Notes 30.4 The Big Bang Theory

Std 2g: How the red-shift provide evidence for the “big bang” model that suggests that the universe has been expanding for 10-20 billion years

Objective 1: Explain how Hubble’s discoveries lead to an understanding that the universe is expanding

Objective 2: Summarize the big bang theory

• Cosmology - the study of the origin, structure and future of the universe

• Scientists study the light given off by an entire galaxy

• They create the spectrum for the galaxy which gives us info about our universe

Hubble’s Observations

• Hubble found that the spectra of most galaxies shifted toward the red end of the spectra – Except a few closest to Earth

The Expanding Universe

• Moving away from Earth

• The faster the galaxy, the faster they are moving

• The Red Shift = the universe is expanding (getting bigger and bigger)

Objective 1: Explain how Hubble’s discoveries lead to an understanding that

the universe is expanding

• What is the study of the origin of the universe?– Cosmology

• What is did Hubble discover about the color of galaxies?– They shifted toward the red end of the spectra

• What does a red shift in galaxies mean for the universe?– It is expanding

The Big Bang Emerges

• The Big Bang theory – the theory that all matter and energy in the universe was compressed into an extremely small volume that 13 to 15 billion years ago exploded and began to expanding in all directions

Evidence for the Big Bang Theory

1. Red shift of distant galaxies – shows universe is expanding

2. Cosmic Microwave Background Radiation (1965) low levels of energy evenly distributed throughout the universe were discovered; considered a remnant of the big bang

3. Ripples in space – indicate the first stages in the formation of the universe’s 1st galaxy

Cosmic Microwave Background Radiation (CMBR)

• It formed shortly after the big bang

• Now, the energy of the background radiation is 3⁰C above absolute zero (-273.15 ⁰C), which is the coldest temp possible

• (Background of this slide show is a picture of CMBR)

Ripples in Space

• Map of temperature differences reveals interesting information– Ripples are irregularities in the CMBR caused by

small fluctuations in matter distribution– Ripples hold the clues to how the early universe

evolved – Video-Super clusters of galaxies

Dark Matter

• Dark Matter- 23% of the universe is made up of matter that does not give off light

• 4% of universe is made of the elements we know to exist

Dark Energy

• Dark Energy- most of the universe is composed of something we don’t know anything about (73%) – Acts as a force that

opposes gravity

– dark energy in pushing galaxies apart

Objective 2: Summarize the Big Bang theory

• What are the 3 pieces of evidence for the Big Bang Theory?– Red shift, CMBR and ripples in space

• What do scientist think the ripples will reveal?– How the early universe evolved

• What do scientist think is pushing the galaxies apart?– Dark energy