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The Reference Frame: Wick rotation Because I believe that most of this criticism is unfair and the Wick rotation is a useful, and in many cases essential mathematical tool to calculate the physical predictions of a quantum theory, let me dedicate a special article to this issue. The Wick rotation is a calculational trick in quantum theory in which we assume that the energy or the time are pure imaginary. Also, even if you assumed that the Wick rotation seems to be a new added element to the structure and definition of quantum field theory, it's completely fine that it is so because the predictions of the (correct) theories, even those that rely on the Wick rotation, have been experimentally tested. motls.blogspot.com /2005/02/wick-rotation.html   (10420 words)

Wick rotation - Wikipedia, the free encyclopedia In physics, Wick rotation is a method of finding a solution to a problem in Minkowski space from a solution to a related problem in Euclidean space, by analytic continuation. Wick rotation connects quantum mechanics to statistical mechanics in a surprising way. It is called a rotation because when we represent complex numbers as a plane, the multiplication of a complex number by i is equivalent to rotating the vector representing that number by an angle of π / 2. en.wikipedia.org /wiki/Wick_rotation   (257 words)

rotation Rotation is the movement of a body in such a way that any given point of that body remains at a constant distance from some other fixed point. In astronomy, rotation is a commonly observed phenomenon. One consequence of the rotation of a planet is the phenomenon of precession. www.fact-library.com /rotation.html   (344 words)

Wick bar lift - Patent 4438592 In one class of wick bar lift, a wick bar for receiving a liquid such as a herbicide is mounted to a vehicle at a selected elevation and moved through a crop to contact escapements with an application surface of the wick bar being adjusted in angle to hit the escapements. The rotation of the wick controls the flow of liquid to the wick because the wick surface is less than 180 degrees around the periphery of the wick bar and is normally not in contact with liquid. The wick bar 16 may be raised or lowered or rotated to control the position of the wick with respect to the fluid in it from a set of controls 20 within the driver's compartment of the tractor 12. www.freepatentsonline.com /4438592.html   (4665 words)

Gian-carlo Wick, October 15, 1909—April 20, 1992 | By Maurice Jacob | Biographical Memoirs Gian-Carlo Wick's name is also associated with the Wick rotation, a theoretical technique using imaginary time, which had an notable impact on the development of fruitful relations between field theory and statistical mechanics. Gian-Carlo Wick is also well known for the insight and clarity that he brought to several questions at a key time in their development, in particular in meson theory and in the many applications of symmetry principles in particle physics. Wick was wrong about the relevance of the weak process, but he was right on the superposition idea, which was later vindicated by meson theory. www.nap.edu /html/biomems/gwick.html   (3984 words)

Plastic orthodontic bracket having rotation wings - Patent 5618175 Furthermore, because of the curvature of the rotation wings, an orthodontist may adjust the rotation wings once the bracket is on the tooth without having to remove the archwire. The rotation wing of the metal insert is adapted to cooperate with an orthodontic archwire located in the archwire slot, in exerting a rotating force on a tooth via the base. 1 and 2, the rotation wings 28 of this particular embodiment are formed in a slightly concave, upswept position, with the archwire-contacting points 46 being positioned at the outer ends 44a, 44b of the rotation wings 28. www.freepatentsonline.com /5618175.html   (4984 words)

Gian-carlo Wick, October 15, 1909—April 20, 1992 | By Maurice Jacob | Biographical Memoirs It is also to Wick that we owe the simple relation between range and mass seen as a direct consequence of the Heisenberg uncertainty principle: the heavier the mass of the exchanged particle that is the origin of the force, the shorter the range of that force. In 1967, Gian-Carlo Wick was awarded the Dannie Heineman Prize for Mathematical Physics by the American Physical Society "for contributions to quantum field theory, for the investigation of the theory of scattering of particles with spin, and his deep analysis of the symmetry principles in physics." Wick is survived by his wife Vanna of Turin and two sons from a first marriage, Lionel of Forest Hills, New York, and Julian, of Tokyo. stills.nap.edu /html/biomems/gwick.html   (3984 words)

C-Flex Bearings - Home Page When a load is applied in an offset manner, it creates a moment load or rotational force through the bearing center as determined by the force and length of lever arm (distance from the center of the bearing). Assuming one end is restrained and the other is rotated, the axis of the rotated member moves radially although remains parallel to the original axis. Loads on the bearing create stress in the flexures, which along with the bending stress created during rotation, must be considered in determining the life expectancy of the bearing. www.c-flex.com /faq.html   (2107 words)

Path integral formulation - Wikipedia, the free encyclopedia Indeed, it is sometimes called a partition function, and the two are essentially mathematically identical except for the factor of i in the exponent in Feynman's postulate 3. Analytically continuing the integral to an imaginary time variable (called a Wick rotation) makes the functional integral even more like a statistical partition function, and also tames some of the mathematical difficulties of working with these integrals. If J (called the source field) is an element of the dual space of the field configurations (which has at least an affine structure because of the assumption of the translational invariance for the functional measure), then, the generating functional Z of the source fields is defined to be: en.wikipedia.org /wiki/Path_integral_formulation   (2766 words)

Wick - Hutchinson encyclopedia article about Wick Fishing port and industrial town in the Highland unitary authority, northeast Scotland, at the mouth of the River Wick; population (1991) 7,800. Wick was once the busiest herring port in Europe. Pultenytown is the name given to the part of the town designed by Telford in the 1800s as a model village. encyclopedia.farlex.com /Wick   (219 words)

Active Skim View of: Gian-Carlo Wick I remember Wick recalling Roman café discussions with E Majorana, who was a great pioneer in the description of particles in terms of quantum fields, with the resulting symmetry between particle and antiparticle. The title of the paper is "Vacuum stability and vacuum excitation in a spin 0 field theory." This new resulting form of matter was proposed long before the same general idea emerged in describing the structure of matter at the quark level, with an expected transition between hadronic matter and a quark gluon plasma. However some of the works of the young Rome theorist—the Wick theorem, the Wick rotation, the Jacob-Wick expansion, the Lee-Wick approach to the vacuum, and his important contributions to meson theory and to symmetry properties—will all long remain in physics textbooks. www.nap.edu /nap-cgi/skimit.cgi?isbn=0309066441&chap=332-349   (813 words)

Encyclopedia: Path integral formulation Statistical mechanics is the application of statistics, which includes mathematical tools for dealing with large populations, to the field of mechanics, which is concerned with the motion of particles or objects when subjected to a force. If one makes a Wick rotation here, and finds the amplitude to go from any state, back to the same state in (imaginary) time iT is given by In physics, a Wick rotation is the process by which a theory in Euclidean space is analytically continued into one in Minkowski space and vice versa. In quantum field theory, if the action is given by the functional S of field configurations (which only depends locally on the fields), then the time ordered vacuum expectation value of polynomially bounded functional F, , is given by Quantum field theory (QFT) is the application of quantum mechanics to fields. www.nationmaster.com /encyclopedia/Path-integral-formulation   (5746 words)

The Statistical Mechanic: Wick rotation scott: Wick rotation always seemed to me like a mathematical trick (akin to many other tricks for using complex numbers to simplify calculations involving real numbers). I’ve never understood the use of Wick rotation that you mention, but I’ve asked many physicists about it over the years. Of course, Wick rotation is a tool familiar to all students and practitioners of quantum field theory. tsm2.blogspot.com /2007/03/wick-rotation.html   (385 words)

Physics and Astronomy Forums - Four spatial dimensions? A rotation about an angle of 90 degrees is impossible (this would correspond to a speed greater than c), but any other lorentztransformation can be seen as a rotation in time and therefore as a change of our direction in time. But I also pointed out that there are theories in which time has a certain structure which makes the Wick rotation impossible (I dont know if it really is impossible, but I guess that time assymetry would spoil this step). The whole question of Wick rotations etc is one for the mathematical physicst. www.physlink.com /community/forums/printthread.cfm?Forum=17&Topic=1722   (2220 words)

Ask An Astronomer > General Physics   (Site not responding. Last check: 2007-09-07) Imaginary Time arises from a "Wick rotation" and is used in the path integral quantization of gravity. It is a computational tool carried over from relativistic quantum field theory (in flat space-time) in which the contour integration that is required to evaluate the Feynman propogator is replaced by an integral in imaginary energy (the contour is "Wick rotated" in the complex energy plane). The final answers must be given in real time of course, so a "wick rotation" back to real time is necessary, but it can be carried out at the end of the computation. www.iiap.res.in /answers/gphysics.html   (1046 words)

Not Even Wrong » Blog Archive » Wick Rotation An approach inspired by the conviction that the difficulties of path integral approach reflect deeper problems of principle is discussed in the mini article which I titled “How to put end to the suffering caused by path integrals?” at http://matpitka.blogspot.com/. The subgroup of Spin(4) corresponding to rotations is the *diagonal* SU(2), is it not? Something analogue to the Wick rotation is still going on in that an imaginary cosmological constant is required to ensure the existence of the continuum limit. www.math.columbia.edu /~woit/wordpress/?p=160   (4192 words)

Wicked Body -- Recommendations and Resources For other uses of the word Wick please see Wick (disambiguation)'' A wick is a cord or strand of loosely woven, twisted, or braided fibers, such as in a candle or oil lamp. Wicked problems, those which have incomplete, contradictory, and changing requirements; and solutions to them are often difficult to recognize as such because of complex interdependencies. It was released in October 1988 and it was re-issued on August 22, 1995. www.becomingapediatrician.com /health/176/wicked-body.html   (537 words)

ELibM Book Review: Fermionic functional integrals and the renormalization group Similarly, the Wick rotation to imaginary time in quantum field theory gives a connection to statistical mechanics that generalizes the Feynman-Kac formula and allows for mathematically rigorous constructions of such theories. Wick ordering with respect to a Gaussian measure is simply introducing orthogonal polynomials for this measure, and the fermionic version is a straightforward variant of it. Wick ordering is also an important ingredient in the ring expansion developed in Part 2 of the book. www.emis.de /misc/articles/FKT   (2102 words)

Re: Wick's Imaginary Time   (Site not responding. Last check: 2007-09-07) The original imaginary time was in the 1950s, called "Wick Rotation". The reason for the imaginary time is that Feynmann's famous path integrals, which worked fine in non relativistic QM, become unstable when you try to compute them in relativistic Minkowski spacetime, with the negative time in the metric. Wick's idea was to multiply Minkowski's time by i, the square root of minus 1. www.superstringtheory.com /forum/scirelig/messages10/133.html   (226 words)

To loose or not to loose information | The String Coffee Table Wick rotation in general is hard to do outside of flat space, as there is no easy notion of time. One proposal is to wick rotate on the space of guage fixed metrics (using the proper time guage), as this will not involve a complexification procedure. When these classical solutions admit a sensible Wick rotation I guess one can ignore any potential problems with that method. golem.ph.utexas.edu /string/archives/000403.html   (2914 words)

Nat' Academies Press, Biographical Memoirs V.77 (1999) He was a wonderful man. Gian-Carlo Wick was born in 1909 in Turin, where he would spend his boyhood and attend the university. Arriving in the United States, Wick found a stimulating research atmosphere and was fascinated by all the activities originating from the results obtained with accelerators that could produce τ mesons. Gian-Carlo Wick was deeply concerned about the special responsibility of physicists in society and the more so through-out the long Cold War years. www.nap.edu /openbook/0309066441/html/332.html   (4331 words)

Wick rotation - Encyclopedia, History, Geography and Biography   (Site not responding. Last check: 2007-09-07) Wick rotation - Encyclopedia, History, Geography and Biography In physics, a Wick rotation is the process by which a theory in Euclidean space is analytically continued into one in Minkowski space and vice versa. This encyclopedia, history, geography and biography article about Wick rotation contains research on www.arikah.net /encyclopedia/Wick_rotated   (120 words)

The Helicity States   (Site not responding. Last check: 2007-09-07) This frame is constructed by rotating the z-axis of S along the direction of the particle's momentum, and then boosting this S' frame so that the particle is now at rest in the new frame S''. This rotation known as the Wick Helicity Rotation, may not simply be reduced to the sum of the rotations in Given that r is simply a rotation, effected by rotations and boosts in the xz plane, it must be a rotation about the y-axis. www.maths.tcd.ie /~rb/masters/node4.html   (839 words)

Welcome to AJC! | ajc.com As first moves go, re-signing Bob Wickman was the best first move John Schuerholz could have done to restore faith and optimism among the Braves and their fans for next season. Wick has made an impact on his bullpen mates, and he’s produced on the field. I happen to think that we have 5 starters that are all very capable of being top-of-the-rotation type of pitchers, along with two other starters that won’t even have a place to start (though they deserve to). www.ajc.com /blogs/content/shared-blogs/ajc/braves/entries/2006/09/21/wicks_signed_bu.html   (10237 words)

Wick rotation Err, a non flat space time is not an ingredient of QFT, which is the formalism where this Wick rotation is very often used and which is indeed the context withint which the OP was asking the question. The main reason why this rotation is used in QFT is that it connects quantum (field) theory to statistical mechanics. I agree that "Wick rotation" refers usually to QFT in flat spacetime. www.physicsforums.com /showthread.php?p=1184392   (941 words)

Reference.com/Encyclopedia/Path integral formulation If one makes a Wick rotation here, and finds the amplitude to go from any state, back to the same state in (imaginary) time iT is given by One aspect of this equivalence was also known to Schrödinger who remarked that the equation named after him looked like the diffusion equation after Wick rotation. Analytically continuing the integral to an imaginary time variable (called a Wick rotation) makes the functional integral even more like a statistical partition function, and also tames some of the mathematical difficulties of working with these integrals. www.reference.com /browse/wiki/Path_integral_formulation   (3209 words)

Wick Backgrounds - For time-dependent backgrounds, the nature of the Wick rotation is more... Interviews with producers Lucy Fisher, Douglas Wick, Patrick McCormick, and cinematography Don McAlpine at the premiere of the movie Peter Pan, directed by PJ Hogan. Wick introduces the main points of the controversy by describing how the theory was developed and the scientific and phylosophical backgrounds... backgrounds.faasv.com /index.php?k=wick-backgrounds   (1036 words)

Socks from Penrith Survival Equipment Use as a liner in winter or on their own in summer the BTS (Better Than Silk) socks are woven from Tactel microfibre, beautifully soft, fast wicking and quick drying. A 3-layer system with abrasion resistant outer, a specially developed inner layer to wick perspiration away from the skin to increase comfort and a hydrophilic waterproof... A 3-layer system with abrasion resistant outer, a specially developed inner layer to wick perspiration away from the skin to increase comfort and a hydrophilic waterproo... www.edirectory.co.uk /penrith_survival/static/55/ca1254.html   (713 words)

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