Afternoon InquisitionScience

AI: When in the Warm Embrace of a SpaceTime Cloak

According to Professor Martin McCall of Imperial College London and his team, new materials with the ability to manipulate the speed of light could enable the creation of a “space-time cloak” capable of masking events or even creating an illusion of “Star Trek”-style transportation.

McCall says his work is mathematically quite closely related to the idea of invisibility cloaking or camouflaging with metamaterials that manipulate light, a field that has blossomed since 2006. For McCall, the metamaterials triggered the theoretical idea to manipulate light rays as they enter a material so that some parts speed up and others slow down, which could create “blind spots” in time, masking an event. While the accelerated light arrives at a space before an event has happened, the rest of the light doesn’t reach it until after the event.

The theory (it should be noted this idea is currently only on paper) is expounded in a series of equations and diagrams in the Journal of Optics, published by the Institute of Physics.

So what do you think? What do all you physicists think? What do all you specialists in optics think? What do all you science fiction enthusiasts think? Do you see any flaws in the theory? How would you apply this technology? Do you have an event or events in mind that you would cloak?

The Afternoon Inquisition (or AI) is a question posed to you, the Skepchick community. Look for it to appear Tuesdays, Thursdays, Saturdays, and Sundays at 3pm ET.

Sam Ogden

Sam Ogden is a writer, beach bum, and songwriter living in Houston, Texas, but he may be found scratching himself at many points across the globe. Follow him on Twitter @SamOgden

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  1. The space time cloat name is really misleading. As far as I can tell they are doing little more than placing a screen between an observer and object, then pausing the image for a of time.

    While the engineering involved is impressive, it looks like they worded their stetement to make a big headline splash.

  2. I know some of this is being developed for military applications. However unless the device/cloaking can also alter other wavelengths or energy emissions such as thermal signatures or ultraviolet silhouettes, it’ll be fairly useless unless there’s a limited application of hiding objects from satellite or spy-plane optical cameras. But if the observed image is on a flexible screen and the technology is developed for a lightweight usable device it would be a cool thing for a spy or solder to have folded up in their gear. And when (if) there are aftermarket civilian versions I’ll invest in the company making invisibility cloak counter measures.

  3. I can happily say that I don’t understand what the practical nature of this would be. As a theoretical, sure sounds nifty, but in practice I fail to grasp how that impacts anything. This is probably due to my not having a solid foundation in physics. How significantly would you have to slow down light in order for an event to be hidden? Events are, at least from my systems analysis background, instantaneous, but the things that lead up to an event take time.

    Take for example the idea of masking an assassination. Yes, you could mask the moment the assassination was effective, but how this would mask the events that led to the assassination is beyond me.

    The idea of an area that could cloak from sight is obviously useful both for military and less yucky uses. But to mask an event from time? Yeah, I’m not getting it.

  4. As far as an invisibility cloak: meta-materials only work in narrow wavelengths. The Second Law of Thermodynamics would prevent you from completely containing all wavelengths, as everything with any thermal energy (that is, everything) radiates. Being invisible doesn’t protect you from entropy.

    Regarding a space-time cloak, I do see one subtle issue. In relativity, the behavior of light is synonymous with the curvature of space-time. Other particles follow paths defined by the geodesics of light.

    However, meta-materials will not redirect non-light particles in the same manner. They work via optical tricks. I don’t think light in matter (i.e. optical components) defines space so much as space defines the optics.

  5. @James Fox: From what little I have read on the subject, a cloak for infrared emissions sounds like a real possibility using metamaterials. Reading between the lines, I would guess that there are already projects ongoing in DARPA to accomplish this.

    As far as getting this to work in the optical range, I’m not holding my breath. The patterning requirements are VERY stringent.

  6. @bebop: According to H2G2, they are likely trying to hide women’s clothing… while the women are wearing them.

    “If we can’t manage an Infinite improbability drive, we can always make women’s clothing invisible!”

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