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