Slashdot Mirror
Scientists Freeze Pulse Of Light
Smitty825 writes "After slowing down light to slow speeds, scientists at Harvard University have been able to stop light for a very brief period of time without destroying its energy. The article explains how it is different from this previous light-stopping science story - this will hopefully help the development of quantum computers and ways to communicate over long distances without being eavesdropped on."
Now if they could only figure out how to stop SPAM
Imagine going out to a club and getting a frozen "light cube" in your drink which releases a stream of photons as it melts.
Could bring a whole new dimesnion to the humble Tequila Sunrise huh?
A little planning goes a long way...
Oh...wait. Voids allow light to travel faster. shame on me. What color is stopped light if it retains its energy?
~mingust
One of the most annoying things about slashdot is their tendency to post completely vacuous science stories. Would it have been that hard to look up the actual paper before posting, or at least any information at all? All this story tells us is that it doesn't involve storing the photons in an atom as other researchers did. Oh, and that it's "very clever". How nice.
Does the laziness of slashdot "editors" truly know no bounds? If you're not interested in doing the work, why not find people who are?
autopr0n is like, down and stuff.
Makes me think of a physics joke.
Q: What is the difference between stopped light and darkness?
A: You know where darkness is.
I thought that light is a visual thing. How does one "eavesdrop" on light?
From excellent karma to terible karma with a single +5 funny post...
The article mentions clearly:
"We have succeeded in holding a light pulse still without taking all the energy away from it," said Mikhail D. Lukin, a Harvard physicist.
This is somehow different from "...without destroying its energy." like it is stated in the posting. Maybe a subtle detail, but not quite the same.
However, a briliant achievement. Kuddos.
Soon we can pack the pocket light full of light in stead of heavy batteries !
At least it sound _light_ not heavy.
"I think it's moving us in the right direction," he said. "Moving forward at the speed of light"? uh oh
~mingust
...if you eavesdrop on it, you capture it and the signal is lost to it's target. And once the recipient notices this, the transmission will end. Grabbing the data is to signal you're eavesdropping.
If the NSA supposedly managed to tap into fiber (light) what makes this guy so sure his studies would minimize/cut/halt the risk of eavesdropping? "Splice the line, and you cut off the light, at least momentarily," says Wayne Siddall, an optical engineer at Corning Fiber in Corning, N.Y. Even a second's interruption could be noticed by a cable's operator. Cable companies typically build systems with duplicate lines that take diverging routes, in case one of them is damaged or severed. One retired NSA optical specialist insists that the NSA devised a way to splice a fiber without being detected. "Getting into fiber is delicate work, but by no means impossible," the former specialist says. Neither he nor the NSA will discuss the matter further.
Spy agency taps into undersea cable
NSA Tapping Underwater Fiber Optics
And the list goes on and on. Bear in mind the NSA's date of achieving this, in comparison to the tech growth scale, I'd be willing to say that whatever Harvard is doing in being closely watched, if not already known.
MoFscker
Sounds like you could use it similar to the initial version of electronic memory (sort of a digital delay line), if it could be harnessed.
:-)
A few hundred-thousandths of a second is an eternity(*) for a photon. That's actually pretty impressive
Simon.
(*) Yes, for the pedants amongst us, I realise it's not actually an eternity. It's a figure of speech, for chrissake!
Physicists get Hadrons!
BBC News has an article which speaks a bit more to Quantum crytography.
"Quantum cryptography might provide very secure forms of electronic encryption, because the process of eavesdropping on an electronic message would introduce errors in the message, garbling it."
"This would allow you to exchange a key on a public channel, but whereas any classical system can be broken by an eavesdropper, in quantum cryptography you would always find out if someone was looking at your message," Professor Zubairy told BBC News Online."
"Academicians are more likely to share each other's toothbrush than each other's nomenclature."
Cohen
Could "Slow Glass" be coming? Bob Shaw wrote about glass that could slow down light so that it took years to pass through and the effects it had on society in his 1972 book Other Days, Other Eyes. Anyone interested in this stuff should hunt down a copy.
Why do you think any communications technology will be untapable ?
It doesn't matter what medium is used, there will always be a point of access for law enforcement or network testing / troubleshooting. Try and get something certified for use without it !
Remember the transmission medium is only part of the story !
Like I did here.
More detailed articles about the research can be found here or here.
Larkin's article itself is here.
Any physics nerds want to explain it to us?
This may prove to be a ray of inspiration for dim wits everywhere, beamed from the heavens to shed a new light on these dark times! Don't take it lightly. How we use this enlightenment will be a reflection on us all.
Altogether now: *grrooaaan*
wouldnt this mean that we have already gone faster than the speed of said light. i mean i think my car goes faster than 0m/s right? what implications would this have?
Dr. Lloyd added, "Who ever thought that you could make light stand still?"
Possible responses:
Mulletboy: Hell Bobby Jo 'an I do it all da time we juss turn on dat dag gon lite dare and it don move a noggin
Psychologist: Well the light has to be willing to move itself you know
Moses: God saith it so Let there be light
Dalai Lama: The light suffers in this state. It learns compassion it is enlightened
k let me actually get a life and some sleep
MoFscker
Here's a quote from Terry Pratchett you might like:
"Light thinks it travels faster than anything but it is wrong. No matter how fast light travels it finds the darkness has always got there first, and is waiting for it."
Why were there no pictures of this stopped light? .. oh wait
It doesn't have any color - it's STOPPED.
If it's STOPPED, it ain't ever going to get to your eye, see? Erm, I mean, not see?
Maybe you you ran your eye into it or something....
paintball
Officer: "Do you know how fast you were going?"
Heisenberg: "No, but I know exactly where I am!"
paintball
The New York Times, February 20, 2001
The Key Vanishes: Scientist Outlines Unbreakable Code
By GINA KOLATA
A computer science professor at Harvard says he has found a way to send coded messages that cannot be deciphered, even by an all-powerful adversary with unlimited computing power. And, he says, he can prove it.
If he is right, and he does have some supporters, his code may be the first that is both practical and provably secure. While there are commercially available coding systems that seem very hard to break, no one can prove that they cannot be cracked, mathematicians say.
In essence, the researcher, Dr. Michael Rabin and his Ph.D. student Yan Zong Bing, have discovered a way to make a code based on a key that vanishes even as it is used. While they are not the first to have thought of such an idea, Dr. Rabin says that never before has anyone been able to make it both workable and to prove mathematically that the code cannot be broken.
"This is the first provably unbreakable code that is really efficient," Dr. Rabin said. "We have proved that the adversary is helpless."
Dr. Richard Lipton, a computer science professor at Princeton, who is visiting this year at the Georgia Institute of Technology, said, "It's like in the old `Mission Impossible,' where the message blows up and disappears."
Someone who uses one of today's commercially available coding systems, Dr. Lipton explained, uses the same key -- mathematical formulas for encoding and decoding -- over and over. Eventually, they may be forced, perhaps by a court order, to give up the key. Or the key may be stolen. But with Dr. Rabin's system, the message stays secret forever because the code uses a stream of random numbers that are plugged into the key for encoding and decoding. The numbers are never stored in a computer's memory, so they essentially vanish as the message is being encrypted and decrypted.
Rest of article mirrored at Cryptome
MoFscker
Messeges in Phillip Morris code are automatically subpoenaed by Congress anyway.
God damn, subpoenaed is an ugly word.
paintball
Two ships using Morse code to communicate with a laser, and a 3rd party positioning their ship in between the two to eavesdrop on the laser, and then you'll have a better analogy. The receiving ship knows that someone is listening to the message because they're not getting it.
Signal lamps are multi-directional, photons only go one way.
paintball
If the speed of light changes, what does this mean for using the speed of light as a measuring rod for interstellar distances? Sounds to me like we'd better rethink the size of our universe. Feel free to correct me (as if I need to say that on /.), but if the universe is truly expanding, doesn't that mean the interstellar gasses and debris have also been "thinning"? How can we be sure that this expansion hasn't affected the speed of light?
"Our experimental apparatus used to demonstrate this effect is shown in Figure 2A. A magnetically sheilded 4 cm cm long 87Rb cell is maintained...." 2nd page, 2nd column of Lukins paper The 87Rb is in vapor form... Sound like a vacuum tube to anyone???
I once read an SF short story that featured windowpanes which light took decades to pass through - thereby letting you look at the past.
The story included the poignant scene of the protagonist looking out at his wife and child playing in the garden - but they had died 15 years earlier. The character used to hang around near the windows, hoping for glimpses of his dead wife, because he, of course, had no control over when he saw her; the windows would "replay the past" in strict linear sequence.
Does anyone know the name & author of the story?
In the story, the windowpanes were made of optical fibre nanotubes that were so tightly coiled up in the windows that the windows could accomodate tubes a few light-years long.
This research suggests more feasibly ways of doing this, though.
If it went in one color, and came out another color, what color was it when it wasn't moving?
paintball
Light doesn't actually have "color". Color is our perception of the wavelength of the light. There's another article on BBC that explains the experiment in greater detail. Essentially, they didn't actually freeze the photons, ie. made them stop moving, but used a different method to make the photons bounce back and forth in place. So the "color" should have remained the same.
According to the Slashdot summary, it is apparently possible to destroy energy!!! Issac Newton may turn in his grave...
Stop lights has caused my whole car, not just the head and tail lights, to a complete stand still, even for minutes, one my way to work for decades !
Uhhh, how about only using VoIP if it's encrypted?
That is a fascinating idea, that by slowing down light you can look into the past. But there is a ramification, that if this would work then everything is pre-determined. And would you only get to look back on what that light ray would have been near, or would it not matter. Either way, it is fascinating.
Rosco: "If brains were gunpowder, Enos couldn't blow his nose."
transmissions (or something like that). If the NSA received these photons instead of the intended receipient, the intended receipient would know (due to loss of signal) and would inform the sender to stop sending (actually, assuming some kind of handshaking protocol, the transmission would be stopped by either end).
Or is it to do with entangled photons? It's certainly not standard fibre optics as it's done at the moment.
IANACE
Ha! if they were able to freeze light, where are the pictures of the stationary beam of light floating in the air!!
Come on guys do you honestly think we will believe that in this day and age??
I am just building my reasoning backwards. To understand what happens to the Photon when it stops, let's first see what happens to the photon when it moves at - well - the speed of light.
From the quickest reference I could dig thru http://www.wired.com/wired/archive/6.07/es_warp.ht ml?pg=3&topic=
So, the faster the photon moves the slower the clocks would appear to move. Then, I guess, the slower the Photon moves the faster the clock would appear to move. And when the photon STOPS, the clock must be moving INSANELY FAST. So how could it be a very brief period of time ? .. I think it is a very very very long period of time.
Guess, it all depends on which perspective you are looking at, and how you are measuring time ...
To see a world in a grain of sand, and then to step back and see the beach where the sand lies
Shame on you too!
Aand running faster than light suddenly isnt that stunning any more.
GAAH! MY PRINTER IS ON FIRE!!! PUT IT OUT! PUT IT OUT!
I thought speed of light was linked to time? If this is the case, what happens to time in this experiment? Apologies if I am being a twat.
Paul.
We have the technology to create a lightsaber. I know what I'm asking Santa for Christmas now.
It was just slashdotted, and completely unable to move under the load.
I think you're missing the point.
These experiments are all a stepping stone towards genuine quantum communication. Previous experiment such as those in Paris (by firing rhubidium through a photon of light)showed that scientists can no measure certain properties of light without destroying the photon, and then re-measure it. The problem was that for quantum communication, you need to disentangle 2 separate photons from an entangled state so that any change you make to one makes ann instantaneous change to the other, it's twin if you like and that can be done it seems. But, keeping the light fixed in a certain place is one of the tricky parts. If they ever succeed at refing these crystals to the extent that a photon can be kept in a deterministic state, then all you need is 2 of these crystals - you can imagine them being placed at opposite ends of our solar system, each crystal containing your premade entangled photon bouncing back and forth, with the crystal itself locked in some kind of black box (cavity).
Presumablt the crystals would have small atomic/sub/atomic sized pin holes to fire the rhubidium or other material through one of the crystals. The the phase shif of the rhubidium caused by this firing also occurs at the other photon (because they are entangled). Then when you measure the phase shift of the second crystal, the difference is twice as great (i.e. the first phase shift plus the second phase shift0 - hence you know at the other end of the solar system, that it was fired. Now all you need is a model, to measure
according to time, t. For example, one crystal could measure every odd microsecond, the other at every even microsecond.
Now you have a unary turing machine, communicating between the stars!!!.
What's wrong with 'Does this smell like chloroform to you?'
As for the frozen light, I'm thinking this will herald a new line in novelty items of the type sold at Spencer Gifts, only to be shoved in a cupboard two days later and never seen again.
Could this lead to harvisting light? As in, freeze large areas (100-1000m3) of light and then using the light to produce energy?
Im not pretending to know what im talking about but it sounds as if one day we'll be able to cut light right out of the sky for where we dont need light, like on the moon or other planets. I was going to say antartica or the ocean but then i thought we'd prolly all die in huge freek weather storms or feeze to death.
But being able to harvest light could be a pretty cool advancement for our growing energy needs. Maybe would could harvest it with huge satelites orbiting the sun and have the light transported back as high energy lazers?
Giving IE users a taste of their own medicine since 2005 - http://pods.-is-a-geek.net/
Oops, and forgot to mention,
Though Einstein, Podosky and Rosen were able to monitor the effects of QE (Quantum Entanglement), no scientists yet know how an entangled pair of photons can have this "weird" communication.
Some suspect a quantum bridge of some kind, whatever that would be..!
I like to think it is one of natures gifts, it is wnough that we can dream of its use and who knows, maybe someday use it.
So thats why eavesdropping would be imnpossible!!!
The only hope for an eavesdropper would be to secretly take over the disentanglement process an manufacture a third photon (for his/her self)
Then however communication would break down, because inevitably, the eaves dropper would measure his/her photon, creating an extra phase shift. Now communication between the 2 law-biding parties would have a triple phase shift, so they would immediately know someone is eavesdropping and cease communication. So, QE really would be the perfect way to communicate!
The article is unfortunately sparse on details, but as a general principle, if you stop a photon without destroying its energy, you have a temporary violation of conservation of energy. This puts an approximate bound on the time you can keep the photon stopped, on the order of h/E, which is an extremely short time.
Informative. I was going to post the same thing, but there it is.
--- 11 meters/second, or 24 miles per hour - the airspeed velocity of an unladen European swallow. Really.
Make windows like this that replay from a few hours before. "I don't know what happened, Officer, but if we just wait about 15 minutes we'll be able to see it all in my window here."
--- 11 meters/second, or 24 miles per hour - the airspeed velocity of an unladen European swallow. Really.
And if we can hook him up to a dynamo and a generator, we've got free energy sorted. Truly, this is an age of wonders.
The Law of Falling Bodies
On the subject securing optical links, quantum crypto is an interesting aproach. It is not useful to transmit a lot of data, but can be used in secure key interchange.
More on this:
here
here
and here
Scitne aliquis remedium potimum crapulae?
Reading the study you linked to, it says that when the atomic excitation that makes this possible is converted back into light, the pulse can be propagated in either a forward or backward direction.
Which should mean that you could create a sort of time-delayed mirror, wouldn't it?
Hard to see how that would be useful, except perhaps as a gag of some sort.
(Ha! Hard to see! Get it?)
Is this truly the only Earth I can live on?
but the damn flash kept getting stuck in the beam we were taking a picture of!
...and that's the way the cookie crumbles.
This article gives a few more details, and here is the actual press release.
So soon we'll be able to Xanadu forever.
"this will hopefully help the development of... ways to communicate over long distances without being eavesdropped on"
We already have that. Light based fiber runs are impossible to tap into without having to break the connectivity to hook up an additional device. Of course, nothing goes coast-to-coast directly, so they're plenty of chances for the spooks to install their logging equipment at a switching station or router.
The only way to communicate securely without encryption is to totally control physical access to the line, which just plain isn't gonna happen over long distances.
They've got it all backwards. They're supposed to be working on a way to increase the speed of light. How else are we going to accomplish a practical form of interstellar travel?
Hee-hee. Dying tickles!
What would happen if you put too much "stopped light" in one place at the same time?
Can we split or combine a photon?
I am the unwilling control for my Origin.
If you have a really, really cold fridge and you open the fridge door really, really fast, you too can witness frozen light.
If you walk past the experiment setup, are you then travelling faster than light?
(sorry, it's a bad morning and I just can't seem to fucs on work)
Is it just my observation, or are there way too many stupid people in the world?
We haven't even reached the speed of light, and already they have a speed trap.
http://www.theMediaBunker.com
...converts stopped light into motion. The gas station replaces the spent stopped light gas with charged gas.
Hmmm...I wonder if I drank stopped light, would the sun would shine out of my.....
Correct me if this is wrong but wound't stopped light be dark... So in turn they have effectively made very expensive and complex light switch??
Some people have posted claims that this is similar to the earlier experiments of Lene Hau, where the light pulse was indeed stored as excitations in trapped atoms (either in a BEC as in Hau's case, or in a vapor cell as in Lukin's earlier experiment).
This is quite different from what's going on here. In this experiment, two lasers are used to polarize the atomic vapor as a function of position, and then bouncing light off that polarization gradient. Think of what happens when you put light in between two highly reflecting mirrors, and let it bounce back and forth. Then think about what happens if you nest thousands of these mirrors within each other, so that if the photon leaks out of one, it has to deal with the next one, only one wavelength away. Since the photon is spending so much time bouncing back and forth, it doesn't really have a chance to escape the gas, and so we say that it's trapped.
It's essentially a new way of making a high quality cavity.
First thought that came to my minds was, if we can slow light down, i wonder if one day we could speed it up..... Isn't that crazy. If we could increase the speed of light could we travel faster ? Sound travels at a specific speed, but we can speed it up.
EOM
"If you're thinking what I'm thinking, you're right." -
If we have basically stopped light bringing it to zero miles per second...does that mean we have traveled faster than the speed of light?
Nick: Thetribble (just applied and cant get my e-mail yet to get my password)
You are incorrect. There is no corresponding frequency of light for the color white, nor for many other colours. White is simply our perception when the red, green and blue photoreceptors in our eyes are equally stimulated. The only colours with corresponding light frequencies are those which you find in the colours of the rainbow.
Hmm.. maybe we now can get cheap fiberoptics? If you lay a few meters with fiberoptic cable in both end, you can freeze the signal and send it by snailmail in between.....
"Since the beginning of time man has yearned to destroy the sun. I will do the next best thing..."Freeze it!
"Watch your cornhole, bud."
I'm no physics expert, but if you could truly stop light (as it seems this experiment has still not really done), does that imply that the photons would age while they are stationary? Perhaps they would still be travelling at c, with significant motion diverted to the time dimension? Any real physicists out there who can elaborate on why I'm talking out my ass?
The speed of light ain't what it used to be.
--- Back to the trees, back to the trees !
I hope you meant that as a joke, cuz they aren't literally "freezing" light.
Yeah! Everyone wants SLOWER NETWORKS!
Hey, dumbass, you're the incorrect one. Red, green, and blue? Eyes aren't cathode ray tubes! It's cyan, yellow, and magenta for human eyeballs.
Read your shit next time before you spout off.
The reason it's old news (Score:5, Funny)
by ch-chuck (9622) on 14:19 08 January 2002
(#2806003)
is that they've not only stopped light, but made it go backwards, reversing time, so this 'discovery' got projected into the future, where we're reading about it now as if it were new, altho it's been done some time ago.
Evil is the money of all root.
Morris code? It's Morse code, you fucking idiot. Read up on your shit before spouting off and making yourself look like a huge moron in front of thousands of people.
This leads us one step closer to every geek's dream - a real working lightsaber. The thing about a lightsaber is that the beam stops at a certain point. If we can freeze light, then perhaps we can also limit the beam to a certain length, allowing geeks everywhere to prepare themselves to do battle...
or something.
Opinionated Law Student Strikes Again!
Thank God! Now there's proof of concept for crippling an optical Internet.
Yeah. In this house we obay the laws of thermodynamics!
Drill baby drill - on Mars
What about a man in the middle attack? You buy your entangled photon pair from my SneakyFactory. What I really sell you is two unrelated photons, while keeping their "actual" twins in my factory. Long before I delivered you your pair, I've set up my end of things to immediately record whatever comes in, and communicate it to the other photon.
Is there anything that stops this sort of attack? The only thing I can imagine is some sort of timing measurement..
-Zipwow
I don't know which is more depressing, that 2/3 didn't care enough to vote, or that 1/2 of those that did are crazy.
Off topic, admittedly, but I just googled 'tequila sunrise recipe' and here are the first three actual recipes returned:
First
Second
third
Battling Beasts
If I remember correctly, there is a very simple reason that communication via light would be secure -
In the quantum world, if you interact with the light, you change it in some way, no matter what, and since eavesdropping would involve interacting with the signal, the signal would not be exactly the same.
-- If an artist saw things as they truly are, they would cease to be an artist.
After looking at the pdf file that describes the process, I have to conclude that this would be ideal for a fibre-optic man-in-the-middle attack on quantum crypto. The whole thing hinges on the idea that the quantum spin of the photos are preserved after being observed, which this process appears to achive. The main focus of the pdf is about the exact nature of the quantum states of the photon's after being stored. This storage (in a supper cold gas cloud) could incorporate detectors with enough thru-put to possibly support the bandwitdh to tap a real quantum crypto setup.
Who knows, but this could lead to new technology that breaks the one-time-pad nature of optical quantum-crypto.
It isn't a lie if you belive it.
This is science fiction come true. Bob Shaw's, "The Light of Other Days" has the concept of slow glass which would transmit light so slowly that it could be used to view the past.
Now it can be done!
Dada ended art.
I did a few calculations on my Windows calculator and discovered that if they really did stop light it would cause a tear in the space-time continuum, so I think they are lying.
but i just cant tell where it is!
Supposedly, if you were able to create a powerful enough light beam, the gravitational attraction of the photons would, over a sufficient distance, narrow the beam down to near-zero diameter. Is this progress in that direction?
What if it just has no wavelength? ;)
paintball
Nothing travels faster than light, with the possible exception of bad news.
The Foo people of Bar actually tried to use this fact, and built a spaceship entirely powered by bad news, but found that wherever they went they were so extremely unwelcome that there wasn't really any point in being there.
My ex wife can stop laser and flashlight beams (pointed at her face) and peel paint off a battleship at 1,000 yards since she let her self go and quit wearing makeup.
I've been trying to get a patent on her technique but Darl's other brother, Darl, has been claiming prior art because she looked a box of redhat once on a shelf.
You just can't win, can ya??
Sure you can tell exactly how fast it is going (not moving) but you will have no clue as to where it is in space!
source: google cache of
www.msu.edu/user/dynicrai/physics/dark.htm
THE DARK SUCKER THEORY
For years, it has been believed that electric bulbs emit light, but recent information has proved otherwise. Electric bulbs don't emit light; they suck dark. Thus, we call these bulbs Dark Suckers.
The Dark Sucker Theory and the existence of dark suckers prove that dark has mass and is heavier than light.
First, the basis of the Dark Sucker Theory is that electric bulbs suck dark. For example, take the Dark Sucker in the room you are in. There is much less dark right next to it than there is elsewhere. The larger the Dark Sucker, the greater its capacity to suck dark. Dark Suckers in the parking lot have a much greater capacity to suck dark than the ones in this room.
So with all things, Dark Suckers don't last forever. Once they are full of dark, they can no longer suck. This is proven by the dark spot on a full Dark Sucker. The dark which has been absorbed is then transmitted by pylons along to power plants where the machinery uses fossil fuel to destroy it.
A candle is a primitive Dark Sucker. A new candle has a white wick. You can see that after the first use, the wick turns black, representing all the dark that has been sucked into it. If you put a pencil next to the wick of an operating candle, it will turn black. This is because it got in the way of the dark flowing into the candle. One of the disadvantages of these primitive Dark Suckers is their limited range.
There are also portable Dark Suckers. In these, the bulbs can't handle all the dark by themselves and must be aided by a Dark Storage Unit. When the Dark Storage Unit is full, it must be either emptied or replaced before the portable Dark Sucker can operate again.
Dark has mass. When dark goes into a Dark Sucker, friction from the mass generates heat. Thus, it is not wise to touch an operating Dark Sucker. Candles present a special problem as the mass must travel into a solid wick instead of through clear glass. This generates a great amount of heat and therefore it's not wise to touch an operating candle. This is easily proven for lightbulbs too. When you compress a gas, it gets hot, right? So the light bulb gets hot because of all the dark being squished into the wires.
Also, dark is heavier than light. If you were to swim just below the surface of the lake, you would see a lot of light. If you were to slowly swim deeper and deeper, you would notice it getting darker and darker. When you get really deep, you would be in total darkness. This is because the heavier dark sinks to the bottom of the lake and the lighter light floats at the top. The is why it is called light.
Finally, we must prove that dark is faster than light. If you were to stand in a lit room in front of a closed, dark closet, and slowly opened the closet door, you would see the light slowly enter the closet. But since dark is so fast, you would not be able to see the dark leave the closet. So next time you see an electric bulb, remember that it is not a light emitter but a Dark Sucker.
Your brain is not a computer.
Imagine a beowulf cluster of these!!!
if you don't like it, close your damn eyes!
Tell that to the nocturnal animals who can't feed or breed properly due to light pollution.
Tell that to the people who enjoy gazing at the wonderful milky way during the night.
Tell that to the astronomers who no longer can do their jobs from the ground.
sheesh indeed...
I liked my next sig a lot better
Can light actually be stopped? Isn't the photon a massless particle that only exists in a state of movement, and if it isn't moving, it doesn't exist?
I was under the impression that the way that quantum communication was to take place was with quantum entanglement. That being the case, there is no transmission line to tap at all. As has been demonstrated, entangled particles effect each other instantly regardless of distance. Meaning you could have one on the moon and one at the sun at when you messed with one the other would be messed with the same way at the same time. So really, it makes no difference weather the NSA or anyone else can tap a fiber cable. Well, now it does, but not at the point when they figure out how to keep particles entangled.
So if you hold the energy for a short time, can you do it for a long time and release it all at once?
This is completely meaningless. Photons don't occupy volume in any well-defined way.
The problem was that for quantum communication, you need to disentangle 2 separate photons from an entangled state so that any change you make to one makes ann instantaneous change to the other, it's twin if you like and that can be done it seems.
This is not how a quantum cryptosystem works. See this article, and note that the technique that currently seems to show the most promise for cryptography is (A). Messages cannot be transmitted faster than the speed of light in a vacuum, as relativity dictates that your actions cannot affect a distant "simultaneous" measurement, and no one has found a reproducible experiment to contradict this assertion (despite lots of trying). It is a popular misconception that quantum entanglement can be used to communicate instantaneously, but the correlations that are measured do not actually cause any exchange of information. If you do something to one of your photons, it will simply destroy the entanglement.
"Your notation sucks!" -- Serge Lang (1927-2005)
I think you misunderstood. I meant that a massive particle travelling faster than light gives off Cherenkov radiation, not that such a particle was Cherenkov radiation. Naturally the radiation itself travels at the (local) speed of light, just like the sonic boom given off by a supersonic jet travels at the speed of sound.
The author of this post asserts his moral rights.
dumbass
You are going faster than that particular light, but not faster than c. You would need to actually be inside the medium that the light was measured in, which seems pretty impossible. Of course, you would also need to walk past it in less than a millisecond, too.