welcome to quantum mechanicsggilfoyl/qm/slides/foundations.pdf · the speciﬁc heat freeze-out of...

Experimental Foundations

Welcome to Quantum Mechanics

“The most important fundamental laws and facts haveall been discovered, and these are so firmlyestablished that the possibility of their ever beingsupplanted in consequence of new discoveries isexceedingly remote. ... Our future discoveries must belooked for in the sixth place of decimals.”

Albert A. Michelson (1894)

– p. 1/18





“I cannot seriously believe in the quantum theory...”Albert Einstein

– p. 1/18





“I cannot seriously believe in the quantum theory...”Albert Einstein

“The more success the quantum theory has the sillier itlooks.”

Albert Einstein

– p. 1/18


The Physics 309 Approach

1. Start with a detectorand take some data.

2. Develop the quantumprogram.

3. Apply the quantumprogram.

4. What are theclassical alternatives?

My detector.

– p. 2/18


The Physics 309 Approach

1. Start with a detectorand take some data.

2. Develop the quantumprogram.

3. Apply the quantumprogram.

4. What are theclassical alternatives?

My detector.

2012-08-28 08:59:24(GeV/c)

mp

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7LT

A’

-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04CLAS, 2.6 GeV

H(e,e’p)n2

Helicity asymmetry

My data.

– p. 2/18


The Spectral Lines Problem

← A toy atom.

– p. 3/18


The Spectral Lines Problem

← A toy atom.

−→

– p. 3/18


The Specific Heat Freezeout

1. The Specific Heat

Q = mc∆T = nCV ∆T for gas in a fixed volume.

2. The Kinetic Model of Ideal Gases

(a) The gas consists of a large number of small, mobile particlesand their average separation is large.

(b) The particles obey Newton’s Laws, but their motion can bedescribed statistically.

(c) The particles’ collisions are elastic.

(d) The inter-particle forces are small until they collide.

(e) The gas is pure.

(f) The gas is in thermal equilibrium with the container walls.

– p. 4/18


The Data

– p. 5/18


The Specific Heat Freeze-out of H2

– p. 6/18


Blackbody Radiation

A black body is an idealized physical body that absorbs allincident electromagnetic radiation, regardless of frequencyor angle of incidence. In thermal equilibrium (at a constanttemperature) it emits electromagnetic radiation calledblack-body radiation with two notable properties.

1. It is an ideal emitter: it emits asmuch or more energy at everyfrequency than any other body atthe same temperature.

2. It is a diffuse emitter: the energyis radiated isotropically, indepen-dent of direction.

– p. 7/18

http://www.amanogawa.com/archive/PlaneWave/PlaneWave-2.html


Measuring The Blackbody Radiation

FrequencyVisible light λ ≈ 400 − 700 nm

Measured by Lummer and Pringsheim (1899).

RT (ν)dν =energy

time-areain the range ν → ν + dν

– p. 8/18


The Ultraviolet Catastrophe

Rayleigh-Jeans Law

u(ν)dν =8π

c3kBTν

2dν in the range ν → ν + dν

T - temperature. kB - Boltzmann constant.

– p. 9/18


Planck’s Guess - the Boltzmann Distribution

Ε

ΕPHΕL

– p. 10/18


Planck’s Guess - Do a Riemannian Sum

Ε

ΕPHΕL

– p. 11/18


Planck’s Guess - Do a Riemannian Sum (low ν)

Ε

ΕPHΕL

– p. 12/18


Planck’s Guess - Do a Riemannian Sum (high ν)

Ε

ΕPHΕL

– p. 13/18


Planck’s Guess - Do a Riemannian Sum (high ν)

Ε

ΕPHΕL

– p. 14/18


Planck’s Guess - Do a Riemannian Sum (higher ν)

Ε

ΕPHΕL

– p. 15/18


The Ultraviolet Catastrophe

Rayleigh-Jeans Law

u(ν)dν =8π

c3kTν

2dν in the range ν → ν + dν

T - temperature. k - Boltzmann constant.

– p. 16/18


The Blackbody Radiation

Scan of first showing of the COBE measurement of cosmicmicrowave background radiation at the AmericanAstronomical Society meeting in January, 1990.

– p. 17/18


The Blackbody Radiation

COBE measurement of the cosmic microwave backgroundradiation from J.C Mather et al., Astrophysical Journal 354,

L37-40 (1990).

– p. 18/18

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