The story of the Universe

Transcription

1 The story of the Universe From the Bi Ban to today's Universe Quantum ravity era Grand unification era Electroweak era Protons and neutrons form Nuclei are formed Atoms and liht era Galaxy formation Today The size of thins Particle Physics The story of the Universe 5

2 Quantum ravity era s Gravity separates as a force, the other forces remain as one (Grand Unification)? t < s : The Bi Ban The universe is considered to have expanded from a sinle point with an infinitely hih enery density (infinite temperature). Is there a meanin to the question what existed before the bi ban? t s, K (10 19 GeV, m) : Gravity freezes out All particle types (quarks, leptons, aue bosons, and undiscovered particles e..his, sparticles, ravitons) and their anti-particles are in a thermal equilibrium (bein created and annihilated at equal rate). These coexist with photons (radiation). Throuh a phase transition ravity "froze" out and became distinct in its action from the weak, electromanetic and stron forces. The other three forces could not be distinuished from one another in their action on quarks and leptons. This is the first instance of the breakin of symmetry amonst the forces. The story of the Universe 6

3 Grand unification era s Inflation ceases, expansion continues Grand Unification breaks. Stron and electroweak forces become distinuishable t s, K (10 16 GeV, m) : Inflation The rate of expansion increases exponentially for a short period. The universe doubled in size every s. Inflation stopped at around s. The universe increased in size by a factor of This is equivalent to an object the size of a proton swellin to liht years across. The whole universe is estimated to have had a size of ~10 23 m at the end of the period of inflation. However the presently visible universe was only 3 m in size after inflation. This solves the problems of horizon (how is it possible for two opposin parts of the present universe to be at the same temperature when they cannot have interacted with each other before recombination) and flatness (density of matter is close to the critical density). t s : Stron forces freezes out Throuh another phase transition the stron force "freezes" out and a sliht excess of matter over anti-matter develops. This excess, at a level of 1 part in a billion, is sufficient to ive the presently observed predominance of matter over anti-matter. The temperature is too hih for quarks to remain clumped to form neutrons or protons and so exist in the form of a quark luon plasma. The LHC can study this by collidin toether hih enery nuclei. The story of the Universe 7

4 Electroweak era s Electroweak force splits t s, K (100 GeV, m) : Electromanetic and Weak Forces separate The enery density corresponds to that at LEP. As the temperature fell the weak force "freezes" out and all four forces become distinct in their actions. The antiquarks annihilate with the quarks leavin a residual excess of matter. W and Z bosons decay. In eneral unstable massive particles disappear when the temperture falls to a value at which photons from the black-body radiation do not have sufficient enery to create a particle-antiparticle pair. The story of the Universe 8

5 Protons and neutrons form 10-4 s Quarks combine to make protons and neutrons t 10-4 s, K (1 GeV, m) : Protons and Neutrons form The universe has rown to the size of our solar system. As the temperature drops quark-antiquark annihilation stops and the remainin quarks combine to make protons and neutrons. t = 1 s, K (1 MeV, m) : Neutrinos decouple The neutrinos become inactive (essentially do not participate further in interactions). The electrons and positrons annihilate and are not recreated. An excess of electrons is left. The neutron-proton ratio shifts from 50:50 to 25:75. The story of the Universe 9

6 Nuclei are formed 100 s Protons and neutrons combine to form helium nuclei t = 3 minutes, 10 9 K (0.1 MeV, m) : Nuclei are formed The temperature is low enouh to allow nuclei to be formed. Conditions are similar to those that exist in stars today or in thermonuclear bombs. Heavier nuclei such as deuterium, helium and lithium soak up the neutrons that are present. Any remainin neutrons decay with a time constant of ~ 1000 seconds. The neutron-proton ratio is now 13:87. The bulk constitution of the universe is now in place consistin essentially of protons (75%) and helium nuclei. The temperature is still too hih to form any atoms and electrons form a as of free particles. The story of the Universe 10

7 Atoms and liht era years The Universe becomes transparent and fills with liht t = years, 6000 K (0.5 ev, m) : Atoms are created Electrons bein to stick to nuclei. Atoms of hydroen, helium and lithium are created. Radiation is no loner eneretic enouh to break atoms. The universe becomes transparent. Matter density dominates. Astronomy can study the evolution of the Universe back to this time. The story of the Universe 11

8 Galaxy formation 1000 million years Galaxies bein to form t = 10 9 years, 18 K : Galaxy Formation Local mass density fluctuations act as seeds for stellar and alaxy formation. The exact mechanism is still not understood. Nucleosynthesis, synthesis of heavier nuclei such as carbon up to iron, starts occurrin in the thermonuclear reactors that are stars. Even heavier elements are synthesized and dispersed in the brief moment durin which stellar collapse and supernovae explosions occur. The story of the Universe 12

9 Today million years Man beins to wonder where it all came from t = 15 x 10 9 years, 3 K : Humans The present day. Chemical processes have linked atoms to form molecules. From the dust of stars and throuh coded messaes (DNA) humans emere to observe the universe around them. The story of the Universe 13

10 The size of thins Bi Ban Instruments at Accelerators LHC LEP (Particle beams) Electron Microscope Microscope Observables SUSY particle? His? (rane of Z/W weak force) (rane of Proton nuclear force) Nuclei Atom Virus Cell 1m Telescope Radio Telescope Earth radius Earth to Sun Galaxies Radius of observable Universe Universe Particles and forces 14

11 Particle Physics Aim to answer the two followin questions - What are the elementary constituents of matter? - What are the fundamental forces that control their behavior at the most basic level? The story of the Universe 15

12 Particles and forces Particles Forces Interactions: couplin of forces to matter Short history and new frontiers Unification of forces Summary Particles and forces 17

13 Tau Electric Chare -1 Particles Leptons Tau Neutrino Electric Chare 0 Muon -1 Muon Neutrino 0 Electron -1 Electron Neutrino 0 Bottom Electric Chare -1/3 Quarks Top Electric Chare 2/3 Strane -1/3 Charm 2/3 Down -1/3 Up 2/3 each quark: R, B, G 3 colors The particle drawins are simple artistic representations Particles and forces 18

14 Forces Stron Electromanetic Gluons (8) Photon Quarks Mesons Baryons Nuclei Atoms Liht Chemistry Electronics Graviton? Gravitational Bosons (W,Z) Weak Solar system Galaxies Black holes Neutron decay Beta radioactivity Neutrino interactions Burnin of the sun The particle drawins are simple artistic representations Particles and forces 19

15 Interactions: couplin of forces to matter Electroweak Electromanetic e + γ q u Chared Weak e - e + Neutral e + e - q d W ν e e - Z o e - e + e + e - ν e e + e+ γ W Z o e - e - u d e - e - Rane, relative strenth 10-2 Rane ~10-18 m, relative strenth q Stron q' q q' q q q' q' Rane ~ m, relative strenth = 1 Particles and forces 20

16 Short history and new frontiers λ = h / p T t -1/ m 10 ev > Y Quantum Mechanics Atomic Physics γ e + e - γ Quantum Electro Dynamics m MeV - GeV 3 min Nuclei, Hadrons Symmetries Field theories m >> GeV 10-6 sec Quarks Gaue theories u Z e + u 6 Leptons 6 Quarks ν e ν µ e µ u d e - c s ν τ τ t b 3 "Colors" each quark R G B SPS, pp m 100 GeV sec ElectroWeak Unification, QCD LEP families Tevatron 1994 Top quark Oriin of masses The next step m 10 3 GeV sec LHC 2005 His? Supersymmetry? Proton Decay? The Oriin of the Universe m GeV sec m GeV (Planck scale) sec Underround Labs GRAND Unified Theories??? Quantum Gravity? Superstrins? Particles and forces 21

17 Unification of forces Terrestrial mechanics Celestial mechanics Universal Gravitation Inertial vs. Gravitational mass (I. Newton, 1687 ) + Electricity Electromanetism N S Manetism Electromanetic waves (photon) (J.C. Maxwell, 1860 ) γ γ Electromanetism ν e n e - p Weak force Electroweak Intermediate bosons W, Z ( )? Probin shorter distances reveals deeper reularities UNIFIED DESCRIPTIONS Particles and forces 22

18 Summary sec sec sec 10-4 sec 100 sec years m m m m m m GeV GeV 10 2 GeV 1 GeV 1 Mev 10 ev Manetism Quantum Gravity? Super Unification Grand Unification Electroweak Model SUSY? Standard model QCD QED Electro manetism Maxwell Weak Theory Universal Gravitation Einstein, Newton Lon rane Electricity Fermi Weak Force Short rane Nuclear Force Kepler Galilei Short rane Celestial Gravity Lon rane Terrestrial Gravity Theories: STRINGS? RELATIVISTIC/QUANTUM CLASSICAL Particles and forces 23