1. The Quark Theory of Matter Developed in early 1960s to help explain a proliferation of mysterious subatomic particles found in “atom smashers” [particle accelerators] Further developed up to present day Proton and neutron are no longer “fundamental” particles They are composed of quarks “Free” quarks are not stable, they quickly recombine Quarks are bound together by “gluons”

2. Size Scales – a Comparison Virus10 -7 m Molecule10 -9 m Atom10 -10 m Nucleus10 -14 m Proton10 -15 m Electron10 -18 m Quark10 -19 m

4. The Quarks NameCharge Up (u)+2/3 Down(d)-1/3 Charm (c)+2/3 Strange (s)-1/3 Top(t)+2/3 Bottom(b)-1/3

5. u d uu d d Proton Neutron Some particles are composed of 3 quarks (above) Some particles (mesons, found in cosmic rays) are made of 2 quarks No single quarks are observed in nature

8. What we don’t know …. Why quarks can have “fractional” charge when the electron (still thought to be “fundamental” has a charge of -1 ? Whether any of the exotic particles we know about now can account for “dark matter” that we believe is in most galaxies Whether there really is a graviton … How to reconcile gravity and quantum/subatomic physics and lots more besides …stay tuned ….