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Scientists Speed up Light
An anonymous reader writes "With off-the-shelf components, scientists have managed to speed up light beyond the 'universal' constant of c, or roughly 300 million meters/sec. This, and the previous ability to slow light down could shake up the telecom world, according to the story at Science Blog." Also, all those posters with 186,000 miles per second as a speed limit need to be amended. At least entropy is still around!
Everyone say it together with me: "Phase velocity vs Group velocity" There are no photons in this experiment that are traveling faster than the speed of light. Only collections of them that 'appear' to be doing so. Think of this as an example: I space people out in a line, each of them two light minutes apart from the people next in line (all at rest with respect to each other). Now I go about talking to them and informing them of my plan. At 12:00 the first person waves, at 12:01 the second person waves, at 12:02 the third person waves, and so forth. My "wave" is propogating, therefore, at twice the speed of light. This is the same thing that this experiment is doing more or less. By spending extra time setting up the experiment, you can make it appear that a light pulse travels faster than c, but like my "wave" it is only an appearance.
but can they achieve warp speed yet?
visit me at www.longdead.net
Hasn't this already been done before?
Were they able to speed it up to ridiculous speed, or perhaps even plaid?
Comment removed based on user account deletion
... it's "only" the phase velocity. This has been done before, and, since information is carried at the group velocity, there aren't any serious "light-cone" repercussions for Einsteinian limits on causality.
Athletic Scholarships to universities make as much sense as academic scholarships to sports teams.
There's more than one measure of the speed of light - the phase velocity and the group velocity. It's the group velocity that can't travel faster than c, the phase velocity is free to travel faster assuming dispersion is allowed. In any event, information travels at the speed of the group velocity, which is why the write-up mentions that Einstein ain't wrong just yet ("only a portion of the signal is affected").
If you look at this treatment of wave velocity, it's reasonably clear ([grin] - at least if you've done undergrad physics, but then in that case you'd know all about it anyway
A good quote from the above link:
The phenomena is also discussed in Feynman's Lectures on Physics ( vol 1, Chapter 48-6) in a bit more rigor - these books ought to be required reading of any physics undergrads
Simon
Physicists get Hadrons!
When people have 'c' recorded, it's assumed that it's referring light in a vacuum and it's not messed around with. So the values can stay the same.
Is this really that new? This has happened before. Read here: CNN: Light can break its own speed limit
And before we all start yapping, I quote from the (CNN) article:
This effect cannot be used to send information back in time," said Lijun Wang, a researcher with the private NEC Institute. "However, our experiment does show that the generally held misconception that `nothing can travel faster than the speed of light' is wrong.
Note that no information is being transmitted faster than the speed of light in such a case. Shadow may traverse across the spotlight faster than the speed of light, but the actual information that creates the shadow is still transmitted at the epeed of light from the spotlight to the wall.
This isn't supposed to happen until 2208
e nces/timeline2.dhtml
http://www.gotfuturama.com/Information/ListsRefer
Suppose you had a chain of people 3,000,000km long, and you had them do a Mexican wave. It'd take (a lot) more than 10 seconds to go from one end of the chain to the other because people don't react that fast.
Now suppose you gave each person a Bleepy Thing (tm) which you have sychronised beforehand so they go off at staggered intervals, the last one at the far end of the line 2 seconds after the first. You have the chain of people do its Mexican wave by standing as soon as their Bleepy Thing goes off. Wave velocity will be approximately 5c. There's no problem synchronising the bleepy things, just set them to go off at the right time intervals when they're all together in one place and then move them fairly slowly (like 100km/s is fine) to the right places in the chain.
So why doesn't that break relativity? Answer: the wave does not carry information that fast. In fact the only information you get from the far end of the wave is the time the bleepy things were set to go off at - which reached you much slower than light speed when the bleepy things were sent down the chain beforehand.
This is much the same trick just done with a light wave not a Mexican wave.
"The US Defense Advanced Research Projects Agency (DARPA) considers it so important that it has been funnelling millions of dollars into projects such as "Applications of Slow Light in Optical Fibers" and research on all-optical routers."
(However, including the nuclear forces is moot since they have no influence nor can they be observed outside the nucleus of an atom.)
If you reply, do so only to what I explicitly wrote. If I didn't write it, don't assume or infer it.
Good news travels at the speed of sound. Bad news at the speed of light. Rumor even faster.
Actually bad news travels faster than light. Some alien civilation tried to build space ships powered by bad news. But they were unwelcome wherever they went. (the hitchhikers guide)
As was evidenced by the new FTL(faster than light) optical data processing center at the core of Slashdot, This article was accidentally Posted INTO the PAST!!!!
/my head asplodes.
Thus, making the first post read a DUPE, and not this one. This is the original!
iceberg
Check journal for info on Anti-TextBook, an idea by me.
"Mod me down again......"
Go not unto/. for advice, for you will be told both yea and nay (but have nothing to do with the question)
You can't use newtonian physics for speeds so close to c. Newtonian physics states that you just can add speeds, ie x = y+z.
This isn't correct which gets noticable when speeds approaches the speed of light. Instead use relativistic physics: x = (y + z)/(1 + y*z/c^2).
So your example becomes:
v = (0.75c + 0.75c)/(1 + 0.75c*0.75c/c^2) = 0.96c
My other comment is funny
Mixing politics with science; always a good idea (especially if you really really hate George Bush enough, which makes anything acceptable).
But seriously, if "nukular" was an acceptable pronounciation by Jimmy Carter -- who was one of the first nuclear engineers in the Navy (Academy class of 1946) -- and tens of millions of other Americans -- including Dwight Eisenhower and Bill Clinton -- why single out George Bush?
See
http://volokh.com/2002_09_15_volokh_archive.html#8 5468441
http://volokh.com/2002_09_15_volokh_archive.html#8 5473616
http://volokh.com/2002_09_15_volokh_archive.html#8 5473709
http://volokh.com/2002_09_15_volokh_archive.html#8 5473746
[Eugene Volokh, 9:53 AM] September 19, 2002
WHAT'S WRONG WITH "NUCULAR"? Today's Slate Explainer reminded me of this question, which I've thought about a bit in the past.
One common answer is that saying "nucular" is wrong because "nuclear" is spelled, well, "nuclear," and not "nucular." But the standard rebuttal (mentioned in the Slate piece) is: How do you pronounce "iron"? I actually remember pronouncing it "iron" as a kid (as in "irony" without the "y"), and being told that this is not the usual pronunciation -- "iern" is probably the best way of representing how you're really supposed to pronounce it. If this phenomenon (called "metathesis") is OK in "iern," why isn't it OK in "nucular"?
But this is just the tip of the objection -- the broader objection is that this is English we're talking about here. English, the language of "women," of "colonel," of "laughter" and "slaughter," of "get" and "gem." As reader Brian Dulisse points out, "forte" can be pronounced "fortay," "fort," or "fortee." "This pronunciation is wrong because it doesn't match the spelling" isn't much of an argument in English.
It seems to me that the only sensible answer to "What is wrong with 'nucular'?" is "This is not the standard way that high-class people say it," coupled with "This term is a shibboleth that high-class people, and those influenced by them, use to sort those they'll call 'high-class' from those they'll call 'low-class.'" That's all the "wrong" there is here. Yes, I know this sounds like a leftist cultural critic position; but sometimes, as here, the leftist cultural critics are right. One day, "nucular" might be treated the same as "ah" for "I" or "crick" for "creek" -- a regional accent that's not wrong, but just different. It might even become the "correct" pronunciation, with "nuclear" sounding archaic or affected. It won't flow from a change to logic or morality, only a change of attitude by enough people in the influential classes, or by a change of who counts as the influential class.
So what of it? Well, if you're teaching a child (or an adult) to speak, of course you should teach him to say "nuclear," simply as an instrumental matter -- sounding high-class is usually (not always, but usually) more profitable, especially where the shibboleths are concerned. If you're making a purely esthetic judgment, well of course you're free to say "'Nucular' sounds ugly to me," just like you can say "Picasso looks ugly to me" or "Broccoli tastes bad to me." And if you're tr
Wow... This is actually an informative thread, because it demonstrates how politics can cause any scientific discussion to degrade into name calling. I think that we can all discuss science without attacks on people.
Living in Ohio, "THE" battleground state, I have seen many casual arguments between two people who for all intents and purposes should be friends, degrade into fistfights.
Discussing points and their merits is great, and we are all capable of that without attacks on people's regions and pronounciations.
Why discuss who can beat up whom on a discussion board? The same way that hot 18 year old girl in a chat room can be a 90 year old fat man, the geek on this board could be a 6'4" former MP who has been to war. My guess is, if we all got into a bar together, we would have fun and get along....
And All I Ask is a Tall Ship And a Star to Steer Her By
I'm not sure if anyone already posted the actual paper. ScienceBlog only links to itself and references a future printed publication. Well, here it is:
X -13-1-82
http://www.opticsexpress.org/abstract.cfm?URI=OPE
Now, create 'extreme conditions', where the first domino block is down, the last one is still standing, and halfway down the row, blocks are falling, but not quite down on the floor. Then, observe the 'wave front' of falling domino blocks. It will appear to move faster than the previously determined 'c'. How come?
Look more closely: as each block falls down, there's a fixed delay before it hits the next block. But what happens under our 'extreme conditions'? At the exact time a previous block would have hit the next one (under normal circumstances), that next block is already falling down! The time it takes for the 1000 blocks to fall down, is less than what normally would be expected.
Did this 'c' constant get violated? Nope, it still took the same amount of time for each block to fall down. Was the maximum 'c' speed exceeded? Nope. After tipping the first block, it still took the same amount of time before this 'information' was passed on to the next block. With a set of 1000 blocks all standing, the time needed for an initial 'disturbance' to be passed on to the last block, is still limited by 'c'.
So these 'extreme conditions' are like pre-tipping each block, and let you observe something that appeared to move faster than 'c'.
Nice for the lab folks, but other than that, sensationalist journalism. Wake me up when trans-atlantic ping times (sending actual packets with random data) dive below the time dictated by the speed of light.This post really ticks me off. Why? because i submitted the same story yesterday and it was rejected. Make up your minds, you evil moderators from the cubicles in the basement. RAWR!!!
Dark is faster than light... when you open a drawer, you see the light going in, but you don't see the dark escaping.
Dark is more dense than light. It settles to the bottom of large bodies of water, while light seems more boyant.
There are no light bulbs, just dark suckers. You notice how a burned out lightbulb can be a dark grey? It's full.
Candles were primative dark suckers.
This sig intentionally left justified.
I was doubtful about this because of entanglement so I quickly googled entanglement information and the first result, from Stanford encyclopedia says this:
Quantum Entanglement and Information
Quantum entanglement is a physical resource, like energy, associated with the peculiar nonclassical correlations that are possible between separated quantum systems. Entanglement can be measured, transformed, and purified. A pair of quantum systems in an entangled state can be used as a quantum information channel to perform computational and cryptographic tasks that are impossible for classical systems. The general study of the information-processing capabilities of quantum systems is the subject of quantum information.
So information transfer isn't limited by C.
FalconShould there be a Law?