das Etikett des Spin Doctors als neutrale Bezeichnung an. Niemand vermochte aber eine absolut positive Konnotation des Wortes erkennen. Ein Sprecher. Spin ist in der Teilchenphysik der Eigendrehimpuls von Teilchen. Bei den fundamentalen Teilchen ist er wie die Masse eine unveränderliche innere Teilcheneigenschaft. Er beträgt ein halb- oder ganzzahliges Vielfaches des reduzierten planckschen. Die Zielrichtung universitärer Spin-off-Strategien beeinflusst dabei naturgemäß auch Basis der Gründung und Gründungsmotivation der entstehenden.
Freunde kennenlernen, Chat, Online-Spiele und mehr1 Akademische Spin - offs 2. 1. 1 Definition und Begriffsabgrenzung akademische Spin - offs An deutschen Hochschulen und Forschungseinrichtungen werden. BANDBREITE VON SPIN-OFF-TYPEN Mit zunehmender Zahl von Fallstudien bei Spin-offs wächst die Vielfalt unterschiedlicher Ausgründungshintergründe. Die Zielrichtung universitärer Spin-off-Strategien beeinflusst dabei naturgemäß auch Basis der Gründung und Gründungsmotivation der entstehenden.
Spin. Custom Spinning Wheel VideoSpin spin verb (TURN) C1 [ I or T ] to (cause to) turn around and around, especially fast: The earth spins on its axis. With Spin, you’re free to move. Founded in San Francisco, in , Spin operates dockless mobility systems in cities and campuses throughout the United States. Our core team is comprised of engineers, designers, operators, lawyers, and public policymakers with experience from Y Combinator, Uber, Lyft, and other technology companies. A distinctive point of view, emphasis, or interpretation: "adept at putting spin on an apparently neutral recital of facts" (Robert M. Adams). Use our free spinning wheel to decide anything. You can do custom text (wheel of names, numbers, etc.) for your own spinning wheel and share with freinds. Medical Definition of spin 1: a quantum characteristic of an elementary particle that is visualized as the rotation of the particle on its axis and that is responsible for measurable angular momentum and magnetic moment.
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Synonyms for spin Synonyms: Verb gyrate , pinwheel , pirouette , revolve , roll , rotate , turn , twirl , wheel , whirl Synonyms: Noun gyration , pirouette , reel , revolution , roll , rotation , twirl , wheel , whirl Visit the Thesaurus for More.
Examples of spin in a Sentence Verb The car hit a patch of ice and spun into the wall. Recent Examples on the Web: Verb The collision caused the car to spin counterclockwise and then hit a concrete bridge support wall on the side of the road.
In quantum mechanics and particle physics , spin is an intrinsic form of angular momentum carried by elementary particles , composite particles hadrons , and atomic nuclei.
Spin is one of two types of angular momentum in quantum mechanics, the other being orbital angular momentum. The orbital angular momentum operator is the quantum-mechanical counterpart to the classical angular momentum of orbital revolution and appears when there is periodic structure to its wavefunction as the angle varies.
The existence of electron spin angular momentum is inferred from experiments, such as the Stern—Gerlach experiment , in which silver atoms were observed to possess two possible discrete angular momenta despite having no orbital angular momentum.
Spin is described mathematically as a vector for some particles such as photons, and as spinors and bispinors for other particles such as electrons.
Spinors and bispinors behave similarly to vectors : They have definite magnitudes and change under rotations; however they use an unconventional "direction".
All elementary particles of a given kind have the same magnitude of spin angular momentum, though its direction may change.
These are indicated by assigning the particle a spin quantum number. Very often, the "spin quantum number" is simply called "spin".
The fact that it is a quantum number is implicit. Wolfgang Pauli in was the first to propose a doubling of the number of available electron states due to a two-valued non-classical "hidden rotation".
When Paul Dirac derived his relativistic quantum mechanics in , electron spin was an essential part of it. As the name suggests, spin was originally conceived as the rotation of a particle around some axis.
While the question of whether elementary particles actually rotate is ambiguous as they are point-like , this picture is correct insofar as spin obeys the same mathematical laws as quantized angular momenta do; in particular, spin implies that the particle's phase changes with angle.
On the other hand, spin has some peculiar properties that distinguish it from orbital angular momenta:.
The value of s for an elementary particle depends only on the type of particle, and cannot be altered in any known way in contrast to the spin direction described below.
The spin angular momentum, S , of any physical system is quantized. The allowed values of S are. In contrast, orbital angular momentum can only take on integer values of s ; i.
The two families of particles obey different rules and broadly have different roles in the world around us. In contrast, bosons obey the rules of Bose—Einstein statistics and have no such restriction, so they may "bunch together" in identical states.
Also, composite particles can have spins different from their component particles. For example, a helium atom in the ground state has spin 0 and behaves like a boson, even though the quarks and electrons which make it up are all fermions.
The spin—statistics theorem splits particles into two groups: bosons and fermions , where bosons obey Bose-Einstein statistics and fermions obey Fermi-Dirac statistics and therefore the Pauli Exclusion Principle.
Specifically, the theory states that particles with an integer spin are bosons while all other particles have half-integer spins and are fermions.
As an example, electrons have half-integer spin and are fermions that obey the Pauli exclusion principle, while photons have integer spin and do not.
The theorem relies on both quantum mechanics and the theory of special relativity , and this connection between spin and statistics has been called "one of the most important applications of the special relativity theory".
Since elementary particles are point-like, self-rotation is not well-defined for them. This is equivalent to the quantum mechanical interpretation of momentum as phase dependence in the position, and of orbital angular momentum as phase dependence in the angular position.
Spin represents polarization for other vector bosons as well. For fermions, the picture is less clear.
However whether this holds for free electron is ambiguous, since for an electron, S 2 is constant, and therefore it is a matter of interpretation whether the Hamiltonian includes such a term.
Nevertheless, spin appears in the Dirac equation , and thus the relativistic Hamiltonian of the electron, treated as a Dirac field , can be interpreted as including a dependence in the spin S.
Particles with spin can possess a magnetic dipole moment , just like a rotating electrically charged body in classical electrodynamics.
These magnetic moments can be experimentally observed in several ways, e. For exclusively orbital rotations it would be 1 assuming that the mass and the charge occupy spheres of equal radius.
The electron, being a charged elementary particle, possesses a nonzero magnetic moment. Composite particles also possess magnetic moments associated with their spin.
In particular, the neutron possesses a non-zero magnetic moment despite being electrically neutral. This fact was an early indication that the neutron is not an elementary particle.
In fact, it is made up of quarks , which are electrically charged particles. The magnetic moment of the neutron comes from the spins of the individual quarks and their orbital motions.
Neutrinos are both elementary and electrically neutral. The minimally extended Standard Model that takes into account non-zero neutrino masses predicts neutrino magnetic moments of:   .
New physics above the electroweak scale could, however, lead to significantly higher neutrino magnetic moments. Experimental results have put the neutrino magnetic moment at less than 1.
On the other hand elementary particles with spin but without electric charge, such as a photon or a Z boson, do not have a magnetic moment.
In ordinary materials, the magnetic dipole moments of individual atoms produce magnetic fields that cancel one another, because each dipole points in a random direction, with the overall average being very near zero.
Ferromagnetic materials below their Curie temperature , however, exhibit magnetic domains in which the atomic dipole moments are locally aligned, producing a macroscopic, non-zero magnetic field from the domain.
These are the ordinary "magnets" with which we are all familiar. In paramagnetic materials, the magnetic dipole moments of individual atoms spontaneously align with an externally applied magnetic field.
In diamagnetic materials, on the other hand, the magnetic dipole moments of individual atoms spontaneously align oppositely to any externally applied magnetic field, even if it requires energy to do so.
The study of the behavior of such " spin models " is a thriving area of research in condensed matter physics. For instance, the Ising model describes spins dipoles that have only two possible states, up and down, whereas in the Heisenberg model the spin vector is allowed to point in any direction.
These models have many interesting properties, which have led to interesting results in the theory of phase transitions. In classical mechanics, the angular momentum of a particle possesses not only a magnitude how fast the body is rotating , but also a direction either up or down on the axis of rotation of the particle.
Quantum mechanical spin also contains information about direction, but in a more subtle form. Quantum mechanics states that the component of angular momentum for a spin-s particle measured along any direction can only take on the values .
Conventionally the direction chosen is the z -axis:. This vector then would describe the "direction" in which the spin is pointing, corresponding to the classical concept of the axis of rotation.
It turns out that the spin vector is not very useful in actual quantum mechanical calculations, because it cannot be measured directly: s x , s y and s z cannot possess simultaneous definite values, because of a quantum uncertainty relation between them.
As a qualitative concept, the spin vector is often handy because it is easy to picture classically. For instance, quantum mechanical spin can exhibit phenomena analogous to classical gyroscopic effects.
For example, one can exert a kind of " torque " on an electron by putting it in a magnetic field the field acts upon the electron's intrinsic magnetic dipole moment —see the following section.
The result is that the spin vector undergoes precession , just like a classical gyroscope. This phenomenon is known as electron spin resonance ESR.
The equivalent behaviour of protons in atomic nuclei is used in nuclear magnetic resonance NMR spectroscopy and imaging.
Mathematically, quantum-mechanical spin states are described by vector-like objects known as spinors. There are subtle differences between the behavior of spinors and vectors under coordinate rotations.
To return the particle to its exact original state, one needs a degree rotation. The Plate trick and Möbius strip give non-quantum analogies.
A spin-zero particle can only have a single quantum state, even after torque is applied. Rotating a spin-2 particle degrees can bring it back to the same quantum state and a spin-4 particle should be rotated 90 degrees to bring it back to the same quantum state.
The spin-2 particle can be analogous to a straight stick that looks the same even after it is rotated degrees and a spin-0 particle can be imagined as sphere, which looks the same after whatever angle it is turned through.
Spin obeys commutation relations analogous to those of the orbital angular momentum :. It follows as with angular momentum that the eigenvectors of S 2 and S z expressed as kets in the total S basis are:.
The spin raising and lowering operators acting on these eigenvectors give:. But unlike orbital angular momentum the eigenvectors are not spherical harmonics.
There is also no reason to exclude half-integer values of s and m s. In addition to their other properties, all quantum mechanical particles possess an intrinsic spin though this value may be equal to zero.
One distinguishes bosons integer spin and fermions half-integer spin. The total angular momentum conserved in interaction processes is then the sum of the orbital angular momentum and the spin.
For systems of N identical particles this is related to the Pauli exclusion principle , which states that by interchanges of any two of the N particles one must have.
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Ja, ich habe die Nutzungsbedingungen und die Datenschutzregelung gelesen und akzeptiere beides! Spielt zusammen Neueste Fotos.Mobilversion von spin. The Plate trick and Möbius strip give non-quantum analogies. Herschbach For example, one can exert a kind of Spin. torque Smarty Bubbels on an electron by putting it in a magnetic field the field acts upon the electron's intrinsic Bonkersbet dipole moment —see Eurolott following section. Each such representation corresponds to a representation of the covering group of SO 3which is SU 2. The manipulation of nuclear spin by radiofrequency waves nuclear magnetic resonance is important in chemical spectroscopy and medical imaging. The resulting irreducible representations yield the following spin matrices and eigenvalues in the z-basis. Please tell us where you read or heard it including the quote, if possible. H Learn More about spin. Need even more definitions? The present convention is used by software such as sympy; while many physics textbooks, Giochi Gratis Slot as Sakurai and Griffiths, prefer to make it real and positive.