Quantum Uncertainty

1. Quantum Uncertainty Project Leader: James Arnemann Members: Jesus Gallegos, Jose Castro, Matthew Constantino

2. Classical World • Waves and Particles • Deterministic • Continuous Quantum World • Particle-Wave Duality • Probabilistic • Discrete

3. 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

4. Now, Some Magic

5. First Experiment: Polarizers • ½ ofunpolarizedlight 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 0 prob. light comes thru

6. First Experiment: Polarizers • When a slanted polarizer is inserted, half goes through that one, and half goes through the third 1/8 prob. light comes thru ½ prob. light comes thru ¼ prob. light comes thru

7. Second Experiment: Laser • Laser pointers make dots Δx

8. 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

9. Second Experiment: Laser • But, when the light does pass through the slit… Δp Δp Δp Δp

10. Second Experiment: Laser • The smaller Δx is the bigger Δp must be • The smaller the slit the more the light spreads

11. 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