Physicists have developed a new kind of matter which is stable but changes periodically over time. It involves a complex quantum effect and is called a 'time crystal'. According to a
report in Physics.org :
"Time crystals may sound like something from science fiction, having more to do with time travel or Dr. Who. These strange materials—in which atoms and molecules are arranged across space and time—are in fact quite real, and are opening up entirely new ways to think about the nature of matter. They also eventually may help protect information in futuristic devices known as quantum computers."
Sondhi said that the work addresses some of the most fundamental questions about the nature of matter. "It was thought that if a system doesn't settle down and come to equilibrium, you couldn't really say that it is in a phase. It is a big deal when you can give a definition of a phase of matter when the matter is not in equilibrium," he said.
