how the universe began
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Topic introduction to The Cosmic EngineTRANSCRIPT
HOW THE UNIVERSE BEGANYear 11 Physics – The Cosmic Engine
Admin stuff
Syllabus Glossary
Syllabus references
Outline the discovery of the expansion of the Universe by Hubble, following its earlier prediction by Friedmann
Identify that Einstein described the equivalence of energy and mass
Identify data sources and gather secondary information to describe the probable origins of the Universe
Where did the universe come from?
The Big Bang theory
The expanding universe Cosmic background radiation
The expanding universe
Scientists who have contributed to the expanding universe Albert Einstein Aleksandr Friedmann Edwin Hubble
Albert Einstein
Special theory of relativity
The speed of light Equivalence of
energy & mass Energy can be
converted into mass Mass can be
converted into energy
E = mc2
Evidence for Einstein’s theory Predicted that light rays can be warped by
space-time and should curl around stars (gravitational lensing) Gravitational lensing of distant quasars has been
studied by astronomers using the Hubble telescope Predicts that time should run slower near an
object as large as a planet Tested and verified in 1962
Predicted that the universe is expanding but Einstein believed in static universe so he put a cosmological constant in the equation to make the universe static
Aleksandr Friedmann
Read Einstein’s work but thought his cosmological constant was wrong, so he tried to solve Einstein’s equations
Assumed that the universe is the same no matter where we look
Friedmann’s maths proposed two models: (1) closed universe and (2) open universe
Closed universe
Time and space have a beginning and an end
Time and space both began with a big bang and will end when gravity stops the universe and pulls everything back into one point – “ the big squeeze”
The universe is finite and the expanding universe is due to space expanding
Open universe
Universe began with a big bang and will continue to expand forever
Time and space has no end
How do we know the universe is expanding?
In 1912, Vesto Slipher examined the spectrum of light produced from a nebulae
Found that the light from the nebulae had frequencies lower than normal light
The light from the nebulae was more shifted towards the red end of the spectrum – red shift
What is redshift?
Remember: light travels at the same speed regardless of how fast you are travelling
Light is made up of different colours; red has the lowest frequency and blue/purple has the highest frequency
Redshift is when light moves towards the red end of the visible light spectrum
The electromagnetic spectrum
Redshift continued ...
http://youtu.be/FhfnqboacV0
Redshift in the universe
The left spectrum is the transmitted frequency of light from a star
The right spectrum is the observed frequency of the star from Earth
The spectral lines are shifted towards the red end
Shows star is moving away from us
Edwin Hubble
Hubble used the redshift idea to propose his expanding universe model where the universe is like an exploding bomb
He also came up with the Hubble constant (Ho) Rate at which universe is
expanding Used to estimate the
size of the universe
Summary The big bang theory proposes that the
universe exploded out of a hot dense point.
The big bang theory is supported by the expanding universe model which various scientists have contributed to Einstein – equivalence of energy and mass
(E = mc2) Friedmann – closed and open universe Hubble – spectral lines and Hubble constant
Redshift demonstration
1. Go to www.tale.edu.au/tale4students
2. Save code: X03RO