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What is the Universe Made of?

What is the Universe Made of?. Scales in The Universe. If the Earth were the size of a golf ball, how far away would the Sun be? How far away would Neptune be? How far away would the nearest star be?. Kepler’s Laws. All planets orbit in ellipses with the Sun at one focus

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What is the Universe Made of?

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  1. What is the Universe Made of?

  2. Scales in The Universe • If the Earth were the size of a golf ball, how far away would the Sun be? • How far away would Neptune be? • How far away would the nearest star be?

  3. Kepler’s Laws • All planets orbit in ellipses with the Sun at one focus • The orbit draws out equal areas in equal times. • The square of the period is proportional to the cube of the radius These apply to all orbiting bodies, not just planets...

  4. Circular Orbits • Centripetal acceleration • Gravitational force • Newton’s 2nd Law

  5. Finding Dark Matter • Use Kepler’s 3rd Law to predict the velocities of stars around the centre of a galaxy: • Mass of Galaxy = 28 billion solar masses • 1 solar mass = 2x1030 kg • G = 6.67x10-11 m3 s-2 kg-1 • 1 light year = 1016m

  6. Measured velocities • Here are the measured velocities • Do they look like what you predicted? • Use Kepler’s 3rd Law to estimate the mass of the galaxy

  7. What is Dark Matter? • It’s matter that’s not visible, but can only be detected by its gravitational effects • Best theory is that it is an exotic particle • If it is what we think it is, we might be close to finding it!

  8. Here are some other examples…

  9. Expansion of the Universe • In 1929 Edwin Hubble found link between distances to galaxies and their radial velocities • Plot Hubble's data

  10. Hubble's Data

  11. The Hubble Space Telescope

  12. The Hubble Space Telescope

  13. The Cosmic Microwave Background

  14. The contents of the Universe • We currently think the Universe is composed of three constituents: • Normal matter (“atoms”) • Dark Matter • Dark Energy • To find out how much of each, we need to look at the evidence

  15. Heavens’ Kitchen • Choose your ingredients • Total Matter, Normal Matter, Dark Energy • How does the Cosmic Microwave Background Compare? • When did Galaxies form? • How to the galaxies compare?

  16. What is the Universe made of? • We think the Universe is made of: • 5% Normal matter • 27% Dark Matter • 68% Dark Energy

  17. The Planck Satellite • 4x4x4m • 2 tonnes on launch • 2m mirror • Cooled to 0.1K • 2 instruments • 300-10000 microns

  18. All sky (visible) DSS www.chromoscope.net

  19. All-sky (microwave) Planck

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