1. 1 Einstein, Time, and Cool Stuff World Science Festival 13 June 2009 Kimmel Center, NYU William D. Phillips

2. 2 What does NIST do? length time mass Images Copyright Shutterstock Among other responsibilities, the National Institute of Standards and Technology is the keeper of the the standards of measurements for the United States.

3. 3 Time and Einstein What is time? Images Copyright Shutterstock Time is what a clock measures.

4. 4 Clocks “tick”… … and different clocks have different “tickers.” Images Copyright Shutterstock

5. 5 The best tickers are atoms. Every quartz watch crystal vibrates at a rate different from every other one. Every 133 Cs atom is absolutely identical to every other one. Image Copyright Shutterstock Image John Vig

6. 6 Spring forward Cesium atom clocks like the one in this cartoon are accurate to one second in 3 million years. Copyright Nick Downs

7. 7 Spring forward Cesium atom clocks like the one in this cartoon are accurate to one second in 3 million years. Copyright Nick Downs 200 meters/sec

8. 8 Spring forward Cesium atom clocks like the one in this cartoon are accurate to one second in 3 million years. Copyright Nick Downs Who needs a clock this good?

9. 9 My goodness, it’s 12:15:0936420175. Time for lunch Time for lunch

10. 10 Who cares? One reason we need atomic clocks is the Global Positioning System. Atomic clocks in satellites guide cars, planes, backpackers, even golfers. For improved navigation, communication, scientific research, and national security, we are always trying to improve atomic clocks, but we hit a snag because the atoms move so fast. Image Copyright Shutterstock Image NASA GPS satellite.

11. 11 How GPS Works All the satellite clocks are synchronized. They broadcast their time and their location.

12. 12 By the time the time signal reaches you, your clock has advanced a little, so you know how far away that satellite is. How GPS Works 2

13. 13 Each satellite, at a different distance, shows a different delay. How GPS Works 3

14. 14 Knowing how far you are from two satellites tells you where you are (if you, and the satellites were on a flat sheet. How GPS Works 4

15. 15 In a 3-dimensional world, you need three satellites in view (four if you don’t have your own clock) to tell where you are. How GPS Works 5

16. 16 # 1: Atoms Animations

17. 17 #2: Hot & Cold Animation

18. 18 Demonstrations

19. 19 The Absolute or “Kelvin” temperature scale 0 K => absolute zero 300 K => room temperature

20. 20 The Absolute or “Kelvin” temperature scale 300 K => room temperature 273 K => ice melts 0 K => absolute zero

21. 21 The Absolute or “Kelvin” temperature scale 0 K => absolute zero 300 K => room temperature 195 K => dry ice 273 K => ice melts

22. 22 The Absolute or “Kelvin” temperature scale 0 K => absolute zero 300 K => room temperature 195 K => dry ice 273 K => ice melts 185 K => a cold day in Antarctica

23. 23 The Absolute or “Kelvin” temperature scale 0 K => absolute zero 300 K => room temperature 195 K => dry ice 77 K => liquid nitrogen 273 K => ice melts 185 K => a cold day in Antarctica

24. 24 pull out balloons

25. 25 #3: balloon animation Hot gas—atoms are free and isolated, but fast. Condensed “gas”— atoms are frozen, stuck to each other and the container.

26. 26 Comet photo courtesy NASA

27. 27 #4: Comet animation

28. 28 Na Optical Molasses How cold are these atoms?

29. 29 The Absolute or “Kelvin” temperature scale 0 K => Absolute Zero 300 K => room temperature 195 K => dry ice 77 K => liquid nitrogen 273 K => ice melts 185 K => a cold day in Antarctica

30. 30 The Absolute or “Kelvin” temperature scale 0 K => Absolute Zero 300 K => room temperature 195 K => dry ice 77 K => liquid nitrogen 3 K => outer space 273 K => ice melts 185 K => a cold day in Antarctica

31. 31 T = 700 nK ( V thermal < 1 cm/s) 100 million times colder than liquid nitrogen 4 million times colder than outer space. We have gotten cesium atoms as cold as: Atoms this cold make great clocks. This was 200 time COLDER than everybody thought was possible!

32. 32 NIST F-1

33. 33 NIST F-1 This clock is accurate to one second in 80 million years…

34. 34 NIST F-1 Clocks with laser cooled ions (electrically charged atoms) are good to 1 second in a billion years…

35. 35 NIST F-1 Clocks with laser cooled ions (electrically charged atoms) are good to 1 second in a billion years… … close enough for government work.

36. 36 But where do you keep the coldest gas in the universe? No ordinary container will do. Where do you keep the coldest gas?

37. 37 But where do you keep the coldest gas in the universe? No ordinary container will do. We use a magnetic bottle. Use a magnetic bottle

38. 38 Trapping-levitation

39. 39 #5 atoms-with-music video

40. 40 laser cooled clock performance Using a magnetic bottle as a container for ultra-cold atoms…

41. 41 laser cooled clock performance …and evaporating atoms from the magnetic container, gets to even colder temperatures—less than one billionth of a degree. Einstein drawing by Bülent Atalay Using a magnetic bottle as a container for ultra-cold atoms…

42. 42 10 000 K 100 K 1 K 10 -2 K 10 -4 K 10 -6 K 10 -8 K 10 -10 K 10 -12 K surface of the sun: 5000 K room temperature: 300 K outer space: 3 K liquid nitrogen: 77 K laser cooling: 0.7  K Bose-Einstein Condensation: 1 nK BEC in space (the future):1 pK log thermometer logarithmic thermometer

43. 43 What’s Next? Better clocks Better tests of Einstein’s theories of time and gravity Ultra-cold collisions New kinds of materials Better understanding of superconductivity Quantum computers More...

44. 44 Laser cooling group

45. 45 The End

46. 46 Atoms in a gas are moving really fast, and that makes it hard to measure their ticking. Fast gas atoms make a fast atomic beam. about 200 meters/sec

47. 47 COLD: slow atoms HOT: fast atoms Hot and Cold

48. 48 How do we cool something without touching it? condensation

49. 49 Comet photo courtesy NASA

50. 50 We use the pressure of light to push on atoms and slow them down. Comet photo courtesy NASA