Physicists have long suspected that hunks of metal could vibrate in a peculiar way that would be all but invisible. Now physicists have spotted these “demon modes.”
https://www.wired.com/story/an-invisible-demon-lurks-in-an-odd-superconductor/?utm_source=dlvr.it&utm_medium=blogger
https://www.wired.com/story/an-invisible-demon-lurks-in-an-odd-superconductor/?utm_source=dlvr.it&utm_medium=blogger