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# How the universe began

## on Aug 15, 2011

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Topic introduction to The Cosmic Engine

Topic introduction to The Cosmic Engine

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## How the universe beganPresentation Transcript

• How the universe began
Year 11 Physics – The Cosmic Engine
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
• The expanding universe
Scientists who have contributed to the expanding universe
Albert Einstein
AleksandrFriedmann
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
• AleksandrFriedmann
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, VestoSlipher 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
Go to www.tale.edu.au/tale4students
Save code: X03RO