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Re: Scientists Punch a Hole in the Fabric of Time with a "Time Cloak"
Invisibility cloaks are the result of physicists' newfound ability to distort electromagnetic fields in extreme ways. The idea is steer light around a volume of space so that anything inside this region is essentially invisible.
The effect has generated huge interest. The first invisibility cloaks worked only at microwave frequencies but in only a few years, physicists have found ways to create cloaks that work for visible light, for sound and for ocean waves. They've even designed illusion cloaks that can make one object look like another.
Today, Moti Fridman and buddies, at Cornell University in Ithaca, go a step further. These guys have designed and built a cloak that hides events in time.
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 it's early days yet. Given the rapid development of spatial cloaks, it'd be a brave man who'd bet on this being the last word.
Fridman and pals have clearly made themselves an interesting toy but they modestly refrain from speculating about the applications for their time cloak.
However, that's a task well suited to readers of the Physics arXiv Blog. If you have any suggestions, leave them here.
- monkeychow
- Rep: 661
Re: Scientists Punch a Hole in the Fabric of Time with a "Time Cloak"
Wow...I didn't even realised they'd perfected the invisibility cloaks.
Starting to get a very scifi world.
Reminds me of something I saw on TV - might have been stargate - where they built some kind of time bomb where inside the bubble everything moved thousands of times slower than normal time.
- mickronson
- Rep: 118
Re: Scientists Punch a Hole in the Fabric of Time with a "Time Cloak"
sg-1 vs the replicators
great show it was 
Re: Scientists Punch a Hole in the Fabric of Time with a "Time Cloak"
Wow...I didn't even realised they'd perfected the invisibility cloaks.
The US military has been using various cloaking devices since the W Bush administration. Saw a demonstration years ago. When you'd look at the guys wearing them, you didn't see them. You saw what was behind them. There were tiny cameras strategy placed around the cloak so you saw anything BUT the troops. Remember the movie Predator? Kinda like that where you'd see a moving out line but not know what was in fact moving.
I would not be surprised if cloaking devices were used when Special Ops invaded the Bin Laden compound. We'll never know because most of the vital info regarding that will forever remain classified.
Re: Scientists Punch a Hole in the Fabric of Time with a "Time Cloak"
Re: Scientists Punch a Hole in the Fabric of Time with a "Time Cloak"
Loved SG-1. Didn't care for the spinoffs Atlantis or Universe (Atlantis was much better tho).
But SG-1 was on a whole nother level. Even when Richard Dean Anderson left, it still found a way to still be good. Kind of wish Beau Bridges had been on the show the whole run.
Miss it alot. Although by Season 10, it was time to go.
Re: Scientists Punch a Hole in the Fabric of Time with a "Time Cloak"
Going back to see 1988 & 1991 GN'R would be awesome. I'd also like to see News Of The World-era Queen, Queen at Live Aid & Wembley '86. I'd also like to see every era of Alice In Chains up though 1996, including the MTV Unplugged show. And i've always wanted to see some Jake E. Lee-era Ozzy shows, and maybe Sticky Fingers-era Stones.
That'd be cool.
But ultimately what the time machine (required to be in a DeLorean) would be cool for me, is to go back to some happy moments in life, maybe if just certain places when they looked certain ways. Maybe certain areas of the U.S. pre-industrialism.
Maybe to go back and ask certain girls out when they were younger and were interested, but we didn't have the guts.
But personally i've always wanted to go back in time and buy up a shitload of LAND. LAND MY FRIEND. I'd buy up tons of land interests in some of the most beautiful places in the U.S. & Canada, and build beautiful homes.
Some of it in the present and future could be sold for nice profits, and the rest would be 24/7 trout fishing in the Western U.S. & Canada baby!
But that's just me.
