Image via Kenneth Lu on Flickr.
In the past, event cloaking, or the concealing of a moment in time by exploiting the physics of light, has only been achievable through the use of expensive man-made metamaterials. However, mathematician Miguel Lerma has proposed that perhaps the metamaterials are not necessary to achieve this effect. In fact, Lerma himself has devised a way to mimic the phenomenon with a simple set of mirrors.
Event cloaks are also known as space-time cloaks, which sound like they popped out of an episode of Doctor Who. But there is no wibbly-wobbly space-time travel here—just a physical manipulation of light before it hits an observer’s eyes. Their effects are perhaps better explained through example.
“Conceptually, a safecracker can enter a scene, steal the cash, and exit, whilst a surveillance camera records the safe door locked and undisturbed all the time," Lerma writes.
Lerma’s suggested setup involves a light source, a system of eight mirrors, an object to cloak, and, of course, an observer who will be the one witnessing, or rather not witnessing, the event. Four of the mirrors should be mirrors that can move between different states of full transparency, full reflection, and degrees of reflection. These mirrors are critical to the operation of Lerma’s plan.
Using the switchable mirrors, it is possible to deflect the path of the light from source to observer. The mirrors should be arranged in such a way that the first four force the light to take a longer path to the object and the last four force the light to traverse the same elongated distance to the observer. As Lerma notes, “it is possible to make the paths…longer by inserting extra mirrors (and so obtain a larger time gap for the event cloaking effect), but the times taken by the light to go through each of those paths must be identical.”
Right now, Lerma’s ideas are purely theoretical. But as he mentions, the technology isn’t out of reach. The special mirrors required for an event-cloaking project like this can be easily found on Google. For example, a quick search spits out this switchable mirror made by KentOptronics that appears to meet all of Lerma’s criteria.
For a more detailed explanation and diagrams of the mirrors, Lerma's paper is available via arXiv.org. So let’s make it happen folks, but preferably not for any of the obvious sinister reasons.