Study co-author Moti Fridman, also of Cornell University's School of Applied and Engineering Physics, devised a method in which he crossed the laser beam aimed at the probe with a strong "pulse" laser inside specialized fiber optic glass.
"It's a way of being able to really control the properties of a light beam in the time domain, and shape and distort and do funny things like this to light in the time domain," Gaeta said. While a conventional optical lens bends a beam of light in space, the time lens modifies the light's temporal-not spatial-distribution. To conduct their time-stopping experiment, described this week in the journal Nature, Gaeta and colleagues aimed a laser beam at a probe and passed the beam through a device called a time lens. "That would put the beam of light back together, so to speak, so the detector would never recognize that anything had happened." You could pass through, and then the device would do the opposite-speed up the part that had been slowed and slow the part that had been sped up," he explained. "But what if a device would perhaps speed up a portion of the beam and slow down another portion of it so that there is an instant of time with no beam. So if you pass through that beam, an alarm goes off," he said. "You have a laser beam and a detector set up to detect when all of a sudden the beam is broken and there is no light. (Related: "Space-Time Cloak Possible, Could Make Events Disappear?")įor example, Gaeta said, think of laser beams crisscrossing a museum display to protect priceless works of art. It appears as if the event never occurred." "In this case, any event that occurs at that instant of time won't lead to scattering of light. "Imagine that you could divert light in time-slow it down, speed it up-so that you create a gap in the light beam in time," said study co-author and Cornell physicist Alex Gaeta. Now Cornell University scientists have used a similar concept to create a hole in time, albeit a very short one: The effect lasts around 40 trillionths of a second. The idea is that, if light moves around an object instead of striking it, that light doesn't get scattered and reflected back to an observer, making the object essentially invisible. The new research builds on recent demonstrations of "invisibility cloaks" that can make objects seem to disappear by bending waves of visible light. Now scientists have demonstrated a way to stop time altogether-or at least, to give the appearance of time stopping by bending light to create a hole in time. Einstein's theories of relativity suggest that gravity can cause time to slow down.