Les Houches Lectures on Cosmic Inflation Four Parts 1)Introductory material 2)Entropy, Tuning and Equilibrium in Cosmology 3)Classical and quantum probabilities in the multiverse 4)de Sitter equilibrium cosmology Andreas Albrecht; UC Davis Les Houches Lectures; July-Aug Albrecht Les Houches Lectures 2013 Pt. 3

Les Houches Lectures Part 3 Classical and quantum probabilities in the multiverse Andreas Albrecht UC Davis Les Houches Lectures July Albrecht Les Houches Lectures 2013 Pt. 3

3 Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse)

Albrecht Les Houches Lectures 2013 Pt. 34 Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse) NB: Very different subject from “make probabilities precise” Stanford sense. (See Silverstein lectures)

Albrecht Les Houches Lectures 2013 Pt. 35 Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse)

Albrecht Les Houches Lectures 2013 Pt. 36 Planck Data --- Cosmic Inflation theory

Slow rolling of inflaton Albrecht Les Houches Lectures 2013 Pt. 37 Observable physics generated here

Slow rolling of inflaton Albrecht Les Houches Lectures 2013 Pt. 38 Observable physics generated here Extrapolating back

Slow rolling of inflaton Q Albrecht Les Houches Lectures 2013 Pt. 39 “Self-reproducing regime” (dominated by quantum fluctuations): Eternal inflation/Multiverse Observable physics generated here Extrapolating back Steinhardt 1982, Linde 1982, Vilenkin 1983, and (then) many others

Classically Rolling Self-reproduction regime 10Albrecht Les Houches Lectures 2013 Pt. 3 Classically Rolling The multiverse of eternal inflation

Classically Rolling Self-reproduction regime 11Albrecht Les Houches Lectures 2013 Pt. 3 Classically Rolling The multiverse of eternal inflation Where are we? (Young universe, old universe, curvature etc)

Classically Rolling A Self-reproduction regime 12Albrecht Les Houches Lectures 2013 Pt. 3 Classically Rolling C Classically Rolling B Classically Rolling D The multiverse of eternal inflation with multiple classical rolling directions

Classically Rolling A Self-reproduction regime 13Albrecht Les Houches Lectures 2013 Pt. 3 Classically Rolling C Classically Rolling B Classically Rolling D The multiverse of eternal inflation with multiple classical rolling directions Where are we? (Young universe, old universe, curvature, physical properties A, B, C, D, etc)

Classically Rolling A Self-reproduction regime 14Albrecht Les Houches Lectures 2013 Pt. 3 Classically Rolling C Classically Rolling B Classically Rolling D The multiverse of eternal inflation with multiple classical rolling directions Where are we? (Young universe, old universe, curvature, physical properties A, B, C, D, etc) “Where are we?”  Expect the theory to give you a probability distribution in this space… hopefully with some sharp predictions

Classically Rolling A Self-reproduction regime 15Albrecht Les Houches Lectures 2013 Pt. 3 Classically Rolling C Classically Rolling B Classically Rolling D The multiverse of eternal inflation with multiple classical rolling directions Where are we? (Young universe, old universe, curvature, physical properties A, B, C, D, etc) “Where are we?”  Expect the theory to give you a probability distribution in this space… hopefully with some sharp predictions String theory landscape even more complicated (e.g. many types of eternal inflation)

Albrecht Les Houches Lectures 2013 Pt. 316 Challenges for eternal inflation “Anything that can happen will happen infinitely many times” (A. Guth) 1)Measure Problems 2)Problems defining probabilities 3)Problems/hidden assumptions re initial conditions  problem claiming generic predictions about state  cannot claim “solution to cosmological problems”  Related to 2 nd law, low S start

Albrecht Les Houches Lectures 2013 Pt. 317 Challenges for eternal inflation “Anything that can happen will happen infinitely many times” (A. Guth) 1)Measure Problems 2)Problems defining probabilities 3)Problems/hidden assumptions re initial conditions  problem claiming generic predictions about state  cannot claim “solution to cosmological problems”  Related to 2 nd law, low S start For this talk, focus on probabilities. Assume all other challenges are resolved

Albrecht Les Houches Lectures 2013 Pt. 318 Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse)

Albrecht Les Houches Lectures 2013 Pt. 319 Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse)

Quantum vs Non-Quantum probabilities Non-Quantum probabilities in a toy model: Page, 2009; These slides follow AA & Phillips 2012 Albrecht Les Houches Lectures 2013 Pt. 320

Quantum vs Non-Quantum probabilities Non-Quantum probabilities in a toy model: Possible Measurements  Projection operators: Measure A only: Measure B only: Measure entire U: Albrecht Les Houches Lectures 2013 Pt. 321

Quantum vs Non-Quantum probabilities Non-Quantum probabilities in a toy model: Possible Measurements  Projection operators: Measure A only: Measure B only: Measure entire U: BUT: It is impossible to construct a projection operator for the case where you do not know whether it is A or B that is being measured. Albrecht Les Houches Lectures 2013 Pt. 322

Quantum vs Non-Quantum probabilities Non-Quantum probabilities in a toy model: Possible Measurements  Projection operators: Measure A only: Measure B only: Measure entire U: BUT: It is impossible to construct a projection operator for the case where you do not know whether it is A or B that is being measured. Could Write Albrecht Les Houches Lectures 2013 Pt. 323

Quantum vs Non-Quantum probabilities Non-Quantum probabilities in a toy model: Possible Measurements  Projection operators: Measure A only: Measure B only: Measure entire U: BUT: It is impossible to construct a projection operator for the case where you do not know whether it is A or B that is being measured. Could Write Classical Probabilities to measure A, B Albrecht Les Houches Lectures 2013 Pt. 324

Quantum vs Non-Quantum probabilities Non-Quantum probabilities in a toy model: Possible Measurements  Projection operators: Measure A only: Measure B only: Measure entire U: BUT: It is impossible to construct a projection operator for the case where you do not know whether it is A or B that is being measured. Could Write Classical Probabilities to measure A, B Does not represent a quantum measurement Albrecht Les Houches Lectures 2013 Pt. 325

Quantum vs Non-Quantum probabilities Non-Quantum probabilities in a toy model: Possible Measurements  Projection operators: Measure A only: Measure B only: Measure entire U: BUT: It is impossible to construct a projection operator for the case where you do not know whether it is A or B that is being measured. Could Write Classical Probabilities to measure A, B Does not represent a quantum measurement Page: The multiverse requires this (are you in pocket universe A or B?) Albrecht Les Houches Lectures 2013 Pt. 326

Quantum vs Non-Quantum probabilities Non-Quantum probabilities in a toy model: Possible Measurements  Projection operators: Measure A only: Measure B only: Measure entire U: BUT: It is impossible to construct a projection operator for the case where you do not know whether it is A or B that is being measured. Could Write Classical Probabilities to measure A, B Does not represent a quantum measurement Page: The multiverse requires this (are you in pocket universe A or B?) Albrecht Les Houches Lectures 2013 Pt. 327

All everyday probabilities are quantum probabilities AA & D. Phillips 2012 Albrecht Les Houches Lectures 2013 Pt. 328

All everyday probabilities are quantum probabilities AA & D. Phillips 2012 Albrecht Les Houches Lectures 2013 Pt. 329 Our *only* experiences with successful practical applications of probabilities are with quantum probabilities

All everyday probabilities are quantum probabilities One should not use ideas from everyday probabilities to justify probabilities that have been proven to have no quantum origin AA & D. Phillips 2012 Albrecht Les Houches Lectures 2013 Pt. 330

All everyday probabilities are quantum probabilities One should not use ideas from everyday probabilities to justify probabilities that have been proven to have no quantum origin AA & D. Phillips 2012 A problem for many multiverse theories Albrecht Les Houches Lectures 2013 Pt. 331

All everyday probabilities are quantum probabilities One should not use ideas from everyday probabilities to justify probabilities that have been proven to have no quantum origin AA & D. Phillips 2012 A problem for many multiverse theories Albrecht Les Houches Lectures 2013 Pt. 332

Quantum vs Non-Quantum probabilities Non-Quantum probabilities in a toy model: Possible Measurements  Projection operators: Measure A only: Measure B only: Measure entire U: BUT: It is impossible to construct a projection operator for the case where you do not know whether it is A or B that is being measured. Could Write Classical Probabilities to measure A, B Does not represent a quantum measurement Page: The multiverse requires this (are you in pocket universe A or B?) Albrecht Les Houches Lectures 2013 Pt. 333

Quantum vs Non-Quantum probabilities Non-Quantum probabilities in a toy model: Possible Measurements  Projection operators: Measure A only: Measure B only: Measure entire U: BUT: It is impossible to construct a projection operator for the case where you do not know whether it is A or B that is being measured. Could Write Classical Probabilities to measure A, B Does not represent a quantum measurement Page: The multiverse requires this (are you in pocket universe A or B?) Albrecht Les Houches Lectures 2013 Pt. 334 Where do these come from anyway?

Albrecht Les Houches Lectures 2013 Pt. 335 Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse)

Albrecht Les Houches Lectures 2013 Pt. 336 Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse)

All everyday probabilities are quantum probabilities One should not use ideas from everyday probabilities to justify probabilities that have been proven to have no quantum origin AA & D. Phillips 2012 Albrecht Les Houches Lectures 2013 Pt. 337

Quantum effects in a billiard gas Albrecht Les Houches Lectures 2013 Pt. 338

Quantum effects in a billiard gas Quantum Uncertainties Albrecht Les Houches Lectures 2013 Pt. 339

Quantum effects in a billiard gas Albrecht Les Houches Lectures 2013 Pt. 340

Quantum effects in a billiard gas Albrecht Les Houches Lectures 2013 Pt. 341

Quantum effects in a billiard gas Albrecht Les Houches Lectures 2013 Pt. 342

Quantum effects in a billiard gas Albrecht Les Houches Lectures 2013 Pt. 343 Minimizing  conservative estimates for my purposes (also motivated by decoherence in some cases)

Quantum effects in a billiard gas Albrecht Les Houches Lectures 2013 Pt. 344 Subsequent collisions amplify the initial uncertainty (treat later collisions classically  additional conservatism)

Quantum effects in a billiard gas After n collisions: Albrecht Les Houches Lectures 2013 Pt. 345

Quantum effects in a billiard gas is the number of collisions so that (full quantum uncertainty as to which is the next collision) Albrecht Les Houches Lectures 2013 Pt. 346

Air Water Billiards Bumper Car for a number of physical systems (all units MKS) Albrecht Les Houches Lectures 2013 Pt. 347

Air Water Billiards Bumper Car for a number of physical systems (all units MKS) Albrecht Les Houches Lectures 2013 Pt. 348

Air Water Billiards Bumper Car for a number of physical systems (all units MKS) Albrecht Les Houches Lectures 2013 Pt. 349

Air Water Billiards Bumper Car for a number of physical systems (all units MKS) Albrecht Les Houches Lectures 2013 Pt. 350

Air Water Billiards Bumper Car for a number of physical systems (all units MKS) Albrecht Les Houches Lectures 2013 Pt. 351

Air Water Billiards Bumper Car for a number of physical systems (all units MKS) Quantum at every collision Albrecht Les Houches Lectures 2013 Pt. 352

Air Water Billiards Bumper Car for a number of physical systems (all units MKS) Quantum at every collision Albrecht Les Houches Lectures 2013 Pt. 353

Air Water Billiards Bumper Car for a number of physical systems (all units MKS) Quantum at every collision Every Brownian Motion is a “Schrödinger Cat” Albrecht Les Houches Lectures 2013 Pt. 354

Air Water Billiards Bumper Car for a number of physical systems (all units MKS) Quantum at every collision Every Brownian Motion is a “Schrödinger Cat” Albrecht Les Houches Lectures 2013 Pt. ICTP, Trieste 7/23/1355 (independent of “interpretation”) 10,000,000,000,00

Air Water Billiards Bumper Car for a number of physical systems (all units MKS) Quantum at every collision Every Brownian Motion is a “Schrödinger Cat” This result is at the root of our claim that all everyday probabilties are quantum Albrecht Les Houches Lectures 2013 Pt. 356

An important role for Brownian motion: Uncertainty in neuron transmission times Brownian motion of polypeptides determines exactly how many of them are blocking ion channels in neurons at any given time. This is believed to be the dominant source of neuron transmission time uncertainties Image from Albrecht Les Houches Lectures 2013 Pt. 357

Analysis of coin flip Coin diameter Using: Albrecht Les Houches Lectures 2013 Pt. 358

Analysis of coin flip Coin diameter Using: coin flip probabilities are a derivable quantum result Albrecht Les Houches Lectures 2013 Pt. 359

Analysis of coin flip Coin diameter Using: coin flip probabilities are a derivable quantum result Albrecht Les Houches Lectures 2013 Pt. 360 Without reference to “principle of indifference” etc. etc.

Analysis of coin flip Coin diameter Using: Albrecht Les Houches Lectures 2013 Pt. 361 NB: Coin flip is “at the margin” of deterministic vs random: Increasing d or deceasing v h can reduce δN substantially

Analysis of coin flip Coin diameter Using: Albrecht Les Houches Lectures 2013 Pt. 362 NB: Coin flip is “at the margin” of deterministic vs random: Increasing d or deceasing v h can reduce δN substantially Still, this is a good illustration of how quantum uncertainties can filter up into the macroscopic world, for systems that *are* random.

Analysis of coin flip Coin diameter Using: Albrecht Les Houches Lectures 2013 Pt. 363 NB: Coin flip is “at the margin” of deterministic vs random: Increasing d or deceasing v h can reduce δN substantially Still, this is a good illustration of how quantum uncertainties can filter up into the macroscopic world, for systems that *are* random.

Albrecht Les Houches Lectures 2013 Pt. 364 Physical vs probabilities vs “probabilities of belief” Bayes: Physical probability: To do with physical properties of detector etc

Albrecht Les Houches Lectures 2013 Pt. 365 Physical vs probabilities vs “probabilities of belief” Bayes: Probabilities of belief: Which data you trust most Which theory you like best

Albrecht Les Houches Lectures 2013 Pt. 366 Physical vs probabilities vs “probabilities of belief” Bayes: This talk is about physical probability only

Albrecht Les Houches Lectures 2013 Pt. 367 Physical vs probabilities vs “probabilities of belief” Bayes: NB: The goal of science is to get sufficiently good data that probabilities of belief are inconsequential

Albrecht Les Houches Lectures 2013 Pt. 368 Physical vs probabilities vs “probabilities of belief” Bayes: NB: The goal of science is to get sufficiently good data that probabilities of belief are inconsequential

Albrecht Les Houches Lectures 2013 Pt. 369 Physical vs probabilities vs “probabilities of belief” Adding new data (theory priors can include earlier data sets):

Albrecht Les Houches Lectures 2013 Pt. 370 Physical vs probabilities vs “probabilities of belief” Adding new data (theory priors can include earlier data sets): …………

Albrecht Les Houches Lectures 2013 Pt. 371 Physical vs probabilities vs “probabilities of belief” Adding new data (theory priors can include earlier data sets): ………… This initial “model uncertainty” prior is the only P(T) that is a pure probability of belief.

Albrecht Les Houches Lectures 2013 Pt. 372 Physical vs probabilities vs “probabilities of belief” Adding new data (theory priors can include earlier data sets): ………… This initial “model uncertainty” prior is the only P(T) that is a pure probability of belief. This talk is only about wherever it appears

Albrecht Les Houches Lectures 2013 Pt. 373 Physical vs probabilities vs “probabilities of belief” Adding new data (theory priors can include earlier data sets): ………… This initial “model uncertainty” prior is the only P(T) that is a pure probability of belief. This talk is only about wherever it appears NB: The goal of science is to get sufficiently good data that probabilities of belief are inconsequential

Albrecht Les Houches Lectures 2013 Pt. 374 Physical vs probabilities vs “probabilities of belief” Adding new data (theory priors can include earlier data sets): ………… This initial “model uncertainty” prior is the only P(T) that is a pure probability of belief. This talk is only about wherever it appears NB: The goal of science is to get sufficiently good data that probabilities of belief are inconsequential This is the only part of the formula where physical randomness appears

Proof by exhaustion not realistic All everyday probabilities are quantum probabilities Albrecht Les Houches Lectures 2013 Pt. 375

Proof by exhaustion not realistic One counterexample (practical utility of non-quantum probabilities) will undermine our entire argument. All everyday probabilities are quantum probabilities Albrecht Les Houches Lectures 2013 Pt. 376

Proof by exhaustion not realistic One counterexample (practical utility of non-quantum probabilities) will undermine our entire argument Can still invent classical probabilities just to do multiverse cosmology All everyday probabilities are quantum probabilities Albrecht Les Houches Lectures 2013 Pt. 377

Proof by exhaustion not realistic One counterexample (practical utility of non-quantum probabilities) will undermine our entire argument Can still invent classical probabilities just to do multiverse cosmology Not a problem for finite theories (AA, Banks & Fischler) All everyday probabilities are quantum probabilities Albrecht Les Houches Lectures 2013 Pt. 378

Proof by exhaustion not realistic One counterexample (practical utility of non-quantum probabilities) will undermine our entire argument Can still invent classical probabilities just to do multiverse cosmology Not a problem for finite theories (AA, Banks & Fischler) Which theories really do require classical probabilities not yet resolved rigorously. All everyday probabilities are quantum probabilities Albrecht Les Houches Lectures 2013 Pt. 379

Proof by exhaustion not realistic One counterexample (practical utility of non-quantum probabilities) will undermine our entire argument Can still invent classical probabilities just to do multiverse cosmology Not a problem for finite theories (AA, Banks & Fischler) Which theories really do require classical probabilities not yet resolved rigorously (symmetry?) All everyday probabilities are quantum probabilities Albrecht Les Houches Lectures 2013 Pt. 380

Albrecht Les Houches Lectures 2013 Pt. 381 Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse)

Albrecht Les Houches Lectures 2013 Pt. 382 Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse)

Implications for the multiverse: Can still invent classical probabilities just to do multiverse cosmology Further discussion Albrecht Les Houches Lectures 2013 Pt. 383

Implications for the multiverse: Can still invent classical probabilities just to do multiverse cosmology Here is how one might avoid needing classical probabilities for the multiverse  Finite theories (AA, Banks & Fischler)  High levels of symmetries  (Observer centered: Noumra, Garriga & Vilenkin. Requires one of the above I think) Further discussion Albrecht Les Houches Lectures 2013 Pt. 384

Implications for the multiverse: Can still invent classical probabilities just to do multiverse cosmology Here is how one might avoid needing classical probabilities for the multiverse  Finite theories (AA, Banks & Fischler)  High levels of symmetries  (Observer centered: Noumra, Garriga & Vilenkin. Requires one of the above I think) No “volume weighting” to “count observers” Further discussion Albrecht Les Houches Lectures 2013 Pt. 385

Implications for the multiverse: Can still invent classical probabilities just to do multiverse cosmology Here is how one might avoid needing classical probabilities for the multiverse  Finite theories (AA, Banks & Fischler)  High levels of symmetries  (Observer centered: Noumra, Garriga & Vilenkin. Requires one of the above I think) No “volume weighting” to “count observers” Further discussion Could these “fix” eternal inflation? Albrecht Les Houches Lectures 2013 Pt. 386

Implications for the multiverse: Can still invent classical probabilities just to do multiverse cosmology Here is how one might avoid needing classical probabilities for the multiverse  Finite theories (AA, Banks & Fischler)  High levels of symmetries  (Observer centered: Noumra, Garriga & Vilenkin. Requires one of the above I think) No “volume weighting” to “count observers” Randomness in large scale cosmic features only (clearly) quantum thanks to inflation  Cosmic probability censorship? Further discussion Albrecht Les Houches Lectures 2013 Pt. 387

Implications for the multiverse: Can still invent classical probabilities just to do multiverse cosmology Here is how one might avoid needing classical probabilities for the multiverse  Finite theories (AA, Banks & Fischler)  High levels of symmetries  (Observer centered: Noumra, Garriga & Vilenkin. Requires one of the above I think) No “volume weighting” to “count observers” Randomness in large scale cosmic features only (clearly) quantum thanks to inflation  Cosmic probability censorship? Further discussion Albrecht Les Houches Lectures 2013 Pt. 388

Here Cosmic structure Albrecht Les Houches Lectures 2013 Pt. 389 Cosmic length scale Scale factor (measures expansion, time) Today Observable Structure comoving Cosmic structure originates “superhorizon” in Standard Big Bag (why would they be quantum?)

Here Cosmic structure Albrecht Les Houches Lectures 2013 Pt. 390 Cosmic length scale Scale factor (measures expansion, time) Today Observable Structure comoving Cosmic structure originates “superhorizon” in Standard Big Bag (why would they be quantum?) Cosmic structure originates in quantum ground state in inflationary cosmology

Implications for the multiverse: Can still invent classical probabilities just to do multiverse cosmology Here is how one might avoid needing classical probabilities for the multiverse  Finite theories (AA, Banks & Fischler)  High levels of symmetries  (Observer centered: Noumra, Garriga & Vilenkin. Requires one of the above I think) No “volume weighting” to “count observers” Randomness in large scale cosmic features only (clearly) quantum thanks to inflation  Cosmic probability censorship? Further discussion Albrecht Les Houches Lectures 2013 Pt. 391

Implications for the multiverse: Can still invent classical probabilities just to do multiverse cosmology Here is how one might avoid needing classical probabilities for the multiverse  Finite theories (AA, Banks & Fischler)  High levels of symmetries  (Observer centered: Noumra, Garriga & Vilenkin. Requires one of the above I think) No “volume weighting” to “count observers” Randomness in large scale cosmic features only (clearly) quantum thanks to inflation  Cosmic probability censorship? Further discussion Compare with identical particle statistics Albrecht Les Houches Lectures 2013 Pt. 392

Many topics that seem “principle-driven” for classical probabilities should actually be derivable from quantum physics (Micro)canonical ensemble (vs “equipartiton”) “principle of indifference” etc Further discussion Albrecht Les Houches Lectures 2013 Pt. 393

Albrecht Les Houches Lectures 2013 Pt Further discussion Bet on the millionth digit of π (or Chaitin’s Ω)

Albrecht Les Houches Lectures 2013 Pt Further discussion Bet on the millionth digit of π (or Chaitin’s Ω) The *only* thing random is the choice of digit to bet on

Albrecht Les Houches Lectures 2013 Pt Further discussion Bet on the millionth digit of π (or Chaitin’s Ω) The *only* thing random is the choice of digit to bet on Fairness is about lack of correlation between digit choice and digit value

Albrecht Les Houches Lectures 2013 Pt Further discussion Bet on the millionth digit of π (or Chaitin’s Ω) The *only* thing random is the choice of digit to bet on Fairness is about lack of correlation between digit choice and digit value Choice of digit comes from  Brain (neurons with quantum uncertainties)  Random number generator  seed  time stamp (when you press enter)  brain  Etc

Albrecht Les Houches Lectures 2013 Pt Further discussion Bet on the millionth digit of π (or Chaitin’s Ω) The *only* thing random is the choice of digit to bet on Fairness is about lack of correlation between digit choice and digit value Choice of digit comes from  Brain (neurons with quantum uncertainties)  Random number generator  seed  time stamp (when you press enter)  brain  Etc The only randomness in a bet on a digit of π is quantum!

Albrecht Les Houches Lectures 2013 Pt Classical Computer: The “computational degrees of freedom” of a classical computer are very classical: Engineered to be well isolated from the quantum fluctuations that are everywhere  Computations are deterministic “Random” is artificial Model a classical billiard gas on a computer:  All “random” fluctuations are determined by (or “readings of”) the initial state. Further discussion Std. thinking about classical probabilities

Albrecht Les Houches Lectures 2013 Pt Classical Computer: The “computational degrees of freedom” of a classical computer are very classical: Engineered to be well isolated from the quantum fluctuations that are everywhere  Computations are deterministic “Random” is artificial Model a classical billiard gas on a computer:  All “random” fluctuations are determined by (or “readings of”) the initial state. Further discussion Std. thinking about classical probabilities

Albrecht Les Houches Lectures 2013 Pt Our ideas about probability are like our ideas about color: Quantum physics gives the correct foundation to our understanding Our “classical” intuition predates our knowledge of QM by a long long time, and works just fine for most things Fundamental quantum understanding needed to fix classical misunderstandings in certain cases. Further discussion

Albrecht Les Houches Lectures 2013 Pt Our ideas about probability are like our ideas about color: Quantum physics gives the correct foundation to our understanding Our “classical” intuition predates our knowledge of QM by a long long time, and works just fine for most things Fundamental quantum understanding needed to fix classical misunderstandings in certain cases. Further discussion

Albrecht Les Houches Lectures 2013 Pt Our ideas about probability are like our ideas about color: Quantum physics gives the correct foundation to our understanding Our “classical” intuition predates our knowledge of QM by a long long time, and works just fine for most things Fundamental quantum understanding needed to fix classical misunderstandings in certain cases. Further discussion

Albrecht Les Houches Lectures 2013 Pt Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse)

Albrecht Les Houches Lectures 2013 Pt Part 3 Outline 1)The multiverse 2)Quantum vs non-quantum probabilities (toy model/multiverse) 3)Everyday probabilities 4)Further Discussion (Implications for the multiverse)

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Albrecht Les Houches Lectures 2013 Pt A few final thoughts:  If you do early universe cosmology, you need to care about these issues (you could “solve the measure problem” and still have a “classical probability problem”)

Albrecht Les Houches Lectures 2013 Pt A few final thoughts:  If you do early universe cosmology, you need to care about these issues (you could “solve the measure problem” and still have a “classical probability problem”)  If you are suspicious of my claims: Just think of one counterexample.

Albrecht Les Houches Lectures 2013 Pt A few final thoughts (Part 3):  If you do early universe cosmology, you need to care about these issues (you could “solve the measure problem” and still have a “classical probability problem”)  If you are suspicious of my claims: Just think of one counterexample.  In any case, I hope you find this mix of ideas as fun as I do!

Albrecht Les Houches Lectures 2013 Pt A few final thoughts (Part 3):  If you do early universe cosmology, you need to care about these issues (you could “solve the measure problem” and still have a “classical probability problem”)  If you are suspicious of my claims: Just think of one counterexample.  In any case, I hope you find this mix of ideas as fun as I do!

Les Houches Lectures on Cosmic Inflation Four Parts 1)Introductory material 2)Entropy, Tuning and Equilibrium in Cosmology 3)Classical and quantum probabilities in the multiverse 4)de Sitter equilibrium cosmology Andreas Albrecht; UC Davis Les Houches Lectures; July-Aug Albrecht Les Houches Lectures 2013 Pt. 3 End Part 3