Robert Kehoe - SMU 2 1.* Introduction 2. The Quantum World 1.* Problems with Light (& Quanta) 2.* Quantum Mechanics (& Quantum Particles) 3.* Atomic Structure (&Nuclei) (S1-12) 3. Within the Nucleus 1.* Sub-nuclear Realm (S19-35) 2.* Particle Spectrum (Elemental Physics) (S57-65) 3.* Fundamental Interactions (& Another Unification) (S44-52,71-76) 4. Relativity 1.* More Problems with Light 2.* Special Relativity 3.* General Relativity 5. Gravity's Domain 1.* Stellar (Evolution &) Collapse 2.* The Cosmos Galactice Observations Big Bang Cosmology Large-scale Structure, CMB, nucleosynthesis 6. Synthesis (The Frontier) 1.* Early Universe (In the Beginning…) Inflation 2.* The Frontier (The Dark) Strings and Extra Dimensions The DarkRobert Kehoe - SMU 5 Microcosmos Quantum Mechanical Phenomena Within the Nucleus Nuclear physics Cosmic rays Particle physics Quarks, neutrinos Superstrings unification Macrocosmos Relativity Special relativity General relativity Gravity’s Domain Black hole formation Big Bang Cosmology Robert Kehoe - SMU 6 The Frontier Superstrings Extra dimensions Dark matter Dark energy What we can see visually is extremely restructed:Robert Kehoe - SMU 7 What is Physics? L1P1 - Human attention to nature’s order - languages form basics (states of matter) - hard:soft, wet:fluid, air:breath - bright:dark – relative presence of radiation - fast:strong – dynamics, motion, force - verb tenses, precedence – notions of time - up, down, right, left - four cardinal points – spatial notions Cultural focus appears to vary: - forces of nature - Zulu (amandala) - Yoruba - call this ‘Interaction’ - structure of time and space - Maya - Lakota - Hopi - call this ‘Dimension’ - building blocks of matter - Greece (atomism) - India (vaisesika atomism) - China - call this ‘Particles’ - the attention to these three primary categories of Nature (Interactions, Dimensions and Particles) is at the heart of the study of Physics Natural Science, or Natural Philosophy L1p2 physiké epistémé: Gr. the knowledge of nature; physis = nature (cognate with L. nasci = to be born, source of word ‘Nature’); phyein = to produce, to bring forth, beget, grow, to plant physis is not about growth of quantity alone - what opened up before them is called ‘physis’, so this means the sky and the earth; stone and plans, animals, people, the work of people and gods. - the universal ‘breeding ground’ Very broad field of thought: it is this broadness that tends to make physics the science exploring underlying mechanisms in Nature - Biophysics, Condensed Matter, Atomic/Molecular/Optical, Astrophysics, Cosmology, Particle Physics... It turns out that there is alot going on in nature that we can’t see, i.e. it has ‘physics’.Robert Kehoe - SMU 8 Where and When is Event? When? (time) • when does an event happen? o does it tend to happen early or late? • when does it occur in relation to other events? o are the events simultaneous? o which one precedes the other? Where? (place) • where does it happen? o 'is it local, or far away? • is what environment does it occur? o is there a lot of other stuff around it? o what kinds of things tend to happen in such an environment?Robert Kehoe - SMU 9 Pre-Classical Thought L1p3 Mathematics Babylonians, base 60 arithmetic gives us our measure of time Greek Geometry - considered a higher math than working with numbers - One axiom: parallel lines never intersect Arab Algebra - the unknown element and its determination - numerical approaches to solving and quantifying - Slopes and curves --> trends, but instantaneous moments difficult Motion and matter Essentially atomistic view: i.e. tiny indestructible particles comprise material with identity Celestial and terrestrial worlds separate Terrestrial phenomena - changeful (weather) - imperfect Celestial phenomena - stars constant motion thru the year - planets and Moon: more erratic but predictable motion - perfect, unchanging - heliocentric and geocentric models of motion - both Greece and India had both views - embedded in mystical or religious beliefs Motion - Apparent stellar and planetary motions, plus falling objects - provide idea of a ‘true point’ to be center of the Earth - Only circular paths (or combinations thereof) are considered - objects fundamentally resist motion - Action of other bodies causes displacementRobert Kehoe - SMU 10 Lecture 2: Classical Picture Galileo – the first Physicist (perhaps the first Scientist) experimental science • must verify ideas with tests by measurement & observation • physical phenomena should adhere to logic of math mathematical science - laws of nature written in language of mathematics swept aside key ideas - natural state not "no motion" - applied action produces change in motion, not just position - geocentrism not correct (phases of Venus) View of Matter • basically atomistic o infinitesimal particles like hard pellets: precise positions & motion Motion velocity is change in position for a given period of time: Δx/Δt - velocity has a magnitude (eg. 60 mph) and a direction (eg. northwest) "change in motion" = change in velocity, v - rate of change of velocity Δv/Δt = a (acceleration) Law of Inertia: any object will remain at rest, or in a constant velocity, unless acted upon Newton's laws of Motion 1) An object will remain at constant velocity unless acted on by a "force" - a force can be applied either directly (e.g. N, collision) or at a distance (e.g. gravity) 2) For every action, there is an equal and opposite reaction 3) F=ma , where "m" is the object mass and "a" is its change in velocity, (its acceleration) - m here is the 'inertial' mass a measure of haw hard it is to move the objectRobert Kehoe - SMU 11 Conservation of Energy & Momentum - Energy of motion (‘kinetic energy’), Ekin = (mv2)/2 - The total energy of a closed system cannot change - momentum, p = mv - The net momentum of a closed system