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BIG BANG
A Stardome presentation
By Dennis Ashton, FRAS
Images by courtesy of NASA
Part 1.
Evidence for the Big Bang
1923: Edwin Hubble, Mt Wilson Observatory, USA.
Hubble used variable stars to measure
distance of galaxies
Andromeda Galaxy, M31 – 1 million light years
Galaxies were star cities,
‘island universes’
huge distances away
Then followed an even more astounding
discovery……
Redshift
The more distant the
galaxy, the faster it is
moving away
The universe is
expanding!
Galaxies seemed to be moving away
from each other.
Space expands – and takes galaxies with it.
So long ago the universe was smaller,
very small.
Then it became larger.
Suddenly – in an explosion.
The Big Bang!
Test of the Big Bang Theory:
1. Galaxies should be moving away as space
expands.
2. Radiation from the Big bang should be
detectable - now at 3 degrees Kelvin
3. The light elements H, He & Li should have been
made in the first minutes of the universe.
1925: Hubble shows recession of galaxies.
Radio telescope picks up
echoes of the Big Bang.
Cosmic microwave
background.
3 degrees K
1965
Penzias & Wilson
1996: COBE spacecraft finds ripples in cosmic
microwave background.
The early universe – 300 000 years old.
Ripples show
early universe was
‘lumpy’.
Galaxies could be
formed.
Year 2000: 2MASS survey – galaxies in filaments.
The first elements
The Big Bang Theory predicts 3 elements were made:
77%
23%
Observations show this to be true.
>1%
Part 2: History of the Universe
14 billion years ago there was nothing.
No space, no time, no emptiness,
Nothing existed.
Then something appeared from the
nothing.
T=0
seconds
BIG BANG
The something was the universe.
Small & dense.
Very hot & expanding slowly.
No centre, no edge.
Space & time had begun.
Suddenly, the tiny universe became bigger –
INFLATION
–35
T =10
seconds
The universe became 100 trillion
trillion trillion trillion times bigger.
T = 10
–32
seconds
Particles formed from energy.
Quarks and leptons collided with their anti-particles
and went out of existence again.
More matter than anti-matter was created.
The universe cooled.
T = 10
–4
seconds
Universe cooled to 10 billion degrees
Protons & neutrons formed
t = 3 minutes
Protons & Neutrons make atomic nuclei
T = 3 minutes to 300 000 years
Opaque fireball universe.
Photons bump into other particles and cannot escape.
T = 300 000 years
3000 degrees K
Universe clears.
Photons free to travel.
Atoms become stable: H, He, Li
The early universe was
made of hydrogen,
helium & lithium….
..but mostly hydrogen
77%
23%
> 1%
T = 1 billion years
Hydrogen
collected into
clouds
Huge gas clouds form galaxies.
Hydrogen gas collapses under gravity to make
stars.
T = 1 billion years
The first galaxies fill with
stars.
Galaxies form filaments with huge spaces between.
Filament = wall
Space = void
4 billion years: our galaxy, the Milky Way, is born
Early stars are huge – become red supergiants
Supergiants make new elements by atomic fusion
Supergiant stars explode as supernovas
Supernova blasts out material.
All the heavy elements made in stars
Heavy elements blasted into space:
raw materials for new stars and planets.
Next
generation of
stars contain
heavy
elements –
metals.
Elements form gas & dust discs around new stars.
Dust around new stars makes planets.
T = 9 billion years
The sun is born.
T = 9.5 billion years
Planets are formed
Old stars die, new stars are born.
The universe continues to expand.
This is the universe
now.
But how will it end?
Part 3: The end of the universe.
Future 1.
Big Bang expansion force balanced by gravity.
Universe remains as it is.
Future 2.
Closed Universe
Gravity overcomes Big Bang expansion force.
Universe collapses to a Big Crunch !
Future 3
Big Bang expansion greater than gravity.
Universe expands forever.
Supernova in distant galaxy shows a strange universe.
The expansion of the universe is
accelerating!
Open universe – expands forever.
T = 19 billion years
The Sun becomes
a red giant star.
Inner planets,
including Earth,
burn & melt.
T = 25 billion years
Sun blasts away its outer layers.
Whole Solar System destroyed.
T = Far future
Giant stars explode and become black holes
Ordinary stars die as white dwarfs, then dark embers.
T = Far future
Galaxies fade as they move away.
T = Far future
Eventually all the stars die
The universe continues to expand
but creates only darkness.
Space becomes dark,
cold and empty
The universe ends in
eternal darkness
T = NOW
So while it lasts, enjoy the universe.
Go out and look at the stars!
The universe still holds many mysteries
There are many unanswered questions
Dark Matter
The stars, gas and dust could not hold galaxies together.
Unseen material also exists – DARK MATTER
DARK ENERGY
The universe is not just expanding.
It is accelerating!
A mysterious force is making the
universe bigger faster.
The force is DARK ENERGY
Contents of the Universe
The stars, gas and dust we can see are only
5% of the universe !
33% is Dark Matter
62% is Dark Energy
We do not yet know what 95% of the
universe really is!
? And the Big Question ?
How did it all begin?
So it is certainly not ………
THE END
If you would like to find out more,
please visit the Cosmic Mystery Tour web site at
http://archive.ncsa.uiuc.edu/Cyberia/Cosmos/CosmicMysteryTour.html