Quantum Uncertainty

Project Leader: James ArnemannMembers: Jesus Gallegos, Jose Castro, Matthew

Constantino

Classical World

Waves and Particles

Deterministic

Continuous

Quantum World

Particle-Wave Duality

Probabilistic

Discrete

What is Quantum Uncertainty?

You cannot know both the momentum and the position of a particle with exact certainty

ΔpΔx≥ħ/2 (uncertainty principle)

Δp = Change in momentum

Δx = Change in position

ħ = h/2π

Now, Some Magic

First Experiment: Polarizers

½ of unpolarized light will go through a polarizer polarized in one direction

No light polarized in one direction will go through a polarizer in an orthogonal (perpendicular) direction

0prob. light comes thru

First Experiment: Polarizers

When a slanted polarizer is inserted, half goes through that one, and half goes through the third

½ prob. light comes thru

¼ prob. light comes thru

1/8 prob. light comes thru

Second Experiment: Laser

Laser pointers make dots

Δx

Second Experiment: Laser

When a laser passes through a slit, its position changes

There is an uncertainty in position (Δx)

This causes uncertainty in momentum (Δp)

If Δx gets small, Δp must be bigger

Remember ΔxΔp must be larger than or equal to ħ/2

Second Experiment: Laser

But, when the light does pass through the slit…

Δp

Δp

Δp

Δp

Second Experiment: Laser

The smaller Δx is the bigger Δp must be

The smaller the slit the more the light spreads

In Conclusion…ΔxΔp≥ħ/2 (uncertainty principle)

We can never know both variables with complete certainty

In trying to measure the position, we inevitably change the momentum and vice-versa

It took a whole lot of math to understand this however, math is a tool to help us conceptualize these abstract ideas