Quarks and the Cosmos

Transcription

1 Quarks and the Cosmos A lecture to the President s Council Purdue University Ian Shipsey(*) (*) one of 15 astrophysicists & particle physicists at Purdue University 1

2 Unfinished business from the 20 th Century 2

3 Quarks and the Cosmos Inner Space / Outer Space 3

4 Inner Space: Atoms 4

5 Inner Space: quarks & electrons 5

6 The size of atoms, quarks and electrons Atomic Nucleus 0.1 nanometer = meter Most of an atom is empty space = 1 atomic radius 100,000 = one millionth of a nanometer electron 1 < radius of nucleus = one billionth of a nanometer Quarks are similar in size to electrons 6

7 Question for the class Proton electric charge = +1 Neutron electric charge = 0 u d d d u u What are the charges of up and down quarks? up = +2/3 down = +1/3 up = +2/3 down = -1/3 7

8 Inner space: The four forces (Nobel prize 2004) Lets quarks change identity (d u) 8

9 The periodic table of the elementary particles anti-matter (antiparticles for each quark & lepton) 9

10 Patterns (symmetry) predict missing particles Missing particle the 6 th quark Top quark found in 1995 More missing particles: Graviton Higgs SUSY 10

11 Unification of the Forces Electricity Magnetism Electromagnetism Weak Electromagnetism Weak Strong Electromagnetism 1864 Requires photon Electroweak Requires Higgs Grand unified force? 11

12 Grand Unified Force Reqiures SUSY Supersymmetry=SUSY SUSY normal+ SUSY Decay chain ends in lightest SUSY particle which is stable 12

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16 SUSY particles are a leading candidate for dark matter 16

17 Expansion of the Universe Distance Velocity 17

18 Expansion of the Universe 18

19 Question for the class Distance B A Graph shows distance compared to velocity for dots on a rubber band. The white solid line is from two slides ago. What do lines A and B correspond to? B faster stretching A slower stretching Velocity B slower stretching A faster stretching 19

20 What would a change in the expansion rate look like? Distance Slower stretching Faster stretching Distance Accelerating expansion Long ago Constant expansion Decelerating expansion Now Velocity Amount of Stretch 20

21 Expansion of the Universe is accelerating Low Relative Intensity of Light Accelerating expansion Decelerating expansion Far Relative Distance 1 High Discovery of the year Amount of stretch Redshift (z) Near Confirmation & refinements Major new satellite JDEM planned 21

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23 Quantum Uncertainity & empty space Particle Antiparticle Disappearance TIME Appearance SPACE Nothing is something! 23

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26 Galaxies born 26

27 Primordial Soup 27

28 Particle Physics 28

29 INNER SPACE- THE QUANTUM * * * * * * * * * * * * * * * * * * * * * * * * * * * * * PARTICLE ACCELERATOR =TIME MACHINE= TELESCOPE 29

30 2 Energy of the beams new particles of the primordial soup 30

31 LHC:27 km (18 mile circumference, 100 m underground) 31

32 Primordial Soup seconds AB 3,000,000,000,000,000 CONDENSED Particle Physics in 50 Earth masses in matter one 50 Earth masses in antimatter can + extra mountain of matter HOT per 10 billion years of total serving energy output of the sun INGREDIENTS In every spoonful every type of elementary particle 32

33 Primordial Soup KNOWN INGREDIENTS: 56% QUARKS 16% GLUONS Particle Physics 16% ELECTRON-LIKE PARTICLES 9% W s AND Z s 5% NEUTRINOS 2% PHOTONS PROBABLE INGREDIENTS: 2% GRAVITONS 1% HIGGS SECRET INGREDIENTS: DARK MATTER DARK ENERGY, EXTRA DIMENSIONS 33

34 How do we see the soup particles? The Eyes of a Insect: 1 billion collisions/second 1,000 particles every 25 nanoseconds Need highly granular detectors that take pictures quickly, and can manipulate the resulting data on board and store it before shipping to a farm of CPUs 34

35 The Eyes of a Piece of Silicon: The length of each side of the square is about the thickness of a piece of paper. Each eye is called a pixel 35

36 The largest Silicon camera ever built at a University was built at Purdue in We are building a more advanced version of this detector for the LHC 36

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39 CMS at LHC 36 Nations 159 Institutions 1940 scientists (including 7 Purdue Professors) 16m 21 m 39

40 Discovery of the Higgs or SUSY or... in 2008? 40

41 Summary The LHC is under construction and will take data in 2008 Many other particle physics and astronomy scientific instruments on Earth, deep below ground and in outer space are coming online soon Particle physicists & astrophysicists are poised to taste the primordial soup, to answer some of the great questions of the 21 st Century What is dark matter? What is dark energy? Is there only one force? Our notion of space and time may be radically altered. We may understand how the universe was born and how it will end Reading assignment: Scientific American September 2004 issue Many research opportunities for undergraduates: Learn more about our exciting research programs at: 41

42 Acknowledgements This talk has drawn heavily on images obtained from CERN, NASA and Scientific American, and excellent talks given by Rocky Kolb, Lawrence Krauss, Gerard `t Hooft, Michael Turner and Jim Virdee. Original artwork was prepared by Steven Lichti (Purdue). Daniela Bortoletto and Francesca Shipsey are thanked for their love and support. 42