Einstein's theories of relativity suggest that gravity can cause time to slow down. 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.
The new research builds on recent demonstrations of “invisibility cloaks” that can make objects seem to disappear by bending waves of visible light.
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.
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.
“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.
“In this case, any event that occurs at that instant of time won't lead to scattering of light. It appears as if the event never occurred.”
(Related: “Space-Time Cloak Possible, Could Make Events Disappear?”)
For example, Gaeta said, think of laser beams crisscrossing a museum display to protect priceless works of art.
“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. So if you pass through that beam, an alarm goes off,” he said.
“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. You could pass through, and then [on the other side of the event] 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.
“That would put the beam of light back together, so to speak, so the detector would never recognize that anything had happened.”