Cindy Wilks, age 11, of Horsham, Pennsylvania, for her question:

What exactly are microwaves?

For years we have been using microwaves in radar, to carry TV and to perform dozens of other useful duties. But recently they have stirred up quite a controversy in the news. We are warned to sit six feet or more from our TV sets because the microwaves that bring their programs could emit hazardous radiation at close range. This warning alerted the world of science. Right now, research teams are pinpointing, the possible dangers and seeking ways to make the useful energy of microwaves safe for people and all other earthlings.

Microwaves are related to light and to radio. All these and other radiant energies are arranged on the electromagnetic spectrum, according to the lengths of their pulsing waves. All of them travel through space in straight lines at 186,000 miles per second. They behave differently because of their various wave lengths and pulsing frequencies per second. The wave lengths of white light are visible as the rainbow colors of the spectrum. We can make the silent, invisible waves of radio carry signals and then translate them into audible sounds.

The longest waves of visible light reveal red rays. Just beyond this range on the electromagnetic spectrum are the slightly longer infrared wave lengths. Radio waves are longer and still longer. The microwaves are tucked between the longest infrared waves and the shortest radio waves. The band of their pulsing frequencies is between 300 million and 300,000 million cycles per second.

Microwaves borrow some features from light and some features from radio. Like beams of light, they can be focused and reflected and most of them are stopped by solid substances. They also.can be generated and used like radio beams. However, their shorter waves make it possible for them to carry more signals. Nowadays, about 90 per cent of our broadcasting is done by microwaves. They also carry most of our long distance telephone conversations and all our satellite communications. They power our radar systems and run our giant radio telescopes.

Their particular wave lengths agitate molecules and generate heat. For this reason, new inventions have put microwaves to work in industry. They are used to dry plastics, textiles and lumber, and even in kilns to bake ceramics. Their heat producing quality led to the microwave ovens now used in homes and restaurants. In hospitals, the diathermy machine is used to generate deep heat inside the human body. Some experts dream that microwaves may be used to transmit electric power and perhaps even harness the radiant energy we get from the sun.

But these future possibilities must wait while serious minded scientists explore the possible dangers in these dynamic microwaves. It stands to reason that energy that can cook also can harm living tissues. We know that they can be dangerous. But at present we are not certain of the possible hazards. Until we know for sure, naturally the sensible decision is to proceed with caution.