Stars, starlight AND The Big Bang

OUTCOME QUESTION(S): S1-4-07: What is the evidence for the Big Bang Theory? Vocabulary & Concepts  Electromagnetic spectrum Doppler Effect Red Shift Big Bang Astronomy Cosmology

Light /heat are types of Electromagnetic Energy 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 HEAT Low energy High energy Because of the shape of the waves, the colours always separate into this same organized pattern ROY G BIV This is why other telescopes and tools are needed – we can only access a small amount of informational energy from stars Red light is low energy – cool Blue is high energy - hot

Red-Shift and the Big Bang There is evidence that the universe is expanding: - Red-shift of light from stars and galaxies - Cosmic Microwave Background Radiation - Gravitational waves (new) 1. Light waves work exactly like any other wave: Waves can be far apart - long wavelength Waves can be close together - short wavelength We’re going to focus on the oldest, and simplest – “red-shift” Long wavelegth Short wavelength

2. Waves are also affected by motion. Noticeable effect is called the Doppler Effect You have experienced this effect with sound waves Moving – compressed in front, spread out in back Stationary: all waves move outward evenly

Higher pitch Lower pitch Doppler effect: Sound waves You brain hears the distorted wave pattern as a different sound then is really being made by the ambulance

Bluer colour Redder colour Doppler effect: Light waves You brain sees the distorted wave pattern as a different colour then is really being made by the object

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 Evidence that the universe is expanding and speeding up too – think of it as the first half of an explosion “red shift” spectra “blue shift” spectra Normal spectra

The universe is expanding: Must have started out from one point – singularity Reverse 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 & Concepts  Electromagnetic spectrum Doppler Effect Red Shift Big Bang Astronomy Cosmology