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Topic: EPR paradox

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  EPR paradox - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-11-07)
In quantum mechanics, the EPR paradox (Einstein-Podolsky-Rosen) is a thought experiment which challenged long-held ideas about the relation between, on the one hand the observed values of physical quantities and on the other, the values that can be accounted for by a physical theory.
As a result of further theoretical and experimental developments since the original EPR paper, most physicists today regard the EPR paradox as an illustration of how quantum mechanics violates classical intuitions, and not as an indication that quantum mechanics is fundamentally flawed.
The EPR paradox draws on a phenomenon predicted by quantum mechanics, known as quantum entanglement, to show that measurements performed on spatially separated parts of a quantum system can apparently have an instantaneous influence on one another.
en.wikipedia.org /wiki/EPR_paradox   (3009 words)

 The Einstein-Podolsky-Rosen Argument in Quantum Theory
EPR is about the interpretation of state vectors ("wave functions") and employs the standard state vector reduction formalism (von Neumann's "projection postulate").
Although the "cat paradox" is usually cited in connection with the problem of quantum measurement (Measurement in Quantum Theory) and treated as a paradox separate from EPR, its origin is here as a compact version of the EPR argument for incompleteness.
To go back to the EPR dilemma between locality and completeness, it would appear from the Bell theorem that Einstein's strategy of maintaining locality, and thereby concluding that the quantum description is incomplete, may have fixed on the wrong horn.
plato.stanford.edu /entries/qt-epr   (7636 words)

 List of Paradoxes - Uncyclopedia
Hot Paradox: The hotter someone is, the uglier they are, and vice-versa to infinity.
EPR Paradox: Ravioli defies one of the major laws of thermodynamics - that pasta can never be destroyed.
Paradox (Arizona): A place where conspiricy theorists believe there is an alien base, but it doesn't exist.
uncyclopedia.org /wiki/List_of_Paradoxes   (449 words)

 Does the EPR paradox prove that quantum theory is incomplete? Philosophy of Science at AhISee - the site for Insight   (Site not responding. Last check: 2007-11-07)
The EPR argument was the last of these many attempts by Einstein to present a reductio ad absurdem in the form of a thought experiment that would disestablish the prevalent acceptance of the CHI.
Hence this is presented as a sort of paradox, and it is known as the 'EPR paradox'.
The EPR argument of course was intended to show that QM was 'incomplete' by demonstrating an 'impossible' implication, and therefore that there were other factors – 'hidden variables' of reality – that were mediating the visible transactions between the separated particles.
www.ahisee.com /content/epressay.html   (4612 words)

 Myswizard » EPR paradox   (Site not responding. Last check: 2007-11-07)
In quantum mechanics, the EPR paradox (Einstein-Podolsky-Rosen) is a thought experiment which demonstrates that the result of a measurement performed on one part of a quantum system can have an instantaneous effect on the result of a measurement performed on another part, regardless of the distance separating the two parts.
The EPR paradox is a paradox in the following sense: if one takes quantum mechanics and adds some seemingly reasonable conditions (referred to as “locality”;, “realism”, and “completeness”), then one obtains a contradiction.
Such explanations, which are still encountered in popular expositions of quantum mechanics, are debunked by the EPR paradox, which shows that a “measurement”; can be performed on a particle without disturbing it directly, by performing a measurement on a distant entangled particle.
www.myswizard.com /2006/03/15/epr-paradox   (2477 words)

 EPR - Einstein, Podolsky and Rosen
EPR discussed such systems as a way of critiquing what they called the completeness (as opposed to the correctness) of the quantum description.
EPR's starting point and central idea is that we can measure some aspect of one of the pair and subsequently predict outcomes of measuring corresponding aspects of the second one.
The line of argument initiated by EPR was formally updated in 1964 when John Bell showed that the assumption of locality made by Einstein, Podolsky and Rosen was itself actually in contradiction with facts predicted by quantum mechanics.
www.nonlocal.com /hbar/epr.html   (425 words)

 New Page 0
This was their paradox and they came to the conclusion that since the particles do not interact, quantum physics in incomplete.
The idealized entangled state proposed by EPR is one where the position and momentum of two particles are perfectly correlated, and can't be executed in the lab.
In conclusion, we have realized the EPR paradox using momentum-position entangled photons in a method that is easier and more attractive than the similar squeezed-light methods.
www.pas.rochester.edu /~howell/mysite2/teleportationmain.htm   (609 words)

 The Einstein Podolsky Rosen paradox
This is a point that has been overlooked by the scientist studying the EPR paper, and also Einstein, Podolsky and Rosen were probably not aware of the 'ex absurdum' status of their proof of incompleteness of quantum mechanics.
Since in the EPR reasoning quantum mechanics is used to describe a situation of quantum entities that have interacted at a certain moment and then fly apart and then behave as separated quantum entities, this leads to a contradiction.
We analyze the quantum paradoxes in the light of these findings and show that they can be divided into two groups: (1) The group (measurement problem and Schrodingers cat paradox) where the paradoxical aspects arise mainly from the application of standard quantum theory as a general theory (e.g.
www.vub.ac.be /CLEA/aerts/publications/EPR_paradox.html   (4322 words)

 EPR Paradox - Uncyclopedia
The Einstein-Pasta-Ravioli (EPR) Paradox was developed as a conceptual challenge to the recently-formed theory of Quantum Elbow Macaronics (QEM).
Alex proclaims that her pasta was "scrumptious!", meaning that Barb's antipasta must, by the laws of QEM, be "satisfying." However, Heisenberg's Rigatoni Uncertainty Principle forbids an instantaneous transfer of taste sensation from pasta to antipasta, which would effectively violate locality.
The EPR paradox has revolutionized our understanding of pasta by spurring chefs around the world to spend more thought and energy on their dishes.
uncyclopedia.org /wiki/EPR_Paradox   (269 words)

 The EPR Paradox and Bell's Inequality Principle
This article is an introduction to EPR, Bell's inequality, and the real experiments that have attempted to address the interesting issues raised by this discussion.
EPR sought to demonstrate that this phenomenon could be exploited to construct an experiment that would demonstrate a paradox which they believed was inherent in the quantum-mechanical description of the world.
QM dictates that this should be impossible, creating the paradoxical implication that measuring one system should "poison" any measurement of the other system, no matter what the distance between them.
math.ucr.edu /home/baez/physics/Quantum/bells_inequality.html   (2076 words)

 Evidences, Implications and Applications by Motta, L. F. D.   (Site not responding. Last check: 2007-11-07)
Although it appears that this paradox was solved recently, there are many other evidences that guide us to believe that Smarandache Hypothesis is right on quantum mechanics and even on the new unification theories.
Pondering about this paradox, Smarandache again suggested in 1993, in a lecture on Brazil, that there is no such thing as a limit speed on the universe, as postulated by Einstein [5].
In practice, this means that a light pulse propagating through the atomic vapour cell appears at the exit side so much earlier than if it had propagated the same distance in a vacuum that the peak of the pulse appears to leave the cell before entering it [10].
www.gallup.unm.edu /~smarandache/Motta/Sm-Hyp.htm   (1415 words)

(EPR) in 1935 is essentially a demonstration that the results of quantum mechanics are logically inconsistent with the premise that a measurement made with one instrument cannot influence the measurement made by another instrument if the measurement events are separated by a spacelike interval.
We note that an observer cannot use the EPR paradox to initiate the sending of a message from one detector to another, permitting another observer to receive it across a spacelike interval.
The EPR paradox, as it applies to this experiment, comes down to the question of how this quantum-mechanical result is enforced when the detection events are separated by a spacelike interval.
www.npl.washington.edu /npl/int_rep/gat_80   (8965 words)

 Brassard, Crépeau, Jozsa, Langlois: The EPR problem is fixed (temporarily)   (Site not responding. Last check: 2007-11-07)
The authors claimed that this protocol was immune to the EPR attack but were not sure about a higher-scale consequence of quantum physics: ``coherent measurements''.
Without explaining much, what they seem to fear is what ultimately would kill the whole enterprise, namely, that the same kind of phenomenon that enabled the EPR attack, the composite state of sets of two or more particles, applies to the composite state of all the particles involved in the protocol.
For a while, however, this was considered to be a sound protocol and the research focused on adding error correction to it, because actual physical quantum transmission channels were beginning to be built and all of them had error probabilities.
www.cs.brandeis.edu /~pablo/qbc/node6.html   (469 words)

 Entrants' System Descriptions
Paradox 1.0 [CS03] is a finite-domain model generator.
Paradox beats last year's winner (2002) in the SAT category, and has also solved a number of "unknown" problems from TPTP within a short time limit.
Paradox is not optimized at all for the EPR category, but should perform reasonably well.
www.cs.miami.edu /~tptp/CASC/19/SystemDescriptions.html   (7638 words)

 The Photon Theory
Einstein and colleagues constructed the EPR Gedankenexperiment, because they wanted to show, that the quantum theory is uncomplete or wrong, because in case that the instantaneous communication of information through two correlated photons happens, the velocity of light is not the highest velocity.
This result appears paradoxical: that both photons „move away“ from each other with speed of light means, that no information exchange can occur between the photons due to the impossibility of the transfer of information at a speed higher than speed of light.
Because of this wrong description the behaviour of the correlated photons seems to be mysterious and paradoxal, because the information of the polarization state of photon 1 is instantaneously present at photon 2, independently of the seeming distance of the two photons.
www.r-haas.de /v4.html   (2065 words)

 The Quantum World
It's ironic that the spooky EPR connection has now been used in the lab to teleport photons, because the original reason for inventing the EPR paradox was to show that one of the implications of quantum theory was so unacceptable that it must be wrong or incomplete in some respect.
What the EPR trio couldn't accept was the idea that measuring a photon in one place could have an instantaneous physical consequence somewhere else -- all because quantum measurements are about probabilities.
In the words of the physicist John Bell, who generally sympathised with Einstein's disquiet over quantum theory, the EPR paradox is one of those questions that most physicists feel they will fully understand if they can ever spare twenty minutes to think about it.
www.idmon.freeserve.co.uk /quant3.htm   (1181 words)

that this paradox is not similar to the correlations between distant events that are understandable in the frame work of ordinary classical ideas...
EPR sought to demonstrate that this phenomenon could be exploited to construct an experiment which would demonstrate a paradox which they believed was inherent in the quantum-mechanical description of the world.
Adam and Eve each have a detector and the geometry is such that the spacetime interval between the arrival of particles 1 and 2, respectively, for the same individual pair, at their respective detectors is spacelike.
www.qedcorp.com /pcr/pcr/epr.html   (4109 words)

 PhilSci Archive - EPR Paradox and the Physical Meaning of an Experiment in Quantum Mechanics   (Site not responding. Last check: 2007-11-07)
EPR Paradox and the Physical Meaning of an Experiment in Quantum Mechanics
It is shown that there is one purely deterministic outcome when measurement is made on the state function chosen by EPR to describe the combined two-particle system - the distance between the two particles is preserved the same.
Further, it is shown that, surprisingly, the psi-function designed according to QM leads to the following paradox - despite the fact that the two particles move in opposite directions, in time the distance between them becomes shorter and shorter.
philsci-archive.pitt.edu /archive/00001009   (133 words)

 The EPR paradox steps in or, the quantum daemon bites its own tail.
The famous EPR (Einstein-Podolsky-Rosen) paradox describes a rather counterintuitive quality of quantum physics: the quantum state space of a set of several particles is the direct product of their individual spaces, and not the direct sum as one would expect.
As a consequence, if A and B have separate particles a and b, which happen to be in an entangled state, then A may be able to gain information on B's measurement of b by measuring a.
This is exactly the EPR paradox (table 4).
www.cs.brandeis.edu /~pablo/qbc/node5.html   (284 words)

 Cycles Research Institute - David Elm's EPR Explanation
Therefore all EPR tests which seem to violate the inequality and support non-local effects are faulty and cannot be used to reject all local reality theories of the universe.
ALL EPR experiments have used this faulty scaling as the basis of their determination of the validity, or lack of, of the local reality views and it so is clear that the local reality models cannot be rejected using these experiments.
The problematic (relative to locality question) rejection in EPR experiments is the rejection of the detection events which _don't fit_ the result template of the Bell's theorem which requires that only one detector for each particle A and B triggers.
www.cyclesresearchinstitute.org /physics/elm.html   (7299 words)

 School of Physics: Colloquia and Seminars in Spring 2005   (Site not responding. Last check: 2007-11-07)
The "Einstein Podolsky Rosen Paradox" was a gedanken experiment proposed in 1935 to point out that the wavefunction description of quantum mechanics was incomplete.
EPR used a two-particle wavefunction, which was continuously entangled in position and momentum, to show that each particle must both be in a position and a momentum eigenstate simultaneously.
Much interest and study over the last several decades has illucidated many of the points in the EPR paradox.
www.physics.gatech.edu /colloquia-seminars/colloquia/030205.html   (122 words)

 Quantum Computing: An Introduction   (Site not responding. Last check: 2007-11-07)
In other words, although our present formulation of quantum mechanics has the spins as only having a probabilistic value, and since 'spooky, faster than light' signaling is out of the question, there must be some 'hidden variables' that make the directions of the spins predetermined from the outset.
After several months of frantic activity devising a response to Einstein's challenge, Bohr declared the EPR paradox not to be a paradox at all and argued essentially that quantum mechanics demands that you are only allowed to treat the electron-positron system as a single quantum system.
The reason is that the EPR state of the electron and positron is an example of an 'entangled state'.
www.qtc.ecs.soton.ac.uk /lecture1/lecture1e.html   (1001 words)

 Nature of Reality Homepage   (Site not responding. Last check: 2007-11-07)
Athough officially Einstein published his critiques in the famous EPR paper, his letters describing the paradox to his collegues seem to put the paradox in a different light.
This solution involves hidden variables and some properties which they would have to have in order to get around the EPR paradox.
Quantum Mechanics - this section is an analysis of this experiment from the quantum mechanical point of view, including a prediction for the outcome.
roxanne.roxanne.org /epr   (420 words)

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