1. Stars, starlight AND The Big Bang

2. OUTCOME QUESTION(S): S1-4-07: What is the evidence for the Big Bang Theory? Vocabulary & People Electromagnetic spectrumDoppler Effect Red ShiftBig BangAstronomy Cosmology

3. 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

4. Electromagnetic Spectrum of Energies Low energy High energy 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

5. 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

6. 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

7. 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

8. 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

9. 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”

10. 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

11. 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

12. Astronomy – study of all objects in the universe. Cosmology – study of the origin of the universe.

13. CAN YOU ANSWER THESE QUESTIONS? S1-4-07: What is the evidence for the Big Bang Theory? Vocabulary & People Electromagnetic spectrumDoppler Effect Red ShiftBig BangAstronomy Cosmology