Quantum Theory

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Quantum Theory

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Black Body Radiation

• Temperature determines the wavelength of emitted
  light.
• Red hot mostly red light - 3,000 oC.
• White hot all colors 6,000 oC.
• http//www.egglescliffe.org.uk/physics/astronomy/b
  lackbody/bbody.html

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• It was assumed light could have any energy.
• The math of the theory did not match the
  distribution of wavelengths observed

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Max Planck solved the black body radiation
dilemma

• He created an equation that fit the observed
  distribution of radiation.
• To do so, he had to assume that energy came in
  packets, called quantum.

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Plancks Constant

• Frequency/energy Plancks constant
• Plancks constant (h) is one of the most
  important constants in nature.
• (h) 6.626 x 10-34 joule seconds

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Photoelectric Effect

• Certain light beams can knock electrons off of
  some metals.
• This was independent of the intensity of the
  light beam. (total energy)
• It WAS dependent on the wavelength of the light.

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• Short wavelengths have larger quanta (packets of
  energy) to knock off electrons.

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Light particle or wave?

• Light followed the wave equation defined by James
  Clark Maxwell.
• Light also seemed to exist as packets, like
  particles.
• The particle/wave designation seems invalid for
  the subatomic world.

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Particles are also Waves

• 1923 Louise de Broglie found that matter had
  both particle and wavelike properties.
• If E hc/wavelength (from Planck) and E mc2
  (from Einstein), than wavelength h/(mass x
  velocity).

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• Very small particles exhibit the same wave
  addition and cancellation characteristics as
  waves do.

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Niels Bohr Planetary Atom

• Electrons orbit the nucleus in specific circular
  orbits.
• Problem a charged particle in acceleration emits
  light.
• Changing direction is a type of acceleration, yet
  orbiting electrons emitted no light.

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• http//www.youtube.com/watch?v45KGS1Ro-scNR1

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Schrodingers Solution

• The orbit of an electron can only be a whole
  number multiple of the electrons wavelength.
• The orbital is a standing wave of an electron.
• There is no changing direction of the electron.

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• The electron simply exists in these locations,
  without actually moving from one point to
  another.

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• http//www.youtube.com/watch?vFw6dI7cguCgfeature
  related

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Schrodinger wave equations

• Any system can be treated as a wave equation in
  quantum mechanics.
• The orbitals of chemistry are solutions to
  Schrodinger wave equations.

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• Electrons materialize from one location to
  another without passing a plane of zero
  probability existence.
• This is just quantum weirdness.

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Paul Diracs improvements of Schrodingers wave
equations

• He generalized the equations to relativistic
  theory.
• He mathematically explained electron spin with
  angular momentum.
• He postulated the existence of antimatter based
  on the negative square root of Emc2.

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Quantum Mechanics gives probabilities

• 1926, Max Born the square of the wave equation
  gave the probability of finding the particle in a
  given location.
• Many (Einstein) felt that probability was not
  good enough.

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• If we really understood something, we should know
  what will happen and what is really going on
  behind the scenes.

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• http//www.twine.com/item/11wp44xsg-xx/youtube-qua
  ntum-mechanics-for-dummies-electrons-are-weird

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Heisenberg Uncertainty Principle

• We cannot know both the velocity and location of
  an electron. The more we know about one, the
  less we know about the other.
• High energy light gives a better location, but
  disrupts the velocity.

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• Low energy light disturbs the velocity less, but
  gives high uncertainty of location. Lower energy
  light gives worse resolution.
• The uncertainty of position times the uncertainty
  of momentum is greater or equal to Plancks
  constant divided by 4p.

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• http//www.youtube.com/watch?vKT7xJ0tjB4A

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Uncertainty vs. Determinism

• Uncertainty was not just a result of the
  crudeness of the instruments, it was a
  fundamental law of nature.
• Determinism the idea that you can state the
  future if you know everything about the present.
• Einstein favored determinism, but uncertainty was
  found to rule.

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Double slit experiment

• The same results are obtained with light,
  electrons, or any other type of wave.
• http//www.youtube.com/watch?vDfPeprQ7oGc
• How does the particle going through the slit
  know that the other slit exists?

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• Since the electron, like all matter, has wave
  characteristics, its final location is defined by
  the probability given by the square of the wave
  equation for the given system it is in.

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Bells Theorem

• John Bell used a thought experiment and logic to
  prove that reality is non-local.
• Non-local means objects are affected by distant
  objects and events that cannot reach them with a
  force, because they are outside of the light cone.

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• Outside the light cone, signals or forces from
  one object must travel faster than the speed of
  light to create the observed behavior.

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Quantum Entanglement

• When two particles or events affect each other
  without any signal or force.
• Determinism, and our common sense, says that this
  is totally impossible.
• http//calitreview.com/51

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• Quantum mechanics predicts when it will or will
  not happen, and what the probability of the
  outcome will be.
• http//www.youtube.com/watch?vJh8uZUzuRhkfeature
  related

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Collapsing Probability Waves

• Quantum mechanics says that the measurement of a
  particle, such as an electron, collapses the
  probability wave to a single event.

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• With entangled particles, the measurement of one
  collapses both of their probability waves
  simultaneously.
• Any interaction, human or not, collapses
  probability waves.

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• http//www.youtube.com/watch?v9lOWZ0Wv218feature
  related

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Quantum Theory and the Universe

• Cause and effect gives way to probability.
• The things you do can instantaneously affect
  things far away (non-local).

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• Events can happen without a force or signal to
  cause it to happen - the fabric of space allows,
  or even causes it to happen.
• Objects do not always have specific properties
  until they are interacted with the properties
  hang in some sort of limbo.

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The Standard Model

• This is the current quantum theory.
• Many new subatomic particles have been
  discovered.
• There are three families of particles.

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• Each family contains two of the quarks, an
  electron (or one of its cousins), and one of the
  neutrinos.
• These are the building blocks of all matter.

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Four Force Particles

• Strong force The gluon holds the nucleus
  together.
• Weak force The W and Z bosons cause
  radioactivity.
• Electromagnetism The photon causes light.

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• Gravity The graviton is the cause.
• Experiments have established all force particles
  except the graviton.
• Gravitons are expected to be discovered soon.

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Standard Model Equation

• It uses an input of 19 pieces of information,
  which are properties of the force and mass
  particles.
• It has been flawless at predicting experimental
  outcomes as probabilities.

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• Everything that happens in the universe, besides
  gravity, can be predicted by the Standard Model.
• Newtons equations fall out of Standard Model for
  normal conditions.

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Particle Behavior

• The uncertainty principle allows for extreme
  particle behavior on the subatomic level.

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• There is a trade off between the energy a
  particle has and the time it takes to measure
  this energy, which allows the energy of a
  particle to fluctuate wildly over a very short
  duration of time, called the quantum jitters.
• Tunneling is allowed.
• http//www.youtube.com/watch?v6LKjJT7gh9sfeature
  related

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More Unification

• Steven Weinberg and his colleagues unified the
  weak and the electromagnetic forces.
• They won a Nobel Prize for this work.

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Weaknesses of Standard Model

• It explains how nature behaves, but not why it
  behaves in the way it does.
• It does not include gravity therefore, it cannot
  be a complete theory of the universe.
• Its use is primarily for the subatomic level.

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A few good web-pages

• http//www3.hi.is/hj/QuantumMechanics/quantum.htm
  l
• http//www-groups.dcs.st-and.ac.uk/history/HistTo
  pics/The_Quantum_age_begins.html
• http//www.youtube.com/watch?vyLprHMq4ZkMfeature
  related
• http//www.youtube.com/watch?vXEZtw1yt8Kcfeature
  related

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• http//www.youtube.com/watch?v1_HrQVhgbeofeature
  related
• LAC collider http//www.youtube.com/watch?v1_Hr
  QVhgbeofeaturerelated
• Quark song http//www.youtube.com/watch?vU0kXkWXS
  XRAsafety_modetruepersist_safety_mode1

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????? Wild possibilities or psudoscience?

• http//www.youtube.com/watch?vfLLIkTo4KLc