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3A03 – GR and Cosmology

3A03 – GR and Cosmology. Ralph Pudritz Dept. of Physics & Astronomy McMaster University. Hubble Space Telescope – time machine. This telescope has enabled our deepest probe at optical wavelengths, of the cosmos – the Hubble “ deep field ”.

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3A03 – GR and Cosmology

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  1. 3A03 – GR and Cosmology Ralph Pudritz Dept. of Physics & Astronomy McMaster University

  2. Hubble Space Telescope – time machine This telescope has enabled our deepest probe at optical wavelengths, of the cosmos – the Hubble “deep field”.

  3. Looking back in time – galaxies long ago • This image, consists entirely of galaxies. Very faint ones are at cosmological distances: • smaller and “blotchier” than galaxies at present. • Evidence for for galactic evolution over cosmic time.

  4. Mapping where galaxies are – “large scale structure” • Da Costa et al (1994) • (Center for Astrophysics survey ) • - 9,325 galaxies shown • The largest structure yet seen: the “Great Wall”.

  5. Coma - cluster of galaxies

  6. THE EXPANDING UNIVESE • Edwin Hubble: 1889 - 1953 At the 48 inch on Mt. Palomar

  7. Cepheid variable stars – measuring distances to other galaxies

  8. Hubble Diagram (1929): galaxies move apart!

  9. Galaxies move away from us - the same for observers in any other galaxy…

  10. Albert Einstein – General Relativity

  11. Fate of the universe - depends on how dense it is…

  12. Geometry of the universe in four dimensions…. Closed Universe Critical Open Universe (sphere) (flat) (saddle)

  13. Discovery of microwave radiation – blackbody at 2.7o K

  14. COBE satellite – mapping the CMBR

  15. COBE map: temperature of universe 2.735 deg above absolute zero - image shows slight “dipole” Dpppler shift, picking out our direction of motion

  16. Cosmic Microwave Background Radiation - temperature fluctuations (one part in 105 )

  17. Inflation – making the universe flat • Cosmic Microwave background radiation is surprisingly smooth – universe probably “inflated” incredibly rapidly from one tiny little region.

  18. The expanding, cooling universe

  19. THE ORIGINS OF STRUCTRE IN THE UNIVERSE • How did galaxies form? - Density fluctuations infinitesimal in size, originate from quantum fluctuations in spacetime soon after the Big Bang. - These are seen in fluctuations in CMBR – baby photo of galaxies!

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