1 / 9

Uncertainty Principle

Uncertainty Principle. Observations generally require energy interacting with matter. Light on a ruler Radar on a car Echoes in a canyon Touch on a surface Voltmeter in a circuit In many cases this is scattering of EM waves. Observation. Direct contact creates an impulse.

dee
Download Presentation

Uncertainty Principle

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Uncertainty Principle

  2. Observations generally require energy interacting with matter. Light on a ruler Radar on a car Echoes in a canyon Touch on a surface Voltmeter in a circuit In many cases this is scattering of EM waves. Observation

  3. Direct contact creates an impulse. Change in momentum EM waves have momentum as photons. Momentum transfer by reflection Planck’s law Impulse reflected photon incident photon Moving charge

  4. At the atomic scale the momentum of a photon may be comparable to the momentum of a particle. The photon as a wave can only be measured in position to about one wavelength. If momentum is transferred the target has a momentum uncertainty. Atomic Scale reflected photon incident photon Moving charge

  5. Uncertainty • The product of the uncertainties in position and momentum is a limit on measurement. • Heisenberg Uncertainty Principle • The relationship is based on the angular frequency. • Shift by a factor of 2p • Use constant h-bar h= h/2p

  6. The uncertainty principle says that if the position is perfectly known the momentum is unknown. If the momentum is perfectly known then the position is unknown. The two variables are interrelated. Conjugate variables Stop Motion Harold Edgerton (1964)

  7. Freezing Time • The energy of a wave is related to its frequency. • Energy and frequency complement like momentum and wavelength. • The uncertainty principle applies to energy and time as well.

  8. An atomic nucleus is 10-14 m in diameter. Find the total energy in eV of an electron confined to that space. Use hc = 1240 eV nm Dx = 10-5 nm Relativity may matter. mc2 = 0.511 MeV The uncertainty principle matches distance to momentum. Energy units here Apply relativity to get total energy. Rest mass relatively small Confined Space

  9. Indeterminate • Newtonian physics is viewed as a deterministic system. • Initial positions allow calculation of final states • Knowledge of all past variables implies future knowledge • Quantum physics has an indeterminate element. • Conjugate variables are of limited measurability • Impossible to have precise initial state • Cannot know precise future states next

More Related