fields compared to weaker fields.

Luminosity

The total amount of energy emitted by a star per unit of time, a fixed property of the star.

Apparent Brightness

How bright a star appears to an observer, which depends on distance from the star.

Main Sequence

A band on the HR diagram where stars are fusing hydrogen in their cores, including most stars like the sun.

Blackbody

An idealized object that absorbs all wavelengths of light that strike it, emitting a continuous spectrum characteristic of its temperature.

CMB (Cosmic Microwave Background)

The thermal radiation filling the universe, a remnant from the early hot state of the universe after the Big Bang.

Hubble’s Law

The observation that galaxies are moving away from us, with their speed proportional to their distance, indicating the expansion of the universe.

Dark Energy

A mysterious form of energy that is theorized to be responsible for the accelerated expansion of the universe.

Supernova

A stellar explosion that occurs at the end of a star's life cycle, dramatically outshining the galaxy it resides in.