DISCOVERING THE QUANTUM UNIVERSE

Transcription

1 DISCOVERING THE QUANTUM UNIVERSE Jonathan Feng University of California, Irvine Physical Sciences Breakfast Lecture Series Beckman Center of the National Academies 28 November 2006

2 QUANTUM UNIVERSE? Quantum theory governs the very small (atoms). The Universe is very big. What do these have to do with each other? In fact, studies of the very small and the very big have become intimately related, and are the focus of an experimental program whose flagship is the Large Hadron Collider. 28 Nov 06 Feng 2

3 VERY SMALL: STATUS REPORT atom electron nucleus proton neutron up quark down quark meters (thickness of human hair ~ 10-5 m) meters meters < meters 28 Nov 06 Feng 3

4 BASIC BUILDING BLOCKS Atoms Light Frederick Reines 1995 Nobel Prize for the Detection of the Neutrino 28 Nov 06 Feng 4

5 PUZZLES vs. Periodic table is periodic. All atom masses are integral multiples of proton/neutron masses. What about elementary particles? 28 Nov 06 Feng 5

6 ELEMENTARY PARTICLE MASSES Mass proportional to area: ν e ν µ ν τ... e µ τ u d s c b top quark photons gluons W Z Are these made of something else? Are there more quark-, neutrino-,and electron-like particles? 28 Nov 06 Feng 6

7 THE HIGGS BOSON In fact, with only the known particles, the current theory is incomplete: it predicts that all particles are massless and travel at the speed of light. A hypothetical particle, the Higgs boson, beautifully fixes this problem, but we ve yet to find it. electron h? top quark Normal particles bouncing off Higgs particles 28 Nov 06 Feng 7

8 VERY BIG: STATUS REPORT galactic solar system galaxy cluster universe meters meters meters > meters 28 Nov 06 Feng 8

9 COMPOSITION OF THE UNIVERSE 28 Nov 06 Feng 9

10 PUZZLES What is dark matter? It is required to understand why galaxies don t fly apart, but it can t be any of the known particles. vs. h? 28 Nov 06 Feng 10

11 EXTRA DIMENSIONS How many dimensions are there? a) 3 b) 4 c) 10 d) 11 e) none of the above 28 Nov 06 Feng 11

12 Edwin Hubble Hubble (1929): The universe is expanding 28 Nov 06 Feng 12

13 Small Dimensions The universe does not expand into space space itself expands Extrapolating back, space was small the Big Bang Other dimensions could exist but still be small. Some theories even require extra spatial dimensions. For example, string theory requires 6 more. 28 Nov 06 Feng 13

14 E = mc 2 Many of these questions involve hypothetical particles. How can we investigate them? Einstein: E = mc 2. Energy can be transformed into mass. To make new, heavy particles, simply smash together known particles at high energy. 28 Nov 06 Feng 14

15 PARTICLE COLLIDERS E. O. Lawrence s Cyclotron (1930s) Livingston Plot: Moore s Law for Particle Colliders 28 Nov 06 Feng 15

16 Large Hadron Collider 18 miles in circumference Operation begins in Nov 06 Feng 16

17 The Accelerator Two proton beams rotate in opposite directions 100 m underground in Geneva on the French-Swiss border. The beams collide at 4 interaction points, which are surrounded by detectors. 28 Nov 06 Feng 17

18 28 Nov 06 Feng 18

19 LHC Detectors 28 Nov 06 Feng 19

20 UCI Faculty Working on the LHC Theorists Experimentalists Jonathan Feng Arvind Rajaraman Andy Lankford Yuri Shirman Mu-Chun Chen Daniel Whiteson Anyes Taffard 28 Nov 06 Feng 20

21 ATLAS The main UCI experimental responsibilities are in triggering and data acquisition. Data acquisition: the data collected by each detector is 1 Terabyte/second 10,000 Encyclopedia Britannicas/second 10 Libraries of Congress/minute 3 300GB hard drives/second 100 full length DVD movies/second 10,000 times the rate your computer can store data 28 Nov 06 Feng 21

22 ATLAS Triggering: finding needles in haystacks D. Akerib 28 Nov 06 Feng 22

23 LHC AS MICROSCOPE High beam energies short wavelengths. The LHC will provide extremely high resolution to probe substructure. Quark seen by current colliders (low resolution) Quark seen by the LHC (high resolution) 28 Nov 06 Feng 23

24 LHC AS HIGGS HUNTER The LHC will discover the Higgs boson if it s there! 28 Nov 06 Feng 24

25 LHC AS TIME MACHINE The LHC will produce energies last seen 1 picosecond (10-12 s) after the Big Bang, and may produce dark matter particles. LHC Deviation from Observed Dark Matter Density (%) Cosmology (current) Cosmology (~2010) Dark Matter Particle s Mass (GeV) 28 Nov 06 Feng 25

26 LHC SOCIOLOGY In each experiment, ~2000 collaborators from ~40 countries (and growing) The procedure for sharing data and credit is not completely clear and is a topic of heated debate 28 Nov 06 Feng 26

27 ACKNOWLEDGMENTS HEPAP Subpanel colleagues Available at registration desk and at 28 Nov 06 Feng 27