2. The must fundamental constituents of matter Physics 100 Chapt 26

3. Anaximenes Anaximenes ~600BC All types of matter are formed from different combinations of: Earth Air Fire Water

4. Closer to home Earth Wind Fire Water Elements

5. Anaximenes idea Good point: Economical –All of matter reduced to 4 easy-to-remember components Bad point: Wrong –Alchemists (including Isaac Newton) tried for centuries to changing one chemical element into another with no success

6. Enter Mendeleev All matter is comprised of different combinations of (now 92) different chemical elements Good point Correct; successfully predicted the existence of Scandium, Gallium & Germanium Bad point Uneconomical; 92 basic constituens

7. Rutherford All elements are constructed from 3 basic particles: electrons neutrons protons Feel the strong force & are heavy  hadrons Doesn’t feel the strong force & is light  lepton

8. The “elementary particles” circa 1935 Categoryparticlesymbolchargemc 2 strongelectricweak Leptons electron e-e- 0.511 MeV noyes neutrino 0~0no yes Hadrons proton p+1 938.3 MeV yes neutron n0 939.6 MeV yes Light photon  00noyesno Economy is restored Forces felt

9. These “good” times didn’t last long

11. Paul Adrien Maurice Dirac 1902 - 1984 Combined relativity & Quantum Mechanics

12. p = mV x p x = mV x E = 1/2 mv 2 p y = mV y y Pre relativity p x can be + or - E is always +

13. p = mV x p x = mV x E = mc 2 2 2 () ± p y = mV y y p x can be + or - E also can be + or - Post relativity:

14. QM waves: =h/p f=E/h Pre relativity: p = m 0 v (v =p/m 0 ) E = 1/2 m 0 v 2 =p 2 / 2 m 0 = h/p  can be + or  f=p 2 / 2 m 0 h  always +

15. QM waves: =h/p f=E/h after relativity: p =  m 0 v (v =p/m 0 ) E 2 = (mc 2 ) 2  E= ± mc 2 = h/p  can be + or  f=  can be + or   mc 2 h

16. Negative wavelength : wave in backward direction. Negative frequency : wave backward in time????

17. What does it mean to move backwards in time?

18. backward time motion          t B when viewed forward in time:  LR : C : P

19. When antimatter comes in contact with matter, what happens?

20. -+- + - +    

21. Anti-hydrogen p + Anti-hydrogen atoms are made routinely at the CERN laboratory in Switzerland. It is found to have the same size and allowed energy levels as ordinary hydrogen

22. Anti-Carbon + + + + + + antielectrons antineutrons antiprotons Although it would be impossibly difficult to make anti-atoms more complex than anti- hydrogen, it is in principle possible

23. CP Violation: Asymmetry matter anti- matter Big Bang matter- antimatter symmetric all matter no antimatter

24. Our research Where did all the anti-people go???

25. Include anti-particles in our list Categoryparticlesymbolchargemc 2 symbolcharge Leptons electron e-e- 0.511 MeV positron e+e+ +1 neutrino 0~0 anti- neutrino 0 Hadrons proton p+1 938.3 MeV anti- proton p neutron n0 939.6 MeV anti- neutron n0 Light photon  00  0 anti-particle particle

26. Quantum Electro-Dynamics (QED) Combined Relativity, Quantum Mechanics and Photons into one single theory Richard FeynmanJulian Schwinger Shinichiro Tomonaga

27. QED explains action-at-a-distance

28. QED is a fabulously accurate theory QED theory measure Strength of electrons magnetic field:

29. Ideas of QED  strong nuclear force Hideki Yukawa  Short range (10 -15 m) of the strong nuclear force: predicts existence of a “  ” particle  M  c 2  140 MeV 1935

30. Look for  in cosmic rays

31. “Spark chamber” tracks

32.  + and  – particle discovered in cosmic rays m  + c 2 = m  - c 2 = 106 MeV Near expectations for Yukawa’s  Experiments show that the  + &  - do not feel the Strong Nuclear Force and, therefore, cannot be Yukawa’s  the  + &  - are additional leptons (i.e. like the e + & e - but with larger mass)

33. Yukawa’s  finally discovered in 1947 In fact there are 3 of them:  +  M  + c 2 = 139.6 MeV  0  M  0 c 2 = 135.0 MeV  -  M  - c 2 = 139.6 MeV Anti- particles Photographic emulsion

34. “Atom smashers”

35. Inside the accelerator tunnel

36. e + e - collider

37. Belle Detector

38. Electronic detectors

39. Fermilab (near Chicago) 2 km detector

40. Inside a Fermilab Tunnel

41. Biggest of all is in Europe ~5 miles

42. Detectors

43. Neutrino interacts in a Bubble Chamber

44. Leptons (circa 2005) anti-particle particle namesymbolchargemc 2 namesymbolcharge electron ee 0.511 MeV positron ee +1 electron neutrino e 0~0 anti-elec neutrino e 0 muon  +1 105.7 MeV anti- muon  +1 muon- neutrino  0~0 anti-mu neutrino  0 tau  1876 MeV anti- tau  +1 tau- neutrino  0~0 anti-tau neutrino  0

45. 1950’s & 1960’s, Many other particles are discovered   p  - M=1116MeV

46. K 0 “meson”      K 0     - M=498 MeV

47. Two classes of hadrons Baryons (p, n, , …..) ultimate decay products include a proton Mesons ( , K, …) ultimate decay products e’s,  ’s & ’s Both baryons & mesons feel the Strong Nuclear Force

48. Lots of baryons have been discovered

49. & even more mesons

51. The elementary particle chart revisited Economy is lost!! 6 leptons: e e ;   ;   (+ 6 anti-leptons) Categoryparticlesymbol Leptons electron e-e- neutrino Hadrons proton p neutron n 1935 NOW hundreds of hadrons + anti-hadrons

52. Elementary Particle Zoo Lepton House Electrons, Muons, Taus, & lots of neutrinos Hadron Savannah 100’s of Baryons, Latest new Mesons +anti particles galore & lots of photons Special today: live pions being exhanged proton neutron