Physicists Create Quantum Link Between Photons That Don't Exist At the Same Time 364
sciencehabit writes "Physicists have long known that quantum mechanics allows for a subtle connection between quantum particles called entanglement, in which measuring one particle can instantly set the otherwise uncertain condition, or 'state,' of another particle—even if it's light years away. Now, experimenters in Israel have shown that they can entangle two photons that don't even exist at the same time. Anton Zeilinger, a physicist at the University of Vienna, says that the experiment demonstrates just how slippery the concepts of quantum mechanics are. 'It's really neat because it shows more or less that quantum events are outside our everyday notions of space and time.'"
Photon model broken (Score:4, Insightful)
'It's really neat because it shows more or less that quantum events are outside our everyday notions of space and time.'"
No, not really. You're simply see the macro effects of partial photons interacting, and unwilling to give up the idea of the discrete photon.
If all you can see (and measure) is a photons promotion and demotion of electrons, you an only see the fast shift of the big circles jumping around in this picture, not the slower smaller drift that is happening.
http://i.imgur.com/AUXb2N9.gif
Give up your photon model, it's based on a faulty understanding.
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Well, so quantization of energy is wrong then? If you can have "fractional photons", then the Rayleigh-Jeans formula is completely correct. Never mind that it predicts that all blackbodies should be emitting radiation with infinite power.
Observation vs model (Score:3, Interesting)
If I had a machine, and it could only see the large circles, then all I would see is the large circles.
If I then made a model of how the large circles appear and disappear, that model would be correct, it would fit the data, it would show the probability of the circles appearing as they jump around. Those circles will jump, they'll go backwards in time, they'll do kinds of weird things.
So my equations all work, and my model of jumping circles works, ergo my model is correct?
Except it isn't, its a function o
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That way from the beginning they'll be wired to accept that the truth is bigger than "gravity's uniform everywhere" or e=m*c*c without the momentum parts even if
Re:Photon model broken (Score:5, Insightful)
The world is made of 4 basic elements, earth, air, fire, water.... No, scratch that, there are a bunch of elemental stuffs, the most holy of which is quicksilver, the universal element... Wait, no, there are over a hundred chemicals with different properties. Ah, look, see, there are atoms, you know, and inside these atoms you have electrons, protons, and neutrons -- See, that's what gives the atoms their properites -- And, wait, the sub atomic particles are made of Quarks, and -- No, there's a zoo of particles, and fields and they all interact in these little quantized packets / waves, Quantum Physics -- No, wait the quanta.......
The rabbit hole is very deep indeed. Better tools show us finer structure. I agree. It would be exceedingly arrogant and foolish to think of light as "photons". We have only approximations, and they are always a bit wrong.
Re:Photon model broken (Score:5, Informative)
Today, we call them "solid", "gas", "plasma", and "liquid" respectively.
Re:Photon model broken (Score:5, Funny)
Re:Photon model broken (Score:5, Funny)
Multipass!
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Well, I tend to think of quantum mechanics as proving the universe functions on call-by-need [wikipedia.org], with faster than light being the lack of support for mutation. Entangling then is really just call-by-need evaluating out a circumstance backwards far enough to note that when two waves/particles/whatever were at the same place, they had to have certain exclusionary properties (for the article, one photon was polarized vertically and the other horizontally) which cause the interpretation of entanglement.
Of course,
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Dude, its, like, totally real, man.
The photon is chillin with the physicists at an event in the parallel university after it went through teh wormhole.
Can i have my grant money now ?
Re:Photon model broken (Score:4, Interesting)
I believed as you did. Then I read this http://quantumtantra.com/bell2.html [quantumtantra.com] - Its like Quantum physics , without the maths, and for the it literate.
Changed my ideas on what QM was all about.
Go read it. Seriously.
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Oh, once you've read it, if you can code, go try making a program to simulate whats going on.... Try it. At some point you'll come to the conclusion that something really weird is happening.
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Entangled Object Oriented language? Certainly you'd need parameter overloading.
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How would we perceive that?
Normal folk would look outside.
Half the /. bunch would trudge up the basement stairs and search for a window.
The other half would find an online camera to check outside.
All joking aside, you made an interesting comment.
I have also suspected the universe has to be moving in odd ways.
I base this on the behavior of surrounding space near a supernova, the odd nebula formations seen in the universe, and the expansion of said universe observed...and they say weather, or nuclear explosions are hard to model!
Science (Score:5, Funny)
At some point, science just got too weird. We had this nice model of the universe with atoms, some laws of motion and thermodynamics. The universe was basically a giant billiards match. It made sense. It was easy to explain. Then we get into quantum mechanics and everything is crap shoot. Multiple universes. Particles that behave differently when being observed. Spooky action at a distance.
Let's all pretend the last 80+ years of science didn't happen and we live under Newton's ideas of how everything behaved. Who's in?
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...
Let's all pretend the last 80+ years of science didn't happen and we live under Newton's ideas of how everything behaved. Who's in?
I'm sure some of the various religions will be glad to join your thinking (if they aren't already there).
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Re:Science (Score:5, Funny)
At some point, science just got too weird. We had this nice model of the universe with atoms, some laws of motion and thermodynamics. The universe was basically a giant billiards match. It made sense. It was easy to explain. Then we get into quantum mechanics and everything is crap shoot. Multiple universes. Particles that behave differently when being observed. Spooky action at a distance.
Let's all pretend the last 80+ years of science didn't happen and we live under Newton's ideas of how everything behaved. Who's in?
That's what you said last time. Look what it got us? We're back to quantum physics AND we have nuclear weapons. Are you really ready to risk Universe hopping again?
Re:Science (Score:5, Funny)
Nature and nature's laws lay hid in night;
God said "Let Newton be" and all was light.
It could not last; the Devil shouting "Ho!
Let Heisenberg be!" restored the status quo.
Re:Science (Score:5, Funny)
Let Heisenberg maybe!" restored the status quo.
No Science, No Porn (Score:3)
Re:Science (Score:5, Funny)
Let's all pretend the last 80+ years of science didn't happen and we live under Newton's ideas of how everything behaved. Who's in?
the Republican Party? large swaths of the American Bible Belt? Scientologists? Liberal Arts majors? Michio Kaku?
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At some point, science just got too weird. We had this nice model of the universe with atoms, some laws of motion and thermodynamics. The universe was basically a giant billiards match. It made sense. It was easy to explain. Then we get into quantum mechanics and everything is crap shoot. Multiple universes. Particles that behave differently when being observed. Spooky action at a distance.
Douglas Adams had some very wise words on this subject, the implied conclusion being that scientists studying the universe are making it more complicated.
Let's all pretend the last 80+ years of science didn't happen and we live under Newton's ideas of how everything behaved. Who's in?
Maybe you could go all the way back to when the universe began, 6000 years ago? But don't look back or you might get turned into a pillar of salt or something like that.
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"I find X to be strange" is another way of saying "I'm pretending that I live in a magical, X-free fantasy world.". There is no such fantasy world and never has been. Nature doesn't care if your brain is mis-configured.
When we get a result that's unexpected, we have an opportunity to deepen our understanding. That's science. When we get a result that's "strange", we're being contrary to our own knowledge. That's not science; I'd say it's more like religion.
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Science is always weird. 100 years ago atom weren' known exist. electricity was some wierd etheral vapor. besides atoms and laws of motion and thermodynamics only cover somethings. we kept noticing funny results at the edge cases. The farther down we go the funnier the results get.
Eventually we will find out that all this quantum stuff actually makes sense and the funny properties are the results of us using planets the size of mars to figure out where the earth is. (relatively speaking).
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Re:Science (Score:5, Interesting)
The latest Scientific American has an article about a newish bayesianized quantum theory. To the limited extent that I understand it, the wave function is just the bayesian priors - what you think before you collect the evidence. The only thing that collapses when you measure something is your ignorance about the state of the universe.
"doesn't exist" (Score:5, Funny)
Hey guys, Einstein just called me using GravePhone(tm) and he had the following to say:
"Okay, maybe God does play dice, but I still stand by the law of conservation. God doesn't just make shit up. Now if you'll excuse me, Aristotle wants some one on one on the basketball court."
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Pfffft. Aristotle made up stuff while "thinking" about the world. This is not science.
This is an extremely childish and anachronistic viewpoint. Newton entertained many unscientific notions alongside those which bore fruit; the scientific method was an invention of his generation. We owe an incalculable amount of our understanding of the universe to philosophy, and selective ignorance of history changes nothing.
Above all else, the classical scholars gave the Renaissance scientists an intellectual authority with which to question the world; it is absolutely absurd to suggest they were ignored
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More to the point, however, they would still be much better basketball players.
You guys really over-thought this. I picked Aristotle because he's a famous scientist. No other reason.
Makes sense enough (Score:2)
Getting so tired of this "instantaneous" BS (Score:5, Interesting)
Special Relativity makes quite clear that if two particles are spacelike [wikipedia.org] separated when measured, that the concept of "instantaneous" is devoid of meaning.
If you have this kind of distance than you will have just one special reference frame where this is true, and infinite more where the events are arbitrarily separated in time. This is already at the core of the EPR paradox [wikipedia.org].
I.e. that you can have entanglement across time follows trivially from SR and the EPR paradox.
It's just astounding how many times the very same insight can get repackaged and sold as new.
Re:Getting so tired of this "instantaneous" BS (Score:5, Funny)
It's just astounding how many times the very same insight can get repackaged and sold as new.
And that my son is why you will never work for the patent office.
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.
Re:Getting so tired of this "instantaneous" BS (Score:4, Insightful)
It's a common misconception that QM as a theory of the microcosm is somehow more general and accurate than SR. Yet, the derivation of SR does not even require the constance of light speed (although that's the route that Einstein oribinally followed), but can be derived from very obvious first principles [ist.utl.pt].
And this is a key difference to QM where this still hasn't been accomplished (despite the theory being such a fantastic empirical success story). Of course as far as empirical evidence goes SR also has a spotless record (which is why the CERN faster than light brewhaha was pretty much a forgone conclusion [wavewatching.net]).
.
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Special Relativity makes quite clear that if two particles are spacelike [wikipedia.org] separated when measured, that the concept of "instantaneous" is devoid of meaning.
If you have this kind of distance than you will have just one special reference frame where this is true, and infinite more where the events are arbitrarily separated in time.
While the above is true, I wonder how is this relevant to the issue at hand?
I mean: who the hell mentioned something about instantaneous?
TFA:
to begin, researchers zap a special crystal with laser light a couple of times to create two entangled pairs of photons, pair 1 and 2 and pair 3 and 4.
1. First zap - they create (1,2)
2. Next zap (delta(t)>0) in the same space (delta(r)==0): they create (3,4)
Seems to me they are working in time-like conditions [wikipedia.org], aren't they?
The experiment shows that it's not strictly logical to think of entanglement as a tangible physical property, Eisenberg says. "There is no moment in time in which the two photons coexist," he says, "so you cannot say that the system is entangled at this or that moment." Yet, the phenomenon definitely exists.
My first read of TFA: the guys managed to "entangle" photons created at different times.
But then... hang on... weirder-and-weirder : they entangled photons that don't even exist in the same ti
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Here's another theory for you (Score:3)
Some time ago I gave some thought to the apparent anomalies and strangeness of the quantum world.
Here's what I came up with as a theory It's all about time [aardvark.co.nz]
Comments would be welcomed from all the (real and wannabe) quantum physicists out there.
Re:Here's another theory for you (Score:5, Insightful)
The problem is that to be accepted in an area of science that's basically nothing more than a consequence of the maths, you have to show the maths that generate the results you expect.
I'm a mathematician. I don't claim to understand 1% of 1% of quantum mechanics at all. But it comes from a mathematical model that happens to have real-world consequences that are weird and wonderful. When we then tested for those consequences, we found out that they exist in nature. Which, to a scientist mind, kind of hints that the maths must have been at least somewhat correct (or at least on the right lines).
I have my own understanding and theories, but I would also have to state, quite clearly, that quantum physics isn't really "physics". This isn't Newton seeing an apple fall and realising there's a force at play. This is someone (probably THE most famous genius) sitting down for decades with almost unsolvable equations that make absolutely no sense until they realise that it works if you have 11 dimensions, or if space and time are two different elements of the same thing, etc. And that was back in the 1900's when quite a lot of physics and maths we enjoy now didn't even exist.
Then you go out and measure in real life and you find that, actually, it turns out that your theory fits what happens in the world, not the other way around.
As such, I don't for a second think that I can just posit a hypothesis (theory is a slightly stronger word in any science) and have any concept of if I'm talking gibberish or not. The maths of quantum mechanics is horrendous and complicated and quantum theorists spend more time in front of the blackboard than they do the LHC.
If you wish to contribute, even if you don't intend to be taken seriously, it's only proper to get yourself a decent grounding in not just "hey, there's something smaller than an electron and weird stuff starts to happen at that scale, I bet I can guess what else happens", but in WHY that's so and HOW we got to that point. And in anything quantum, that means understanding the maths behind it.
As someone with a degree in maths, I tell you now, you're going to need a decent grounding in quite a lot of basic physics and huge amounts of maths and that "real world intuition" will basically be next-to-useless until the very end. That's not to mention the level of things like calculus and linear algebra you'd need to even get close to learning how we got to all of the old "wrong" models, let alone the newer ones.
This doesn't mean that wild ideas and theories have no merit, it's just that you're theorising about something that you probably don't understand the basics of. I know I don't. And I *can* read the mathematics and, given enough time, understand it.
It just comes across to any mathematician or physicist as someone who is looking at a car for the first time and saying "You know, I bet if you made the whole thing ten times bigger, it would go even faster" or "If it goes that fast with four wheels, imagine what it'll do with 10!".
In a way it reminds me of the Moon conspiracy theorists. They can come up with a million weird and wonderful things that intuition says "must be wrong". But it turns out that a few simple tests or bits of maths show them to all be nonsense. "The shadows are wrong" - fine, go out into the street on a sunny day and try hard to replicate them. If someone can replicate something that's "wrong" in the space of ten minutes, then maybe you are reading far too much into the image, or commenting on something you just don't understand.
https://en.wikipedia.org/wiki/Introduction_to_quantum_mechanics [wikipedia.org]
Seriously, just on that page there are some 16 equations, and that's not even a millionth of what you need to understand where those equations come from.
Honestly, I DON'T understand quantum mechanics at all. I believe it, because it's accepted as the best self-consistent theory we have that has made verif
The summary makes a bigger deal of this than it is (Score:5, Informative)
When you read the article, this isn't actually too controversial. All that's being done is changing the timing of of when the measurements are taken and when the intermediate photons become entangled. It's really just using the entanglement process to spread out the time over which the quantum state data is transmitted. You basically have a quantum data historical record.
I can certainly see this opening up useful new capabilities in quantum computing and measurement of quantum phenomena, but it doesn't change our understanding of quantum events and how they interact with our "everyday notions of space and time.".
Slower than the speed of light (Score:2)
Superposition, wave function collapse and other quantum effects are supposed to govern everything. But I don't seem to recall any such weird experiments that do not involve any particle traveling slower than the speed of light.
Are there any such demonstrations that involve only interactions between particles having nonzero rest mass?
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42? (Score:2)
????
Star Trek era looming (Score:3, Funny)
Yes! Subspace communications!
How can they tell if 1 and 4 do not coexist? (Score:5, Interesting)
According to the article, particles 1 and 4 do not coexist. Therefore, one must be destroyed before the other is created.
But if 1 is destroyed before 4 is created, then the entanglement of 1 and 2 is broken before 3 and 4 are created (because 3 and 4 are created together, and then 2 and 3 are entangled).
So, by the time 2 and 3 are entangled, 1 does not exist, because 3 already exists and is entangled with 4.
The question that arises is then how do they know that 1 and 4 are entangled?
It could simply be that 1 and 4 show the same state when measured, because 1 and 2 were entangled, then 3 and 4, then 2 and 3. Which means that whatever entanglement existed between 1 and 2 will exist between 1 and 3 and 1 and 4, even if 1 does not exist.
That does not mean particles are entangled across time. It may mean that entaglement is simply peristent and transmiitable.
Most probably there is a misunderstanding somewhere between the announcement and the article, so please anyone that knows more, elaborate.
No surprise, due to different reference frames. (Score:2)
Entanglement exists outside of reference frames. So, it exists across time.
This means that there is a super reference frame which includes all possible frames and allows for things to persist (and perhaps move) across time.
Spooky action at a distance.... (Score:2)
Now I understand Einstein's wild hairdo....
I think the rabbit hole may be a wormhole without the other end!
*head asplodes!*
Trying to find a way home. (Score:4, Funny)
mmm, I wonder if (Score:2)
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Not edgy, like the previous thread?
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A subtle knife has quite the edge.
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Before and after (Score:3, Insightful)
Question: Within the context of quantum mechanic, what is the behavior of TIME ?
What I read from TFA is that they observe a certain particle at the before time frame, and then compare it with another particle at the after time frame, and found some "entanglement"
What if the experiment is carried out on the reverse --- someone checking out a particle at the after time frame and then, some others compare it with another particle at the before time frame and see if they entangle or not
I do understand that expe
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But what if someone later decides to NOT do the after step, even though the before step has already happened and its answer is in the sealed envelope?
Re:Before and after (Score:4, Funny)
But what if someone later decides to NOT do the after step, even though the before step has already happened and its answer is in the sealed envelope?
That's when you let the cat out of the box!
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Actually we know very VERY little about the Time dimension. Only recently did we prove frame dragging even existed. we still have not proved other distortions of time NOR if the rules of time change for quantium level.
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AFAIK, it's simplest to describe things with the time-independent Schrödinger equation [wikipedia.org]: H Psi = E Psi. This is close enough for most stable molecular states in chemistry. However, if you're talking about state transitions or spectroscopy or (as in this case) entanglement, you have no choice but to use the time-dependent Schrödinger equation: i h-bar d Psi / d t = H Psi, which is MUCH more difficult.
That H is not a v
Re:Before and after (Score:4, Funny)
QM is not so hard, once a person realizes that quantum mechanics is all about semantics and has nothing to do with physics.
For instance, the difficulty in understanding this quantum entanglement of photons separated by time collapses into meaninglessness as soon as one accepts that "time" is an attribute of "observation" and has nothing to do with reality (whatever that might be).
As soon as you get past the desire to structure your memories in a simplistic linear fashion, you will realize that was zen, this is tao.
[Did author of this post intend to convey any kind of meaning to the reader? That doesn't matter--- what matters is whether the reader extracts any kind of meaning from the words of the author. Confused? Good. To be other than confused in this universe is to deny the reality of what you observe.]
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Can an "after" happen _before_ a "before" ?
As far as we can tell, yes. This is known as retrocausality, and experiments have been done [wikipedia.org] that it's at least plausible to interpret as having observed it.
This is a very thorny subject because we have so many biases about how the universe "ought to" be, and it's hard to even talk about the subject, much less interpret an experiment, without bringing in all those biases. But I'll describe the interpretation that I find the cleanest, simplest, and most appealing. Other people have other views.
First, you n
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This is basically correct. Most people state the 2nd law of thermodynamics backwards. There isn't any fundamental law of nature that causes entropy to increase with time. Rather, we define "forward in time" to mean, "the direction of increasing entropy." In our local region of spacetime, that translates to, "away from the big bang."
What's surprising is how few physicists really understand this. None of my textbooks ever described it that way. Yet Boltzmann understood this perfectly well in the 19th ce
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If it is actually possible to utilize the entanglement there are a number of commercial possibilities as well as governmental. Communication that is hard to spy on, faster communication across the globe, instant communication with remote operated vehicles on other planets.
But we don't know until we have freed Schrödingers Cat - or has it actually teleported itself to another plane of existence?
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I'm pretty sure we already know the answer. The cat is dead. Curiosity killed it. [iwastesomuchtime.com]
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Everything is theoretically impossible, until it is done.
Robert A. Heinlein
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Re:Wait for the retraction (Score:5, Informative)
Entanglement can be used to exchange keys for secret communication. It allows two parties to create a shared key without anyone being able to intercept it. In principle, this key can be as long as the message itself and perfectly random, so a simple 'xor' operation is all it takes to make the message completely undecryptable. In more detail:
Alice wants to send a secret message to Bob.
They (or anybody else, really) create a bunch of entangled photons, half going to Alice and the entangled counterparts going to Bob. This all happens at normal speeds (not faster than light), but can be prepared in advance.
If anyone tries to eavesdrop during transmission of the entangled photons, Alice and Bob are able to detect the fact that the photons are no longer in a superimposed state and start over with a new bunch.
Now Alice and Bob measure the photons. They have no control over the outcome of the measurements, which will be completely random, but they do know that they will both get the same result (or rather, exactly the opposite result). This becomes their cryptographic key.
Now Alice encrypts her message with this key and sends it to Bob using traditional communication channels, for example a carrier pidgeon.
Bob uses his identical key to decrypt the message.
The only faster-than-light part of the story is that the entangled photons "chose" their state at the time of the measurement. Before the measurement, they were in a superimposed state. This means the information for the key didn't even exist yet in any way and can therefore never be intercepted by anyone. It only came into existence at the time the photons were measured, simultaneously for Alice and Bob. (Take the word "simultaneously" with a grain of salt, because as the article shows, they can even be separated in time). And the encrypted message without the key is just a series of random bits.
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Because the information needed to test the entanglement requires conventional transmission. There is no way to prove the postulated quantum teleportation of the information. Or both particles need to be created under lab like perfect conditions and moved apart. Which won't happen faster then relativistic speeds. Therefore we observe no breaking of causality.
I think a few people have claimed causality breaking on occasion but the general scientific consensus is that isn't what is happening. There was a much
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I think in the most simple terms the experiment went like this:
Particle A set was measured having a statistically consistent result, particle set B was not measured.
Particle set A was measured again.
Particle set B was measured for the first time and had a different result then particle set A.
They postulated that performing the measurement #2 is what caused A's measurement to be consistent.
The interesting bit of the experiment was how they were measuring particles. However I can't explain it.
In other words I
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Let me guess, tl;dr?
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Re:Wait for the retraction (Score:5, Informative)
Yeah, this. What the AC may be confused about is that faster than light travel is (as far as we know) not possible in space, but the distance between two points can increase faster than light could travel because there's nothing stopping space itself from expanding that fast.
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So what's stopping space itself from contracting that fast, ie reducing the distance between two points?
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Dark energy - a term coined to hide the fact that "we don't know". Dark energy seems to be accelerating the expansion after a period of deceleration, this is baffling but fits observational results. The theory is that gravity used to slow the expansion down, but apparently we passed a cut-off point where space has become stretched enough so that gravity is too weak - another force is taking over and stretching space again. A force with no obvious cause, not to us at least.
Re:Wait for the retraction (Score:4, Insightful)
Dark energy - a term coined to hide the fact that "we don't know".
It's not a term to hide the fact that "we don't know", it's a term to punctuate that "we don't know". If we were really trying to hide stuff, we'd define it as stuff we already know about rather that come up with a new term (like the MOND guys are doing with dark matter).
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Lorentz transformations only cover special relativity. In general relativity, you can indeed have the distance between two points grow faster than light. Of course not if the points are at the same place.
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Precisely.
OK, not precisely. Two points at the same place at the same time is one point, not two points. But I knew what you meant.
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Lorentz transformation and Einstein's theories govern motion in space. Space itself can expand at much greater velocities than c. The Observable Universe is something like ~80 billion LY across (today), but the objects furthest from us are ~14 billion LY away (when they emitted the light). If space could not expand faster than c, it would only be ~14 billion LY across today. Look up inflation if you're genuinely interested.
Re:Wait for the retraction (Score:5, Interesting)
Space itself can expand at much greater velocities than c.
To explain this in a little more depth, what we call "space" is really just tied to an arbitrary choice of space-time coordinates. If we choose a different reference frame, distances and times will be different. Just to give a silly example, if I define a meter to be the width of an atom, or if I define a second to be the time required for the earth to go around the sun a thousand times, I can easily travel faster than c. So how does this apply to cosmology and general relativity?
Depending on the coordinate system you choose, the universe can really look radically different, even to the point of no longer being infinite. I will give two possible views, both equally valid even thought the first may appear strange. (So read the rest as well before labeling it as rubbish).
You can apply a classic "special(ly?) relativistic" coordinate system to the universe, with us at the center. The speed of light is the same everywhere, relative to us, just like Einstein said in the beginning. Things that are far away from us are moving away at high speed (but less than the speed of light) and are therefore aging more slowly. This means that some far away galaxy isn't just younger (defined as the amount of local evolution after the big bang) because we had to wait for its light to get to our telescope, it actually is younger "right now" even if we take the traveling time of light into account. Local clocks are really advancing more slowly. The effect increases with increasing distance, and at a distance of c times the age of the universe, the big bang is happening as we speak. Right now. This also means that the universe is finite (assuming nothing existed before the big bang, which is a big assumption). Not that it matters much, because we could never reach this "edge" anyway. It is retreating at the speed of light.
This model is quite interesting but a bit cumbersome for cosmology, so most people prefer to use the "cosmological model". They simply adjust the coordinates of time and space so that the whole universe is the same age and looks roughly the same everywhere, "right now". See, we just changed the definition of "now" and chose a coherently matching set of space coordinates so everything looks rougly the same size, that's all we did. In General Relativity, we are completely free to do so, you can pick pretty much any coordinate system you like. Things can move from the future into the past and back again as we change our variables, without impacting causality (which is all that matters).
Using the cosmological model, the universe is now truly infinite, the big bang is in the distant past everywhere and all the clocks are running at the same speed (as long as they are stationary relative to "space", i.e. moving away from us at the same speed as the average local galaxy). Now, however, the assumptions of special relativity no longer hold. In particular, the speed of light is no longer the same everywhere. Light speed is still the same everywhere locally, relative to "space" (the speed of the average galaxy in that area), but you have to take the properties of our peculiar coordinate system ("expanding space") into account. If at some distance, "space" and the objects in it are expanding away from us faster than the speed of light, the light from those galaxies will never reach us since it will actually be retreating as if it were running towards us on a conveyor belt moving the other way at a higher speed. The conveyor belt isn't "real", it's just an artifact of our choice of coordinates which does not comply with special relativity.
In the first model, those distant galaxies simply never come into existence since the local "space" is asymptotically stuck at a time shortly after the big bang. Things over there are moving away from us at increasing velocity approaching c, and time (rate of aging of that part of the universe) is grinding to a halt.
But do those places exist or not?
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Re:Wait for the retraction (Score:5, Informative)
We already knew that.
Whatever "we" you mean count me out.
According to GR gravity is facilitated via a retarded potential [wikipedia.org], and of course GR survived so far every conceivable test and has been shown to make correct predictions were Newtonian gravity failed.
So no, gravity does not operate faster than light.
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Rubbish. Gravity is not FTL, and your argument is BS.
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Rubbish. Gravity is not FTL, and your argument is BS.
I suspect a whoosh might be in order here... "The Sun is of course moving" should have been a dead giveaway.
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Except that the Earth's motion relative to the galactic core already roughly matches that of the Sun (relative to the galactic core).
Lern2frameofreference.
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Ooooh, So much ooohs.
Somehow, suddenly I want to play Monkey Island again.
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s/much/many/g
Just waking up and writing in non-native language requires coffee.
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Why not just take a little piece of paper, and write "see other side" on both sides?
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The moment you create a time loop that timeline collapses. Everyone knows this.
Bonus points for creating entanglements across time lines and collapse TWO or more time lines.
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Photons can send states, you can send binary ascii this way. therefore send classical information foreward, very easy to do and then use that classical information to send backwards through the limited communication medium. If I had a single wire to only send a 1 or 0 I could send you anything.
Granted you can only send a single bit right now before the entanglement evaporates, but at some point when they can send more than a single bit of information you will have the possibility.
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keep sending 0's to the end of time... HA! I have you now moose and squirrel!