Ch 0 The Scientific framework and Physics The 2 complementary aspects of Physics Theoretical physics Experimental Physics

0.1 The scientific framework & physics Scientific Paradigm Abstract Realm: Theories, Models,… Theoretical Prediction Experimental Test Reality: all phenomena in the Universe Physics: the science of fundamental processes Empirical Science (Based on observation) Fundamental Science Complex systems: Large number of processes involved. Fundamental Systems: Only a few processes at play

Physics: What is is? Theoretical Physics: Mathematical structures (models, laws, theories) represent the workings of the universe Reductionism : theories should strive to represent larger classes of phenomena Experimental Physics: Measurements: Theoretical predictions are tested experimentally: theories are falsifiable and rejected if they don’t pass experimental tests.

Physics: What is is? Standard: Physical (material) representation of a intuitive concept we want to measure. Example: distance: standard is the “ meter” bar with a scratch at either end to indicate the “meter” standard. Example: time: the standard could be a periodic phenomenon like the consecutive passing of the sun at its highest position in the sky; we could then call the time standard “the day” standard. To get consistent measurements, standards must be unique: there can only be 1 standard of time for instance! But standards do evolve: Nowadays the time standard is defined in terms of the extremely consistent vibrations of atoms in what is called an atomic clock. And the distance standard is not defined independently anymore. It is defined in terms of the time standard and the speed of light which is assume to be a constant of nature. Unit: The number associated with the standard. For the meter standard above if we associate the value 1 with it the unit will then be called the “Meter”. If we associate the value 100 with the meter standard, the unit we are using is called the “centimeter”, etc…. If we associate the value 24 with our day standard above, the corresponding unit is called the “hour”.