Heating up?
V. Vemuri, Pleasanton, CA
The other day I received a bowl of chakkera pongali after it was warmed it up in a microwave oven. I placed a spoonful of it in my mouth and promptly jumped out of my seat as it seared my palate. The problem with microwave ovens, I am sure you will agree, is that they are unpredictable. Try warming up a cup of water, you end up proving the adage, "a watched pot never boils."
What is the problem? There is nothing wrong either with us or with the microwaves. The problem is in the items we heat. You see, some things take longer to heat up than others. Why this is so is not really known; even if it is known, it is hard to explain without throwing mouth-twisting words like quantum mechanics or molecular dynamics. The fact of the matter is that the heating speeds of things is entirely arbitrary; there is not much of a rule or rhyme.
Having admitted to that, let me assure you that we do know something though. (1) The more stuff there is, the longer it takes to heat. (2) The higher the specific heat of a substance, the harder it is to heat. The reason it takes so long to heat water is because it has just about the highest specific heat of any substance found on this planet Earth. That is why it takes so long to heat water, be it the water in your cup in the microwave oven, in the pot over the stove, or the water in your pool. It is much easier to heat oil and raise it to a much higher temperature than boiling water. (3) Things that are compact (dense) heat up much faster. No wonder my chakkera pongali got so hot so fast.
Finally, a couple of mystery factors. One mystery surrounds the molecular structure of water. Water molecules are arranged so nicely that they allow microwaves to go right through. That is, the molecules are agitated the least as microwaves go through them. Remember, what we think of as heat is nothing but agitated state of molecules in a substance. It is very much like our anger; when we are angry, we are agitated. The second mystery factor is due to "runaway heating," or "nonlinear effects," as scientists prefer to call it. Simply, this means that some things heat up faster the hotter they get. That is why some plastic containers are not "microwave safe." They "run" into your food if you do not watch out.