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Quantum Theory

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

- It was assumed light could have any energy.
- The math of the theory did not match the

distribution of wavelengths observed

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.

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

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.

- 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.

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).

- Very small particles exhibit the same wave

addition and cancellation characteristics as

waves do.

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.

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

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.

- The electron simply exists in these locations,

without actually moving from one point to

another.

- http//www.youtube.com/watch?vFw6dI7cguCgfeature

related

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.

- Electrons materialize from one location to

another without passing a plane of zero

probability existence. - This is just quantum weirdness.

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.

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.

- If we really understood something, we should know

what will happen and what is really going on

behind the scenes.

- http//www.twine.com/item/11wp44xsg-xx/youtube-qua

ntum-mechanics-for-dummies-electrons-are-weird

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.

- 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.

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

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.

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?

- 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.

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.

- Outside the light cone, signals or forces from

one object must travel faster than the speed of

light to create the observed behavior.

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

- 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

Collapsing Probability Waves

- Quantum mechanics says that the measurement of a

particle, such as an electron, collapses the

probability wave to a single event.

- With entangled particles, the measurement of one

collapses both of their probability waves

simultaneously. - Any interaction, human or not, collapses

probability waves.

- http//www.youtube.com/watch?v9lOWZ0Wv218feature

related

Quantum Theory and the Universe

- Cause and effect gives way to probability.
- The things you do can instantaneously affect

things far away (non-local).

- 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.

The Standard Model

- This is the current quantum theory.
- Many new subatomic particles have been

discovered. - There are three families of particles.

- 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.

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.

- Gravity The graviton is the cause.
- Experiments have established all force particles

except the graviton. - Gravitons are expected to be discovered soon.

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.

- 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.

Particle Behavior

- The uncertainty principle allows for extreme

particle behavior on the subatomic level.

- 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

More Unification

- Steven Weinberg and his colleagues unified the

weak and the electromagnetic forces. - They won a Nobel Prize for this work.

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.

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

- 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

????? Wild possibilities or psudoscience?

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