1. March 16th 2005Inaugural Lecture Einstein’s Biggest Blunder Professor Bob Nichol (ICG, Portsmouth)

2. March 16th 2005Inaugural Lecture Acknowledgements Maricar Jagger for all the organisation Prof Craven and Dean Claridge for hosting this event EU Marie Curie Excellence Chair ICG for a world-class stimulating environment SDSS colleagues and collaborators

3. March 16th 2005Inaugural Lecture Overview Space and Time General Relativity and  Hubble Diagram & SDSS Supernovae and Dark Energy

4. March 16th 2005Inaugural Lecture Space and Time Every event in the Universe has a coordinate (x,y,z,t) e.g. March 16th 2005 @ 6pm in the Richmond Building. Newton believed space and time was absolute, a big clock and ruler in the sky Einstein’s genius was to say “speed of light” was absolute not space-time (the centennial year of Einstein’s theory of relativity)

5. March 16th 2005Inaugural Lecture TIME DISTANCE (SPACE) Speed = distance/time Traditional to think speed is variable but space-time is fixed. But what if the speed of light was fixed? Opens up a new way of thinking of space-time, as a “dynamical” quantity Time to play!

6. March 16th 2005Inaugural Lecture Newtonian Gravity Force between two masses (M, m) Works well on scale of our planet But action at a distance? M m r F = GMm/r 2

7. March 16th 2005Inaugural Lecture General Relativity I In GR, a mass “warps” space-time and then other masses travel the shortest distance in this “curved” space-time: Looks like gravity!

8. March 16th 2005Inaugural Lecture General Relativity II Einstein’s genius was to describe gravity as a geometrical effect of mass No problem with action at a distance We are presently sitting in the “warped” space-time of the Earth. If the floor and crust wasn’t there you would fall towards the core of Earth in this curved space-time! Not just mass, energy can warp space-time (E=mc 2 )

9. March 16th 2005Inaugural Lecture General Relativity III GPS system would loose 10km a day! Cassini: 1 / 40000

10. March 16th 2005Inaugural Lecture Friedman’s Equation Using GR, we can write a simple equation for the dynamics of the Universe Hubble Parameter (see later) Average density of matter R is the scale factor (“radius”) of the Universe k is the curvature of space-time of the Universe (a constant)

11. March 16th 2005Inaugural Lecture 3 Solutions to Friedman R time Bang Never stop! Stop at infinity Big crunch! Value of  decides the fate of Universe! Like throwing a stone into space Larger universe Later in Universe

12. March 16th 2005Inaugural Lecture Einstein didn’t like it Remember in ~1920’s the Universe was thought to be static and infinite! Therefore, he introduced the cosmological constant  which acts as a negative pressure counteracting 

13. March 16th 2005Inaugural Lecture R time Very unstable - need “precise” value of  or it goes crazy! Should  be a constant? Very contrived! Larger universe Later in Universe  (t)  Just right!

14. March 16th 2005Inaugural Lecture 1929 - Enter Hubble Recession Velocity due to doppler shift of light Distance from Cepheid variable stars Less than 80 years ago! velocity = H o x distance H o = 500 km/s/Mpc

15. March 16th 2005Inaugural Lecture Biggest Blunder! Hubble’s Law is a natural consequence of Friedman equations When Einstein heard of Hubbles discovery he removed  calling it “his biggest blunder”

16. March 16th 2005Inaugural Lecture Hubble Flow

17. March 16th 2005Inaugural Lecture Hubble Flow II v v 2v Galaxies appear to be speeding away from us with increasing velocity, but it’s just the space between us expanding! Distance can be inferred from their recession velocity (v = H o x d)

18. March 16th 2005Inaugural Lecture Cosmology 1930-1990’s Since 1930’s, cosmologists have used Hubbles Law to map more and more galaxies, driven by technology Today, SDSS gives us a million galaxies! 100x more than pre-1990’s Digital “data flood”

19. SDSS Portsmouth joined in 2005 and is the only UK university in SDSS

20. SDSS

22. March 16th 2005Inaugural Lecture 1998 - Enter Supernovae Supernovae are “standard candles” - like having a 100W light bulb in the Universe! As you know they true brightness, you can estimate their distance from us Two projects used tens of supernovae to remake Hubbles Diagram but over much larger distances in the Universe; critical breakthrough!

23. March 16th 2005Inaugural Lecture Supernovae II

24. March 16th 2005Inaugural Lecture Supernovae III R time Today What is accelerating the Universe? “Dark Energy!” Larger universe Later in Universe Bang

25. March 16th 2005Inaugural Lecture Dark Energy Repulsive force - “anti-gravity” accelerating the late Universe Could be a constant - maybe not! Greatest mystery in modern physics Thousands of scientists on the hunt spending billions of dollars Nobel prizes! Bet on it…..

26. March 16th 2005Inaugural Lecture

27. March 16th 2005Inaugural Lecture Integrated Sachs-Wolfe Effect

28. March 16th 2005Inaugural Lecture My Experiment: SDSS

29. March 16th 2005Inaugural Lecture CMB as seen by WMAP

30. March 16th 2005Inaugural Lecture Combine them

31. March 16th 2005Inaugural Lecture Lens Experiment

32. March 16th 2005Inaugural Lecture What will we measuring?

33. March 16th 2005Inaugural Lecture SDSS WMAP

34. March 16th 2005Inaugural Lecture No Signal - No DE Positive Signal - DE! Most direct evidence yet that dark energy exists we see it’s repulsive force counteracting gravity directly

35. March 16th 2005Inaugural Lecture “It is one of the ultimate discoveries in basic science,” 2003

36. March 16th 2005Inaugural Lecture 2005 - Yet More Evidence Using a “standard ruler” the SDSS measured the geometry of the Universe Universe is flat to 1%! (3 times better than measured before) Need 77% of Universe to be dark energy to make it this way

37. March 16th 2005Inaugural Lecture

38. March 16th 2005Inaugural Lecture Or maybe it’s Energy associated with empty space- time (the rest mass of the vaccum) GR is wrong on the scale of the Universe like Newton’s Laws were wrong on scale of our planet Or….. Portsmouth leading the way

39. March 16th 2005Inaugural Lecture Summary Cosmology is a young subject and continues to amaze us Universe is full of a mysterious “dark energy” pushing the acceleration of the expansion of the Universe SDSS has provided us the most direct evidence yet of this bizarre stuff Ironically, it smells a lot like “Einstiens Biggest Blunder”  his greatest legacy?