Physicists Create a Hole In Time to Hide Events

[MJ12]

Researchers at Cornell University have made an astounding leap forward in cloaking technology. While other teams have been working on what have been traditionally seen as “invisibility cloaks” – using meta-materials to hide an object from visible light — this team has been working on something a bit more ambitious: hiding an actual event in time.

Current work in developing invisibility cloaks tries to hide an object spatially. Like a magician using a complex set of mirrors to hide his tricks, a invisibility cloak uses materials that change the shape of light so that it moves around an object, hiding it from view. What the researchers at Cornell are doing is similar: they’re taking advantage of the fact that, according to current theories in physics, time and space are equivalent – and instead of focusing on changing the shape of light, they’re focused on changing its time.

The researchers began their experiment by creating two time lenses. Unlike a normal lens, which compresses or changes the actual shape of a light wave through diffraction, a time lens magnifies or compresses the time of a light wave through dispersion.

The time lenses that were created for this experiment were split time lenses. Essentially, two halves of a lens were placed so that the points met in the middle. There was one split time lens on one side of the cloaked event and another split time lens on the other side. A laser was then passed through the first time lens. This dispersed the light around the events happening between the lenses. The light then passed through the second split time lens and returned to its original phase. So to an observer, it’s as though the events between the lenses never happened. (See the figure above for a visual about how this works.)

Now, this “hole in time” was only created for the briefest of instants – about 110 nanoseconds. And the research indicates that the maximum amount of time an event could be hidden is also small – perhaps no longer than 120 microseconds. Still, this is a pretty fascinating breakthrough, and it’d be interesting to see if this could be combined with a spatial cloak in a practical way.

Follow me on Twitter or Facebook. Read my Forbes blog here.

http://www.forbes.com/sites/alexknapp/2011/07/18/physicists-create-a-hole-in-time-to-hide-events/

 

[DEATHMASTER]

time lens

What.

110 nanoseconds

**** it.

 

[Remus]

What.

A special lens that slows down any light that passes through it, I think.

 

[Krynn72]

So in the future, cloaking devices will just be like playing on server with a high ping?

 

[MFL]

****ing timespikes. IRL latency sucks.

 

[Raziaar]

You can get away with murder as long as you get it done in 120 microseconds!

All this is really above my level of understanding. I don't understand what they're talking about changing the shape of light and thus are hiding time.

If I'm in a completely light-less environment I'm still part of time!

I hate being so dumb.

 

[Stylo]

This doesn't seem very practical at all for sneaking into women's changing rooms.

 

[MiccyNarc]

I like Douglas Adams "Somebody Else's Problem" Cloaking device better.

 

[Acepilotf14]

This doesn't seem very practical at all for sneaking into women's changing rooms.

might be good for hiding weed

 

[Bad^Hat]

You can get away with murder as long as you get it done in 120 microseconds!

All this is really above my level of understanding. I don't understand what they're talking about changing the shape of light and thus are hiding time.

If I'm in a completely light-less environment I'm still part of time!

I hate being so dumb.

I think it has more to do with the observer's perception of time.

Maybe.

Okay I don't know either.

 

[EversorAssassin]

This is how it works (I believe!)

Say I want to steal a car.

I set up two gigantic lenses. Both are between you and the car. I will set the furthest lens (lens 1) off the side, on wheels, so I can move it. Lens 1, the closer to you, is stationary.

-Now, when light moves from the car to you, it is only normally passing through one lens. Quickly, I wheel lens 1 across so that for a short instance it is in line with you, lens 2, and the car.
-In that short instance that the lenses are in line, any moving light (say the image of the untouched car) will be slowed by the moving lens. While that slowed light moves between the two lenses, I'll take the car and go. The light (image of stationary car) will hit the second lens, reach you, and you'll still be seeing nothing. When lens 1 is out of alignment again, light will kick back into speed (rather, no more will be slowed) and you'll simply see that the car is gone.

Another way to explain this, is that.. Say I take a ten second video clip. You can normally watch all ten seconds in real time. But what this lens does, is basically take seconds 1-3 of the clip, and slows it down to take 6 seconds to view. Then remove seconds 3-6 and play the slow version of the first 3 seconds. So you see seconds 1-3, then it kicks ahead to 7-10. But it still takes the full ten seconds to view, and with some work you won't even know you missed something.

I hope I was clear enough with that?

 

[Stigmata]

I think I need new glasses, something in your explanation isn't getting through to me.

[edit] No, wait, I get it now.

 

[Robbo]

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.

From here. I think what they do is similar to bending light around objects to hide them but somehow this works with time too. There is not really enough info in these articles to figure it out.

 

[Bad^Hat]

Personally I'd like to hear more of Remus' opinion on the matter.

Spoiler

Spoiler

Get it Max Payne.

Spoiler

Bullet time.

Spoiler

I'll get me coat.

 

[Raziaar]

This is how it works (I believe!)

Say I want to steal a car.

I set up two gigantic lenses. Both are between you and the car. I will set the furthest lens (lens 1) off the side, on wheels, so I can move it. Lens 1, the closer to you, is stationary.

-Now, when light moves from the car to you, it is only normally passing through one lens. Quickly, I wheel lens 1 across so that for a short instance it is in line with you, lens 2, and the car.
-In that short instance that the lenses are in line, any moving light (say the image of the untouched car) will be slowed by the moving lens. While that slowed light moves between the two lenses, I'll take the car and go. The light (image of stationary car) will hit the second lens, reach you, and you'll still be seeing nothing. When lens 1 is out of alignment again, light will kick back into speed (rather, no more will be slowed) and you'll simply see that the car is gone.

Another way to explain this, is that.. Say I take a ten second video clip. You can normally watch all ten seconds in real time. But what this lens does, is basically take seconds 1-3 of the clip, and slows it down to take 6 seconds to view. Then remove seconds 3-6 and play the slow version of the first 3 seconds. So you see seconds 1-3, then it kicks ahead to 7-10. But it still takes the full ten seconds to view, and with some work you won't even know you missed something.

I hope I was clear enough with that?

I just don't understand why they say they're hiding time. It just sounds like a dumb thing to say, in my opinion. "We're hiding time!" It makes you think it's something epic and fascinating done to time like what happens in a black hole... but it's not.

At least, it doesn't seem to be to me. It just seems to be a geeky way of saying you obfuscated something from view.

 

[Lobster]

The public reporting of scientific research has been like this for a long time. The more catchy buzz words and popular terminology you can add to your press releases, the more attention it gets, and the more attention it gets, the easier it is to maintain your funding.

Just be glad they didn't resort to using Harry Potter in order to explain the complex and tricky term Invisibility Cloak.

 

[DEATH eVADER]

F***ing LAG you piece of S**t!!!

"invisibility cloak" made famous by Harry Potter

I'm sure there were some other stuff that came before that made Invisibility Cloak famous

 

[Dan]

So basically this:

 

[Dan]

I mean this:

 

[Bad^Hat]