Fly by Night Physics How Physicists Use the Backs of Envelopes

455 Pages·2020·8.457 MB·English

by  A. Zee

Fly by Night Physics

Fly by Night Physics
How Physicists Use the Backs of Envelopes
A. Zee
PRINCETON UNIVERSITY PRESS PRINCETON AND OXFORD
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LibraryofCongressControlNumber:2020942704
ISBN978-0-691-18254-4
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∗
To the memory of my late colleague Joseph Polchinski
∗IfeelsurethatJoewouldhavelikedthiskindofphysics.

Contents
Preface xi
Dimensionsandfundamentalconstants xxi
I Dimensional analysis: from a not so secret
to an allegedly secret weapon 1
1. Dimensionalanalysis:anotsosecretweapon 3
2. FromKepler’slawtoblackholes 12
3. Bohr’satomandHeisenberg’suncertaintyprinciple:
oppositionandcompromise 22
4. Thedullfunctionhypothesis 28
5. MatchwitswithEinsteinoverdiffusionanddissipation 34
6. Energyreleasedinthefirstatomicbombtest 40
Interlude:Mathmedley1 45
II Telecommunication is possible 51
1. Electromagnetism:strangedimensions 53
2. Theemissionofelectromagneticwaves 58
3. Electromagneticradiationfrommovingpointcharges
andComptonscattering 65
4. Relativisticeffectsbypromotionandcompletion 78
III Quantum physics: tunneling in stars, scaling, atoms,
and black holes 83
1. FromdrawingtheSchrödingerwavefunction
totunnelinginstars 85
2. Scalingandtheimportanceofbeingclean 96
3. TheLandauprobleminquantummechanics 105
viii Contents
4. Atomicphysics 110
5. Blackbodyradiation 116
Awordofencouragementtothereader:
ongettingconfusedbyphysics 126
IV Planck gave us units: black hole radiation
and Einstein gravity 129
1. PlanckgaveusGod-givenunits 131
2. Aboxofphotonsandthepowerofnaturalunits 139
3. Blackholeshaveentropy:Hawkingradiation 144
4. WhenEinsteingravitymeetsthequantum 152
Interlude:Mathmedley2 158
V From ideal gas to Einstein condensation 163
1. IdealBoltzmanngas 165
2. VanderWaals:masteroftheenvelope 169
3. Quantumgases 175
4. GuessingtheFermi-Diracdistribution 181
5. Einsteincondensation 191
VI Symmetry and superb theorems 197
ProloguetoPartVI 199
1. Symmetry,fearfulorfearless 200
2. Galileo,viscosity,andtimereversalinvariance 207
3. Newton’stwosuperbtheorems:whereishell? 214
VII Stars, black holes, the universe, and gravity waves 221
1. Stars 223
2. Collapseintoblackholes 234
3. Theexpandinguniverse 238
4. Powerradiatedingravitywaves 249
Interlude:Mathmedley3 260
VIII From surfing to tsunamis, from dripping faucets
to mammalian lungs 267
1. Waterwaves 269
2. Aphysicistattheseashore 278
Contents ix
3. Surfacetensionandripples 285
4. Fromdrippingfaucetstomammalianlungs
andwaterstriders 291
5. Drag,viscosity,andReynoldsnumber 295
IX From private neutrinos to charm 301
ProloguetoPartIX 303
1. Alightningintroductiontoparticlephysics
andquantumfieldtheory 305
2. Weakinteraction:afewbasicfacts 316
3. Privateneutrinos 328
4. Strangenessandcharm 336
Appendices 347
Cp: Criticalpoints 347
Del: Deltafunction 350
Eg: Einsteingravity:alightningreview 354
ENS: FromEulertoNavierandStokes 363
FSW: Finitesquarewell 367
Gal: Galileaninvarianceandfluidflow 371
Gr: Greenfunctions 374
Grp: Groupversusphasevelocity 380
L: RadialpartoftheLaplacian 383
M: Maxwell’sequations:abriefreview 389
N: Newton’stwosuperbtheoremsandthesecond
squarerootalert 396
VdW: FlybydayderivationofvanderWaals’slawfrom
firstprinciples 398
Timeline 401
Solutionstoselectedexercises 403
Suggestedreading 411
Index 413