1st

• This two-year course in physics is presented from the point of view that you, the reader, are going to be a physicist
• You will have to go to graduate school too
• It is possible to condense the enormous mass of results to a large extent
• The first three chapters will outline the relation of physics to the rest of the sciences
• The concept of a molecule of a substance is only approximate and exists only for a certain class of substances
• Equilibrium


  The situation in which the rate at which atoms are leaving just matches the rate at which they are coming back
• If there is almost no salt in the water


  More atoms leave than return, and the salt dissolves
• If there are too many “salt atoms”


  More return than leave, and the salt is crystallizing
• The atoms are 1 or 2 ¥ 10–8 cm in radius
• Angstrom


  10–8 cm
• Atoms in an apple are approximately the size of the original apple if the apple is magnified to the size of the earth
• The jiggling motion is what we represent as heat
• If we increase the temperature

  We increase the motion
• When we heat the water, the jiggling increases and the volume between the atoms increases
• When the pull between the molecules is not enough to hold them together


  They fly apart and become separated from one another
• This is how we manufacture steam out of water—by increasing the temperature
• Crystalline array


  An arrangement in which atoms are arranged in some kind of an array
• The position of the atoms on one side of the crystal is determined by that of other atoms millions of atoms away on the other side of the crystal
• Atomic hypothesis


  All things are made of atoms—little particles that move around in perpetual motion
• Atoms attract each other when they are a little distance apart, but repel upon being squeezed into one another
• Everything we know is only some kind of approximation
• The test of all knowledge is experiment
• Experiment is the sole judge of scientific “truth”
• Imagination is needed to create from hints the great generalizations
• There are theoretical physicists who imagine, deduce, and guess at new laws, but do not experiment
• There are experimental physicists who experiment, imagine, deduce, and guess
• The laws of nature are approximate
• We first find the “wrong” laws, and then we find the “right” ones
• Imagination is needed to create great generalizations from hints in physics
• Theoretical physicists


  • Imagine, deduce, and guess at new laws
  • Do not experiment
• Experimental physicists


  • Experiment, imagine, deduce, and guess
• We first find the "wrong" laws and then the "right" ones
• An experiment can be "wrong" if there is something wrong with the apparatus
• Results of an experiment can be wrong by being inaccurate
• Mass


  Constant, independent of speed (approximate law)
• Mass is found to increase with velocity
• A true law states that if an object moves with a speed of less than one hundred miles a second, the mass is constant to within one part in a million
• For ordinary speeds, the constant-mass law is a good approximation
• For high speeds, the constant-mass law is incorrect
• Even a small effect can require profound changes in our ideas