Lecture #20 (?)

The Universe: shape, age, size, fate

The Hubble Diagram

Distance vs. redshift (velocity) graph

Slope is Hubble constant

Redshift: measure using spectra

Distance: very difficult to measure

Standard candles: type Ia supernovae

Peak luminosity is same

Decreases as 1/D²

Shape of curve on Hubble Diagram depends on model of universe

Lecture #21 (?)

Parameters of the Universe

Deceleration parameter, q_o

Density parameter, W

Age of the universe

Hubble constant, H_o

Best estimate, H_o = 70 km/s/Mpc

Age: 15 billion years

Shape: flat (slightly closed)

Fate: expansion slow down

Lecture #22 (?)

Black Hole evaporation

Virtual particles

Photon --> e⁺ + e^- --> photon

Feature of quantum mechanics

Causes BH to lose energy

Look-back time

Further away = further back in time

Inflation: exponential expansion

Solves isotropy of universe

Caused by a "false vacuum"

Lecture #23 (?)

Cosmological Constant

A term in Einstein's GE equations

Contributes to W

May be explained by vacuum energy

The Density Parameter

Made up of matter (visible and dark) and cosmological constant term

Big Bang Neucleosynthesis

"Fusion" early on in universe

Produced H, D, He, and Li