Why does cheese melt?
The melting properties of cheese is an entire branch of food science! Found this great answer to your question:When you melt cheese, you're essentially softening the milk proteins and fats to varying degrees of pliability and usability. When a cheese is heated, the protein matrix -- which trapped the fats and proteins in milk and helped form solid curd when the cheese was made -- collapses, encouraging the flow of cheese into a more liquid form. http://www.thekitchn.com/thekitchn/the-cheesemonger/cheese-on-melting-the-cheesemonger-088264
Lots of things melt when heat is applied. Water is melted ice. Metals melt, although at much higher temperatures. Nitrogen is in a melted form at well below zero.
everything melts when it is heated up, the reason cheese melts is because it was originally a liquid state and was made to a semi solid state so there for when introduced to heat it melts