It all started with the big bang - University of Ulster

Science in Society
This resource is part of the
Forward Thinking project.
For more information visit:
www.ulster.ac.uk/scienceinsociety/
It all started with the
BIG BANG
13.7 BILLION YEARS AGO
Space and time began when the infinitely small, dense universe began to expand. The universe has been
getting larger and cooler ever since. How will it end? With a big crunch or expansion and cooling forever?
No-one knows.
OBJECTIVES
To describe the characteristics of a good
theory;
To explain the evidence that supports the
Big Bang theory; and
To generate questions for enquiry.
STARTER
Bring a helium balloon to class and show
that it will float when you let go of the string.
Present the class with several theories that
claim to explain why the helium balloon floats
(see supporting floor cards, page 2). Read the
theories together and ask students to discuss
in pairs which they think is the best theory, and
explain to each other their reason why. Stress
that we are interested in what makes it a good
theory, rather than which is “correct”. Ask
everyone to stand next to the card that they
think is the best theory, and try to convince
others to move. Ideas that may be drawn out
are that theories help to explain the world, are
supported by observations, are generalizable,
useful and don’t involve contradictions. They
may be asked to refer back to these
characteristics when they understand the Big
Bang theory
STIMULUS
The stimulus for this discussion is The
Big Bang Theory theme tune by The
Barenaked Ladies (available on iTunes, lyrics
provided on page 2). A supporting video can
be made in iMovie, to include information on
three pieces of evidence that are used to
support the Big Bang theory: the redshift of
distant galaxies, the cosmic microwave
background radiation, and the composition of
the universe. Further ideas for demonstrations
and models that may be incorporated in the
video are found on page 3.
REFLECTING ON THE ENQUIRY
KSU: ask students to reflect on the
knowledge they have gained, the skills they
have used to gain it, and what they now
understand better. Write these on an exit
ticket to be handed in as they leave the
classroom (see page 2).
NEXT STEPS
This lesson can be followed up by:
a) Asking students to find out what the
Large Hadron Collider at CERN is doing to
help us understand the universe.
Hydrogen: the most abundant
element in the universe.
b) Creating a cartoon timeline for our
universe. More able students can be asked
to scale this to an Earth year.
c) Exploring the similarities and
differences between the Big Bang theory and
other theories, e.g. evolution. Focus on their
qualities as theories.
The Forward Thinking project is funded by the Wellcome Trust [1] www.ulster.ac.uk/scienceinsociety/

Print the cards below, or copy them on to A4 pages. Place
them on the floor and ask students to stand beside the card
that represents the best theory.
Some birthday balloons float in the air. Here are six theories to explain why
they float. Which is the best theory and why? It does not matter if you do
not know which theory is correct!
The foil on these
balloons is a metal.
This metal is
magnetically attracted
to the sun.
These balloons are
special.
These balloons have a
property called levity.
Anything that contains
“levity” floats.
Exit Ticket
Knowledge I have
gained
The balloons are less
dense than air. Less
dense objects float in
more dense fluids.
There is a force
produced in the
ribbon that acts to
push the balloon up.
The balloons are
sprinkled with magic
dust.
Skills I have used What I understand
better
Something I still want to know...
BIG BANG THEORY
Barenaked Ladies
Our whole universe was in a hot
dense state,
Then nearly fourteen billion years
ago expansion started. Wait...
The Earth began to cool,
The autotrophs began to drool,
Neanderthals developed tools,
We built a wall (we built the
pyramids),
Math, science, history, unraveling
the mysteries,
That all started with the big bang!
Since the dawn of man is really
not that long,
As every galaxy was formed in
less time than it takes to sing
this song.
A fraction of a second and the
elements were made.
The bipeds stood up straight,
The dinosaurs all met their fate,
They tried to leap but they were
late and they all died (they froze
their asses off)
The oceans and pangea
See ya, wouldn't wanna be ya
Set in motion by the same big
bang!
It all started with the big bang!
It's expanding ever outward but
one day
It will cause the stars to go the
other way,
Collapsing ever inward, we won't
be here, it wont be hurt
Our best and brightest figure that
it'll make an even bigger bang!
Australopithecus would really
have been sick of us
Debating out while here they're
catching deer (we're catching
viruses)
Religion or astronomy, Encarta,
Deuteronomy
It all started with the big bang!
Music and mythology, Einstein
and astrology
It all started with the big bang!
It all started with the big BANG!
The Forward Thinking project is funded by the Wellcome Trust [2] www.ulster.ac.uk/scienceinsociety/

Red light ➙
longer waves
EVIDENCE FOR THE BIG BANG
Visit the online Big Bang Time Machine at
http://resources.schoolscience.co.uk/PPARC/bang/bang.htm
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When we look at all the colours of light coming from
stars like the sun, we notice that some colours are
missing, and in their place are dark “absorption
lines.” These colours are missing because atoms in the
star are absorbing these colours. Atoms of different elements
absorb different colours (or wavelengths of light), so we can tell
which elements are present in a star from the position of the
lines. They look a bit like a bar code.
However, when we look at these “bar codes” of distant
galaxies, we see the same pattern of lines, but shifted towards
the red end of the spectrum. This is an example of the Doppler
shift (the same effect that causes ambulance sirens to change
pitch as they pass).
absorption lines from distant star: red-shifted
Red shift of light from
distant galaxies
This can be modeled by drawing
Blue light ➙
shorter waves
a wave on a long, thick
elastic band or length
of latex and asking
one student to
represent an
observer on Earth
(holding one end
of the band) and
another to
represent a distant
galaxy. As they move apart (to demonstrate the expansion of
space), students can see that the waves get longer, i.e. are red
shifted. Students can then identify the limitations of the model.
The cosmic microwave background radiation was
discovered when two scientists (Penzias and Wilson)
were trying to get rid of interference to satellite
broadcasts. They detected microwaves from all areas of
the sky, with a temperature of 2.7K (we can see this interference
as the snow pattern on untuned televisions). This discovery
supported the theory of the Big Bang, which could account for
these microwaves as energy left over from the Big Bang.
A third piece of evidence to support the Big Bang
theory is the composition of the universe. The Big
Bang theory predicts that in the first few minutes of
the universe, only the lightest elements, hydrogen and
helium, were formed. This is consistent with what we observe
today: the universe is mainly hydrogen (about 73%) and helium
(25%), with heavier elements created in stars and in supernova
explosions since the Big Bang.
However, a mystery remains. Between 90 - 99% of the
universe is unknown but scientists are currently looking for this
“dark matter” and “dark energy”.
The Forward Thinking project is funded by the Wellcome Trust [3] www.ulster.ac.uk/scienceinsociety/
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The Cosmic Microwave
Background Radiation
The composition
of the universe
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