Stars, starlight AND

The Big Bang

OUTCOME QUESTION(S):S1-4-07:What is the evidence for the Big Bang Theory?

Vocabulary & People Electromagnetic spectrum Doppler EffectRed Shift Big BangAstronomyCosmology

Star light can be used to determine temperature, composition and size (mass)

• Light /heat are types of Electromagnetic Energy

Hot objects (like stars) radiate different types of energies too – as temperature changes so does the main energy released

Electromagnetic Spectrum of Energies

Low energy High energy

ROY G BIV

Red light is low energy – cool

Blue is high energy - hot

Because of the shape of the waves, the colours always separate into this same organized pattern

HEAT

This is why other telescopes and tools are needed – we can only access a small amount of informational energy from stars

There is evidence that the universe is expanding: - Red-shift of light from stars and galaxies - Cosmic Microwave Background Radiation - Gravitational waves (new)

We’re going to focus on the oldest, and simplest – “red-shift”

1. Light waves work exactly like any other wave:• Waves can be far apart - long wavelength• Waves can be close together - short wavelength

Red-Shift and the Big Bang

Long wavelegth

Short wavelength

2. Waves are also affected by motion. • Noticeable effect is called the Doppler Effect

Stationary:all waves move outward evenly

Moving – compressed in front, spread out in back

You have experienced this effect with sound waves

Higher pitch Lower pitch

You brain hears the distorted wave pattern as a different sound then is really being made by the ambulance

Doppler effect:Sound waves

You brain sees the distorted wave pattern as a different colour then is really being made by the object

Doppler effect:Light waves

Bluer colour Redder colour

• a compressed green light appears more blue “blue shift”• a s t r e t c h e d green light appears more red “red shift”

Your eyes don’t know what colour it “should” be, it can only interpret the waves it sees – it can’t tell the difference

between “red” and “s t r e t c h e d green”

3. Spectra of ALL stars / galaxies show red shift.Far away galaxies show more red shift - faster

“red shift” spectra

“blue shift” spectra

Normal spectra

Evidence that the universe is expanding and speeding up too – think of it as the first half of an explosion

The universe is expanding:• Must have started out from one point –

singularityReverse the explosion – the Universe must have started from a packed, dense mass of material under pressure

Big Bang • Rapid expansion of Universe from the singularity • Evidence suggests Universe is 14 billion years

old• Scientists cannot yet explain all “how” or “why”• Not the only explanation of the universe origin

BUT beliefs are not theories – only scientific theories can be tested and proven

Astronomy – study of all objects in the universe.

Cosmology – study of the origin of the universe.

CAN YOU ANSWER THESE QUESTIONS?S1-4-07:What is the evidence for the Big Bang Theory?

Vocabulary & People Electromagnetic spectrum Doppler EffectRed Shift Big BangAstronomyCosmology