Update: Time cloaking is real and it's pretty wicked

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Update: Time cloaking is real and it’s pretty wicked

Last week, there was an article on IHC from November of last year on how temporal cloaking was very possible and recently, a team at Cornell university actually fucking did it— they created a temporal cloak and a hole in time itself. Fuck.

Time cloaking is possible because of a kind of duality between space and time in electromagnetic theory. In particular, the diffraction of a beam of light in space is mathematically equivalent to the temporal propagation of light through a dispersive medium. In other words, diffraction and dispersion are symmetric in spacetime. That immediately leads to an interesting idea.

Just as its easy to make a lens that focuses light in space using diffraction, so it is possible to use dispersion to make a lens that focuses in time. Such a time-lens can be made using an electro-optic modulator, for example, and has a variety of familiar properties. “This time-lens can, for example, magnify or compress in time,” say Fridman and co.

This magnifying and compressing in time is important. The trick to building a temporal cloak is to place two time-lenses in series and then send a beam of light through them. The first compresses the light in time while the second decompresses it again. But this leaves a gap. For short period, there is a kind of hole in time in which any event is unrecorded. So to an observer, the light coming out of the second time-lens appears undistorted, as if no event has occurred. In effect, the space between the two lenses is a kind of spatio-temporal cloak that deletes changes that occur in short periods of time.

The device has some limitations. The Cornell time cloak lasts only for 110 nanoseconds—that’s not long. And Fridman and co say the best it can achieve will be 120 microseconds.

But this crazy technology is in its infancy, so it’s possible to create longer and larger time distortions. That would be just fucking fantastic. Imagine a future where a short war could be hidden in a time bubble and there’s no way for anyone outside to know that it happened.