Quantum and Waves

Quantum and Waves:

University of Oxford

Next peergrade assignment 5 due Monday, February 3!Respond to your question on waves in an everyday context

4 different types of waves:

1. Electromagnetic and light (oscillating electric and magnetic fields)2. Mechanical (vibration of atoms, molecules, solids, spins, charges,…)3. Quantum (any particle)4. Gravitational waves

What is Quantum Physics?

1. Particle-wave duality (wave is particle, particle is wave)2. Non-locality (1 particle can be in two places at the same time) 3. Entanglement (spooky action at a distance)4. Statistics (spin)5. Fock space (almost infinite dimensions)

What is Quantum Physics?

1. Particle-wave duality (wave is particle, particle is wave)

Is electromagnetic radiation composed of particles?A. Yes

B. No

Radioactivity experiment

Radioactivity:

beta decay

The so-called weak force drives the radioactive transition:neutron (n) -> electron (β-)+proton (p) +neutrino (ν)This transforms cesium into barium. But the barium created is in a very high energy state so it quickly releases its energy by emitting a electromagnetic wave/particle (ϒ). This ϒparticle is what is measured with the Geiger counter.

ϒ

(source: Phys 339 lab notes)

Can you get gold from mercury by radioactivity?A. Yes

B. No

C. I hope so

Radioactive mercury will transform into gold!

Srce: Joao Pedro Araujo

Radioactivity:

beta decay

weak force: n -> electron + proton + neutrino + electromagnetic wave/particle

Perfect random process: Commercial random number generator base on radioactivity

www.imagesco.com/kits/random-number-generator.html

by Rob AtkinsonBathys Hawaii

Caesium atomic clock

U.S. Naval Observatory

(source: Phys 339 lab notes)

Geiger counter:

High energy electromagnetic radiation (ϒ-rays) behave like individual particles!

What about visible light?

Sun radiation:http://qdl.scs-inc.us/2ndParty/Pages/10522.html

Wave is particle

http://www.physast.uga.edu/~rls/1010/ch5/ovhd.html

Color

Temperature [K]

Hot bodies emit radiation

1.You press in the trigger to put the detector into "reference" mode.

2.An internal heat source, whose temperature is known, fires out infrared

radiation.

3.A mirror picks up the infrared.

4.A detector picks up the reflected infrared from the mirror.

5.A microchip notes the reading of the internal reference source.

6.Now you release the trigger to put it in operating mode.

7.The mirror swings back to face the front of the detector.

8.The hot sample you're interested in gives off its own pattern of infrared

radiation.

9.The infrared fires in through the front and bounces off the mirror into the

detector.

10.The chip compares the infrared wavelengths from the reference source

and the sample and figures out the sample's temperature.

Infrared thermometers are based on the principle of black body radiation: