How the Universe evolved
Science and Religion in Schools - Unit 4a
The Scientific Account of the Beginning
1
The Big Bang



The old Steady State theory
has now been rejected
The universe and all the
structures in it has evolved things have changed over
time
The initial events are still
mysterious, but we
understand the broad outline
of history from the first few
seconds onwards
Simple starting points





The universe is 13.7
billion years old
This images dates
from 300 000 years
into history
It shows how matter
was arranged in the
universe
Red means lower
density of matter,
blue means higher
Very little structure in
the early universe
Clusters of galaxies





Galaxies are grouped in
collections or clusters
Gravity is pulling these
galaxies together
Sometimes galaxies collide
(see later)
On the largest scales,
clusters of galaxies are
grouped into superclusters
Between superclusters there
are vast empty regions of
space
The large scale structure of the
universe



This picture has been
generated by computer
using information from
special telescopes
Every ‘dot’ is a cluster
of galaxies
The ‘filaments’ and
‘voids’ can be seen
Colliding galaxies




63 million light years from
Earth, two galaxies are
seen colliding
Left hand image shows an
over-all view and the
galaxies are seen again in
more detail on the right
Star formation can be
seen along the arms
where the collision is
taking place
Such collisions were
frequent in the early
universe and may have
had a lot to do with how
stars formed
Triggering star formation



Galaxies in collision 500
million light years from
Earth
One of the two objects on
the right punched a hole
through the main galaxy
on the image
A ring of bright, hot,young
stars has been formed as
a result of the shock wave
from the collision
Star formation in gas clouds



M16 Eagle nebula
6,500 light years from
Earth
Long, thin pillars of gas
At the end of each
pillar, there is a star
forming


Another image of
the Eagle nebula in close up
The ‘fingers’ can
easily be seen
Life of a star





Stars are giant balls of ‘burning’
gas - mostly hydrogen
Nuclear reactions in their cores
generate energy
They also ‘fuse’ light elements
(like hydrogen and helium) into
heavier ones (like carbon and
oxygen)
Without stars there would be no
life as we understand it
We need their warmth, the
planets that orbit them and the
elements they create
Death of a star



When stars die, they shed material
into space
This includes the heavier elements
made during the star’s life
As new stars form, they pull these
elements towards them
Stars explode




Sometimes stars die by
exploding (supernova)
In these gigantic events, the
exploding star can be
brighter on its own than a
whole galaxy
The explosion blasts
elements into space
Heavy elements (iron etc)
are made in these
explosions
The start of solar systems




These are images of stars in the
Orion nebula
Each star (red dot) is about a
million years old and surrounded
by a ring of dark material
The dark material will probably go
on to form planets
It is the heavier material left over
from when the star formed
Evidence for planets



The star is Gliese 229,
about 18 light-years
away
It is 20-50 times
heavier than Jupiter,
but only about the
same size
It is roughly the same
distance from its star
as Pluto is from our
Sun
Another possible planet




450 light years from Earth
It is about 2-3 times the size of
Jupiter
Could be a background star
(perhaps 2% chance)
Possible planet is about 210
billion km from the stars and
moving at 10 km/s
Recipe for life





Origin of life is not well
understood
Perhaps the formation of
organic molecules in the
chemical bath of the Earth
was triggered by lightning
Perhaps Earth was ‘seeded’
with organic molecules from
space
Seems likely that to take
hold, life would need a set of
circumstances not found on
all planets
Oxygen is a clue to the
presence of life
DNA







Self replicating molecule
Twin helix (coil) with the two arms
cross-linked to each other
The two arms can be un-coiled and
each can reproduce the other
Segments of DNA can also link
chemically to specific amino acids
Amino acids assembled in sequence
build proteins
Sequences of DNA can hence make
specific proteins
DNA contains the information to
build copies of itself and specific
chemicals within the organism
Cells






A vital step in the evolution of life
All living forms are composed of
one or more cells
In complex forms, cells contain
nuclei and organelles
Organelles carry out various
functions within the cell
Nucleus contains DNA molecules
coiled up into chromosomes
Cells probably evolved to protect
the DNA from the environment
The tree of life






Evolution well established as a
biological theory
Links Mendel’s idea of genes with
Darwin’s natural selection
Mutation of the gene gives rise to
changes in the organism
These changes can be beneficial
(more offspring) or not (fewer
offspring)
Beneficial changes are passed to
offspring
Gives rise to biological diversity
The brain




The most complex system known
to science
One million billion synaptic
connections
Constructed out of the same
material as the rest of the universe
(carbon, oxygen, nitrogen etc as
made by stars)
The seat of consciousness that
understands the universe