The Origin of the Universe: Big Bang Theory

Flashcards covering the definitions, proponents, evidence, and limitations of the Big Bang Theory based on lecture notes.

Big Bang Theory

A cosmological model explaining that the universe started its expansion about $13.8$ billion years ago; it is not a literal explosion but an expansion.

Bread-Raisin Model

An analogy for the Big Bang where the bread represents the universe and the raisins represent the galaxies that do not expand themselves but move apart as the bread (universe) grows.

Singularity

An area predicted to be in the core of a black hole with very high temperature and density, considered the starting point of the universe.

Primeval atom

The single point from which the first proponent of the theory suggested the universe originated.

Edwin Powell Hubble

The scientist who established Hubble’s law, providing evidence that the universe is expanding rather than being static.

Hubble’s Law

A law stating that the universe is expanding and that the farther galaxies are from us, the faster they move away.

Arno Penzias and Robert Wilson

American radio astronomers who, in 1964, accidentally discovered the cosmic microwave background (CMB) radiation.

Cosmic Microwave Background (CMB) radiation

Leftover radiation from the Big Bang, appearing as microwaves with wavelengths of about $7 cm$ present in space.

Rapid inflation, expansion and cooling

The processes the universe underwent immediately after birth, leading to the stretching of original high-energy gamma and ultraviolet light waves.

Nucleosynthesis

The formation of elements, such as $H$ and $He$, which led to the creation of stars, galaxies, and other cosmic bodies like planets, comets, and asteroids.

Doppler Effect

The shift in wavelengths of sound and light that occurs when there is relative motion between the wave source and an observer.

Redshift

The phenomenon where electromagnetic waves shift toward longer wavelengths (the red end of the spectrum) when the source is moving away from the observer.

Limitations of the Big Bang Theory

The theory fails to explain how the universe was created, where it originated, or how galaxies were formed; it only explains how the universe evolved.