People always tell me that microwave ovens heat food by exciting the water molecules in food. This is done by blasting food with 2.4 Ghz radiation, the people that say this, also say that the frequency that is used is critical because that frequency interacts with the water molecules. I wonder why then we use that frequency for wireless communications, for instance wifi. If it heats our tissues. My major question is how does a visible light laser heat tissue if it uses a very different frequency? Also, can exposure to non ionizing radiation cause a atoms electron to be dislodged making the atom a ion, leading to cancer?