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 2.7 o 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 10 5 )

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!