What are the dangers of microwaves in the em spectrum?

The answer to this one is Electromagnetic radiation because it is dangerous.

Prolonged exposure to significant levels of microwaves is known to cause "cataracts" in your eyes, which is a clouding of the lens preventing you from seeing clearly. People who work on aircraft carrier decks wear special suits which reflect microwaves, to avoid being "cooked" by the powerful radar units in modern military planes. But that's to guard against powerful radar - not mobile phones or wifi. Some research in the past has indicated that the small doses of microwaves from mobile phones might affect parts of your brain - after all, you're holding the transmitter right by your head. Other research is inconclusive, although there is a feeling that you're more vulnerable if you're young and your brain is still growing.

Hope this answer helps! feel free to ask any additional questions :)

The rocks expand when there hot/warm  and contract when they are cold.