1. PUBLIC UNDERSTANDING OF SCIENCE
W. G. SCOTT
RAL/PPD
24 Jan 2006
PUBLIC UNDERSTANDING OF SCIENCE
PPARC encourages us to spend 1% of our research grant funding on “outreach” activities, promoting understanding, appreciation and awareness of our science to the general public:
Targeting yr olds in schools etc. can help attract more young people into a scientific career. (e.g. RAL MasterClass Mar 2007).
Helps produce highly qualified researchers with advanced skills needed by academia, industry and commerce.
Helps ensure that the UKs front line contribution in this science is recognised by opinion formers, decision-takers/politicians.
Taxpayers can have an appreciation and awareness of the research being funded on their behalf.

2. THE STANDARD MODEL: where:
(schematic)
higgs
kinetic term
fermion
kinetic term
yukawa
term
gauge
“kinetic” term
where:
“higgs potential”
field-strength tensor
“covariant derivative”
vector potential

3. gives masses to the pointlike particles :
THE HIGGS FIELD:
quarks
leptons
W,Z etc.
gives masses to the pointlike particles :
refraction?.

4. …but not to the neutron/proton!
u=“UP” (+2/3)
QUARKS
d=“DOWN” (-1/3)

7. ELECTRO-MAGNETIC INTERACTION
see “QED: the
strange theory of
light and matter”
A FEYNMAN DIAGRAM

9. QUARK CONFINEMENT
The “Strong” Force
Quark
Antiquark

10. “CHROMOSTATICS”

11. “CHROMOSTATICS”
THE “COLOUR” FORCE

12. QCD
quarks
3 colours
gluons
8 colours

14. WEAK INTERACTION u e- W+ d

15. NEUTRAL CURRENTS (1973)

16. ELECTRO-WEAK

17. THE “FORCE” PARTICLES
g1 g2 g3 g4 g5 g6 g7 g8 W- Z0 W+ γ

18. CERN

24. THE “MATTER” PARTICLESQ
-1/3 +2/3

26. ELECTROWEAK TGCs w+ w- z0 e+ e-

27. “The Ambidextrous Universe”
see M. Gardner
“The Ambidextrous Universe”
The Left-Right
Problem

28. WHAT IS THE DIFFERENCE BETWEEN A LEFT AND A RIGHT HABD?
RH IS BIGGER THAN LH ???

29. His right hand IS much bigger!

30. WHAT IS THE DIFFERENCE BETWEEN A LEFT AND A RIGHT HAND?
RH IS BIGGER THAN LH ???.
THUMBS ON OPPOSITE EDGES ?
OR PALMS ON OPPOSITE SIDES ?
LH AND RH ARE
MIRROR REFLECTNS!!

31. WHY DOES A MIRROR REVERSE LEFT AND RIGHT BUT NOT UP AND DOWN?
A CONFUSING QUESTION !!!
SURELY IT REVERSES FRONT AND BACK ?
BUT IT DOES SEEM TO CHANGE RH TO LH!

32. CLOSE TO THE HEART OF THE PROBLEM: How would you communicate left and right over the phone?

33. IT’S A RIGHT-HANDER’S WORLD
SPIRAL STAIRCASE BUILT FOR DEFENDER WIELDING SWORD IN RIGHT HAND
IN THE POPULATION AT LARGE:
APPROX. 90% RIGHT-HANDED
APPROX. 10% LEFT- HANDED
LATIN:
DEXTRA = RIGHT (cf “DEXTROUS”)
SINISTRA = LEFT (cf “SINISTER”)

34. Mirror Twins

35. MORE ABSTRACTLY z z x y y x RIGHT HANDED LEFT HANDED COORDINATE SYSTEM

36. MORE ABSTRACTLY z z x y y x RIGHT HANDED LEFT HANDED COORDINATE SYSTEM

37. A molecule that, like your hands, cannot be made to look like its mirror-image by rotating it or displacing it, is called chiral.
This group of atoms is IN FRONT here, but goes BEHIND in the rotating reflection

38. OPTICAL ACTIVITY OPTICALLY ACTIVE SUBSTANCES ROTATE THE
PLANE OF POLARISATION OF POLARISED LIGHT

39. Double Refraction (in a Calcite Crystal)

40. Louis Pasteur
Pateur felt that handedness could only be distinguished/separated by living things.

41. Names for clockwise and anticlockwise helices:
The DNA structure is a double helix looking something like a twisted ladder.
The two cross-linked helices are always right-handed, twisting in the same direction as a normal screw.
Names for clockwise and anticlockwise helices:
Away from your eye
Away from your eye

42. ALICE WAS RIGHT !!! “Perhaps looking glass milk isn’t good to drink”
- Lewis Carroll, Alice through the looking glass
ALICE WAS RIGHT !!!

43. Fleming’s Left Hand Motor Rule:
NOW FOR SOME A/S PHYSICS
Fleming’s Left Hand Motor Rule:
IS THE PROBLEM SOLVED ?

44. We DO know the direction of the curremt+
The positive terminal is connected to the central carbon rod
The negative terminal is connected to the zinc casing -
Conventional Current flows from positive to negative (opposite to electron flow)

45. But do we REALLY know the Magnetic Field Direction?
Yes, here on Earth
the North Pole
of a magnet
points North!
Problem Solved !?
But you can’t be sure it is the same on another planet?
Even the Earth’s field reverses sometimes

46. left/right convention to an alien living
How would you radio our
left/right convention to an alien living
on a distant galaxy?

47. We could set up our magnetic field using a current?
RIGHT HAND GRIP RULE:
But applying a right hand rule followed by a left hand rule is equivalent to no handed rule at all.
i.e. The wrong hand used for the grip rule followed by the wrong hand used for the motor rule produces the same predicted motion
Magnetic field

48. DEFINING LEFT AND RIGHT ABSOLUTELY WITH
ELECTRO-MAGNETIC FORCES IS IMPOSSIBLE !!
FLEMINGS LEFT-HAND RULE MERELY SWAPS THE LEFT/RIGHT PROBLEM FOR A NORTH/SOUTH PROBLEM WITH MAGNETS !

49. DEFINING LEFT AND RIGHT ASOLUTELY WITH
ELECTRO-MAGNETIC FORCES IS IMPOSSIBLE !!
FLEMINGS LEFT-HAND RULE MERELY SWAPS THE LEFT/RIGHT PROBLEM FOR A NORTH/SOUTH PROBLEM WITH MAGNETS !
MOST PHYSICISTS ASSUMED THAT AN ABSOLUTE DEFINITION OF LEFT AND RIGHT WAS COMPLETELY IMPOSSIBLE !!
BUT IN 1956 THERE WAS THE SHOCKING DISCOVERY OF `PARITY VIOLATION’ BY THE `WEAK FORCE’ IN NUCLEAR BETA DECAY:

50. Beta Decay
neutron

51. Beta Decay
electron
proton
anti-neutrino

52. Feynman diagram for Beta Decay

53. NEUTRONS AND PROTONS IN NUCLEUS
NET ROTATION =
“CURRENT”
NUCLEUS
BEHAVES LIKE
SMALL BAR MAGNET S

54. DISCOVERED Madame Wu “PARITY VIOLATION” Anti-neutrinos Magnetic field
Electrons
Anti-neutrinos
Magnetic field
DISCOVERED
“PARITY VIOLATION”
Madame Wu

55. Cobalt-60 experiment solves the L/R problem!
anti-neutrinos
electrons (e)
Magnetic field
Mirror Experiment
Original Experiment
electrons (e-)
anti-neutrinos
Magnetic field

57. Neutrinos and Anti-neutrinos
The weak interaction is a fundamental source of Left-Right asymmetry in nature

58. Proving a neutrino is left-handed (Goldhaber’s Experiment)
An Eu atom takes in an electron which reacts with a proton to form a neutron.
Both a neutrino and a gamma ray are released.
The “handed-ness” of the gamma ray and the neutrino are the same due to angular momentum because they are emitted in opposite directions.
The photon in the gamma ray emitted was shown to be left-handed (using compton scattering), proving that the neutrino is also left-handed. +
Analyse
polarisation
of photon
in compton
scattering

59. Co-60 expt. doesn’t solve matter vs. anti-matter!
positrons (e+)
neutrinos
Magnetic field
Anti-Mirror Experiment
Original Experiment
electrons (e-)
anti-neutrinos
Magnetic field

60. WHAT IF HE PUTS OUT HIS LEFT HAND ?

61. we measure
CP violation!
Nowadays of course

62. Summary Left & right hands are mirror reflections
Mirrors invert front and back
L/R convention not verbally communicanle
Left and right symmetry nearly perfect but broken by the weak interaction
The Cobalt-60 experiment can distinguish left and right (and so north and south poles)
Neutrinos are left handed and anti-neutrinos are right handed
Aliens made of antimatter will get left and right wrong – so don’t get too close!!!!. z y x