Download Presentation - WaveParticleDuality and HUP

Wave Particle Duality & the
Heisenberg Uncertainty Principle
By: Nick Day, Edward Moore, Sarah Russell
Wave particle duality (WPD)
• “Both matter and electromagnetic radiation
exhibit some properties of waves and some
properties of particles.” (McGraw-Hill)
• Matter sometimes acts like a wave, sometimes
like a particle, depending on the experiment.
• Early development of quantum theory
http://woodahl.physics.iupui.edu/Astro105/OLDindex.html
• Matter has dual nature = duality
• Experiments show light seems to go only in a
straight line: particle nature. Experiments
show that light has frequency and wavelength:
wave nature.
• 1909, Geoffrey Taylor: “double-slit
experiment” – light is a wave. Special camera
tool photos of the light exiting he experiment
– tiny pinpoints of light, light is a particle.
Heisenberg Uncertainty Principle
(HUP)
• “The position and momentum of a particle
cannot simultaneously measured with
arbitrarily high position.” (Hyperphysics)
• Particle’s momentum & position cannot both
be known at the same time.
• Result of wave particle duality
photon
A particle can be seen only by scattering light off it. The scattering
changes the electron momentum.
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• If particle momentum is measured, position
will be changed.
• Bonus: If energy of the particle is known, we
cannot know length of time it has that energy
(vise versa).
• Example:
http://science.howstuffworks.com/innovation
/science-questions/quantum-suicide2.htm
• Star Trek Transporter Beams: Take a person
apart molecule by molecule, kept organized,
reassembled elsewhere. HUP: impossible to
identify individual particles and keep track of
them.
http://realityviews.blogspot.ca/2011/04/quantum-teleportation-successful.html
http://www.coolest-gadgets.com/20070607/beam-me-up-scottyscientists-make-breakthrough-with-trek-transporter-theory/
http://www.youtube.com/watch?v=H-AlfuvjPYM
Homework
1. The HUP states that a particle's _______ and
______ cannot both be known at the same time.
2. A particle can be seen only by scattering light off
of it. The scattering:
a) changes the size of the particle
b) changes the mass of the particle
c) changes the momentum of the particle
d) all of the above
3. What is wave particle duality?
4. Define the Heisenberg Uncertainty Principle.
5. T/F? Only matter can have wave-like
characteristics and particle-like characteristics.
Corrections
• 1. position and momentum
2. c) changes the momentum of the particle
3. Matter sometimes acts like a wave,
sometimes like a particle, depending on the
experiment.
4. A particle’s momentum & position cannot both
be known at the same time.
5. False, matter and electromagnetic radiation
can have wave-like characteristics and particlelike
characteristics.
Sources
• http://simple.wikipedia.org/wiki/Waveparticle_duality
• http://hyperphysics.phyastr.gsu.edu/hbase/uncer.html
• http://www.aip.org/history/heisenberg/p08.htm
• McGraw-Hill textbook
• Physics Principles and Problems textbook
• Physics Concepts and Connections textbook