Quantum Entanglement Survives, Even Across an Event Horizon 152
StartsWithABang writes: One of the more puzzling phenomena in our quantum Universe is that of entanglement: two particles remain in mutually indeterminate states until one is measured, and then the other — even if it's across the Universe — is immediately known. In theory, this should be true even if one member of the pair falls into a black hole, although it's impossible to measure that. However, we can (and have) measured that for the laboratory analogue of black holes, known as "dumb holes," and the entanglement survives!
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Percent means "per hundred". Percentages are calculated by dividing by 100. 0/100 = 0.
I have no idea why you're trying to talk about 0/0, which is undefined.
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Undefined, for 0/0, means that any value is permissible. For different uses, it can mean no value is permissible. In this case, 0% is a perfectly valid answer, since 0*0 = 0. Any other answer is possible; for example, 53.6% of the people I've stabbed with murderous intent survived.
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You're an absolute idiot.
Division by 0 is undefined.
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Its undefined unless you define it.
- Division by zero does have a defined value of - imaginary infinite. That is a positive infinity and a negative infinity, or if you sum them together zero.
- An alternative derived using permutation also sums to zero, with the numerator becoming the remainder.. This is the value that computer ALU's would actually produce if allowed to calculate division by zero..
0/0 = 1 is just a formalism, and is technically incorrect because it produces a signed value from a signless ope
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0/0 does not equal 1, and anyone ever stating that it does needs to be shot in the fucking face.
Division by zero is undefined. It is not infinite - positive or negative. It is incalculable by the definition of the operation of division.
It is not a "formalism" to state anything other than the fact that it is undefined. It is not a formalism to state roots as positive values, either. Maybe I'm old, but I ALWAYS consider both positive and negative values unless I explicitly limit my domain. To do otherwis
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You can dry run a computer division by zero operation, and the operation produces a result of zero leaving a remainder that equals the nominator. At its heart division is a multiple subtraction and the result is an accumulation therefore division by zero produces zero..
On the opposite when you do the formal theory of calculus you get to play with infinitesimals and zero, and the infinitesimals map the graph of division and multiplication by zero - to produce the familiar tangent curve. (summing the (+)(-) i
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A billionaire businessman and a successful brain surgeon have nothing on you, right?
Get back to me when you match their success.
One has been divorced two more times than me than me and declared bankruptcy four more times and may or may not have more hair than me. The other can apparently sleep while standing, sitting and conversing and may or may not have tried to stab his friend (or relative) while trying to decide whether to accept his "scholarship" to West Point, before reminding a robber to rob someone else.
All in all, I think I'm doing pretty well - in comparison. Occupation, money and success aren't everything.
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Yeah, I'm better than the both of them put together.
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So Hillary and Bernie are quantum entagled AND faced with imminent Pauli Exclusion Principle issues!
Feel better now?
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I've known a few. Whenever they are around, everything intelligent seems to get sucked away.
Hey be nice! I was ENGAGED to one!
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No shit, Sherlock (Score:3, Interesting)
This should come as a surprise to exactly no one. Anyone who can apply logic can tell you that the physical universe is a layer above the non-physical energy (matter is merely 'bound energy') that is the fundamental substance of existence. Quantum particles are known to "flicker in and out of physical reality". That has been directly observed. So where do you think that energy goes when it's no longer *physically* present? Just disappears into nothingness, the one state that's simply not possible whatsoever? Of course it's still there, and of course the rules that apply to that non-physical energy still apply even when you can't physically access it. Energy is information, matter is merely a storage medium. The information is always extant, even if it's not currently represented on any physical storage medium.
A simple way to understand this is to visualize the universe as being made of numbers. The positive numbers can be represented by matter (regardless of polarity, so yes, anti-matter is positive numbers) and negative numbers cannot be represented physically, but are nonetheless just as 'real'.
Anyone who argues otherwise, yet agrees that 2 minus 5 equals negative 3, should be required to demonstrate physical proof that 2 minus 5 equals negative 3 before being allowed to speak further on the subject... ;)
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This is complete utter BS. Waves cancel each other out all the time. Look up interference patterns and wave propagation on Wikipedia.
Yes, let's look at those things. The first thing we notice when we look at wave propagation is that energy is conserved which in itself is completely at odds with your assertion that waves can cancel themselves.
When we look at interference patterns (which occur when waves interact at best weakly with each other), we see not only local cancellation, but also local reinforcement. When there are regions where waves subtract from each others' amplitude, this process also results in regions where the waves ad
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Oh boy if only it were that simple. Technically the modern definition of antimatter defines it as matter with positive mass but opposite charge. We can add another type of antimatter that has negative mass, but this isn't generally compatible with a lot of modern physics theory, which says that with negative mass you also get negative time. I'm working on a new physics model that solves this problem, but to do it the model has to replace general relativity at FTL speeds with a new modified 'absolute frame'
So.. for a non-physicist (Score:2, Interesting)
- For everything above quantum, the maximum speed is the speed of light.
- This dictates cause and effect, and therefore time.
- If we send out a steady stream of entangled particles, and sometimes change and sometimes don't (at the one end), and measure at the other (this is how I imagine how a bitstream would work using quantum entanglement, correct me if I'm wrong), we can send information quicker than the speed of light.
- Therefore the information goes back in time.
Or something?
Re:So.. for a non-physicist (Score:4, Interesting)
Maybe this will help?
Can some physics types comment on the quality of the explanation.
https://www.youtube.com/watch?v=v657Ylwh-_k [youtube.com]
Re:So.. for a non-physicist (Score:5, Informative)
1. No. The maximum speed is the speed of light in quantum mechanics. Entanglement doesn't even have a speed. It is, from all measurements that have been done, valid in any reference frame.
2. No. c is defined in terms of time, not the other way around.
3. No. The correlations from entanglement transfer zero bits of information. They can only be observed with the assistance of normal communication channels. Combining the two allows you to hide but not send data.
4. Obligatory xkcd: No. [xkcd.com]
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If you send information faster than light, then the information is going backwards in time wwith respect to some reference frame.
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That is correct if Special Relativity holds. Now, I'm as positive that it holds as I am about any scientific theory, but it still could be wrong.
If we toss Special Relativity and have a preferred inertial reference frame, then FTL does not mean backwards in time.
If you have Special Relativity and FTL, you've got time travel, or at least the potential of such.
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"Re point 4: my understanding of current theory was that if you can send information faster than light, then it is possible to send information back in time."
That would only be correct if General Relativity remains correct at FTL speeds, and there's more empirical proof for Leprechauns or homeopathy than there is for that.. A much simpler FTL model is that time is point like and not a dimension, and that dimensional time is just a delusion - an abstraction.. As for dilation and space like time they can be
Quantum encryption protocol BB-84 (Score:3)
Quantum encryption protocol BB-84
You set up the experiment so that you can polarize a photon at 4 angles: 0, 45, 90 and 135 degrees ( | / - \ ).
There are two distant terminals, let's call them A and B, where the photons can be polarized and then checked whether they passed the polarizer or not. There's also a (dumb) source of entangled pairs in the middle, that sends one photon from the pair to each of the terminals.
Take a single (non-entangled) photon: If you polarize it at 0 degrees, it will pass the 0 de
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Do they need to interact further?
They collapse when one passes through one polarizer. This will result in the other, passing through the other polarizer in a "modulo 90" orientation to behave predictably, either pass at mathing polarity or vanish at wrong polarity, with no uncertainty; "the same" measurement gets repeated, producing "the same" results.
If one passes at a "superfluous" polarizer at 45 degrees orientation, their wavefunction collapses to that. Afterwards, being no longer entangled, they may pa
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Neutrinos are particular with mass that go slower than light, although the mass is like 0.000000(...)00001 and the speed like 99.999999(...)9 % the speed of light.
So I don't think they do anything funny ; neutrinos merely go faster than light when that light goes through a non-vacuum medium, like beta radiation that makes a nuclear reactor glow blue in the swimming pool.
Cherenkov radiation (Score:2)
neutrinos merely go faster than light when that light goes through a non-vacuum medium, like beta radiation that makes a nuclear reactor glow blue in the swimming pool.
The blue glow is Cherenkov radiation which is caused by electrons from beta decay of fission products travelling through the water faster than the speed of light in water. However only charged particles cause Cherenkov light and neutrinos, being neutral, will not cause this effect and pass through matter almost entirely unaffected unless they have extremely high energies and even then they interact via the weak force and not electromagnetism.
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So I don't think they do anything funny ...
Let's test that with a joke... "Two neutrinos pass through a bar ..." - You're right: not funny.
No such thing (Score:2)
So tachyons or neutrinos are "below quantum"? If so, what does it mean to be below quantum?
There is no such thing as "below quantum". Tachyons don't exist (or at least we have zero experimental evidence that they do) and neutrinos are most decidedly quantum in nature since they are extremely well described by quantum field theory.
Re: So.. for a non-physicist (Score:1)
And this is where you always lose me.
Nothing here proves it wasn't -1 the whole time.
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There's a measurable difference [wikipedia.org].
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Don't see how that answers anything.
what is so special about having some set
[A,B]
dividing them.
then measuring one of them, determining it is say A
And implying the other is B.
And, why, when the most interesting bit of all this is the superconductors.
Are we not discussing them.
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Re: So.. for a non-physicist (Score:1)
If bob or Alice leave for the shop.
When you measure if it was bob or Alice that left for the shop.
You know if Alice or bob didn't leave for the shop.
There is nothing magical or even that interesting happening here.
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But this is just set theory.
Why is it a "miracle" that if you throw one element of a set into a black hole, that doesn't affect the other elements of the set.
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what else is
-> you can set it up such that the spins are vertical and opposite
Other than
"two objects from a single set with predetermined values"
So yes, If it means something different I don't understand the example. which is why I started with "and this is where you lose me everytime".
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->but the second thing he suggested, with state superposition, were non-set-theory.
Why.
We're mostly talking about electrons in a superconductor as far as I can tell.
And the "infinities" that produces is ALL set theory.
Re: So.. for a non-physicist (Score:1)
Pretty sure all this requires interactions with super conductors at some point.
That's how dwave is doing it anyway.
Re: So.. for a non-physicist (Score:1)
What link would that be?
Stack exchange linking to Wikipedia doesn't count for much with this stuff imo.
And that's the only link I see in this thread.
Any experiment running close to absolute zero is using superconductivity. All these experiments, photons or electrons are currently using super cooled materials as far as I've seen.
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->No, this is not true at all as only certain materials will transition in to superconductivity.
At absolute zero all conductors are super conductors.
some materials transition at higher temperatures.
The "useful" super conductors are the ones that transition above the boiling point on liquid nitrogen.
->Experiments involving electrons or photons travelling
But they are "entangled" in a super conductor first.
https://en.wikipedia.org/wiki/... [wikipedia.org]
"As I understand it"
->Stern-Gerlach experiment
Does that have Qu
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Pretty sure that fermions , bosons and helium-4 aren't conductors.
As I understand the Stern-Gerlach it shows you entanglement exists, it doesn't give a set of entangled things you can experiment on that we have been discussing so far. Even your link to the "original test" says nothing about the photon source.
Further more, I don't see any of this actually explaining anything, other than reinforcing what I said ealier, in that the "CHSH inequality" IS a set experiment, testing set theory (and crudely at that)
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So maybe we consider "superconductivity" differently.
Your text says:
3.1. The free particle
Now we consider a free, spin-1/2 particle. The Hamiltonian consists only of translational kinetic energy
Are you saying that is achievable in a material with resistance?
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There is something I have not seen an answer for.
If you measure it and get a -1 but do not write it down and do not tell anyone. Then you are the only one that knows the state.
If I come in after you and measure it, will I get a -1 or is there a chance of me getting a 1?
So I guess the question is, does the particle exist in a superposition when not being observed and return to that superposition after observation, does the particle exist in a superposition until observed then lock into a position, or has it
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You threw that in there.. The very definition of the unanswerable question. What is the nature of the observer paradox? Answering that question can take you down some very pretty rabbit holes. The answer that the consciousness does collapse the wave function would be pretty irrefutable evidence that some 'psychic' model of the universe is correct.. There are two obvious alternatives - a physical mechanism in the observers brain, or in the process and instrumentation of the observation itself.
What we are loo
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>- Therefore the information goes back in time.
How and why did you get to that conclusion? There is a giant leap of logic here, and I want to explained
Re:So.. for a non-physicist (Score:4, Informative)
Re:So.. for a non-physicist (Score:4, Informative)
"The no-communication theorem states that, within the context of quantum mechanics, it is not possible to transmit classical bits of information by means of carefully prepared mixed or pure states, whether entangled or not."
See The No-Communication Theorem [wikipedia.org] and the Einstein-Podolsky-Rosen Paradox [wikipedia.org].
Some corrections (Score:3)
For everything above quantum, the maximum speed is the speed of light.
No, for everything which can transmit information the fastest speed is the speed of light. If we find anything which can transmit information faster than light then time travel is immediately possible. You will know if this ever happens because the physicist who discovers it will get extremely rich winning lotteries.
If we send out a steady stream of entangled particles...we can send information quicker than the speed of light.
No - as witnessed by the the fact that we still rely on government grants to fund us and not winning the lottery. Quantum entanglement does not allow any information to be sent. It is like shi
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It would go back in time only from the perspective of an outside observer. From the perspective of the particle itself, it is still in what it would perceive to be normal time, if a particle could perceive such a thing.
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The misconception comes from:
"Pack your particle in your car and send it there, no information is known still. Now measure the particle at your end and at the other end simultaneously. You'll get the same result instantly".
The problem is this doesn't really transmit information. You could get two sealed envelopes, put two identical cards, either with "1"s on them or with "0"s, one in each, then deliver one to the distant place. If two people now simultaneously open the envelopes, "the information about the
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This particular thing about event horizons always bugs me (i am no scientist at all): If the stuff falling in never enters from an outside perspective, shouldn't black holes look like Katamari balls and be quite visible?
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This i understand this far.
So now, i have this black hole that i can't see. I send an object toward it. From my perspective, time slows to a halt on the sent objective at the event horizon, so it looks like it never enters. So it actually stays visible, right? Over time, the black hole would look like a big ball of stuff frozen in time? What am i missing here?
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This i understand this far.
So now, i have this black hole that i can't see. I send an object toward it. From my perspective, time slows to a halt on the sent objective at the event horizon, so it looks like it never enters. So it actually stays visible, right? Over time, the black hole would look like a big ball of stuff frozen in time? What am i missing here?
The red shift. Drop a flashlight down into a black hole (you'l need a big black hole so that tidal forces don't destroy the light on the way in). As it falls, the red shift increases rapidly and so the flashlight both reddens and dims rapidly. (That is, fewer photons per second AND each photon has lower energy.) After a short time near the event horizon, you will receive the last photon you will ever get from the flashlight - and the same is true no matter how bright the light. So, no, it is no longer visib
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Thanks. All those "popular" explanations always only go so far as to exclaim "time slows for the object, so you never see it enter the event horizon" which misses this crucial info :)
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No. As things approach the event horizon the light from them is increasingly red-shifted, so that by the time they actually reach the event horizon it's been red shifted down to 0 hertz. Also, the light almost goes into orbit, so it needs to make an ever increasing number of orbital passes
finally! (Score:2, Funny)
Bob finally has an excuse to throw that cheating bitch, Alice into a black hole: science!
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Eve will cackle with joy.
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While Claire and Dave are, as usual, left out entirely.
In MWI, this is obvious (Score:2)
In the many-worlds [wikipedia.org] interpretation [stanford.edu] of QM, also called "QM without collapse", becoming more and more mainstream, this is a straightforward consequence of entanglement. When you measure the spin or polarization of your entangled particle, you become entangled with it, so in a sense all you're doing is discovering which "universe" you're in. And of course that universe is correlated with the corresponding other particle, no matter where it is now.
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I discover which universe I'm in simply by reading the brand, title and issue number of the comic.
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I prefer the many-worlds interpretation also, but I think it's a mistake to say it's "becoming more mainstream". It was originally published by (among others) J. Archibald Wheeler, and you can't get much more mainstream.
For that matter there are several valid interpretations of Quantum Mechanics, and it's probably a mistake to choose between them. There's even merit to the Copenhagen interpretation ("Don't try to understand it, just calculate.") Until there's an experimental way to choose between the int
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Re: "becoming" mainstream, don't think it's there yet: I think something over 50% of practicing physicists accept it as of a few years ago, which is a change from even a decade ago. As for other interpretations, experiments like this one [phys.org] are making the CI much harder to swallow - instantaneous collapse? Really? FTL signaling?
Besides, Copenhagen is just a worse explanatory framework. If we're going to make any progress on quantum computation, thinking about what's _really_ going on rather than about mysteri
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http://phys.org/news/2015-11-n... [phys.org] 404 error, page cannot be found.
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Sorry, try this: http://phys.org/news/2015-11-n... [phys.org]
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A much simpler explanation is that general relativity fails at the light speed barrier. In that case we only need three dimensions and one universe. General relativity still works except that the time dimension is restricted to quantum scales..
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In the many-worlds interpretation of QM, also called "QM without collapse", becoming more and more mainstream, this is a straightforward consequence of entanglement.
The most outlandish explanations usually are the most straightforward once their assumptions have been discounted.
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Indeed. But I'd argue Copenhagen is the one with the outlandish assumption here (instantaneous collapse on "measurement").
Misleading title (Score:2)
Not that the actual paper or press release is linked at this time (who reads those?) but there have been experiments lately that close loopholes in bells theorm and show that the details are truly random until measured yet correlated upon measurement. This includes determining the experiment details randomly from outside the ligh
Information is lost (Score:4, Informative)
What I think is the really important thing in the original paper [arxiv.org] is that information actually seems to be lost in the black hole. There is an enormous amount of theoretical musing about how to prevent information loss at event horizons (remember the black hole firewall [scientificamerican.com]?); this, if taken seriously, could have implications in quite a number of areas in theoretical physics.
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Conclusions
In conclusion, thermal Hawking radiation stimulated by quantum vacuum fluctuations has been observed in a quantum simulator of a black hole. This confirms the prediction of Hawking regarding spontaneous pair production in the presence of a horizon. This has implications beyond the physics of black holes, as it confirms the semiclassical step toward the understanding of quantum gravity. The Hawking spectrum is observed, as are the correlations between the Hawking radiation exiting the black hole and the partner particles inside the black hole. These correlations are surprisingly narrow in position space, which implies that the high frequency tail of the distribution of Hawking pairs are entangled. On the other hand, the overall weakness of the correlations in position space implies that the low frequencies are not entangled. The entanglement confirms that there is an issue of information loss within the semiclassical approximation.
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I don't follow that - I interpret "issue of information loss" as meaning that it is happening - i.e., that there is loss to worry about. Read at the bottom of page 1
Entanglement survives across the event horizon (at least, in this analogue). It would be presumably de
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Yes, who would have thought that a black hole could have multiple singularities (and even maybe, just maybe, life [arxiv.org]) inside it.
But what about (Score:1)
Imperial Entanglements? Can we at least avoid those
ELI5, please help me understand (Score:1)
So, one thing I don't understand about quantum entanglement. In the simplest terms, you can have 2 photons generated from a specific process, and if you measure the spin (polarization?) of one of the photons, the other one will always have the opposite spin. And that's what they call quantum entanglement, right? But to me it simply means that the said specific process always generates a pair of photons with opposite spin. Where is the magic of entanglement here? Please help me understand. It's kind of like
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I can't explain it like you're five, because you're not five and you have been indoctrinated into the classical world. But this video is pretty good.
https://www.youtube.com/watch?... [youtube.com]
"Quantum Entanglement & Spooky Action at a Distance "
If you haven't grasped the quantum way of thinking, this next one is a great video. It doesn't get all technical and assumes some basic information, but the pictures should start you in the quantum direction.
https://www.youtube.com/watch?... [youtube.com]
"Delayed Choice Quantum Eraser
As somebody who worked on entanglement (Score:4, Insightful)
a) entanglement does not transfer information faster than light. Why? if i send entangled pairs of photons from a to b and c, and b and c detect these photons, the photons took time to reach b and c. If b does something to the photon, the entanglement is lost. If b and c measure they will know the state the other one received, however they can not influence what is received in the other place, so sorry guys, no FTL transmission of information
b) What is weird about entanglement is actually not so much it statistical property of the correlation. If a packs a white and black marble in two packages and mixes the packages and sends them out, the result from the viewpoint of b and c will be the same - each one will know which marble the other one received. The weird property is that the state is prepared in a way that the two possibilities are quantum states, which can be subject to phase shift, transitions etc, and are "collective" in that sense that b and c can transfer their state to particles (and possibly create further entanglement) - the basis for Quantum key distribution networks - and that the information which exists exists only in the form of a shared posteriori observation. i.e. the classical marble can be looked at without destroying the correlation, while a quantum entangled photon will be entangled with your measurement apparatus when looking at it.
c) what these guys did-AFAIU (my topic was very far away) is to create a model system of a black whole, which tries to represent a black whole in a way which we assume it is, observed some properties which can be predicted from this model (temperature of emitted radiation), and checked for some others - correlation, where they found correlation which they interpret as entanglment.
d) While did not look into the details, i can say from my own experience that such experiments are tricky, and i find the interpretation a little vague. But i have to look closer. I did use quantum state/operator tomography, which usually is the benchmark measurement when you want to prove entanglement, or properties of the superoperators describing your quantum operations. I understand that this may not be possible in this case, which is why one can go for other phenomenological approaches
e) One should be careful. Proving entanglement is not so simple (Look for entanglement measures), and proving that is actually *survives* the event horizon, instead of being created there, may be very nontrivial. It could very well be that non-entangled state are transformed in entangled states to some degree.
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You are talking about non-demolition measurements, but these are a different issue, since they do actually not leave the state undisturbed, but only do a "pure measurement" i.e. project its own state precisely into one of the conjugate variables of the quantum system, and leave the other one intact.
since entanglement is.... (Score:2)
since entanglement is the like writing a 1 on one index card and writing a 0 on another, then dropping the envelopes into a box, grabbing one of the envelopes and opening it which reveals what the value of the card in the box is, I would expect this situation to be the case.
Ken Spam (Score:2)
faster than light (Score:2)
Well I guess that's settled then. A year or two ago I posted that scientists potentially thought that quantum changes could occur faster than light because nothing is "traveling" it's merely updating to current reality in real time. People replied like crazy and downvoted me to oblivion. Well I guess we found out who was right after all, didn't we? In fact I recall a story about NASA wanting to test this onboard t
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All science is based on statistics, you anonymous moron. There is always uncertainty in experiments and measurements because one can never be certain about anything - even the instruments used to measure observations have inherent uncertainties. Is the ruler you're using precise down to the atomic level? No! Can you be certain your instruments are perfectly calibrated?!?!? No!
This higgs was discovered with 6 sigma accuracy, which is more certain than the precision of manufacturing of most things you
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I disagree. It would probably have lasted at least 6 months.