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What is the Big Bang theory?
The Big Bang Theory states that the Universe began 13.6 billion
yrs ago as a singularity and has been expanding ever since.
But it wasn’t big, and there was no bang!
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Scientists examining the light
emitted by stars observe dark
lines in the spectrum caused by
different elements, such helium,
in the stars being studied.
What is Red Shift?
This red shift suggests that distant galaxies are moving away
from Earth and supports the idea of an expanding Universe.
Edwin Hubble observed that the pattern of dark lines
produced by the light coming from distant galaxies is shifted
towards the red end of the spectrum.
Red shift occurs because of the Doppler effect, which can
be observed in sound waves and electromagnetic waves.
The observation of red shift is a key piece of evidence for the
Big Bang theory about the origin of the Universe.
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What is Red Shift?
Red shift occurs because of the Doppler effect, which can
be observed in sound waves and electromagnetic waves.
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The Doppler effect means that sound
moving away from an observer appears
to be lower in frequency.
It has also been observed that the further away a galaxy is,
the greater the amount of red shift.
How does the Doppler effect work in space?
This means the distant galaxies must be
moving away from the Earth.
The same thing happens with light from
distant galaxies, which appears to be
shifted towards the low frequency, red
end of the spectrum.
This means that very distant galaxies must be moving faster
than near, all of which is evidence for the Big Bang theory.
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Prediction: If the universe was denser and hotter in the past, we
should see evidence of left-over heat from early universe.
Observation: Left-over heat from the early universe. (Penzias and Wilson, 1965)
Testing the Big Bang model
Big Bang Proof
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Evidence of the Big Bang – CMB
The other key piece of evidence for the Big Bang theory
is cosmic microwave background radiation (CMB).
CMB is
microwave
radiation coming
from every
direction in space
CMB was discovered accidentally right in New Jersey.
Searching for radio waves in the Milky Way, they heard a
humming sound in their antenna that they couldn’t explain.
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The Future of the Universe
Dark Energy
74%
Dark
Matter
22%
Normal Matter
4%
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The Future of the Universe
Dark Matter, discovered by Vera
Rubin, is a new and unknown form of
matter that exists. But its gravity
works the same way as matter.
In order for a new particle to behave
as dark matter, it must be heavy
(probably heavier than a neutron) and
weakly interacting with normal matter
so that it does not emit light.
Dark matter must be the basic
building block of the largest structures
in the universe: galaxies and clusters.
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The Future of the Universe
We know the universe is
expanding faster than we
thought. The answer may be
dark energy.
We don’t know what dark
energy is, but it is
everywhere and it’s force
increases as space expands.
Therefore, as the Universe
expands, gravity weakens
and dark energy strengthens.
This supports an open
Universe theory.
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The big-bang theory states that the Universe is expanding
due to a large ‘explosion’ (big bang) billions of years ago.
Evidence to support this theory includes:
1. The Cosmic Microwave Background Radiation (CMB),
which is thought to be an ‘echo’ of the initial explosion.
2. Hubble’s observations about red shift.;
This theory gives rise to different fates for the Universe:
1.If the mass of the Universe is smaller, it will eventually
start to contract due to gravity – closed Universe.
2.If the mass of the Universe is large enough, it will expand
forever as there is not enough gravity to halt its expansion –
open Universe. Dark matter and dark energy may prove
this!
Summary
Cosmic Microwave Background Radiation
big bang theory
red shift
Closed Universe
open Universe matter energy
