1. Space-time Lego Willem Westra And Stefan Zohren

2. Our goal • Find a theory of Gravity for very, very small scales • Einstein’s theory of gravity: works well for big things such as stars and planets • Small scales: Quantum Mechanics...

3. The big stuff: Gravity Einstein’s theory of general relativity, 1918

4. Gravity?

5. Gravity = Geometry Gravity: curvature of space-time • Matter curves space-time • Curved space-time tells matter how to move

6. The small: Quantum mechanics Schrödinger’s equation, 1927

7. What is quantum mechanics?

8. Quantum Mechanics • Everything that can happen... does happen • What we see is the stuff that is most probable to happen

9. big + small gravity + quantum curved space-time + probability

10. Curved space + quantum • Task: count all possible curved space-times Compute the most probable ones • Solution: build space time from little “Lego blocks” Count the number of ways the Lego blocks can be put together

11. 1+1 dimensional space times • One dimension of space • One dimension of time • Simplest Lego blocks: triangles • Task: count the number of ways one can glue triangles together

12. N N N Counting the triangles

13. N Counting the triangles N+1 N+1

14. An example

15. An example

16. An example

17. An example

18. An example

19. An example

20. An example

21. An example

22. An example

23. An example

24. An example

25. An example

26. An example

27. An example

28. An example

29. An example

30. An example

31. An example

32. An example

33. An example

34. An example

35. An example

36. An example

37. An example

38. An example

39. An example

40. An example

41. An example

42. An example

43. An example

44. An example

45. An example

46. An example

47. An example

48. An example

49. An example

50. An example