On Food and Cooking

When thermal energy is exchanged from one
particle to a nearby one by means of a
collision or a movement that induces
movement (for example, through electrical
attraction or repulsion), the process is called
conduction. Though it’s the most
straightforward means of heat transfer in
matter, conduction takes different forms in
different materials. For example, metals are
usually good conductors of heat because,
while their atoms are fixed in a lattice-like
structure, some of their electrons are very
loosely held and tend to form a free-moving
“fluid” or “gas” in the solid that can carry
energy from one region to another. This same
electron mobility makes metals good
electrical conductors. But in nonmetallic
solids like ceramics, conduction is more
mysterious. It seems that heat is propagated
not by the movement of energetic electrons —
in solids of ionic-or covalent-bonded
compounds, the electrons are not free to move