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Wave Particle Duality & the Heisenberg Uncertainty Principle By: Nick Day, Edward Moore, Sarah Russell Slide 2 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 Slide 3 http://woodahl.physics.iupui.edu/Astro105/OLDindex.html Slide 4 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. Slide 5 Slide 6 Slide 7 Heisenberg Uncertainty Principle (HUP) The position and momentum of a particle cannot simultaneously measured with arbitrarily high position. (Hyperphysics) Particles momentum & position cannot both be known at the same time. Result of wave particle duality Slide 8 A particle can be seen only by scattering light off it. The scattering changes the electron momentum. photon Slide 9 http://www.google.ca/imgres?q=heisenberg+uncertainty+principle&hl=en&biw=1326&bih=586&gbv=2&tbm=isch&tbni d=zUOmu4klq9tIBM:&imgrefurl=http://www.physicsoftheuniverse.com/topics_quantum_uncertainty.html&docid=xuIbj vw0aiRKfM&imgurl=http://www.physicsoftheuniverse.com/images/quantum_microscope.jpg&w=372&h=591&ei=GsCd T934DOLD0QGD3KCTDw&zoom=1&iact=hc&vpx=170&vpy=186&dur=8313&hovh=283&hovw=178&tx=119&ty=243&si g=108975557308224056383&page=2&tbnh=128&tbnw=81&start=21&ndsp=29&ved=1t:429,r:0,s:21,i:116 Slide 10 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 http://science.howstuffworks.com/innovation /science-questions/quantum-suicide2.htm Slide 11 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-scotty- scientists-make-breakthrough-with-trek-transporter-theory/ Slide 12 http://www.youtube.com/watch?v=H-AlfuvjPYM Slide 13 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. Slide 14 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 particles momentum & position cannot both be known at the same time. 5. False, matter and electromagnetic radiation can have wave-like characteristics and particle- like characteristics. Slide 15 Sources http://simple.wikipedia.org/wiki/Wave- particle_duality http://hyperphysics.phy- astr.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