Big Bang Theory and Cosmology (Video Notes)

Vocabulary flashcards covering key cosmology concepts from the video notes.

Big Bang Theory

The prevailing explanation for the origin of the universe, beginning from a hot, dense singularity and expanding over 13.8 billion years.

Singularity

A point of infinite density and temperature from which the Big Bang is thought to have begun.

Cosmology

The study of the universe’s origin, structure, and evolution.

Cosmic Microwave Background Radiation

The oldest light in the universe, a snapshot of the universe about 380,000 years after the Big Bang, now observed as microwaves.

Recombination

The epoch when electrons combined with nuclei to form neutral atoms, making the universe transparent to photons (~380,000 years after the Big Bang).

Nucleosynthesis

Formation of light elements (hydrogen, helium, traces of lithium and beryllium) in the first minutes after the Big Bang.

Hydrogen

The lightest and most abundant element formed in the early universe; primary building block of matter.

Helium

Second most abundant element formed during Big Bang nucleosynthesis.

Lithium

Trace element formed during Big Bang nucleosynthesis.

Protons

Positively charged subatomic particles that combine with neutrons to form nuclei.

Neutrons

Electrically neutral subatomic particles that help form atomic nuclei like helium.

Quarks

Fundamental constituents of matter that combine to form protons and neutrons.

First Stars

The earliest generation of stars formed about 200 million years after the Big Bang from hydrogen and helium gas.

Galaxy

A massive bound system of stars, gas, dust, and dark matter formed from density fluctuations in the early universe.

Black Hole

A region whose gravity is so strong that light cannot escape; often found at galaxy centers.

Sagittarius A* (Sag A*)

The supermassive black hole at the center of the Milky Way, about 4.3 million solar masses.

Dark Matter

Invisible matter that exerts gravity and helps shape galaxies and large-scale structures.

Dark Energy

Unknown energy causing the accelerated expansion of the universe; a major driver of cosmic acceleration.

Redshift

Shift of spectral lines toward longer wavelengths, indicating objects are moving away and the universe is expanding.

Hubble's Law

The observation that a galaxy’s recession velocity is proportional to its distance from us.

Inflation

A brief, rapid expansion early in the universe that seeded density fluctuations leading to structure formation.

Cosmic Structure Formation

Growth of galaxies and clusters from initial density fluctuations in the early universe.

Spectral Signature

The characteristic absorption or emission lines of an element used to identify its presence in spectra.

Age of the Universe

Approximately 13.8 billion years old.

Big Freeze

A fate where the universe expands forever, stars burn out, and everything becomes cold and dark.

Big Crunch

A potential fate where the universe collapses back to a dense singularity.