So, Twid and Vitriol have asked about it. It's both weird and banal, and (as most QM) neither makes sense in the macro world, nor is applicable to it.
Anyway, most of the following is paraphrased or quoted from
Beneath Reality:
First off, we need to be clear: Nearly all the information we can read from a single measurement is inserted ahead of time as we set up our detectors. When the detectors click, all we know is at that instant the part of nature under inspection actually possesses the attributes for which the detectors were tuned. It is probably better to think about it as we are not measuring nature, we are registering clicks on our detectors.
So, we can learn from nature only what we are clever enough to build detectors for. From this perspective, a principal aim of physics is to discover how many essentially different kinds of detectors we can make. The Standard Model is, among other things, an inventory of detector types. That Nature produces clicks in them gives evidence that this is Nature's inventory too. But Nature is also intertwined with the detectors we have built.
So, we put a detector in a location, and tell it which piece of the Standard Model we're looking for. You then tell it what it's Reference Frame is (if a particle can be "spin up" or "spin down", you need to tell it what "up" means). Simple enough, right? The weird bits happen when you start using more than one detector.
Quote
It is easy to imagine apparatus that will produce clicks in two separate detectors that are correlated in some way (I mean for the pattern of clicks to be correlated, not the detector settings, which are always under our control).
For example, an excited nucleus might shed energy by radiating two electrons and nothing else. Imagine that two detectors, A and B, are set up to register them. If the original nucleus were standing still (zero momentum), then the electrons would necessarily be detected moving with identical speeds in opposite directions, because momentum is conserved even in the quantum world (equal and opposite momenta add to zero).
So the momenta are perfectly correlated. Similarly, if the excited nucleus had no spin then the observed spins of the emitted electrons must also cancel (to conserve angular momentum). If the spin detectors are both set at the same angle, we can be sure this apparatus of stationary radiating nucleus plus detectors will cause one detector to register "up" and the other one "down."
Therefore the detector registrations in opposite settings at the two different detectors will be perfectly correlated. This implies that for this system looking at detector A suffices to to determine the result at detector B. The electron excitations at A and B in this case are said to be entangled.
Translation: if you have two detectors, and a nucleus throws off two electrons in equal and opposite direction, the detectors will show a relationship between the two electrons. Not weird yet.
Ok, so if you take the detectors and you misalign one of them, then you're going to get some errors in detection: there will appear to be no correlation between the two electrons. After a bunch of theoretical math, a guy named Bell came up with a theorem that predicted an upper limit of errors (called "Bell's Inequality"). However, when you do a bunch of QM equations, the numbers
violate Bell's Inequality. And when they did experiments, the results
also violated Bell's Inequality. So, something else was going on that couldn't be accounted for. Weird.
The only assumption Bell made was that the two ways of getting an error (misaligning detector A and misaligning detector B) are independent of each other. I can tilt Detector A, and that shouldn't have an effect on what happens at detector B. But because of the experiments and QM equations, somehow the orientation of the detector at A must influence what happens at B and vice versa so as to introduce an additional correlation between events at the two detectors.
Another weird thing: Nothing in the QM equations say how quickly changing A will influence B. The A orientation can be changed just prior to the click of the detector, so there is essentially
no time for a signal propagating at the speed of light to reach from A to B. Experiments show the extra quantum correlation even in this case, suggesting that the influence travels essentially
instantly from A to B, that is, faster than the speed of light. Physicists call this kind of influence "nonlocal".
And that's QUIP. Changing detector A will influence what happens at detector B instantly, which shouldn't be the case.
The main reason this is such a freak out for physicists comes from a paper by Einstein and others, which appears to be more philisophical than anything else. It was not really about physics at all, but about what a physical theory should look like. The authors asserted that a complete theory should have symbols in it that correspond to each "element of physical reality," for which they adopted the following definition:
"If, without in any way disturbing a system, we can predict with certainty ... the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity."That is to say, Einstein decided what reality "should" look like, and decided that since QM didn't match up, it couldn't possibly be right. What is very clear, however, is that QUIP is not compatible with any picture of nature in which the object under inspection is isolated from the instruments of detection.
Now, feel free to make the case for telepathy and teleportation.
:asplode:
Ok, this is going to take a bit of processing.
Short version:
If you have two detectors on opposite sides of an event, A and B, then changing the angle of A shouldn't change what B is detecting.
But when really fucking small, it does. And the change happens faster than the speed of light.
Good summary LMNO!!!
In a practical encryption application, the detectors hold a specific number of quantum bits. The direction these bits 'spin' in make up a 'key'. If we change the spin in detector A, the spin changes nonlocally in detector B. Ergo, if we change the spin, we change the key instantly.
Generally, encryption requires some method to securely transport the key from point A to point B. This application makes it no longer necessary, we simply need to get detector B to the endpoint... and then make up a key.
In true quantum fashion, it also means if someone tries to 'snoop' on the key by measuring it, it will change states and the sender/receiver will know someone is trying to snoop on them.
Quantum = Weird Shit.
Quote from: LMNO on June 25, 2010, 06:13:09 PM
Short version:
If you have two detectors on opposite sides of an event, A and B, then changing the angle of A shouldn't change what B is detecting.
But when really fucking small, it does. And the change happens faster than the speed of light.
Gotcha, thanks man
http://www.nature.com/news/2010/100317/full/news.2010.130.html
QuoteA team of scientists has succeeded in putting an object large enough to be visible to the naked eye into a mixed quantum state of moving and not moving
QuoteSo if trillions of atoms can be put into a quantum state, why don't we see double-decker buses simultaneously stopping and going? Cleland says he believes size does matter: the larger an object, the easier it is for outside forces to disrupt its quantum state.
Quote from: Ratatosk on June 25, 2010, 06:20:01 PM
http://www.nature.com/news/2010/100317/full/news.2010.130.html
QuoteA team of scientists has succeeded in putting an object large enough to be visible to the naked eye into a mixed quantum state of moving and not moving
QuoteSo if trillions of atoms can be put into a quantum state, why don't we see double-decker buses simultaneously stopping and going? Cleland says he believes size does matter: the larger an object, the easier it is for outside forces to disrupt its quantum state.
That's a little hard to wrap my mind around as well
Quote from: Nephew Twiddleton on June 25, 2010, 06:31:15 PM
Quote from: Ratatosk on June 25, 2010, 06:20:01 PM
http://www.nature.com/news/2010/100317/full/news.2010.130.html
QuoteA team of scientists has succeeded in putting an object large enough to be visible to the naked eye into a mixed quantum state of moving and not moving
QuoteSo if trillions of atoms can be put into a quantum state, why don't we see double-decker buses simultaneously stopping and going? Cleland says he believes size does matter: the larger an object, the easier it is for outside forces to disrupt its quantum state.
That's a little hard to wrap my mind around as well
Me too...
Quote from: Ratatosk on June 25, 2010, 06:39:13 PM
Quote from: Nephew Twiddleton on June 25, 2010, 06:31:15 PM
Quote from: Ratatosk on June 25, 2010, 06:20:01 PM
http://www.nature.com/news/2010/100317/full/news.2010.130.html
QuoteA team of scientists has succeeded in putting an object large enough to be visible to the naked eye into a mixed quantum state of moving and not moving
QuoteSo if trillions of atoms can be put into a quantum state, why don't we see double-decker buses simultaneously stopping and going? Cleland says he believes size does matter: the larger an object, the easier it is for outside forces to disrupt its quantum state.
That's a little hard to wrap my mind around as well
Me too...
So with all this weird quantum stuff, wait ok, before I ask that question, I have another one- So, lets say we have a quantum boat going in a forward direction. So when it's moving-notmoving, are there then two of the quantum boat? We'll ignore that the water would disrupt it's quantum state for now.
Original question, so does QUIP have possible applications for feasible interstellar travel? I guess this goes under the teleportation category mentioned by LMNO
What the hell is a quantum boat?
Quote from: LMNO on June 25, 2010, 06:47:52 PM
What the hell is a quantum boat?
I just made it up now for a thought experiment.
Your response though, made me laugh realizing how absurd the image of a quantum boat is.
Quote from: Nephew Twiddleton on June 25, 2010, 06:45:46 PM
Quote from: Ratatosk on June 25, 2010, 06:39:13 PM
Quote from: Nephew Twiddleton on June 25, 2010, 06:31:15 PM
Quote from: Ratatosk on June 25, 2010, 06:20:01 PM
http://www.nature.com/news/2010/100317/full/news.2010.130.html
QuoteA team of scientists has succeeded in putting an object large enough to be visible to the naked eye into a mixed quantum state of moving and not moving
QuoteSo if trillions of atoms can be put into a quantum state, why don't we see double-decker buses simultaneously stopping and going? Cleland says he believes size does matter: the larger an object, the easier it is for outside forces to disrupt its quantum state.
That's a little hard to wrap my mind around as well
Me too...
So with all this weird quantum stuff, wait ok, before I ask that question, I have another one- So, lets say we have a quantum boat going in a forward direction. So when it's moving-notmoving, are there then two of the quantum boat? We'll ignore that the water would disrupt it's quantum state for now.
1 quantum object, 2 states simultaneously.
Quote
Original question, so does QUIP have possible applications for feasible interstellar travel? I guess this goes under the teleportation category mentioned by LMNO
Who knows? The biggest breakthrough is that we can now see quantum behavior in a "mechanical resonator made of aluminium and aluminium nitride, measuring about 40 µm in length and consisting of around a trillion atoms".
So that is technically 'visible' but just barely... Also it had to be at Absolute 0 (well nearly) to be able to detect it.
I think that it may provide us with a lot better understanding of quantum mechanics, and maybe even help with figuring out a Grand Unified Theory... but teleporting or interstellar travel? I dunno.
Quote from: Nephew Twiddleton on June 25, 2010, 06:48:47 PM
Quote from: LMNO on June 25, 2010, 06:47:52 PM
What the hell is a quantum boat?
I just made it up now for a thought experiment.
Your response though, made me laugh realizing how absurd the image of a quantum boat is.
I don't know if you've seen the other QM threads, but the basic principle I hold is this: What happens on the quantum level has no comparable metaphor in the experiential world. All metaphors are Fail. That's where the biggest misconception of the "Particle/Wave" thing comes from, that we're trying to describe quantum behavior in terms of billiard balls and oceans.
Quote from: LMNO on June 25, 2010, 06:13:09 PM
Short version:
If you have two detectors on opposite sides of an event, A and B, then changing the angle of A shouldn't change what B is detecting.
But when really fucking small, it does. And the change happens faster than the speed of light.
So let me see if I get this - we're talking about tiny little things and tiny little distances, right? Like these detectors aren't three miles apart or anything? We're talking about no more than a couple of nanometres or some bullshit like that? So basically there is some factor (gravity, magnetic field, some new kind of shit we haven't worked out yet... etc) that is still kind of binding these two little things together? I'm picturing them flying off in opposite directions, pushing an invisible "bubble" out in front of them and if you turn the bubble around both the little things will rotate correspondingly?
How close am I?
Quote from: Doktor Vitriol on June 25, 2010, 06:55:11 PM
Quote from: LMNO on June 25, 2010, 06:13:09 PM
Short version:
If you have two detectors on opposite sides of an event, A and B, then changing the angle of A shouldn't change what B is detecting.
But when really fucking small, it does. And the change happens faster than the speed of light.
So let me see if I get this - we're talking about tiny little things and tiny little distances, right? Like these detectors aren't three miles apart or anything? We're talking about no more than a couple of nanometres or some bullshit like that? So basically there is some factor (gravity, magnetic field, some new kind of shit we haven't worked out yet... etc) that is still kind of binding these two little things together? I'm picturing them flying off in opposite directions, pushing an invisible "bubble" out in front of them and if you turn the bubble around both the little things will rotate correspondingly?
How close am I?
No, they can be extremely far away... in fact we have yet to test a distance that doesn't work....
Quote from: LMNO on June 25, 2010, 06:54:45 PM
Quote from: Nephew Twiddleton on June 25, 2010, 06:48:47 PM
Quote from: LMNO on June 25, 2010, 06:47:52 PM
What the hell is a quantum boat?
I just made it up now for a thought experiment.
Your response though, made me laugh realizing how absurd the image of a quantum boat is.
I don't know if you've seen the other QM threads, but the basic principle I hold is this: What happens on the quantum level has no comparable metaphor in the experiential world. All metaphors are Fail. That's where the biggest misconception of the "Particle/Wave" thing comes from, that we're trying to describe quantum behavior in terms of billiard balls and oceans.
Ok, cool, so we have this one particle just floating around in void, and it's in a moving state and a non-moving state. Maybe I'm mistaking movement to mean something other than vibration. Does the moving state start moving away from the non-moving state?
Quote from: Doktor Vitriol on June 25, 2010, 06:55:11 PM
Quote from: LMNO on June 25, 2010, 06:13:09 PM
Short version:
If you have two detectors on opposite sides of an event, A and B, then changing the angle of A shouldn't change what B is detecting.
But when really fucking small, it does. And the change happens faster than the speed of light.
So let me see if I get this - we're talking about tiny little things and tiny little distances, right? Like these detectors aren't three miles apart or anything? We're talking about no more than a couple of nanometres or some bullshit like that? So basically there is some factor (gravity, magnetic field, some new kind of shit we haven't worked out yet... etc) that is still kind of binding these two little things together? I'm picturing them flying off in opposite directions, pushing an invisible "bubble" out in front of them and if you turn the bubble around both the little things will rotate correspondingly?
How close am I?
The math says distance is not a factor. You aren't changing what the other particle does, you're changing how the other particle interacts with the other detector.
Quote from: Nephew Twiddleton on June 25, 2010, 07:00:48 PM
Quote from: LMNO on June 25, 2010, 06:54:45 PM
Quote from: Nephew Twiddleton on June 25, 2010, 06:48:47 PM
Quote from: LMNO on June 25, 2010, 06:47:52 PM
What the hell is a quantum boat?
I just made it up now for a thought experiment.
Your response though, made me laugh realizing how absurd the image of a quantum boat is.
I don't know if you've seen the other QM threads, but the basic principle I hold is this: What happens on the quantum level has no comparable metaphor in the experiential world. All metaphors are Fail. That's where the biggest misconception of the "Particle/Wave" thing comes from, that we're trying to describe quantum behavior in terms of billiard balls and oceans.
Ok, cool, so we have this one particle just floating around in void, and it's in a moving state and a non-moving state. Maybe I'm mistaking movement to mean something other than vibration. Does the moving state start moving away from the non-moving state?
Rat, you brought this point up. Care to address it?
Quote from: LMNO on June 25, 2010, 07:06:37 PM
The math says distance is not a factor. You aren't changing what the other particle does, you're changing how the other particle interacts with the other detector.
Okay I'm definitely not getting this "interacting with detector" distinction. That's the key here isn't it? Any way you can dumb it down just a little bit more? :oops:
Moving can mean multiple things in quantum physics, mostly because, as LMNO pointed out, our words/metaphors are not very good for really talking about this sort of thing.
For example, in some quantum experiments we can shoot a electron from point A to point B and measure either its location or its speed, but not both.
In the example at the macro level linked above, they're discussing movement as a vibration.
In quantum entanglement, the two qbits are often said to be in a state of 'spin up' or 'spin down' .
But of course, its unlikely that any of these provide a mental picture that is really accurate. I think the terms 'energy states' and 'wave functions' get used a lot more these days.
Ok, lessee...
Howabout something Visual?
Detector A = A
Tilting Detector A = A'
Detector B = B
Tilting Detecor B = B'
Nucleus event = (N)
Electron 1 = X
Electron 2 = Y
Setup:
A (N) B
A and B are set up with the same "up" alignment. If the Nucleus event throws off 2 electrons equally, then one will be recorded as spin "up" and one will be spin "down". This is more or less self explanatory. (A=up, B=down). This is "entaglement"
A <---X (N) Y---> B
If you misalign A (making it A'), then it will cause errors in detection: Sometimes it will be correct (A'=up, B=Down) and sometimes it will be incorrect (A'=down, B=down).
A' <---X (N) Y---> B
If you misalign both detectors, it increases the chance for error. Bell's inequality estimates the rate of error for two misaligned detectors.
A' <---X (N) Y---> B'
However...
The QM equations, and experiments, show that the error rate is much lower than Bell's inequality. That means that X and Y shows entaglement at a higher rate than expected. Currently, the only thing that can account for that is information exchange at a rate that is faster than the speed of light.
Okay - I think I'm nearly there. Could you expand a bit on "misalign"
Sorry for being such a retard but I really would like to get this :oops:
Well, if you really want to get it, you can go to school and get a doctorate in Physics and come back to explain it to us ;-)
Let's see... trying to use as little as possible in the way of metaphor:
QbitA and QbitB are placed in the same state and 'entangled'. We can use our detector to measure the state.
We then move these QBITS far away from each other keeping Detector A with QbitA and Detector B with Qbit B.
Now we change the state of QbitA, and immediately measure the state of Qbit B.
We find that QbitB has also changed states.
If you want to imagine the 'state' as spinning or tilting or whatever it doesn't really matter.
The important, interesting totally weird bit... is that the change in state happens more quickly than a photon could get from one location to the other. As far as we know, nothing can travel faster than the speed of light... except whatever is telling Qbit B that it needs to change states.
EDIT: and I fell into metaphor at the end damint!
AHA! I got it. So this "entagled" thing, this is a process you have to do to the qbits before they'll behave this way? Like two "unentagled" qbits don't have the link?
Is the entanglement indefinite or do they become disentangled at some point?
QuoteWhen particles decay in to other particles, these decays must obey the various conservation laws. As a result, pairs of particles can be generated that are required to be in certain quantum states. For ease of understanding, consider the situation where a pair of these particles are created, have a two state spin and one must be spin up and the other must be spin down. As described in the introduction, these two particles can now be called entangled since you can not fully describe one particle without mentioning the other. This type of entangled pair where the particles always have opposite spin is known as the spin anti-correlated case. The case where the spins are always the same is known as spin correlated.
Now that entangled particles have been created, quantum mechanics also holds that an observable, for example spin, is indeterminate until a measurement is made of that observable. At that instant, all of the possible values, that the observable might have had, "collapse" to the value that is measured. Consider, for now, just one of these created particles. In the singlet state of two spin, it is equally likely that this particle will be observed to be spin-up or spin-down. Meaning if you were to measure the spin of many like particles, the measurement will result in an unpredictable series of measurements that will tend to a 50% probability of the spin being up or down. However, the results are quite different if you examine both of the entangled particles in this experiment. When each of the particles in the entangled pair is measured in the same way, the results of their spin measurement will be correlated. Measuring one member of the pair tells you what spin of the other member is without actually measuring its spin.
The controversy surrounding this topic comes in once you consider the ramifications of this result. Normally under the Copenhagen interpretation, the state a particle occupies is determined the moment the state is measured. However, in an entangled pair when the first particle is measured, the state of the other is known at the same time without measurement, regardless of the separation of the two particles. This knowledge of the second particle's state is at the heart of the debate. If the distance between particles is large enough, information or influence might be traveling faster than the speed of light which violates the principle of special relativity. One experiment that is in agreement with the effect of entanglement "traveling faster than light" was performed in 2008. the experiment found the "speed" of quantum entanglement has a minimum lower bound of 10,000 times the speed of light.[5]
From Wikipedia...
Quote from: Nephew Twiddleton on June 25, 2010, 07:49:07 PM
Is the entanglement indefinite or do they become disentangled at some point?
Jesus, I've seen the future - we get a fuckton of these entangled qbits and then we break them up and put them in seperate routers and then we mould even more of them into a controller and the rest into the console ... BAM ... You got no input lag and no ping in your online game
QUANTUM GAMING WILL BE FUCKING AWESOME!
Quote from: Doktor Vitriol on June 25, 2010, 07:58:44 PM
Quote from: Nephew Twiddleton on June 25, 2010, 07:49:07 PM
Is the entanglement indefinite or do they become disentangled at some point?
Jesus, I've seen the future - we get a fuckton of these entangled qbits and then we break them up and put them in seperate routers and then we mould even more of them into a controller and the rest into the console ... BAM ... You got no input lag and no ping in your online game
QUANTUM GAMING WILL BE FUCKING AWESOME!
I think it would be safe to say that such an application would be more likely than teleporting or interstellar travel ;-)
Quote from: Ratatosk on June 25, 2010, 07:54:37 PM
QuoteWhen particles decay in to other particles, these decays must obey the various conservation laws. As a result, pairs of particles can be generated that are required to be in certain quantum states. For ease of understanding, consider the situation where a pair of these particles are created, have a two state spin and one must be spin up and the other must be spin down. As described in the introduction, these two particles can now be called entangled since you can not fully describe one particle without mentioning the other. This type of entangled pair where the particles always have opposite spin is known as the spin anti-correlated case. The case where the spins are always the same is known as spin correlated.
Now that entangled particles have been created, quantum mechanics also holds that an observable, for example spin, is indeterminate until a measurement is made of that observable. At that instant, all of the possible values, that the observable might have had, "collapse" to the value that is measured. Consider, for now, just one of these created particles. In the singlet state of two spin, it is equally likely that this particle will be observed to be spin-up or spin-down. Meaning if you were to measure the spin of many like particles, the measurement will result in an unpredictable series of measurements that will tend to a 50% probability of the spin being up or down. However, the results are quite different if you examine both of the entangled particles in this experiment. When each of the particles in the entangled pair is measured in the same way, the results of their spin measurement will be correlated. Measuring one member of the pair tells you what spin of the other member is without actually measuring its spin.
The controversy surrounding this topic comes in once you consider the ramifications of this result. Normally under the Copenhagen interpretation, the state a particle occupies is determined the moment the state is measured. However, in an entangled pair when the first particle is measured, the state of the other is known at the same time without measurement, regardless of the separation of the two particles. This knowledge of the second particle's state is at the heart of the debate. If the distance between particles is large enough, information or influence might be traveling faster than the speed of light which violates the principle of special relativity. One experiment that is in agreement with the effect of entanglement "traveling faster than light" was performed in 2008. the experiment found the "speed" of quantum entanglement has a minimum lower bound of 10,000 times the speed of light.[5]
From Wikipedia...
Holy shit
10000+ times the speed of light?!?
So, I think I get it now. Damn. And they do not become disentangled because they're halves of the same particle.
Quote from: Ratatosk on June 25, 2010, 08:01:36 PM
Quote from: Doktor Vitriol on June 25, 2010, 07:58:44 PM
Quote from: Nephew Twiddleton on June 25, 2010, 07:49:07 PM
Is the entanglement indefinite or do they become disentangled at some point?
Jesus, I've seen the future - we get a fuckton of these entangled qbits and then we break them up and put them in seperate routers and then we mould even more of them into a controller and the rest into the console ... BAM ... You got no input lag and no ping in your online game
QUANTUM GAMING WILL BE FUCKING AWESOME!
I think it would be safe to say that such an application would be more likely than teleporting or interstellar travel ;-)
Not nearly as cool though. But fuck it would do a lot for computing.
Might lead to that AI breakthrough Sig seems to want.
Quote from: Nephew Twiddleton on June 25, 2010, 08:02:04 PM
Quote from: Ratatosk on June 25, 2010, 07:54:37 PM
QuoteWhen particles decay in to other particles, these decays must obey the various conservation laws. As a result, pairs of particles can be generated that are required to be in certain quantum states. For ease of understanding, consider the situation where a pair of these particles are created, have a two state spin and one must be spin up and the other must be spin down. As described in the introduction, these two particles can now be called entangled since you can not fully describe one particle without mentioning the other. This type of entangled pair where the particles always have opposite spin is known as the spin anti-correlated case. The case where the spins are always the same is known as spin correlated.
Now that entangled particles have been created, quantum mechanics also holds that an observable, for example spin, is indeterminate until a measurement is made of that observable. At that instant, all of the possible values, that the observable might have had, "collapse" to the value that is measured. Consider, for now, just one of these created particles. In the singlet state of two spin, it is equally likely that this particle will be observed to be spin-up or spin-down. Meaning if you were to measure the spin of many like particles, the measurement will result in an unpredictable series of measurements that will tend to a 50% probability of the spin being up or down. However, the results are quite different if you examine both of the entangled particles in this experiment. When each of the particles in the entangled pair is measured in the same way, the results of their spin measurement will be correlated. Measuring one member of the pair tells you what spin of the other member is without actually measuring its spin.
The controversy surrounding this topic comes in once you consider the ramifications of this result. Normally under the Copenhagen interpretation, the state a particle occupies is determined the moment the state is measured. However, in an entangled pair when the first particle is measured, the state of the other is known at the same time without measurement, regardless of the separation of the two particles. This knowledge of the second particle's state is at the heart of the debate. If the distance between particles is large enough, information or influence might be traveling faster than the speed of light which violates the principle of special relativity. One experiment that is in agreement with the effect of entanglement "traveling faster than light" was performed in 2008. the experiment found the "speed" of quantum entanglement has a minimum lower bound of 10,000 times the speed of light.[5]
From Wikipedia...
Holy shit 10000+ times the speed of light?!?
So, I think I get it now. Damn. And they do not become disentangled because they're halves of the same particle.
Actually, some scientists have observed what is called "entanglement sudden death" which basically results is a clean break between the two particles. Though last I read, no one has figured out what the hell is going on there.
I think being a quantum physicist must be fun... get up in the morning, observe an experiment, become confused, go get drunk and go to bed.
:lulz:
EDIT: Apparently its more correctly called "early-stage disentanglement"
http://www.sciencemag.org/cgi/content/abstract/323/5914/598
http://www.scientificamerican.com/article.cfm?id=quantum-entanglement-sudden-death
It's interesting that they tie this to environmental 'noise' . Maybe its related to the earlier discussion of macro effects which 'get canceled out by other forces', I dunno...
Quote from: Ratatosk on June 25, 2010, 08:06:04 PM
Quote from: Nephew Twiddleton on June 25, 2010, 08:02:04 PM
Quote from: Ratatosk on June 25, 2010, 07:54:37 PM
QuoteWhen particles decay in to other particles, these decays must obey the various conservation laws. As a result, pairs of particles can be generated that are required to be in certain quantum states. For ease of understanding, consider the situation where a pair of these particles are created, have a two state spin and one must be spin up and the other must be spin down. As described in the introduction, these two particles can now be called entangled since you can not fully describe one particle without mentioning the other. This type of entangled pair where the particles always have opposite spin is known as the spin anti-correlated case. The case where the spins are always the same is known as spin correlated.
Now that entangled particles have been created, quantum mechanics also holds that an observable, for example spin, is indeterminate until a measurement is made of that observable. At that instant, all of the possible values, that the observable might have had, "collapse" to the value that is measured. Consider, for now, just one of these created particles. In the singlet state of two spin, it is equally likely that this particle will be observed to be spin-up or spin-down. Meaning if you were to measure the spin of many like particles, the measurement will result in an unpredictable series of measurements that will tend to a 50% probability of the spin being up or down. However, the results are quite different if you examine both of the entangled particles in this experiment. When each of the particles in the entangled pair is measured in the same way, the results of their spin measurement will be correlated. Measuring one member of the pair tells you what spin of the other member is without actually measuring its spin.
The controversy surrounding this topic comes in once you consider the ramifications of this result. Normally under the Copenhagen interpretation, the state a particle occupies is determined the moment the state is measured. However, in an entangled pair when the first particle is measured, the state of the other is known at the same time without measurement, regardless of the separation of the two particles. This knowledge of the second particle's state is at the heart of the debate. If the distance between particles is large enough, information or influence might be traveling faster than the speed of light which violates the principle of special relativity. One experiment that is in agreement with the effect of entanglement "traveling faster than light" was performed in 2008. the experiment found the "speed" of quantum entanglement has a minimum lower bound of 10,000 times the speed of light.[5]
From Wikipedia...
Holy shit 10000+ times the speed of light?!?
So, I think I get it now. Damn. And they do not become disentangled because they're halves of the same particle.
Actually, some scientists have observed what is called "entanglement sudden death" which basically results is a clean break between the two particles. Though last I read, no one has figured out what the hell is going on there.
I think being a quantum physicist must be fun... get up in the morning, observe an experiment, become confused, go get drunk and go to bed.
:lulz:
And get paid for saying, "Uh, nothing makes sense"
At least the scientists in the past who made their discoveries in the patterns made out of chicken intestines, were a more honest form of hustler. I declare QM to be nothing more than an elaborate hoax meant to keep brainy math dudes in a constant supply of nubile and gullible undergrads.
Quote from: Captain Utopia on June 25, 2010, 08:44:19 PM
At least the scientists in the past who made their discoveries in the patterns made out of chicken intestines, were a more honest form of hustler. I declare QM to be nothing more than an elaborate hoax meant to keep brainy math dudes in a constant supply of nubile and gullible undergrads.
:lulz:
Quote from: Captain Utopia on June 25, 2010, 08:44:19 PM
At least the scientists in the past who made their discoveries in the patterns made out of chicken intestines, were a more honest form of hustler. I declare QM to be nothing more than an elaborate hoax meant to keep brainy math dudes in a constant supply of nubile and gullible undergrads.
You might be on to something there!
Quote from: Ratatosk on June 25, 2010, 08:01:36 PM
Quote from: Doktor Vitriol on June 25, 2010, 07:58:44 PM
Quote from: Nephew Twiddleton on June 25, 2010, 07:49:07 PM
Is the entanglement indefinite or do they become disentangled at some point?
Jesus, I've seen the future - we get a fuckton of these entangled qbits and then we break them up and put them in seperate routers and then we mould even more of them into a controller and the rest into the console ... BAM ... You got no input lag and no ping in your online game
QUANTUM GAMING WILL BE FUCKING AWESOME!
I think it would be safe to say that such an application would be more likely than teleporting or interstellar travel ;-)
I've thought the same thing, but my understanding is that this still does not make it possible to transfer information in less time than it would take for the information to travel the same distance at the speed of light.
This always leaves me with 4 basic unanswered questions:
1.)Wut?
2.)Why?
3.)Why not?
4.)Huh?
Quote from: Jerry_Frankster on June 25, 2010, 09:30:39 PM
Quote from: Ratatosk on June 25, 2010, 08:01:36 PM
Quote from: Doktor Vitriol on June 25, 2010, 07:58:44 PM
Quote from: Nephew Twiddleton on June 25, 2010, 07:49:07 PM
Is the entanglement indefinite or do they become disentangled at some point?
Jesus, I've seen the future - we get a fuckton of these entangled qbits and then we break them up and put them in seperate routers and then we mould even more of them into a controller and the rest into the console ... BAM ... You got no input lag and no ping in your online game
QUANTUM GAMING WILL BE FUCKING AWESOME!
I think it would be safe to say that such an application would be more likely than teleporting or interstellar travel ;-)
I've thought the same thing, but my understanding is that this still does not make it possible to transfer information in less time than it would take for the information to travel the same distance at the speed of light.
This always leaves me with 4 basic unanswered questions:
1.)Wut?
2.)Why?
3.)Why not?
4.)Huh?
I'm pretty sure no 3 can be answered with the aid of a microscopic cat and two slits
Quote from: Doktor Vitriol on June 25, 2010, 09:38:57 PM
Quote from: Jerry_Frankster on June 25, 2010, 09:30:39 PM
Quote from: Ratatosk on June 25, 2010, 08:01:36 PM
Quote from: Doktor Vitriol on June 25, 2010, 07:58:44 PM
Quote from: Nephew Twiddleton on June 25, 2010, 07:49:07 PM
Is the entanglement indefinite or do they become disentangled at some point?
Jesus, I've seen the future - we get a fuckton of these entangled qbits and then we break them up and put them in seperate routers and then we mould even more of them into a controller and the rest into the console ... BAM ... You got no input lag and no ping in your online game
QUANTUM GAMING WILL BE FUCKING AWESOME!
I think it would be safe to say that such an application would be more likely than teleporting or interstellar travel ;-)
I've thought the same thing, but my understanding is that this still does not make it possible to transfer information in less time than it would take for the information to travel the same distance at the speed of light.
This always leaves me with 4 basic unanswered questions:
1.)Wut?
2.)Why?
3.)Why not?
4.)Huh?
I'm pretty sure no 3 can be answered with the aid of a microscopic cat and two slits
The results of this experiment have already been observed at the macroscopic scale:
http://www.youtube.com/watch?v=f_tSSn22-FI
http://www.youtube.com/watch?v=3ID149JSVkU&feature=related
Quote from: Jerry_Frankster on June 25, 2010, 09:30:39 PM
Quote from: Ratatosk on June 25, 2010, 08:01:36 PM
Quote from: Doktor Vitriol on June 25, 2010, 07:58:44 PM
Quote from: Nephew Twiddleton on June 25, 2010, 07:49:07 PM
Is the entanglement indefinite or do they become disentangled at some point?
Jesus, I've seen the future - we get a fuckton of these entangled qbits and then we break them up and put them in seperate routers and then we mould even more of them into a controller and the rest into the console ... BAM ... You got no input lag and no ping in your online game
QUANTUM GAMING WILL BE FUCKING AWESOME!
I think it would be safe to say that such an application would be more likely than teleporting or interstellar travel ;-)
I've thought the same thing, but my understanding is that this still does not make it possible to transfer information in less time than it would take for the information to travel the same distance at the speed of light.
Quantum Encryption systems, at this moment can transmit information (the encryption key value = the 'state' of X number of entangled qbits) faster than the speed of light.
Its a limited application but the 'spooky action at a distance' somehow breaks the
rules model.
While the effects of the entanglement do appear to be instantaneous, you cannot actually transmit information with them.
Unfortunately, I seem to have forgotten the details as to why this is. I think it was something to do with having to compare the results at both ends before you can derive the information content. So you need a classical information channel as well.
This means you can have the security of a Quantum Entanglement-based cryptography system, but not the speed.
Edit: Actually, this bit on the talk page of the wikipedia article explains it better:
http://en.wikipedia.org/wiki/Talk:Quantum_entanglement#Quantum_Entanglement_not_violating_speed_of_light
Quote from: Igor on June 28, 2010, 06:33:00 PM
While the effects of the entanglement do appear to be instantaneous, you cannot actually transmit information with them.
Unfortunately, I seem to have forgotten the details as to why this is. I think it was something to do with having to compare the results at both ends before you can derive the information content. So you need a classical information channel as well.
This means you can have the security of a Quantum Entanglement-based cryptography system, but not the speed.
Edit: Actually, this bit on the talk page of the wikipedia article explains it better:
http://en.wikipedia.org/wiki/Talk:Quantum_entanglement#Quantum_Entanglement_not_violating_speed_of_light
Hrmmm...It seems the argument is that since measuring requires our POV, we can't 'get' the information faster than light... so information doesn't travel faster than light. The entanglement 'state change' (according to the math) happens faster than light, but since we can't measure it faster than light then information wasn't really transferred FTL?
Yeees, that sounds about right.
It's annoying, the way the universe has all this cool stuff going on, but whenever you try make it do something useful it disappears.
Almost as bad as the Cosmic Censorship Hypothesis, or the Chronology Protection Conjecture! :argh!:
Quote from: Igor on June 29, 2010, 06:32:46 PM
Yeees, that sounds about right.
It's annoying, the way the universe has all this cool stuff going on, but whenever you try make it do something useful it disappears.
Almost as bad as the Cosmic Censorship Hypothesis, or the Chronology Protection Conjecture! :argh!:
Well, I suppose it could still be useful. If I got the gist of it, the information can't travel faster than the speed of light because the particle in question (in this example a photon) can't go faster than that. Can't do shit with it now, but say if you were able to have a conglomeration of particles in some sort of analog to a radio on Earth and the same on Pluto. The particles in one would be entagled with the particles in the other and stabilized so they don't go flying off somewhere else. You could then send a message to Pluto instantaneously instead of a broadcast that would take 5 hours.
Don't ask me how this is doable. I'm just thinking shit up without a strong understanding of the subject. Naturally the radio would have to get to Pluto first in order for it to be useful. But if we can figure out how to do this sort of thing it might be useful in deep space probes.
So what happens at a distance between qbits measured in Light Years? Obviously the observation is still slower than the speed of light, but not by 'years'... or would it be?
Quote from: Nephew Twiddleton on June 29, 2010, 06:42:08 PM
Well, I suppose it could still be useful. If I got the gist of it, the information can't travel faster than the speed of light because the particle in question (in this example a photon) can't go faster than that. Can't do shit with it now, but say if you were able to have a conglomeration of particles in some sort of analog to a radio on Earth and the same on Pluto. The particles in one would be entagled with the particles in the other and stabilized so they don't go flying off somewhere else. You could then send a message to Pluto instantaneously instead of a broadcast that would take 5 hours.
That won't work. The only time information is passed between the two particles is when they are "set up" on Pluto and Earth. Once they're in place, no more can go through. It's the fact of their being set up that
is the information, in a way.
You really can't get around the speed of light.
Rat, if I understand you correctly; there isn't really much difference in the case where the particles are kilometres apart and when they're light years apart. You have to use the classical channel in both cases to get the information out. In the case of lightyears, it'll just take years instead of minutes.
Easier to use radio waves, really. They're as fast as you can get. The entanglement thing is really only useful for encryption.
Quote from: Igor on June 29, 2010, 09:33:21 PM
Quote from: Nephew Twiddleton on June 29, 2010, 06:42:08 PM
Well, I suppose it could still be useful. If I got the gist of it, the information can't travel faster than the speed of light because the particle in question (in this example a photon) can't go faster than that. Can't do shit with it now, but say if you were able to have a conglomeration of particles in some sort of analog to a radio on Earth and the same on Pluto. The particles in one would be entagled with the particles in the other and stabilized so they don't go flying off somewhere else. You could then send a message to Pluto instantaneously instead of a broadcast that would take 5 hours.
That won't work. The only time information is passed between the two particles is when they are "set up" on Pluto and Earth. Once they're in place, no more can go through. It's the fact of their being set up that is the information, in a way.
You really can't get around the speed of light.
Rat, if I understand you correctly; there isn't really much difference in the case where the particles are kilometres apart and when they're light years apart. You have to use the classical channel in both cases to get the information out. In the case of lightyears, it'll just take years instead of minutes.
Easier to use radio waves, really. They're as fast as you can get. The entanglement thing is really only useful for encryption.
Yep, after reading some more I see what they're saying.
It's not 'technically' information, because its simply either/or. That is I can have quantum Encryption Key A 10 light years from Quantum Encryption key B... If I change the qbits in A, it will change the qbits in B FTL... but to get the encrypted message from A to B it will still take 10 light years.
Even for something like Paul Revere of the Quantum Kind, we'd have to communicate "Spin Up if by Land and Spin down if by sea" in some normal fashion, even if the entanglement change happened FTL.
?
Quote from: Igor on June 29, 2010, 09:33:21 PM
Quote from: Nephew Twiddleton on June 29, 2010, 06:42:08 PM
Well, I suppose it could still be useful. If I got the gist of it, the information can't travel faster than the speed of light because the particle in question (in this example a photon) can't go faster than that. Can't do shit with it now, but say if you were able to have a conglomeration of particles in some sort of analog to a radio on Earth and the same on Pluto. The particles in one would be entagled with the particles in the other and stabilized so they don't go flying off somewhere else. You could then send a message to Pluto instantaneously instead of a broadcast that would take 5 hours.
That won't work. The only time information is passed between the two particles is when they are "set up" on Pluto and Earth. Once they're in place, no more can go through. It's the fact of their being set up that is the information, in a way.
You really can't get around the speed of light.
Rat, if I understand you correctly; there isn't really much difference in the case where the particles are kilometres apart and when they're light years apart. You have to use the classical channel in both cases to get the information out. In the case of lightyears, it'll just take years instead of minutes.
Easier to use radio waves, really. They're as fast as you can get. The entanglement thing is really only useful for encryption.
You can't respin them? I was figuring a sort of binary system, but if it can't be done more than once, then, fair enough. But is there other research to suggest that?
Rat:
You could - theoretically - send a series of entangled particles. Up up down up down etc. So you've got binary and an arbitrary amount of information.
Twid:
I'm afraid I can't quote any research, this is mostly off the top of my head
But it's the process of generating the entangled particles is what causes them to be "linked" like this. That's the only way for the two particles to be linked. The only way to send more info is to entangle more particles and send them.
Or to borrow from LMNO: what we're dealing with here is an event and two detectors. Thus:
D1 -------- E ------------ D2
Once D1 goes bleep, D2 must go bloop. But once the detectors have sounded, no more info can be gained. Grabbing one particle and twisting would probably cause the superposition to decohere and the link to be lost.
This is fun!
Igor,
degree in theoretical physics,
temp job in an office cube.
Quote from: Igor on June 29, 2010, 10:37:52 PM
Rat:
You could - theoretically - send a series of entangled particles. Up up down up down etc. So you've got binary and an arbitrary amount of information.
Twid:
I'm afraid I can't quote any research, this is mostly off the top of my head
But it's the process of generating the entangled particles is what causes them to be "linked" like this. That's the only way for the two particles to be linked. The only way to send more info is to entangle more particles and send them.
Or to borrow from LMNO: what we're dealing with here is an event and two detectors. Thus:
D1 -------- E ------------ D2
Once D1 goes bleep, D2 must go bloop. But once the detectors have sounded, no more info can be gained. Grabbing one particle and twisting would probably cause the superposition to decohere and the link to be lost.
This is fun!
Igor,
degree in theoretical physics,
temp job in an office cube.
I originally wanted to be a scientist but decided to go a very different route, so all of this is hard for me to grasp. I get the fact that once they pass the detectors, one does this, the other does that.
That's why I said having a stable set of particles on Pluto entangled with a stable set of particles on Earth.
For example, in the binary example:
You have 8 particles that aren't going anywhere but are entangled with 8 particles that aren't going anywhere on Pluto. You want to express to Pluto 11010011 (whatever that actually means) which would be up-up-down-up-down-down-up-up. So you would program into this solid state (for lack of a better term) set of 8 entangled particles: down-down-up-down-up-up-down-down....
Oh wait. Ok, I see what you're saying, sort of. I just don't understand why those particles can't be reused. Like those same above mentioned particles can't be respun to send a different message.
Please make any responses as dumbed down as possible, because I apparently am not getting it...
It might help to consider how the particles are generated. A typical way is to make a nucleus (collection of protons and neutrons) decay. It sends out (say) two electrons in opposite directions.
So you do this 8 times and you have your setup on Pluto and Earth. The only reason that the electrons are entangled (and have transmitted the 8 bits of information) is that they both used to be part of that nucleus. It's that decay that generates the information, not the particle state at either end. To send more info you need more decays, not more changes to the particle state
If you did take one of the electrons and changed it from 0 to 1, the link would break. It's the same as looking into Schrodinger's box. A larger system of particles has interacted with the carefully-prepared quantum state and this causes it to collapse. So the cat is dead and the link is broken.
Quote from: Igor on June 29, 2010, 11:08:37 PM
It might help to consider how the particles are generated. A typical way is to make a nucleus (collection of protons and neutrons) decay. It sends out (say) two electrons in opposite directions.
So you do this 8 times and you have your setup on Pluto and Earth. The only reason that the electrons are entangled (and have transmitted the 8 bits of information) is that they both used to be part of that nucleus. It's that decay that generates the information, not the particle state at either end. To send more info you need more decays, not more changes to the particle state
If you did take one of the electrons and changed it from 0 to 1, the link would break. It's the same as looking into Schrodinger's box. A larger system of particles has interacted with the carefully-prepared quantum state and this causes it to collapse. So the cat is dead and the link is broken.
I still don't get why the change would cause a break in the entanglement. The way I understand it is that if you spin up the spin down, it will spin down the sipin up. I'll just have to take your word on it. I probably just read into this wrong, but I got the sense that if you changed the state the complementary particle would instantaneously take the opposite state...
Maybe I'm going to go with Captain Utopia's take and chalk it up to tricking hot research assistants.
The reason they're entangled in the first place is conservation of spin. It's analogous to conservation of momentum, so I'll try to explain it using that conservation law.
You're a space-flight controller on Pluto. A rocket ship radios in, "Hello, this is the solid-propellant rocket Galileo making approach to Pluto spaceport; requesting permission to dock. Our mass is 10,000 kilograms and our approach velocity is 10 meters per second towards Pluto, so our momentum is 100,000 kilogram-meters per second." Now, since you know that momentum is conserved, you can deduce that somewhere in the solar system is a cloud of propellant gases with equal and opposite momentum as the rocket ship (in the reference frame of the rocket ship + propellant system.) You know this because you know that rocket ships start out with the propellant inside fuel tanks and at rest (i.e., at zero momentum.) As long as the rocket and it's propellant don't interact with anything else, the momentum of the system must remain at a constant zero kilogram meters per second. So if you know the momentum of the rocket, you can calculate the momentum of the cloud of propellant gas it ejected, and if you know the momentum of the propellant, you can calculate the momentum of the rocket.
The same thing happens in the creation of the entangled pair of electrons. A particle with zero spin (like a rocket with zero momentum that is loaded with fuel) is split into two particles with equal and opposite spin (like the rocket and propellant with equal and opposite momentum.) If you know the initial condition (the spin of the originating particle, or the initial momentum of the rocket with fuel) and the condition of one of the two halves of the system (the spin of one particle, or the momentum of either the fuel or the rocket) you can calculate the condition of the other half. If you were to then do something to one of the particles, the other particle would be unaffected in exactly the same way (and for the same reason) as the cloud of propellant gas ejected from the rocket doesn't suddenly reverse direction if you were to turn the rocket around from Pluto.
Quote from: Golden Applesauce on June 30, 2010, 12:51:49 AM
The reason they're entangled in the first place is conservation of spin. It's analogous to conservation of momentum, so I'll try to explain it using that conservation law.
You're a space-flight controller on Pluto. A rocket ship radios in, "Hello, this is the solid-propellant rocket Galileo making approach to Pluto spaceport; requesting permission to dock. Our mass is 10,000 kilograms and our approach velocity is 10 meters per second towards Pluto, so our momentum is 100,000 kilogram-meters per second." Now, since you know that momentum is conserved, you can deduce that somewhere in the solar system is a cloud of propellant gases with equal and opposite momentum as the rocket ship (in the reference frame of the rocket ship + propellant system.) You know this because you know that rocket ships start out with the propellant inside fuel tanks and at rest (i.e., at zero momentum.) As long as the rocket and it's propellant don't interact with anything else, the momentum of the system must remain at a constant zero kilogram meters per second. So if you know the momentum of the rocket, you can calculate the momentum of the cloud of propellant gas it ejected, and if you know the momentum of the propellant, you can calculate the momentum of the rocket.
The same thing happens in the creation of the entangled pair of electrons. A particle with zero spin (like a rocket with zero momentum that is loaded with fuel) is split into two particles with equal and opposite spin (like the rocket and propellant with equal and opposite momentum.) If you know the initial condition (the spin of the originating particle, or the initial momentum of the rocket with fuel) and the condition of one of the two halves of the system (the spin of one particle, or the momentum of either the fuel or the rocket) you can calculate the condition of the other half. If you were to then do something to one of the particles, the other particle would be unaffected in exactly the same way (and for the same reason) as the cloud of propellant gas ejected from the rocket doesn't suddenly reverse direction if you were to turn the rocket around from Pluto.
Ok, that makes sense. But it negates my understanding of previous posts. I'll have to reread.
I could be wrong. I had to drop out of my QM class because I just couldn't wrap my head around bra-ket notation. The physicist approach to math is bizarre if you come to it via a mathematician approach to math. At at least one point the textbook flat-out said "This derivation is wrong. If that bothers you, you should be change your major to mathematics."
It's like they think that just because they can show that their results are correct by doing an actual experiment they don't feel the need to bother with hundreds of lines of proof using nonlinear differential equations, matrices, and a vector space with the rigorous mathematical definition of "only the things a particle can do in real life."
Quote from: Nephew Twiddleton on June 30, 2010, 01:02:45 AM
Quote from: Golden Applesauce on June 30, 2010, 12:51:49 AM
The reason they're entangled in the first place is conservation of spin. It's analogous to conservation of momentum, so I'll try to explain it using that conservation law.
You're a space-flight controller on Pluto. A rocket ship radios in, "Hello, this is the solid-propellant rocket Galileo making approach to Pluto spaceport; requesting permission to dock. Our mass is 10,000 kilograms and our approach velocity is 10 meters per second towards Pluto, so our momentum is 100,000 kilogram-meters per second." Now, since you know that momentum is conserved, you can deduce that somewhere in the solar system is a cloud of propellant gases with equal and opposite momentum as the rocket ship (in the reference frame of the rocket ship + propellant system.) You know this because you know that rocket ships start out with the propellant inside fuel tanks and at rest (i.e., at zero momentum.) As long as the rocket and it's propellant don't interact with anything else, the momentum of the system must remain at a constant zero kilogram meters per second. So if you know the momentum of the rocket, you can calculate the momentum of the cloud of propellant gas it ejected, and if you know the momentum of the propellant, you can calculate the momentum of the rocket.
The same thing happens in the creation of the entangled pair of electrons. A particle with zero spin (like a rocket with zero momentum that is loaded with fuel) is split into two particles with equal and opposite spin (like the rocket and propellant with equal and opposite momentum.) If you know the initial condition (the spin of the originating particle, or the initial momentum of the rocket with fuel) and the condition of one of the two halves of the system (the spin of one particle, or the momentum of either the fuel or the rocket) you can calculate the condition of the other half. If you were to then do something to one of the particles, the other particle would be unaffected in exactly the same way (and for the same reason) as the cloud of propellant gas ejected from the rocket doesn't suddenly reverse direction if you were to turn the rocket around from Pluto.
Ok, that makes sense. But it negates my understanding of previous posts. I'll have to reread.
I could be way off here but I'm thinking that the important distinction vis a vis quantum encryption is that the qbits are not transferring information from one side to the other, rather the particle is acting like a random seed, generating a key simultaneously at both ends. The advantage of this would be that the key is only going to arrive at the two ends of the conversation and nowhere else, as opposed to the current system where it happens over wires or radio and is subject to potential eavesdropping scenarios.
For Twid: I might have left this out in the OP to save space. Hope it helps.
It is easy to imagine apparatus that will produce clicks in two separate detectors that are correlated in some way (I mean for the pattern of clicks to be correlated, not the detector settings, which are always under our control).
For example, an excited nucleus might shed energy by radiating two electrons and nothing else. Imagine that two detectors, A and B, are set up to register them.
If the original nucleus were standing still (zero momentum), then the electrons would necessarily be detected moving with identical speeds in opposite directions, because momentum is conserved even in the quantum world (equal and opposite momenta add to zero).
So the momenta are perfectly correlated. Similarly, if the excited nucleus had no spin then the observed spins of the emitted electrons must also cancel (to conserve angular momentum).
If the spin detectors are both set at the same angle, we can be sure this apparatus of stationary radiating nucleus plus detectors will cause one detector to register "up" and the other one "down."
Therefore the detector registrations in opposite settings at the two different detectors will be perfectly correlated.
The conservation of momentum analogy explains the correlation part well, but it fails to emphasise the weirdness of the situation.
Like in GA's example, you would expect there to be a correlation even without quantum entanglement. The classical world already has correlations, but the quantum has even more.
So here's another analogy:
You have two balls, one is black and one is white. You put them in a bag. You blindly pick one out of the bag, let's say it's white. Then you know the next ball you pick out must be black. That's the classical situation.
In the quantum situation, you have several pairs of balls. Each pair is a different colour. Two white, two black, two red, etc. You reach into the bag and randomly pick out a green one. Now you know that the next ball you pick will be green. No matter how many balls there are in the bag.
That's how weird this is.
So it would be like having two coins spinning, when you knock Coin A over, its Heads... so you know that the other coin will be tails. Whereas if you knock Coin A over and its tails, you will know that Coin B is heads?
STOP USING METAPHORS, MOTHERFUCKERS.
Quote from: Dok Howl
The universe cheats.
Quote from: LMNO on June 30, 2010, 08:17:18 PM
STOP USING METAPHORS, MOTHERFUCKERS.
This. Analogy has to be among the most facile forms of understanding.
Not to mention, the first thing to know about QM is that it isn't analagous to macro world events.
Sure, it makes it sound freakier, and it really confuses people, but it obscures what is really going on.
Quote from: LMNO on June 30, 2010, 08:47:39 PM
Not to mention, the first thing to know about QM is that it isn't analagous to macro world events.
Sure, it makes it sound freakier, and it really confuses people, but it obscures what is really going on.
Too late.
Here's what I'm going to do. I'm just going to try and forget everything in this thread for now, because everything I've taken in has made it seem like everything is contradicting everything everyone else is saying.
For example, these two entangled particles do spooky action at a distance with an instantaneous transfer of information but not really it's more like Newton's 3rd Law of Motion, and there really isn't any information transfer because you can't change the spin so nothing's really happening. Even though it's not happening faster than the speed of light and it's extremely interesting.
Sometime next week, I'll see if I can read up on QM independently, from a very basic sort of stand point, to grasp all the ground work. Becuase strangely the more that this gets explained to me the less I know about it.
Quote from: Nephew Twiddleton on June 30, 2010, 11:12:51 PM
Becuase strangely the more that this gets explained to me the less I know about it.
I think that's the way it works for the scientists too. What they seem to be dealing with is a predictable series of measurements which produce results but they've no idea what it is that's being measured or why the results behave the way they do. It's like putting a glass up against your living room wall at 3:00pm every day and listening and there's always a sound like a cow chainsaw raping a dolphin. You've no idea what the fuck is going on in there but 3:00pm on the dot, every day, there is is.
As explained to me, science is like finding islands of truth in a sea of ignorance, and then trying to build bridges between the two.
They do experiments, or work out formulas, and they show evidence A. They then look at whether this is supported by the current framework. If it fits, great. If it doesn't, we should either reject it (recent cold fusion claims) or we have to completely restructure the framework (relativity).
Quote from: Cain on June 30, 2010, 08:45:54 PM
Quote from: LMNO on June 30, 2010, 08:17:18 PM
STOP USING METAPHORS, MOTHERFUCKERS.
This. Analogy has to be among the most facile forms of understanding.
What's wrong with that?
you need a cursory understanding before you can get into the nitty gritty, and i don't think the people on this thread really
want more than that, anyways...
if it's impossible to draw any analogy to give an impression of what is going on, then just say, "no offense but you wouldn't understand unless you're willing to do the math and accept a model beyond what you have in the past (or possibly
can) experience..."
furthermore, in the modern physics class that i took in university, they did, in fact, start out with analogy. it's for good reason, i think. it just becomes important to say where the analogy breaks down, and why...
also, aren't those similes being used, rather than metaphors? :)
:news:
Quantum entanglement holds your DNA together!
http://www.technologyreview.com/blog/arxiv/25375/
Quote from: Doktor Vitriol on July 02, 2010, 08:04:02 AM
Quote from: Nephew Twiddleton on June 30, 2010, 11:12:51 PM
Becuase strangely the more that this gets explained to me the less I know about it.
I think that's the way it works for the scientists too. What they seem to be dealing with is a predictable series of measurements which produce results but they've no idea what it is that's being measured or why the results behave the way they do. It's like putting a glass up against your living room wall at 3:00pm every day and listening and there's always a sound like a cow chainsaw raping a dolphin. You've no idea what the fuck is going on in there but 3:00pm on the dot, every day, there is is.
I believe it, but what I meant was, the phrase quantum entanglement is meaningless to me as a result. I thought I had a vague understanding of what it meant, but now, I haven't the foggiest of even what the definition of the phrase is. All I think of it now is, "weird stuff happens, but really it's not that weird, because what is described isn't what's really going on. Or maybe it's weirder. But believe me, it's interesting." I'd go into further detail but I'm giving my brain a break from it for now.
"Entanglement is the weird quantum process in which a single wavefunction describes two separate objects. When this happens, these objects effectively share the same existence, no matter how far apart they might be."
http://www.technologyreview.com/blog/arxiv/25375/
Which says to me time and/or space and/or spacetime doesn't work anything like I think it does.
Quote from: Telarus on July 05, 2010, 01:09:20 AM
"Entanglement is the weird quantum process in which a single wavefunction describes two separate objects. When this happens, these objects effectively share the same existence, no matter how far apart they might be."
http://www.technologyreview.com/blog/arxiv/25375/
Not exactly what I was looking for when I said that the phrase was meaningless to me. It's the apparent details of it that are not getting across to me. Hence the this is what's happening but really that's not what's happening at all sort of thing.
So these two particles effectively share the same existence while entangled, per the definition you provide. Sounds to me like what happens to one happens to the other. But that's not the case because that would break the entanglement. So they're not really sharing an existence. The way it sounds to me at that point is then is, particle A goes through this thing and tells us it's spin up. Therefore particle B is spin down. Since they're complementary particles emitted off by something else, that doesn't sound very weird to me.
So how is "information" (which I'm not getting either unless it's this is spin up so that's spin down, which really isn't information transfer) is transferred between the two particles 10000 x speed of light (but that apparently also can't happen because of observation)?
See where I'm confused? Maybe I just won't be able to grasp the idea and the significance, but I would like to try.