Chapter 1 is meant as a review, for the most part. Indeed, if you have taken a good general physics course, then much of chapters 2 and 3 will be review also. Thermal physics has some subtle aspects, however, so it is best that we recapitulate basic ideas, definitions, and relationships. We begin in section 1.1 with the ideas of heating something and of temperature.

Heating and temperature

Suppose you want to fry two eggs, sunny-side up. You turn on the electric range and put the copper-bottomed frying pan on the metal coil, which soon glows an orangish red. The eggs begin to sizzle. From a physicist's point of view, energy is being transferred by conduction from the red-hot coil through the copper-bottomed pan and into the eggs. In a microscopic description of the process, one would say that, at the surface of contact between iron coil and copper pan, the intense jiggling of the iron atoms causes the adjacent copper atoms to vibrate more rapidly about their equilibrium sites and to pass such an increase in microscopic kinetic energy along through the thickness of the pan and finally into the eggs.

Meanwhile, your English muffin is in the toaster oven. Near the oven's roof, two metal rods glow red-hot, but there is no direct contact between them and the muffin. Rather, the hot metal radiates electromagnetic waves (of a wide spectrum of frequencies but primarily in the infrared region); those waves travel 10 centimeters through air to the muffin; and the muffin absorbs the electromagnetic waves and acquires their energy. The muffin is being heated by radiation.