Making sense of Quantum Mechanics A wikiversity collaborative project aiming to present Quantum...

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Making sense of Quantum Mechanics A wikiversity collaborative project aiming to present Quantum Mechanics in an intuitive perspective http://en.wikiversity.org/wiki/Making_sense_of_quantum_mech anics Arjen Dijksman mail:materion at free.fr web: http://materion.free.fr blog: http://commonsensequantum.blogspot.com Problem 2: Resolve the problems in the foundations of QM, either by making sense of the theory as it stands or by inventing a new theory that does make sense. Lee Smolin

Transcript of Making sense of Quantum Mechanics A wikiversity collaborative project aiming to present Quantum...

Page 1: Making sense of Quantum Mechanics A wikiversity collaborative project aiming to present Quantum Mechanics in an intuitive perspective .

Making sense of Quantum Mechanics

A wikiversity collaborative project aiming to present

Quantum Mechanics in an intuitive perspectivehttp://en.wikiversity.org/wiki/Making_sense_of_quantum_mechanics

Arjen Dijksmanmail:materion at free.fr

web: http://materion.free.frblog: http://commonsensequantum.blogspot.com

Problem 2: Resolve the problems in the

foundations of QM, either by making sense of the theory as it stands or by inventing a new theory that does make sense.

Lee Smolin

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Summary What are the first principles of Quantum Mechanics?

A quantum system may be represented by a vector

The orientation of the vector representing a quantum system evolves

Kets are transformed into other kets by means of operations that reveal an observational property

In quantum measurements, the result is always undetermined

Quantum probabilities involve interaction cross sections of both observed and observing particles

Examples

Particle in a box, particle in its wave, collision of particles

Do Quantum mechanics and Classical Mechanics address the same questions?

Path for a classical particle is that of least action

Most probable path for a quantum particle is that of least action

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Quantum system is represented by a vector

quantum system of needles Its representation as vectors (or kets)

Addition rule for vectors (a set of vectors is just another vector)

All we do is draw little arrows, that’s

all.

Richard Feynman

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Orientation of the vector evolves (1/2)

Vectors of the generalized evolution law

1

2

3

4

5

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Orientation of the vector evolves (2/2)

The generalized Schrödinger equation (evolution law)

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Example: Particle in a box

Arrow bouncing back and forth between both walls (animated gif)

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Example: Particle in a box

Arrow bouncing back and forth between both walls (animated gif)

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Example: Particle in a box

Arrow bouncing back and forth between both walls (superposition)

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Example: Particle in its wave

Arrow spinning in its pilot wave

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Example: Particle in its wave

Arrow spinning in its pilot wave

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Example: Particle in its wave

Arrow spinning in its pilot wave

Tout se passe comme si l'Ether

et la Terre avaient le même

mouvement de translation...

Maurice Allais

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Interaction between two particles

E1

E2 =2E1vE1

t

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Collision between two particlest

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Other spinning modes

z

y

x

z s

a) s=2z

b) s=-2z

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Classical Mechanics vs Quantum Mechanics (1/2)

In classical mechanics, an elementary particle is represented by a point that follows a path of least action

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Classical Mechanics vs Quantum Mechanics (2/2)

In QM, an elementary particle is represented by a vector whose most probable path is that of least action