Microwave Ovens. What the...

If I knew that running my microwave empty would damage it, could I have saved them?

A few weeks ago my microwave wasn’t heating properly.  I know what you’re thinking, that in itself isn’t that extraordinary.  This is the third microwave from I’ve replaced/repaired in almost as many years.  So the next day, after they have already replaced the magnetron, the microwave started making a funny noise.  I contacted the GE Appliance Service Department (who, by the way, provides EXCELLENT SERVICE) and they scheduled an appointment for the next day. 

The service technician arrived as scheduled and asked, “what was wrong with the microwave?”  I described the rattling sound I hear when running the microwave; and how it was just fixed a few days ago.  He grabbed a measuring cup that was on the counter, filled it with water and walked right up to the unit, turned it on and pressed one of the buttons (which by the way I never-ever noticed before) and the noise stopped.  WTF? Why is it when any service people check something we say is not working, all they have to do is just look at it and VOILÁ it’s working?  The button he pressed was the turn table on/off button.  Apparently, the rollers or the microwave glass had something on it, causing the rattling noise.

Come to think of it, as I read this, It kind of sounds like I may not be the brightest bulb in the kitchen (when it comes to appliance stuff).  Not to prove that last statement as fact (or maybe I just did) I turned on the microwave and hit the button.  The serviceman stopped me dead in my tracks.  He yelled said in a stern voice, “DON’T EVER RUN A MICROWAVE EMPTY!”

Apparently this is not a good thing.  Not that anyone would ever run a microwave empty. Right? Why would you? Anyway, he told me that running a microwave empty damages the unit.  I don’t think a microwave is ever actually empty or maybe I've done it and subsequently have had to repair/replace them.  I mean, isn’t there that glass plate you put your food on?

For better or worse, I decided to do a little research and here is what I've found:

The GE service technician told me never to run the microwave while it’s empty.

Because the electromagnetic fields inside it will build up to extremely high levels. Since the walls of the oven are mirror-like and the plate is almost perfectly transparent to microwaves, the electromagnetic waves streaming out of the oven's magnetron tube bounce around endlessly inside the oven's cooking chamber. The resulting intense fields can produce various types of electric breakdown along the walls of the cooking chamber and thereby damage the surface with burns or arcs. 
Furthermore, the intense microwaves in the cooking chamber will reflect back into the magnetron and can upset its internal oscillations so that it doesn't function properly. Although magnetrons are astonishingly robust and long-lived, they don't appreciate having to reabsorb their own emitted microwaves.

Boiling water in the microwave can be explosive:

When you use a microwave oven to heat water in a glass or glazed container, the water will have difficulty boiling properly. That's because boiling is an accelerated version of evaporation in which water vapor evaporates not only from the water's upper surface, but also through the surface of any water vapor bubbles the water happens to contain.

Below water's boiling temperature, bubbles of water vapor are unstable they are quickly crushed by atmospheric pressure and vanish into the liquid. At or above water's boiling temperature, those water vapor bubbles are finally dense enough to withstand atmospheric pressure and they grow via evaporation, rise to the surface, and pop.

Forming water vapor bubbles in the midst of liquid water, a process called nucleation, is surprisingly difficult and it typically happens at hot spots or non-wetted defects (places where the water doesn't completely coat the surface and there is trapped air). When you boil water in a metal pot on the stove, there are hot spots and defects galore and nucleating the bubbles is not a problem. When you boil water in a glass or glazed container using a microwave oven, however, there are no significant hot spots and few non-wetted defects. The water boils fitfully or not at all. The "not at all" possibility can lead to disaster.

Water that's being heated in a metal pot on the stove boils so vigorously that the stove is unable to heat it more than tiny bit above its boiling temperature. All the heat that's flowing into the water is consumed by the process of transforming liquid water into gaseous water, so the water temperature doesn't rise. Water that's being heated in a glass container in a microwave oven boils so fitfully that you can heat it above its boiling temperature. It's simply not able to use up all the thermal energy it receives via the microwaves and its temperature keeps rising. The water becomes superheated.

Most of the time, there are enough defects around to keep the water boiling a bit and it superheats only a small amount. When you remove the container of water from the microwave oven and toss in some coffee powder or a teabag, thus dragging air bubbles below the surface, the superheated water boils into those air bubbles. A stream of bubbles suddenly appears on the surface of the water. Most people would assume that those bubbles had something to do with the powder or teabag, not with the water itself. Make no mistake, however, the water was responsible and those bubbles are mostly steam, not air.

Occasionally, though, the water fails to boil at all or stops boiling after it manages to wet the last of the defects on the glass or glazed surface. I've made this happen deliberately many times and it's simply not that hard to do. It can easily happen by accident. With no bubbles to assist evaporation, the water's only way to get rid of heat is via evaporation from its top surface. If the microwave oven continues to add thermal energy to the water while it is having such difficulty getting rid of that energy, the water's temperature will skyrocket and it will superheat severely.

Highly superheated water is explosive. If something causes nucleation in that water, a significant fraction of the water will flash to steam in the blink of an eye and blast the remaining liquid water everywhere. That boiling-hot water and steam are a major burn hazard and the blast can break the container or blow it across the room.

Here is a video from Mythbusters proving the point:

How microwaves are killing the foods we eat:
Consumers are dying today in part because they continue to eat dead foods that are killed in the microwave. They take a perfectly healthy piece of raw food, loaded with vitamins and natural medicines, then nuke it in the microwave and destroy most of its nutrition. Humans are the only animals on the planet who destroy the nutritional value of their food before eating it. All other animals consume food in its natural, unprocessed state, but humans actually go out of their way to render food nutritionally worthless before eating it. No wonder humans are the least healthy mammals on the planet.
The invention of the microwave and its mass adoption by the population coincides with the onset of obesity in developed nations around the world. Not only did the microwave make it convenient to eat more obesity-promoting foods, it also destroyed much of the nutritional content of those foods, leaving consumers in an ongoing state of malnourished overfeeding. In other words, people eat too many calories but not enough real nutrition. The result is, of course, what we see today: Epidemic rates of diabetes, cancer, heart disease, depression, kidney failure, liver disorders and much more. These diseases are all caused by a combination of malnutrition and exposure to toxic chemicals (plus other factors such as emotional trauma, lack of exercise, etc.). Microwaves make malnutrition virtually automatic, and being exposed to toxic chemicals is easy to accomplish by simply eating processed foods (which are universally manufactured with the addition of toxic chemicals that act as preservatives, colorings, flavor enhancers and so on).
Microwaving is, technically, a form of food irradiation. I find it interesting that people who say that would never eat "irradiated" food have no hesitation about microwaving their food. It's the same thing (just a different wavelength of radiation). In fact, microwaves were originally called "radar ranges." Sounds strange today, doesn't it? But when microwaves were first introduced in the 1970's, they were proudly advertised as radar ranges. You blast your food with high-intensity radar and it gets hot. This was seen as some sort of space-age miracle in the 1970's. Perhaps someday an inventor will create a food heating device that does not radically alter the nutritional value of the foods in the process, but I'm not holding my breath on this one. Probably the best way to heat foods right now is to simply use a countertop toaster oven, and keep the heat as low as possible.
The microwave does work as advertised, by the way. It makes your food hot. But the mechanism by which heat is produced causes internal damage to the delicate molecular structures of vitamins and phytonutrients. Minerals are largely unaffected, however, so you'll still get the same magnesium, calcium and zinc in microwaved foods as you would in non-microwaved foods, but the all-important B vitamins, anthocyanins, flavonoids and other nutritional elements are easily destroyed by microwave ovens.