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Topic: Point particle

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boiling point

neutral point of view

West Point

floating point

point of view

Lagrangian point

fixed point

West Point, New York

Point to Point Protocol

critical point

fixed point mathematics

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	Taking the Particle out of Particle Physics
		Particle physics is the most fundamental area of science in that its goal is to reduce the wonderful diversity and complexity of our universe to a few simple mathematical laws.
		On the other hand, there exist other particles which are massless, especially the graviton, photon, and gluons, and this suggested that these string theories be used instead to describe these fundamental particles, including the quarks and gluons from which the hadrons are made.
		Although quantization of the particle is straightforward, consistency of the quantization of the string introduces a particularly unusual feature: The dimension of spacetime is determined to be 26 for the simplest string, and 10 or 2 for those with extra degrees of freedom.
	insti.physics.sunysb.edu /~siegel/quo.html (1777 words)

	Point particle - Wikipedia, the free encyclopedia
		In Newtonian gravitation and classical electromagnetism, for example, the respective fields outside of a spherical object are identical to those of a point particle of equal charge/mass located at the center of the sphere.
		In general relativity a point particle with mass only "exists" in the sense of "test particle", inasmuch as its influence on the curvature of spacetime must be ignored.
		quantum field theory), "point particle" is synonymous with "elementary particle", which is defined as a particle without structure or, equivalently, as a particle lacking component parts.
	en.wikipedia.org /wiki/Point_particle (233 words)

	Ending the Mystery of Wave / Particle Duality
		It is a long accepted surety that a particle such as the electron in some cases tests as being an energetic point, and in other cases appears to act like a wave.
		It is the recent scientific acceptance of structure in fundamental particles that has introduced interior "spin-rotation" as a major element in progress towards a New Standard Model.
		Particle waves may be transient effects of the motion of points, but those motions never cease.
	www.metaparticles.com /page13.htm (1581 words)

	[No title]
		The reference point for the particle type is used to position the particle on the clock face.
		By default, the reference point for a particle type is set at the center of the shape image, so the particle appears at the center of the clock face.
		As you move the reference point away from the center of the shape image, the particle (on the clock face) moves away from the local axis (the center of the clock).
	web.tiscali.it /olgab/09b_Particles36.html (1158 words)

	Wikinfo \| Classical mechanics
		True point particles, such as the electron, are properly described by quantum mechanics.
		The position of a point particle is defined with respect to an arbitrary fixed point in space, which is sometimes called the origin, O.
		In general, the point particle need not be stationary, so r is a function of t, the time elapsed since an arbitrary initial time.
	www.wikinfo.org /wiki.php?title=Classical_mechanics (1427 words)

	Quantum Theory
		The quantum particle is inherently random when it is not being observed, and in the sense of probability exists everywhere in space and hence is wave-like; when a measurement is performed to ascertain the position of the quantum particle, it is always found to be pointlike and hence the particle-like behaviour of the quantum particle.
		The answer is no; the particle is in a probabilistic state in which both its position and momentum have a likelihood of having a whole range of values, and has discussed at length in the Section 11.6.
		Hence, unlike a classical particle whose complete description at time t is given by specifying its position and velocity, to describe the state of a quantum particle we have to specify the likelihood of finding the particle at all the points of space.
	srikant.org /core/node12.html (10012 words)

	Born Rigidity and Acceleration
		Each particle is subjected to a constant proper acceleration (hyperbolic motion) such that, with respect to its instantaneously co-moving inertial rest frames, the distances to each of the other particles remain constant.
		It follows that this pivot event is fixed for the entire acceleration, the particle's path is a hyperbola asymptotic to the lightlines through this pivot event, and the particle's proper distance from this event (with respect to it's co-moving inertial frames) is constant.
		The equation of motion of the jth particle is
	www.mathpages.com /home/kmath422/kmath422.htm (1973 words)

	5.5 Concluding remarks
		This problem is likely due [45] to the fact that the field that is averaged over the surface of the shell is sourced by a point particle and not by the shell itself.
		In this picture, the particle simply interacts with a free radiative field (whose origin can be traced to the particle’s past), and the procedure of mass renormalization is sidestepped.
		In the method of matched asymptotic expansions, the small body is taken to be a nonrotating fl hole, and its metric perturbed by the tidal gravitational field of the external universe is matched to the metric of the external universe perturbed by the fl hole.
	relativity.livingreviews.org /Articles/lrr-2004-6/articlesu30.html (2850 words)

	Gravity and String Theory
		The main distinction between strings and point particles is the fact that strings have spatial extent, whereas point particles are literally zero-dimensional.
		If the particles were ordinary objects - billiard balls are a common example - they would simply collide and be deflected to different trajectories depending on their relative momenta.
		If the particle involved here is supposed to be a graviton instead of a photon, this blurring significantly "spreads out" the force delivered, to the point that the infinities formerly obtained when gravity was calculated on short distance scales are replaced by logical finite answers.
	library.thinkquest.org /27930/stringtheory2.htm (1036 words)

	Point limitations...can be easily fixed - Right Hemisphere Forum
		The snowflakes are points, each point is created on the fly by the particle generator.
		The best "point" particle would be one where you basically have an alpha channel (in this case the shape of the snowflake), and a plain material (that you can change the colors of to suit).
		I think it will be possible to change the opacity on point objects (it's changing the size that's a big problem, few cards support that, since particle systems are rendered as a single object).
	www.righthemisphere.com /forum/showthread.php?p=6025 (462 words)

	Common Sense Science \| Contradictions
		Even when a point particle model is used for physics calculations, the particle is also said to have a wavelength that must be used in other calculations.
		And the point particle assumption for elementary particles has been proven false by Hofstadter (Nobel Laureate in Physics, 1961) who showed that neutrons, protons, and other elementary particles have a measurable finite size, an internal charge distribution (indicative of internal structure), and elastically deform in interactions.
		Evidently, the point particle assumption is contradicted by the known rest mass of an electron.
	www.commonsensescience.org /contradictions.html (1548 words)

	Classical mechanics - Article from FactBug.org - the fast Wikipedia mirror site (Site not responding. Last check: 2007-10-10)
		The motion of a point particle is characterized by a small number of parameters: its position, mass, and the forces applied to it.
		True point particles, such as the electron, are normally better described by quantum mechanics.
		However, the results for point particles can be used to study such objects by treating them as composite objects, made up of a large number of interacting point particles.
	www.factbug.org /cgi-bin/a.cgi?a=6048 (2071 words)

	the bit-101 Particle class
		Can be set to "wrap", "bounce", or "remove" wrap causes the particle to disappear and appear on the opposite edge of the space bounce causes the particle to bounce off the edge at a speed determined by the bounce property remove causes the particle to be permanently deleted if it leaves the space.
		default is 1000 springToMouse(bSpring:Boolean [, force:Number]) - causes the particle to spring to the mouse - arguments: bSpring.
		any number of points can be added, but the result will be that the particle will spring to an point which is the average of all points.
	www.bit-101.com /Particles (1113 words)

	Particle System - Point Sprites? - GameDev.Net Discussion Forums
		I have made fl-hole effect using particles for example, with several spiraly positioned magnets points that pulled particles toward them combinated with self-gravity.
		Posted - 10/24/2006 8:48:41 AM Point Sprites pose several limitations, which might be crucial in your implementation of particle system.
		Their only real benifit in a simple particle system is that they require less data to be uploaded to the GPU each frame, but if done right this isn't much of an issue even with 4 per particle.
	www.gamedev.net /community/forums/topic.asp?topic_id=420753 (577 words)

	Time Travel and Modern Physics (Stanford Encyclopedia of Philosophy)
		Points on line L represent the position x that the younger pointer should develop into, given that it encountered the older pointer emerging from the time machine set at position y.
		From the particle's point of view, it is traveling to the right at a constant speed until it hits an older version of itself and comes to rest.
		The point labeled P is the left edge of the time-travel region; the two labels are a reminder that the point at the bottom and the point at the top are one and the same.
	plato.stanford.edu /entries/time-travel-phys (12643 words)

	Inside Zero Point Energy
		Therefore, as the plates are brought closer, the virtual particles outside the plates increasingly overpower the decreasing quantity of virtual particles appearing between the plates with an exponentially increasing force.
		Since ZPE is due to virtual particle flux and high electric field gradients cause the flux to increase, it is reasonable to assume that near the surface of an electron, the ZPE virtual particle flux would be very high, like a bunch of flies buzzing around it.
		and the interesting point is that the bulk of the contribution to the effect, in this case the inertial mass, comes from the very-high-frequency components of the ZPF.” He then demonstrates a causal and quantifiable basis for Mach’s principle and explains that the magnetic component of the Lorentz force arises in ZPE and matter interactions.
	www.seaspower.com /InsideZeroPoint-Valone.htm (5597 words)

	Electron as a Particle (Site not responding. Last check: 2007-10-10)
		This >makes sense if it > > >is a fundamental particle, since if it had non-zero volume whatever it > > >was made out of would be more fundamental.
		> >A "point charge" is an approximation, a mental construction that is quite >good for many cases.
		The electron is a member of a class of particles called fermions.
	www.newton.dep.anl.gov /askasci/phy00/phy00061.htm (354 words)

	Eric Poisson
		The particle produces a retarded scalar field which interacts with the particle and influences its motion via the action of a self-force.
		Although each mode is bounded at the position of the particle, a mode-sum evaluation of the self-force requires regularization because the sum does not converge: the retarded field is infinite at the position of the particle.
		The field's action on the particle is difficult to calculate because of its singular nature: the field diverges at the position of the particle.
	www.physics.uoguelph.ca /~poisson/research/publications.html (1866 words)

	Linear Dynamics
		This point is called the centre of mass, and it is the point where all the mass of the atom or molecule might be considered to reside.
		He found that the force was proportional to the product of the charge, being attractive if the particles had opposite sign and repulsive if they had the same sign, and that the force decayed in magnitude in proportion to the inverse square of their separation.
		Since both particles have the same mass, m, and charge e it is clear that they will behave as mirror images of each other, so we will simply investigate the dynamics of the proton on the right hand side.
	www.ch.ic.ac.uk /local/physical/mi_2.html (7151 words)

	SUPERSTRINGS! String Basics
		This mode is characteristic of a spin-2 massless graviton (the particle that mediates the force of gravity).
		Notice that the interaction point occurs at a topological singularity in the diagram (where the 3 world-lines intersect).
		[In point particle field theories the number of diagrams grows exponentially at higher orders.] The bad news is that extracting answers from diagrams with more than about two handles is very difficult due to the complexity of the mathematics involved in dealing with these surfaces.
	www.sukidog.com /jpierre/strings/basics.htm (584 words)

	Problems With an Old Universe / Young Earth Model (Site not responding. Last check: 2007-10-10)
		The Bohr Atomic Model with a nucleus containing protons and neutrons that is surrounded by orbiting point particle electrons is being challenged by Creationist Physicists associated with "Common Sense Science, Inc." and a few Naturalist Physicists who are convinced that the Bohr Model is false.
		The inverse relationship between particle size and rest mass energy requires a small charged particle to generate a force that would become infinitely large if that charge were confined to a point.
		However, if area is assigned to a point particle electron, the electron would emit radio waves, loosing energy that would destroy the particle structure.
	www.youngearth.org /New_Atom_Model.htm (1252 words)

	On Existence
		To exist means to be in the current state of all point particles.
		Therefore, X is a point particle or X is a body (CDL).
		Therefore, if X exists then (X is a point particle or X is a body), and if X is a point particle or X is a body then X exists(C).
	www.theendofevolution.com /Existence.html (390 words)

	Zero-point energy - Encyclopedia of Earth
		In conventional quantum physics, the origin of zero-point energy is the Heisenberg uncertainty principle, which states that, for a moving particle such as an electron, the more precisely one measures the position, the less exact the best possible measurement of its momentum (mass times velocity), and vice versa.
		The Higgs field was first proposed in 1964 and is still a key element of the Standard Model of particle physics; it is needed to confer the property of mass on the fundamental particles.
		This points to the electromagnetic quantum vacuum as the origin of forces which appear as inertial mass.
	www.eoearth.org /article/Zero-point_energy (3544 words)

	How does one electron go through two slits at the same time? In Young's Double-Slit experiment Hawking, Feynman and ...
		If you picture an electron as merely a point particle travelling like a billiard ball through space, it is impossible to imagine one travelling through two slits at once; but the quantum universe of the very small is not just a miniature version of reality as we perceive it at our macro level of understanding.
		The electron as a small particle is merely a model of reality that helps us visualize some of its behaviors, but obviously not all of them.
		Just to clarify one point, if a single photon is fired at the two slits, an interference pattern will not appear.
	www.physlink.com /Education/AskExperts/ae193.cfm (413 words)

	divinem_I_blav
		A zero point is not exactly a ‘thing’ in itself, so much as it is a condition, or a place at which certain processes occur.
		It is not a ‘point particle’ but a whole inner world, where influences and forces emerge from deeper levels of being into physical manifestation—as a particle, or cosmos.
		The notion of zero points is easily mistaken, as these points are likely to be viewed as existing within the four dimensional space-time continuum—like a spiritual spark ‘in’ the heart.
	www.zeropoint.ca /microIII3c-zpfounds.htm (1975 words)

	Notation and terminology: phase space
		Just as the three position coordinates (x, y, z) of a pointlike atom can be envisioned as a point in a 3-dimensional space, so also the 6N coordinates needed to describe N pointlike particles can be imagined as a single point in a 6N-dimensional space.
		Since the position of the point in phase space fixes the 6N variables that comprise a complete microscopic description of the system, each point in phase space corresponds uniquely to a single state of the system, and vice versa: every allowed point in phase space corresponds to a state of the system.
		A ``point in phase space'' is known as a phase point, whose customary notation is
	users.wpi.edu /~phillies/stat4/node4.html (364 words)

	Angular momentum of a point particle
		Figure 85: Angular momentum of a point particle about the origin.
		Note that the derivative of a vector product is formed in much the same manner as the derivative of an ordinary product, except that the order of the various terms is preserved.
		is the torque acting on the particle about an axis passing through the origin.
	farside.ph.utexas.edu /~rfitzp/teaching/301/lectures/node118.html (187 words)

	The Q Function
		In classical mechanics, the state of a point particle is completely speciﬁed by giving its position and momentum at any given time.
		In quantum mechanics, it is impossible to specify both x and p simultaneously because of the uncertainty principle, which asserts that the “uncertainty” (as given by the standard deviation of a series of measurements on identically-prepared systems) in x and p must satisfy
		For a quantum free particle, or a harmonic oscillator, minimum uncertainty states where the relation (1) is satisﬁed with the equal sign are given by Gaussian wavefunctions.
	comp.uark.edu /~jgeabana/blochapps/qfunction.html (464 words)

	General distribution functions and correlation functions
		For simplicity, we consider the case that all the particles are of the same type.
		Having established the equivalence of the ensembles in the thermodynamic limit, we are free to choose the ensemble that is the most convenient on in which to work.
		Thus, integrating over the available volume, one finds, not surprisingly, all the particles in the system.
	www.nyu.edu /classes/tuckerman/stat.mech/lectures/lecture_8/node2.html (255 words)

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