Cosmology — Origins and Large-Scale Structure

Manual: General · Subject: Cosmology

Big Bang, inflation, dark matter, and dark energy

The Universe at the Largest Scales

The Big Bang and Cosmic Expansion

The universe originated ~13.8 billion years ago in the Big Bang. Hubble's law: $v = H_0 d$ where $H_0 \approx 67\ \text{km/s/Mpc}$ .

Friedmann equation: $H^2 = \frac{8\pi G \rho}{3} - \frac{kc^2}{a^2} + \frac{\Lambda c^2}{3}$ where $a(t)$ is the scale factor, $k$ the curvature parameter ( $k=0$ for flat universe), and $\Lambda$ the cosmological constant.

Inflation, Dark Matter, and Dark Energy

CMB (Cosmic Microwave Background): relic radiation from 380,000 years post-Big Bang at $T \approx 2.725\ \text{K}$ . Tiny fluctuations ( $\Delta T/T \sim 10^{-5}$ ) seeded structure formation.

Cosmic inventory: ~5% ordinary matter, ~27% dark matter (evidenced by rotation curves, gravitational lensing), ~68% dark energy (driving accelerated expansion, $\Lambda$ ).

Inflation (~ $10^{-36}$ to $10^{-32}$ s) explains flatness and horizon problems.

ℹ️

Type Ia Supernovae and Acceleration

In 1998, studies of distant Type Ia supernovae showed they were fainter than expected — the universe's expansion is accelerating. This discovery (Nobel 2011) implies dark energy ( $\Lambda > 0$ ).

Hubble's constant $H_0 \approx 67\ \text{km/s/Mpc}$ relates:

Recession velocity of galaxies to their distance Size of the universe to its age CMB temperature to redshift Dark matter density to galaxy mass

The Cosmic Microwave Background provides evidence for:

The hot early universe and the Big Bang Dark matter particles directly Black hole formation Stellar nucleosynthesis

What evidence supports the existence of dark matter? List three independent lines of evidence.

Neuroanatomy Explorer

Memory Deck

Match the Pairs

Concept Constellation

Cosmology — Origins and Large-Scale Structure

The Universe at the Largest Scales

The Big Bang and Cosmic Expansion

Inflation, Dark Matter, and Dark Energy