Transcript Big Bang Theory

The Universe
- Astronomer Edwin Hubble observed that distant galaxies were
moving away from the Milky Way.
- How did he know this and what did it mean???
The Doppler Effect
Waves in front
bunch up
(short wavelength)
Waves behind
spreadout
(long wavelength)
Redshift and Blueshift
- light travels as a wave – blue light has short wavelengths
- red light has long wavelengths
Redshift and Blueshift
- the wavelength of light coming from galaxies all around
is getting longer (towards the red wavelength of light)
- galaxies are moving apart, but they themselves do not expand because of
gravity
How does this relate to the
Universe?
• Hubble found that most galaxies had redshifted (meaning…)
• They are moving away from the observer
• This means that the universe is expanding
• In honour of this discovery: the first large
space telescope was named after Hubble
Big Bang Theory
http://www.youtube.com/watch?v=Vtk8eO_1ieU
- between 10 & 15 billion years
ago, all the matter of the entire
universe expanded outwards
from one small extremely hot
mass under tremendous
pressure
- the “beginning” (time zero)
- what happened before this
is not known
QuickTime™ and a
decompressor
are needed to see this picture.
Evidence for the Big Bang Theory
In 1965, two scientists detected
unexpected radiation coming
from all directions in space that
could be the remains of the
enormous amount of energy
that exploded outwards at the
time of the Big Bang.
The Big Bang Theory
• Cosmologist observe that at some time in
the distant past the universe was
extremely compact, small and
unimaginably dense. Modern satellites can
look back in time almost to the very
beginning (approx. 14 billion years
• Most cosmologist believe the beginning
occurred in the Big Bang
The Supporting Evidence
• Distance-Redshift relationship, Hubble
Constant
• Cosmic microwave background (CMB)
radiation-radiation left over from the Big Bang
– Initially the universe was very hot, filled with
gamma rays at short wave lengths. As the
universe expanded the wavelengths expanded
from gamma rays to visible rays
– Today astronomers observe that CMB radiation
has a wavelength of 1.07 mm (the microwave
spectrum)
What does it mean?
• A young universe-the images captured by
the satellites COBE and WMAP show a
young universe at about 0.002% its
present age. At this time it was very small,
yet from our point of view it seems a huge
shell that surrounds us. We see it in all
directions as red-shifted when in fact it
was still really small
The Images
• COBE
Blue is colder,
yellow red is
warmer
• WMAP
How does this make sense
• The light from our Sun take 8 minutes to reach
us-that means the sunlight we see existed 8
minutes ago
• The closest star is 4 light-years away-that
means we see star light as it was 4 years ago
• The galaxies are 10 billion light years awayshowing us what the galaxy was 10 billion years
ago
• Remember-the universe formed 14 billion years
ago
The Large Hadron Collider (LHC)
What Is It? The largest particle accelerator ever built. It will
recreate conditions just after the Big Bang.
http://www.youtube.com/watch?v=2jup2R9Jtnc
http://www.youtube.com/watch?v=sxAxV7g3yf8
How Does It Work?
Two proton beams will be steered by magnets in opposite directions
around a circular tunnel at close to the speed of light. At designated
points around the tunnel, the beams will cross paths.
Why Was It Built?
Scientists hope previously unseen particles will be discovered
when the beams smash together.
When Will the Experiment Happen?
It has already taken two decades to get this far. Physicists may
have to wait between five and 10 years before they get any
significant results.
Evidence for the Big Bang Theory
Read the article on the Big Bang. Highlight main points.
Write a few paragraphs explaining the Big Bang Theory IN
YOUR OWN WORDS. Imagine you were explaining it to a
5th grade student, so try to simplify it as much as possible.
Make sure use full sentences and paragraphs. Make sure
your work is neat and organized. Watch your spelling and
grammar.
Explain the theory and the evidence to support it.