HuffPost

“Microwaves use microwave sound energy waves to heat up food or liquids. There has to be something inside the microwave to absorb these waves. Otherwise, the microwave will absorb the waves instead. The waves will heat up the microwave’s cooking chamber, trying to find something to be absorbed by. The waves will eventually reach the microwave’s magnetron, which is the source for the microwaves. The magnetron cannot handle a huge amount of power, so it continues to send it to other parts of the microwave. Running a microwave with nothing in it will damage the magnetron and other parts of the microwave as well. In a worst case scenario, the microwave parts will overheat and possibly catch fire” (Abacus Appliance Service Corporation, “Will I Destroy My Microwave If It Runs Empty?” Aug. 16, 2012, abacusappliance.com; see also Julie R. Thomson, “13 Things You Should Never Put in the Microwave,” June 13, 2014, huffpost.com).