Cloaking Device Hides Events in Space-Time Wrinkles
Cloaking devices are a staple of science fiction. Bend light around an object in just the right way and it will appear to blink out of existence, swallowed into a dark gullet of space. However, there are many ways to hide something, and a bending light is just one of them. Researchers are proposing a similar way to pinch open the fabric of space-time and edit out entire events before the light reaches its audience.
Like editing a movie, this new technology could snip events out of time by bending reality around the events, according to a new paper by optical physicists Martin McCall and Paul Kinsler. In contrast to cloaking that bends light , all of the light headed toward an object actually hits its target in McCall's theory.
"The light in our case doesn't bend in space at all. It travels in a straight line," McCall told InnovationNewsDaily.
In essence, it travels like cars on a highway. The spacing between the cars depends on how they move relative to one another, explained McCall. If a heavy rain suddenly begins to beat down on a section of traffic, the cars will lose pace with those ahead and a gap will open between them.
This is what McCall proposes doing with light. By speeding up the photons in front and slowing down the ones behind, a dark space opens up.
"Once that dark region has occurred, you have to undo the process of creating the gap," McCall said.
Reversing the process would bring the light back into formation and stitch the gap. However, anything that happened in the dark would stay off the record.
If scientists could do all of this before a beam of light reached a detector or a human eye, then an edited image would seem completely continuous. A magician could use the gap in light to shuffle an assistant off stage. To the audience, it would seem as though someone had simply disappeared.
But, in reality, very little action can be squished into the light traveling between a stage and an audience.
"The real problem is the speed of light," McCall said. "You would only be able to cloak a few nanoseconds."
Humans perceive the world on a much larger time scale. But computers collect information in mere fractions of a second, and there are scenarios where it could be useful to trick them. McCall argues that space-time cloaks could be used to smooth out some of the problems with dual processing in quantum computers.
"The idea seems to be that, by controlling the speed of light, you could force, say, several photons to arrive at a beam splitter or other optical element at the same time. That would indeed be very useful for quantum computing, if you could do it," said Scott Aaronson, an associate professor of computer science at MIT.
Even that kind of magic has a physical limit. Before physicists begin tucking events into the dimples of space-time, engineers will have to invent materials that perfectly control the speed of light as it travels through. Only then will scientists find out whether these illusions are really possible.