What is Heisenberg: Definition and 308 Discussions

Werner Karl Heisenberg (; German pronunciation: [ˈvɛɐ̯nɐ ˈhaɪzn̩ˌbɛɐ̯k] (listen); 5 December 1901 – 1 February 1976) was a German theoretical physicist and one of the key pioneers of quantum mechanics. He published his work in 1925 in a breakthrough paper. In the subsequent series of papers with Max Born and Pascual Jordan, during the same year, this matrix formulation of quantum mechanics was substantially elaborated. He is known for the uncertainty principle, which he published in 1927. Heisenberg was awarded the 1932 Nobel Prize in Physics "for the creation of quantum mechanics".Heisenberg also made important contributions to the theories of the hydrodynamics of turbulent flows, the atomic nucleus, ferromagnetism, cosmic rays, and subatomic particles. He was a principal scientist in the German nuclear weapons program during World War II. He was also instrumental in planning the first West German nuclear reactor at Karlsruhe, together with a research reactor in Munich, in 1957.
Following World War II, he was appointed director of the Kaiser Wilhelm Institute for Physics, which soon thereafter was renamed the Max Planck Institute for Physics. He was director of the institute until it was moved to Munich in 1958. He then became director of the Max Planck Institute for Physics and Astrophysics from 1960 to 1970.
Heisenberg was also president of the German Research Council, chairman of the Commission for Atomic Physics, chairman of the Nuclear Physics Working Group, and president of the Alexander von Humboldt Foundation.

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  1. L

    Cause of the Heisenberg Uncertainty Principle

    Hi! So I know what the Uncertainty principle states and everything, but I can't find anywhere the "causes" of the uncertainty. Like, what is it exactly that "causes" the uncertainty. If it's not the measurement tools/technology, then what is it?? Please explain in terms of physical phenomena...
  2. J

    Heisenberg Uncertainty Principle question

    given 2 unnormalized wave functions: Y1(x)=e^i(x/m) Y2(x)=1/2*[e^2i(x/m) + e^3i(x/m) + e^-2i(x/m) + e^-3i(x/m)] if the positions of the particles were measured, which would be found to be more localized in space? (that is, which has a position known more precisely?) to my...
  3. pellman

    Time derivative in the Heisenberg picture?

    On the Wikipedia page for http://en.wikipedia.org/wiki/Heisenberg_picture#Mathematical_details" we find this relation \frac{d}{dt}A(t)=\frac{i}{\hbar}[H,A(t)]+\left(\frac{\partial A}{\partial t}\right) I don't understand what the distinction between \frac{d}{dt}A(t) and...
  4. D

    Heisenberg Principle in Context of Absorption/Emission Spectroscopy

    Why do we get line spectra from absorption/emission of atoms, but band spectra from absorption/emission of molecules? As I understand the Heisenberg Uncertainty Principle mathematically, some operators do not commute and as such, the order of measurements determines the results. In regard...
  5. L

    Heisenberg Uncertainty Principle

    Does the uncertainty principle apply only to electrons or other particles as well?
  6. T

    Heisenberg uncertainty derivation

    Hi, I am trying to teach myself some quantum mechanics and here is something I am stuck on. Various derivations of Heisenberg uncertainty start out with two Hermitian operators, usually called A and B to represent position and momentum. Then they define another two operators ∆A and ∆B as...
  7. rubenvb

    General Relativity and Heisenberg Uncertainty

    First, I'm not sure where this fits (here or Quantum Mechanics), because it's completely in-between the two... Is there a way to account for the fundamental uncertainty in quantum mechanics through a modification of general relativity? I have very limited experience in Quantum mechanics, and...
  8. fluidistic

    Is Heisenberg principle applicable to a photon?

    I wonder if Heisenberg principle (both \Delta p \Delta x \geq \frac{\hbar }{2} and \Delta E \Delta t \geq \frac{\hbar }{2}) can be applied to photons. Say I have a laser emitting a flash. I know very well the wavelength of the photon, therefore its momentum. Also, I know well where it might...
  9. H

    Beta decay and Heisenberg principle

    Homework Statement One could imagine that beta decay was due to a electron initially inside the nucleus and than leaving it. Proof by using Heisenberg uncertainty principle that this is not possible. There is a hint which says you can use energy spectra and values for the energy of beta...
  10. S

    From Heisenberg to Superposition states

    Hi All, I am trying to remember the logical argument that leads from Heisenberg's uncertainty principle to the existence of quantum superposition states. Here's my sketchy version: 1) postulate of Quantization leads to non-commuting operators 2) This leads to Heisenberg Unc. Principle...
  11. fluidistic

    Heisenberg principle, about time

    \Delta E \Delta t \geq \frac{\hbar}{2}. If I understand well, if I measure the energy of a particle (or system of particles) with a great precision, I cannot know well at all when the system had this energy... right? My doubt is: The system had (or will have?!) the energy I measured, but when...
  12. fluidistic

    Heisenberg principle, little question

    \Delta x \Delta p \geq \frac{\hbar}{2}. Say I want to measure the best I can the position of an electron, in detriment of its momentum (i.e. velocity since I assume that I know its mass quite well). When \Delta x \to 0, \Delta p should tend to +\infty but there's the c limit so that I can't...
  13. N

    Applying Heisenberg Picture Confusion

    I was trying to follow http://www.youtube.com/watch?v=dCua1R9VIiQ&p=EFD655A9E0B979B7&playnext=1&index=54" lecture at the 4:15 mark but am having a little difficulty. In particular, why doesn't he have to take the commutator of all four of the terms you get when you square (p-eA). Is he using...
  14. Z

    Calculating Heisenberg Uncertainty for Nuclei of Radius r

    Homework Statement hi i am new to this principle if i was to calculate the Heisenberg uncertainty of a nuclei of radius r would i take my delta x as r or as the diameter of the nuclei thanks Homework Equations The Attempt at a Solution
  15. A

    Probability amplitude in Heisenberg e Schrodinger pictures

    Hi, this is my question: suppose that at time t' our system is in the state | \psi(t')\rangle The probability for the system to be in the state | \phi\rangle at the time t'' is the norm of \langle \phi| \psi(t'')\rangle This in the Schrodinger picture. But how i can write the same thing in...
  16. N

    Heisenberg vs Schrodinger Picture

    Please tell me where my understanding of the Heisenberg and/or the Schrodinger picture falls apart. -Schrodinger says the state vector of a system changes with time according to a unitary operator that doesn't change with time. -Hesienberg says the state vector of a system doesn't change...
  17. P

    Interacting Spins , Heisenberg Hamiltonian , Tensor product

    Hello, I'm studying the Heisenberg Model. Given the Hamiltonian H = - 2 \frac{J}{\hbar^2} \vec{S}_1 \vec{S}_2 with \begin{equation} \vec{S} = \frac{\hbar}{2} \; \left( \begin{array}{ccc} \sigma_x \\ \sigma_y \\ \sigma_z \end{array} \right) \end{equation} \sigma_{x,y,z} \quad...
  18. E

    Stability of Electron/Nucleus; Heisenberg Unc.

    In Six Easy Pieces: Fundamentals of Physics by Feynman, the claim is made that the reason why electrons don't just collide “ontop” of the nucleus is due to the Heisenberg uncertainty principle. This perplexes me greatly; it sounds wrong to me. The moon and the Earth do not collide because...
  19. nomadreid

    How does the uncertainty principle relate to Maxwell's equations?

    There are two basic facts that I have difficulty reconciling: (a) the magnetic and electrical components make up a complementary pair of variables (b) Maxwell's equations describe the magnetic component in terms of the electrical one and vice-versa My question is definitely not original...
  20. M

    Heisenberg Uncertainty Principle - Why Is It Real?

    From what I understand, the Heisenberg Uncertainty Principle means that we can never know the position and velocity of a particle at the same time, as the measurement of one necessarily affects the measurement of the other. Great. I understand that theory, and it makes perfect sense. But what...
  21. L

    Heisenberg uncertainty principle

    I got in an argument with my dad over the weekend. Is the Heisenberg uncertainty principle a result of technological limitation or a basic premise in quantum mechanics? Basically is the information fundamentally "unknowable" or simply unmeasurable?
  22. A

    Heisenberg Uncertainty, Need Some Clarification. TIME SESITIVE, HELP

    Heisenberg Uncertainty, Need Some Clarification. TIME SESITIVE, HELP! Homework Statement Use the Heisenberg uncertainty principle to calculate Deltax for a ball (mass = 100 g, diameter = 6.65 cm) with Deltav = 0.645 m/s. Homework Equations PX = h/(4*3.14) The Attempt at a Solution...
  23. S

    Heisenberg Uncertainty Relations - angular momentum and angular displacement

    Homework Statement Starting from one of the more familiar Heisenberg Uncertainty Relations, derive the Uncertainty Relation involving angular momentum and angular displacement and explain its significance. Homework Equations The relevant uncertainty relationship is that between...
  24. T

    Heisenberg Uncertainty Principle and Kinetic Energy

    Homework Statement 18. A ball of mass 50 g moves with a speed of 30 m/s. If its speed is measured to an accuracy of 0.1%, what is the minimum uncertainty in its position? 19. A proton has a kinetic energy of 1.0 MeV. If its momentum is measured with an uncertainty of 5.0%, what is the...
  25. S

    S-orbitals, angular momentum and Heisenberg uncertainty

    After about 20 years I'm going back and brushing up on quantum. I am confused about an electron in an s-orbital having zero angular momentum as well as how angular momentum in general relates to Heisenberg uncertainty. I probably have a few misconceptions as well as missing some key pieces...
  26. H

    Does the Heisenberg Uncertainty Principle make human teleportation impossible?

    Scientists have reportedly been able to transport atoms and molecules as much as 1800 feet. Could the same be done for humans, or would the Heisenberg Uncertainty Principle ultimately make it impossible?
  27. T

    Critical exponents of quantum Heisenberg model

    Hey guys, I ran some simulation of thermal phase transition of three dimensional quantum antiferomagnetic cubic lattice. I'm pretty happy with critical temperature, but I'm not sure about critical exponents because I'm having trouble locating some reference with their best known values. I know...
  28. W

    Heisenberg Uncertainty Principal

    Hi All, I understand that it is impossible for man to know both the position and momentum of a particle with arbitrary accuracy. This is a result of the physics of photons which are necessary to observe an object. Now although man cannot know the exact position and momentum...
  29. edpell

    Heisenberg Uncertainty Principle

    Is the Heisenberg Uncertainty Principle as statement about the state of a particle or only a statement about what can be observed about a particle?
  30. C

    Heisenberg Uncertainty Principle Question

    a 1.0 micrometer diameter dust particles (mass 1.0x10^-15kg) in a vacuum chamber pass through a hole (diameter assumed to be exactly that of particle) onto a detection plate 1.0m below. By how much does the diameter of the circle increase Homework Equations This is clearly a Heisenberg...
  31. P

    Heisenberg Feromagnet: Chaotic Phases @ Low Temp

    What is approximation of the chaotic phases for Heisenberg feromagnet in low temperatures?
  32. T

    Heisenberg Uncertainty Principle

    Hi, I have a problem with the uncertainty principle. The way I understand it, Heisenberg used ideas from classical mechanics and the concept of wave/particle duality to show a contradiction in classical mechanics, i.e. that it is impossible to know with exact precision both the momentum and...
  33. M

    IS THIS the Heisenberg uncertainity principle?

    I read that the Heisenberg uncertainty principle arises for stuff like electrons simply because the observer affects the observed . That is,because photons (or what ever the observer uses to detect the position) will affect the trajectory of the particle... That doesn't make much sense to...
  34. S

    Simplified Heisenberg Hamiltonian; Linear combinations of basis states

    So, I'm doing some undergraduate research in quantum spin systems, looking at the ground states of the Heisenberg Hamiltonian, H=\sum{J_{ij}\textbf{S}_{i}\textbf{S}_{j}}. But I think I have a critical misunderstanding of some fundamental quantum mechanics concepts. (I'm a math major, only had...
  35. K

    Heisenberg Uncertainty Principle homework Question

    Sorry about not using symbols but I haven't learned how to do that yet. 1. Homework Statement A woman is on a ladder of height H. She drops small rocks of mass m toward a point target on the floor. Show that according to the Heisenberg Uncertainty Principle, the average miss distance...
  36. B

    Critical exponents for the Heisenberg AFM spin-1/2 chain

    Hi everybody! I'm looking for the critical exponent ν (i.e. the one of the correlation length) of the Heisenberg (i.e. equal coupling in all directions) antiferromagnetic spin-1/2 model in 1D... Furthermore, do you know to which universality class it belongs? Is it true that it's the...
  37. Z

    Solitons and Heisenberg uncertainty

    if we can find a 'soliton' solution for Nonlinear Schroedinguer equation , then does this imply that Uncertainty principle is false ?? since a soliton is a localized wave packet then i can find the position of the soliton and its momentum so apparently i have violated uncertainty.
  38. H

    The Heisenberg Uncertainty Principle and velocity

    Hello all I have a question concerning The Heisenberg Uncertainty Principle. The principle mathematically looks like this- \Delta x\Delta p \geq \hbar/2 The principle states that you can not measure more than two quantities simultaneously. If you know a...
  39. Y

    Neutron, minimum potential energy, heisenberg uncertainty

    hi folks, last problem I can't get done here. I usually have a good idea of where to start, what to use. but I'm a bit flummoxed. Homework Statement A neutron, of mass m = 1.67 10-27 kg, is localized inside a carbon nucleus, of radius 7.0 fm (1 fm 10-15 m). Use the uncertainty relations...
  40. W

    Deriving Klein-Gordon from Heisenberg

    Homework Statement Sort of stuck deriving the Klein-Gordon equation from Heisenberg equation of motion \dot{\varphi} = i [H, \varphi ] Homework Equations \dot{\varphi} = \frac{\partial\varphi}{\partial t} H = \int d^3x \mathcal{H} \Pi (x) = \dot{\varphi}(x) \mathcal{H} = \Pi...
  41. X

    Heisenberg Uncertainty Derivation

    Homework Statement Using the uncertainty relation for momentum and position, show that the quantum-mechanical uncertainty in the position of a particle at temperture T is \Delta x~\sqrt{\frac{h^{2}}{4mkT}} where T is the temperature and k is the Boltzmann's constant. Homework Equations...
  42. L

    Does Commuting with the Hamiltonian Guarantee Conservation of Angular Momentum?

    Just reading about how if an operator commutes with the Hamiltonian of the system then its corresponding obserable will be a conserved quantity. my notes say that if \hat{L} commutes with the hamiltonian then the angular momentum will be conserved. this kind of makes sense but surely it's...
  43. N

    Question on Heisenberg uncertainty principle

    Homework Statement Particles pass through a single slit of width 0.2 mm in a diffraction setup. The de Broglie wavelength of each particle is 633 nm. After the particles pass through the slit, they spread out over a range of angles. Use the Heisenberg uncertainty principle to determine the...
  44. S

    Heisenberg uncertainty - uncertainty about its meaning

    HUP states that "certain physical quantities, like the position and momentum, cannot both have precise values at the same time. The narrower the probability distribution for one, the wider it is for the other." (Wikipedia) I am not a physicist, but I have been pondering this question: In this...
  45. L

    Ehrenfest theorem and Heisenberg quantum mechanics

    Wich are the differences between the theorem of ehrenfest and the Heisenberg's rappresentation of quantum mechanics?
  46. N

    How can the Heisenberg formula be proven in simple terms?

    Can anyone prove, in layman terms (or as close an approximation to layman terms as is possible), why exactly ∆p ∆x ≥ h-bar /2 ? Please explain every step in the deduction, and not just with formulae. I can't just take something for granted. Thanks in advance.
  47. A

    What Tore Apart the Friendship of Niels Bohr and Werner Heisenberg?

    Amazing British documentary. :!) BBC - The Copenhagen Fall Out In World War II, there were mounting fears that Hitler was building an atomic bomb. Such a prospect depended on two of the world's top nuclear scientists; brilliant German physicist Werner Heisenberg, and his Danish mentor, Niels...
  48. S

    Doubleslit experiment and heisenberg uncertainty

    Hello there!I have a small question regarding Heisenberg uncertainty relationship. If one sets up a double slit experiment and one looks through which hole the electron passes, so it acts as a particle and you know exactly where it is. If immediately after that slit, you place some sort of...
  49. Q

    Heisenberg Uncertainty

    Consider and electron in ground state in the Hydrogen atom. Suppose the Bohr orbit lies in the x-y plane. Assume that the position of the electron along the orbit is completely unknown. a)Estimate the uncretainties in x,px, y, py, z and pz. b)Repeat for and excited state n>1. With the given...
  50. C

    Design an expiriement/lab/activity related to Heisenberg Uncertainty Principle

    Any guidance towards designing an expiriement/lab/activity related to Heisenberg Uncertainty Principle? It doesn't have to be complex or anything, just something at least related to the HUP. I can't think of anything, my understanding is that this principle only really applies at the quantum...
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