Skip to comments.Physicists spooked by faster-than-light information transfer
Posted on 08/14/2008 5:42:56 PM PDT by LibWhacker
Quantum weirdness even stranger than previously thought.
Two photons can be connected in a way that seems to defy the very nature of space and time, yet still obeys the laws of quantum mechanics.
Physicists at the University of Geneva achieved the weird result by creating a pair of entangled photons, separating them, then sending them down a fibre optic cable to the Swiss villages of Satigny and Jussy, some 18 kilometres apart.
The researchers found that when each photon reached its destination, it could instantly sense its twins behaviour without any direct communication. The finding does not violate the laws of quantum mechanics, the theory that physicists use to describe the behaviour of very small systems. Rather, it shows just how quantum mechanics can defy everyday expectation, says Nicolas Gisin, the researcher who led the study. Our experiment just puts the finger where it hurts, he says. The study is published in Nature.
Spooky and unsettling
In the everyday world, objects can organize themselves in just a few ways. For example, two people can coordinate their actions by talking directly with each other, or they can both receive instructions from a third source.
In both these cases, the information is communicated at or below the speed of light, in keeping with Einsteins axiom that nothing in the Universe can go faster. But quantum mechanics allows for a third way to coordinate information. When two particles are quantum mechanically entangled with each other, measuring the properties of one will instantly tell you something about the other. In other words, quantum theory allows two particles to organize themselves at apparently faster-than-light speeds.
Einstein called such behaviour spooky action at a distance, because he found it deeply unsettling. He and other physicists clung to the idea that there might be some other way for the particles to communicate with each other at or near the speed of light.
But the new experiment shows that direct communication between the photons (at least as we know it) is simply impossible. The team simultaneously measured several properties of both photons, such as phase, when they arrived at their villages and found that they did indeed have a spooky awareness of each others behaviour. On the basis of their measurements, the team concluded that if the photons had communicated, they must have done so at least 100,000 times faster than the speed of light something nearly all physicists thought would be impossible. In other words, these photons cannot know about each other through any sort of normal exchange of information.
The team also ruled out other possible reasons for the apparently coordinated behaviour. For example, one could imagine that the photons might have shared information before they left Geneva but Gisins measurements showed that they could not.
A second test ensured that the scientists in the two villages werent missing some form of communication thanks to Earths motion through space. According to Einsteins theory of relativity, observers moving at high speeds can have different reference frames, so that they can potentially get different measurements of the same event. The Geneva results could possibly be explained if the two photons were communicating through a frame of reference that wasnt readily apparent to the scientists."
But theoretical calculations2 have shown that performing tests over a full spin of the globe would test all possible reference frames. The team did just that, and they got the same result in all cases.
The bottom line, says Gisin is that there is just no time for these two photons to communicate.
The experiment shows that in quantum mechanics at least, some things transcend space-time, says Terence Rudolph, a theorist at Imperial College London. It also shows that humans have attached undue importance to the three dimensions of space and one of time we live in, he argues. We think space and time are important because thats the kind of monkeys we are.
If you are baffled by the result, fear not youre not alone. For me, honestly, it doesnt make any sense, says Gisin. I dont think we can today claim that we have a good story to tell how this all happens. He hopes that the work will stimulate theorists to come up with new ways of explaining the spooky effect.
Mr. Bell & Mr. Bohm were right.
Open a subspace channel to Star Fleet Command, Lt. Uhura.
Okaaaaay....I so do not get the distinction.
Our experiment just puts the finger where it hurts, he says.
Where it hurts? Snort. Namely my brain, from trying to figger this out.
Bump for later read....C
This is news? The Demicans and Republicrats have been demonstrating ‘entanglement’ like this for decades.
“if you are not confused and annoyed by quantum theory you do not understand it”
Ummm...aren't photons, like, inanimate objects?
Dang, Mr. Mew just gave up trying to explain this to me, and he's usually got the patience of Job.
I don’t know why they are surprised at this. There has been experiment after experiment showing this. I know many scientists have been in denial and have claimed for some time that entanglement would not allow faster than light information travel but it does. There has also been some very good experiments using entangled photons in remote scanning where two beams of photons are used. The one beam of entangled photons are used to scan a target while the other is directed to a sensor and from the resultant information of the second beam only there has been some success generating an image.
I wouldn’t be surprised if a crude quantum semaphore system couldn’t be devised to show clearly that information can be transmitted faster than the speed of light.
You and me, Mew! I still can’t wrap my brain around the concept that the speed of light is constant, and any circumstance where the speed of light appears to be faster or slower, than time is either slower or faster, respectively. Why can’t it be the other way around?
Hee hee. I feel better now!
You’re not alone, buddy, lol!
First they say that direct communication is impossible. Then they say that if it occurred it had to have taken place at least 100,000 times faster than light! Huh?
There was no FTL information transfer. The wavefunction instantaneouly collapsed into an observable, by the book, sourcing consistent data. Information existed only after opposite ends compared datasets - and that transmission happens no faster than lightspeed. Viewing one dataset allows no conclusions to be drawn. It won't even do FTL Morse code. The universe is causal.
The secret lives of subatomic particles! I just love this stuff.
I just wish I could stop thinking like a monkey!
complicated by the fact that observation has an impact on the outcome.
There are a few other examples in quantum physics of instantaneous effects, but to call it “information” is misleading. It can never be used for communication purposes, for instance, because the “information” is really only partial. Altering an entangled particle will effect the other one similarly, but also randomly. In order to compare the two, you still need to communicate the information at light speed (or less).
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.