Enlarge Image Laser-induced switching. Experimental images showing two small domains with magnetic orientation up (white) and down (black). Each laser pulse reverses the direction repeatedly. Credit: Johan Mentink; Richard Evans (inset) An ultrashort heat pulse can predictably flip a bit in a magnetic memory like the one in your hard drive. The surprising effect could ultimately lead to magnetic memories hundreds of times faster and more energy efficient than today's hard drives. It also provides a way to control the direction in which a bit is magnetized without applying something else that has a direction, such as a magnetic...