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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
Were they able to speed it up to ridiculous speed, or perhaps even plaid?
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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.
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.
(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.
"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)
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
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.Which is why if you go faster than light, your reality is backwards and cause follows effect. You aren't even really going faster than light, you're going slower than light and backwards in time. If you were to approach 2x the speed of the light, you'd appear to slow down to everyone else, and end up casually strolling facing the wrong way. (And this would be trival to do, as going 2x the speed of light would be a simple matter of going 1.00001x and then trying to stop.)
So it's not a premise about the speed of light. The speed of light defines time. It is absolute. While you can't accelerate faster than the speed of light, that's not the point. The point is that light always travels at exactly the same speed, and light carries reality along with it.
By 'reality, I mean exactly that. I can see you do something while I did something else, and those events happened at the same time to me. You, being a light year away, saw them two years apart, and we're both right, from our frame of reference. That's relativity. Events happen when the light reaches you. (And by light, I mean hypothetical vacuum light, not artifically slowed light.)
People hear 'nothing can travel faster than light', and 'everything is relative' and don't quite grasp is. According to relativity, time doesn't exist independent of the speed of light, just like gravity doesn't exist independent of the distortion in space caused by mass. In fact, energy:time::matter:gravity is a pretty good analogy of what's going on.
And everything I just wrote, according to quantum mechanics, is a complete and utter lie.
Quantum mechanics has been proven to be non-local (operating faster than light) with Bell's Theorem. It's not even a theory, we have actual physical proof that events at one place can effect the outcome at another faster than light. We don't even need quantum tunnelling, good ole quantum interference does it for us.
Now, Bell's Theorem doesn't let us get information faster than light. However, it clearly knows what's going on faster than light, so at least bookkeeping information can go faster than light.
And, incidentally, you don't need quantum tunneling or any sort of equipment to get light going faster than light. Light, until you measure it, is smeared into a probability wave. Sometimes, by sheer chance, you can measure one and it will end up collapsing at the front of the wave. Thus having moved a tiny fraction faster than light.
And some will collapse at the end of the wave, moving a tiny fraction slower than light, which is just as much a crime for light to do in relativity.
I'm fairly certain we've actually measured what we think is this happening, from pulsars. Probablity waves from photons from stars can spread across meters until they hit something, where they instantly collapse into one point. (At which point relativity runs screaming from the room, because points a meter away from each other should not be able to communicate instantly.) A meter isn't a long time, lightwise, but I seem to recall something about measuring 'fast' photons.
This is why physicists have so many drunken fistfights.
If corporations are people, aren't stockholders guilty of slavery?