Origin of probabilities and their application to the multiverse Andreas Albrecht UC Davis Phy 262 lectures Adapted from a U. Penn Seminar April, 2014 1A.

Origin of probabilities and their application to the multiverse

Andreas AlbrechtUC Davis

Phy 262 lecturesAdapted from a U. Penn Seminar

April, 2014

1A. Albrecht Prob. Lectures for Phy 262

A. Albrecht Prob. Lectures for Phy 262 2

My history with this topic

AA: All randomness/

probabilities are quantum (coin flip, card choice

etc)


My history with this topicAll

randomness/probabilities are

quantum (coin flip, card choice etc)



Page: Quantum probabilities cannot

address key multiverse questions.

(OK, just use classical

ones)

All randomness/proba

bilities are quantum (coin flip,

card choice etc)



Page: Quantum probabilities

cannot address key multiverse

questions. (OK, just use

classical ones)



card choice etc)

AA: All randomness/


etc)






classical ones)

AA: All randomness/


etc)



card choice etc)

Hartle, Srednicki, Aguirre, Tegmark, …






classical ones)

AA: All randomness/


etc)



card choice etc)

AA: A deeper problem than the measure problems for

the multiverse






classical ones)

AA: All randomness/


etc)



card choice etc)

AA: A deeper problem than the measure problems for

the multiverseA potential issue even for finite models






classical ones)

AA: All randomness/


etc)



card choice etc)

AA: A deeper problem than the

measure problems for the

multiverseAA: Write paper

explaining this with Phillips






classical ones)

AA: All randomness/


etc)



card choice etc)





AA: This is fundamentally about giving permission to dismiss certain probability

questions (the non quantum ones) as “ill posed”.






classical ones)

AA: All randomness/


etc)



card choice etc)






questions (the non quantum ones) as “ill

posed”.

Perhaps this type of discipline can help

resolve the measure problems of the

multiverse/eternal inflation






classical ones)

AA: All randomness/


etc)



card choice etc)







posed”.

Perhaps this type of discipline can help



X ?






classical ones)

AA: All randomness/


etc)



card choice etc)







posed”.

Apparently this type of discipline can help



X ?


Outline

1) Quantum vs non-quantum probabilities (toy model/multiverse)

2) Everyday probabilities

3) Be careful about counting!

4) Implications for multiverse/eternal inflation


Outline





NB: Very different subject from “make probabilities

precise” in “Stanford sense”.


Outline






Planck Data--- Cosmic Inflation theory

-200 -100 0 100 2000

0.5

1

1.5

2

2.5x 10

4

/MP

V/M

GU

T4

Slow rolling of inflaton


Observable physics

generated here

-200 -100 0 100 2000

0.5

1

1.5

2

2.5x 10

4

/MP

V/M

GU

T4



Observable physics

generated here Extrapolating

back

-200 -100 0 100 2000

0.5

1

1.5

2

2.5x 10

4

/MP

V/M

GU

T4


Q


“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

A

Self-reproduction regime

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


Classically Rolling

C

Classically Rolling

B

Classically Rolling

D



“Where are we?” Expect the theory to give you a probability distribution in this space… hopefully with some sharp predictions


Classically Rolling

A


Classically Rolling

C

Classically Rolling

B

Classically Rolling

D



“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)


Quantum vs Non-Quantum probabilities

Non-Quantum probabilities in a toy model:

U A B : 1 , 2A A

A : 1 , 2B B

B

: 11 , 12 , 21 , 22UA B

ij i j

Page, 2009; These slides follow AA & Phillips 2012/14



ˆ 1 1 2 2A AA B

iP i i i i i i 1

ˆ 1 1 2 2B BB A

iP i i i i i i 1


U A B : 1 , 2A A

A : 1 , 2B B

B

: 11 , 12 , 21 , 22UA B

ij i j

Possible Measurements Projection operators:

Measure A only:

Measure B only:

Measure entire U: ijP ij ij



ˆ 1 1 2 2A AA B

iP i i i i i i 1

ˆ 1 1 2 2B BB A

iP i i i i i i 1


U A B : 1 , 2A A

A : 1 , 2B B

B

: 11 , 12 , 21 , 22UA B

ij i j


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.

ijP ij ij



ˆ 1 1 2 2A AA B

iP i i i i i i 1

ˆ 1 1 2 2B BB A

iP i i i i i i 1


U A B : 1 , 2A A

A : 1 , 2B B

B

: 11 , 12 , 21 , 22UA B

ij i j


Measure A only:

Measure B only:

Measure entire U:


Could Write

ˆ ˆ ˆA Bi A i B iP p P p P

ijP ij ij



ˆ 1 1 2 2A AA B

iP i i i i i i 1

ˆ 1 1 2 2B BB A

iP i i i i i i 1


U A B : 1 , 2A A

A : 1 , 2B B

B

: 11 , 12 , 21 , 22UA B

ij i j


Measure A only:

Measure B only:

Measure entire U:


Could Write


ijP ij ij

Classical Probabilities to measure

A, B



ˆ 1 1 2 2A AA B

iP i i i i i i 1

ˆ 1 1 2 2B BB A

iP i i i i i i 1


U A B : 1 , 2A A

A : 1 , 2B B

B

: 11 , 12 , 21 , 22UA B

ij i j


Measure A only:

Measure B only:

Measure entire U:


Could Write


ijP ij ij

ˆ ˆ ˆi j ij jPP P


A, B

Does not represent a

quantum measurement



ˆ 1 1 2 2A AA B

iP i i i i i i 1

ˆ 1 1 2 2B BB A

iP i i i i i i 1


U A B : 1 , 2A A

A : 1 , 2B B

B

: 11 , 12 , 21 , 22UA B

ij i j


Measure A only:

Measure B only:

Measure entire U:


Could Write


ijP ij ij



A, B


quantum measurement

Page: The multiverse requires

this (are you in pocket universe A

or B?)



ˆ 1 1 2 2A AA B

iP i i i i i i 1

ˆ 1 1 2 2B BB A

iP i i i i i i 1


U A B : 1 , 2A A

A : 1 , 2B B

B

: 11 , 12 , 21 , 22UA B

ij i j


Measure A only:

Measure B only:

Measure entire U:


Could Write


ijP ij ij



A, B


quantum measurement



or B?)


• All everyday probabilities are quantum probabilities

AA & D. Phillips 2012




Our *only* experiences with successful practical

applications of probabilities are with quantum

probabilities



• One should not use ideas from everyday probabilities to justify probabilities that have been proven to have no quantum origin






A problem for many

multiverse theories





A problem for many

multiverse theories (as practiced)



ˆ 1 1 2 2A AA B

iP i i i i i i 1

ˆ 1 1 2 2B BB A

iP i i i i i i 1


U A B : 1 , 2A A

A : 1 , 2B B

B

: 11 , 12 , 21 , 22UA B

ij i j


Measure A only:

Measure B only:

Measure entire U:


Could Write


ijP ij ij



A, B


quantum measurement



or B?)



ˆ 1 1 2 2A AA B

iP i i i i i i 1

ˆ 1 1 2 2B BB A

iP i i i i i i 1


U A B : 1 , 2A A

A : 1 , 2B B

B

: 11 , 12 , 21 , 22UA B

ij i j


Measure A only:

Measure B only:

Measure entire U:


Could Write


ijP ij ij



A, B


quantum measurement



or B?)

Where do these come from anyway?


Outline






Outline






Quantum effects in a billiard gas

l

b

r



lQuantum Uncertainties

b

r


b


l

r

pb x t

m



l2

2

p lb x t a

m a mv

2

2exp

2

x

a

b

r



l

min 3/2

22

2 / 22 dB

p lb x t a

m a mv

ll

mv

b

r

2

2exp

2

x

a



l

min 3/2

22

2 / 22 dB

p lb x t a

m a mv

ll

mv

b

r

2

2exp

2

x

a

Minimizing conservative estimates for my purposes (also motivated by decoherence in some cases)


1b


l

b

r

Subsequent collisions amplify the initial uncertainty (treat later collisions classically additional conservatism)


1b


l 1 2 /

n

nb b l r

After n collisions:

b

r



Qn is the number of collisions so thatQnb r

log

2log 1

Q

br

nlr

(full quantum uncertainty as to which is the next collision)


AirWater BilliardsBumper Car

r l m v dB b Qn

for a number of physical systemsQn(all units MKS)



r l m v dB b Qn


1 2 150 0.5 361.4 10 183.4 10 25



r l m v dB b Qn


0.029 1 0.16 1 346.6 10 175.1 10 8

1 2 150 0.5 361.4 10 183.4 10 25



r l m v dB b Qn


103.0 10 105.4 10 263 10 460 127.6 10 101.3 10 0.6

0.029 1 0.16 1 346.6 10 175.1 10 8

1 2 150 0.5 361.4 10 183.4 10 25

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=WXF7paCe2iBZaM&tbnid=aNngNbalrziQcM:&ved=0CAUQjRw&url=http://fullcircle.asu.edu/2012/02/scientific-advances-promise-better-ways-to-engineer-water-safety-systems/&ei=jQGbUezhC4WXiQLFzoCQCA&bvm=bv.46865395,d.cGE&psig=AFQjCNEh2AiuWyzKmMV1ckJuPdVpRIIh_A&ust=1369199357485821



r l m101.6 10 73.4 10 264.7 10

v dB b Qn360


126.2 10 92.9 10 0.3103.0 10 105.4 10 263 10 460 127.6 10 101.3 10 0.6

0.029 1 0.16 1 346.6 10 175.1 10 8

1 2 150 0.5 361.4 10 183.4 10 25


http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=1h1Sbi3mIomKHM&tbnid=xrwWtfLGXbN-fM:&ved=0CAUQjRw&url=http://www.minusspace.com/2008/10/presque-rien-2-curated-by-gavin-turk-cedric-christie-laure-genillard-gallery-london-united-kingdom/&ei=vwGbUemOKOmciALW4IHQDQ&bvm=bv.46865395,d.cGE&psig=AFQjCNF1l5ELwqrZ4fBRTRocQm3Bky8hIg&ust=1369199415691303



r l m101.6 10 73.4 10 264.7 10

v dB b Qn360


126.2 10 92.9 10 0.3103.0 10 105.4 10 263 10 460 127.6 10 101.3 10 0.6

0.029 1 0.16 1 346.6 10 175.1 10 8

1 2 150 0.5 361.4 10 183.4 10 25

Quantum at every collision





r l m101.6 10 73.4 10 264.7 10

v dB b Qn360


126.2 10 92.9 10 0.3103.0 10 105.4 10 263 10 460 127.6 10 101.3 10 0.6

0.029 1 0.16 1 346.6 10 175.1 10 8

1 2 150 0.5 361.4 10 183.4 10 25

Quantum at every collision

( breakdown of formula,

but conclusion robust)





r l m101.6 10 73.4 10 264.7 10

v dB b Qn360


126.2 10 92.9 10 0.3103.0 10 105.4 10 263 10 460 127.6 10 101.3 10 0.6

0.029 1 0.16 1 346.6 10 175.1 10 8

1 2 150 0.5 361.4 10 183.4 10 25

Quantum at every collisionEvery

Brownian Motion is a

“Schrödinger Cat”





r l m101.6 10 73.4 10 264.7 10

v dB b Qn360


126.2 10 92.9 10 0.3103.0 10 105.4 10 263 10 460 127.6 10 101.3 10 0.6

0.029 1 0.16 1 346.6 10 175.1 10 8

1 2 150 0.5 361.4 10 183.4 10 25




Albrecht @ ICTP, Trieste 7/23/13 58

(independent of “interpretation”)

10,000,000,000,00





r l m101.6 10 73.4 10 264.7 10

v dB b Qn360


126.2 10 92.9 10 0.3103.0 10 105.4 10 263 10 460 127.6 10 101.3 10 0.6

0.029 1 0.16 1 346.6 10 175.1 10 8

1 2 150 0.5 361.4 10 183.4 10 25




This result is at the root of our claim that

all everyday probabilities are

quantum



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 1nt ms

Image from http://www.nature.com/nrn/journal/v13/n4/full/nrn3209.html

http://www.nature.com/nrn/journal/v13/n4/full/nrn3209.html




Analysis of coin flip

hv

fv

Coin diameter d

hf n

h f

vt t

v v

2t ft t

4 fvfd

0.5tN f t

Using:1nt ms 5 /h fv v m s

0.01d m



hv

fv

Coin diameter d

hf n

h f

vt t

v v

2t ft t

4 fvfd

0.5tN f t


0.01d m

50-50 coin flip probabilities are

a derivable quantum result



hv

fv

Coin diameter d

hf n

h f

vt t

v v

2t ft t

4 fvfd

0.5tN f t


0.01d m

50-50 coin flip probabilities are

a derivable quantum result

Without reference to “principle of

indifference” etc. etc.



hv

fv

Coin diameter d

hf n

h f

vt t

v v

2t ft t

4 fvfd

0.5tN f t


0.01d m

NB: Coin flip is “at the margin” of deterministic vs random: Increasing d or deceasing vh can reduce δN substantially



hv

fv

Coin diameter d

hf n

h f

vt t

v v

2t ft t

4 fvfd

0.5tN f t


0.01d m


Still, this is a good illustration of how quantum uncertainties can filter up into the macroscopic world, for

systems that *are* random.



hv

fv

Coin diameter d

hf n

h f

vt t

v v

2t ft t

4 fvfd

0.5tN f t


0.01d m


Still, this is a good illustration of how quantum uncertainties can filter up into the macroscopic world, for

systems that *are* random.


Physical vs probabilities vs “probabilities of belief”

Bayes:

|

|P Data Theory

P Theory Data P TheoryP Data

Physical probability: To do with physical properties of detector etc



Bayes:

|

|P Data Theory


Probabilities of belief:• Which data you trust most• Which theory you like best



Bayes:

This talk is about physical probability only

|

|P Data Theory




Bayes:

NB: The goal of science is to get sufficiently good data that probabilities of belief are inconsequential

|

|P Data Theory




Bayes:


|

|P Data Theory




Adding new data (theory priors can include earlier data sets):

5

5 5 45

||

P D TP T D P T

P D

4

4 4 34

||

P D TP T D P T

P D




5

5 5 45

||

P D TP T D P T

P D

4

4 4 34

||

P D TP T D P T

P D

…………

1

1 1 01

||

P D TP T D P T

P D




5

5 5 45

||

P D TP T D P T

P D

4

4 4 34

||

P D TP T D P T

P D

…………

1

1 1 01

||

P D TP T D P T

P D

This initial “model uncertainty” prior is the only P(T) that is a pure probability of belief.




5

5 5 45

||

P D TP T D P T

P D

4

4 4 34

||

P D TP T D P T

P D

…………

1

1 1 01

||

P D TP T D P T

P D


This talk is only about wherever it appears

|P D T




5

5 5 45

||

P D TP T D P T

P D

4

4 4 34

||

P D TP T D P T

P D

…………

1

1 1 01

||

P D TP T D P T

P D



|P D T





5

5 5 45

||

P D TP T D P T

P D

4

4 4 34

||

P D TP T D P T

P D

…………

1

1 1 01

||

P D TP T D P T

P D



|P D T


This is the only part of the formula where physical

randomness appears




5

5 5 45

||

P D TP T D P T

P D

4

4 4 34

||

P D TP T D P T

P D

…………

1

1 1 01

||

P D TP T D P T

P D



|P D T


This is the only part of the formula where physical

randomness appears


• Proof by exhaustion not realistic

All everyday probabilities are quantum probabilities


• Proof by exhaustion not realistic• One counterexample (practical utility of non-quantum

probabilities) will undermine our entire argument.




probabilities) will undermine our entire argument• Can still invent classical probabilities just to do multiverse

cosmology





cosmology• Not a problem for many finite theories (AA, Banks &

Fischler)






Fischler)• Which theories really do require classical probabilities

not yet resolved rigorously.







not yet resolved rigorously (symmetry?... simplicity? See below)









Some further thoughts:


-60 -50 -40 -30 -20 -10 0 10-70

-60

-50

-40

-30

-20

-10

0

10

log(a/a0)

log(

RH/R

H0)

Here

Cosmic structureCo

smic

leng

th s

cale

Scale factor (measures expansion, time)

Today

Observable Structure

comoving

SBBHR

Cosmic structure originates “superhorizon” in Standard Big Bag

(why would they be quantum?)

A note on “probability censorship”


-60 -50 -40 -30 -20 -10 0 10-70

-60

-50

-40

-30

-20

-10

0

10

log(a/a0)

log(

RH/R

H0)

Here

Cosmic structureCo

smic

leng

th s

cale

Scale factor (measures expansion, time)

Today

Observable Structure

comoving

SBBHR

Cosmic structure originates “superhorizon” in Standard Big Bag

(why would they be quantum?)InfHR

Cosmic structure originates in quantum

ground state in inflationary cosmology

A note on “probability censorship”








Compare with identical particle statistics


3.141592653589793238462643383279502884197169399375105820974944592307816406286 208998628034825342117067982148086513282306647093844609550582231725359408128481 117450284102701938521105559644622948954930381964428810975665933446128475648233 786783165271201909145648566923460348610454326648213393607260249141273724587006 606315588174881520920962829254091715364367892590360011330530548820466521384146 951941511609433057270365759591953092186117381932611793105118548074462379962749 567351885752724891227938183011949129833673362440656643086021394946395224737190 702179860943702770539217176293176752384674818467669405132000568127145263560827 785771342757789609173637178721468440901224953430146549585371050792279689258923 542019956112129021960864034418159813629774771309960518707211349999998372978049 951059731732816096318595024459455346908302642522308253344685035261931188171010 003137838752886587533208381420617177669147303598253490428755468731159562863882 353787593751957781857780532171226806613001927876611195909216420198938095257201 065485863278865936153381827968230301952035301852968995773622599413891249721775 283479131515574857242454150695950829533116861727855889075098381754637464939319 255060400927701671139009848824012858361603563707660104710181942955596198946767 837449448255379774726847104047534646208046684259069491293313677028989152104752 162056966024058038150193511253382430035587640247496473263914199272604269922796 782354781636009341721641219924586315030286182974555706749838505494588586926995 690927210797509302955321165344987202755960236480665499119881834797753566369807 426542527862551818417574672890977772793800081647060016145249192173217214772350 141441973568548161361157352552133475741849468438523323907394143334547762416862 518983569485562099219222184272550254256887671790494601653466804988627232791786 085784383827967976681454100953883786360950680064225125205117392984896084128488 626945604241965285022210661186306744278622039194945047123713786960956364371917 287467764657573962413890865832645995813390478027590099465764078951269468398352 595709825822620522489407726719478268482601476990902640136394437455305068203496

Further discussion

Bet on the millionth digit of π (or Chaitin’s Ω)

(Carroll)


3.141592653589793238462643383279502884197169399375105820974944592307816406286 208998628034825342117067982148086513282306647093844609550582231725359408128481 117450284102701938521105559644622948954930381964428810975665933446128475648233 786783165271201909145648566923460348610454326648213393607260249141273724587006 606315588174881520920962829254091715364367892590360011330530548820466521384146 951941511609433057270365759591953092186117381932611793105118548074462379962749 567351885752724891227938183011949129833673362440656643086021394946395224737190 702179860943702770539217176293176752384674818467669405132000568127145263560827 785771342757789609173637178721468440901224953430146549585371050792279689258923 542019956112129021960864034418159813629774771309960518707211349999998372978049 951059731732816096318595024459455346908302642522308253344685035261931188171010 003137838752886587533208381420617177669147303598253490428755468731159562863882 353787593751957781857780532171226806613001927876611195909216420198938095257201 065485863278865936153381827968230301952035301852968995773622599413891249721775 283479131515574857242454150695950829533116861727855889075098381754637464939319 255060400927701671139009848824012858361603563707660104710181942955596198946767 837449448255379774726847104047534646208046684259069491293313677028989152104752 162056966024058038150193511253382430035587640247496473263914199272604269922796 782354781636009341721641219924586315030286182974555706749838505494588586926995 690927210797509302955321165344987202755960236480665499119881834797753566369807 426542527862551818417574672890977772793800081647060016145249192173217214772350 141441973568548161361157352552133475741849468438523323907394143334547762416862 518983569485562099219222184272550254256887671790494601653466804988627232791786 085784383827967976681454100953883786360950680064225125205117392984896084128488 626945604241965285022210661186306744278622039194945047123713786960956364371917 287467764657573962413890865832645995813390478027590099465764078951269468398352 595709825822620522489407726719478268482601476990902640136394437455305068203496

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


3.141592653589793238462643383279502884197169399375105820974944592307816406286 208998628034825342117067982148086513282306647093844609550582231725359408128481 117450284102701938521105559644622948954930381964428810975665933446128475648233 786783165271201909145648566923460348610454326648213393607260249141273724587006 606315588174881520920962829254091715364367892590360011330530548820466521384146 951941511609433057270365759591953092186117381932611793105118548074462379962749 567351885752724891227938183011949129833673362440656643086021394946395224737190 702179860943702770539217176293176752384674818467669405132000568127145263560827 785771342757789609173637178721468440901224953430146549585371050792279689258923 542019956112129021960864034418159813629774771309960518707211349999998372978049 951059731732816096318595024459455346908302642522308253344685035261931188171010 003137838752886587533208381420617177669147303598253490428755468731159562863882 353787593751957781857780532171226806613001927876611195909216420198938095257201 065485863278865936153381827968230301952035301852968995773622599413891249721775 283479131515574857242454150695950829533116861727855889075098381754637464939319 255060400927701671139009848824012858361603563707660104710181942955596198946767 837449448255379774726847104047534646208046684259069491293313677028989152104752 162056966024058038150193511253382430035587640247496473263914199272604269922796 782354781636009341721641219924586315030286182974555706749838505494588586926995 690927210797509302955321165344987202755960236480665499119881834797753566369807 426542527862551818417574672890977772793800081647060016145249192173217214772350 141441973568548161361157352552133475741849468438523323907394143334547762416862 518983569485562099219222184272550254256887671790494601653466804988627232791786 085784383827967976681454100953883786360950680064225125205117392984896084128488 626945604241965285022210661186306744278622039194945047123713786960956364371917 287467764657573962413890865832645995813390478027590099465764078951269468398352 595709825822620522489407726719478268482601476990902640136394437455305068203496

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


3.141592653589793238462643383279502884197169399375105820974944592307816406286 208998628034825342117067982148086513282306647093844609550582231725359408128481 117450284102701938521105559644622948954930381964428810975665933446128475648233 786783165271201909145648566923460348610454326648213393607260249141273724587006 606315588174881520920962829254091715364367892590360011330530548820466521384146 951941511609433057270365759591953092186117381932611793105118548074462379962749 567351885752724891227938183011949129833673362440656643086021394946395224737190 702179860943702770539217176293176752384674818467669405132000568127145263560827 785771342757789609173637178721468440901224953430146549585371050792279689258923 542019956112129021960864034418159813629774771309960518707211349999998372978049 951059731732816096318595024459455346908302642522308253344685035261931188171010 003137838752886587533208381420617177669147303598253490428755468731159562863882 353787593751957781857780532171226806613001927876611195909216420198938095257201 065485863278865936153381827968230301952035301852968995773622599413891249721775 283479131515574857242454150695950829533116861727855889075098381754637464939319 255060400927701671139009848824012858361603563707660104710181942955596198946767 837449448255379774726847104047534646208046684259069491293313677028989152104752 162056966024058038150193511253382430035587640247496473263914199272604269922796 782354781636009341721641219924586315030286182974555706749838505494588586926995 690927210797509302955321165344987202755960236480665499119881834797753566369807 426542527862551818417574672890977772793800081647060016145249192173217214772350 141441973568548161361157352552133475741849468438523323907394143334547762416862 518983569485562099219222184272550254256887671790494601653466804988627232791786 085784383827967976681454100953883786360950680064225125205117392984896084128488 626945604241965285022210661186306744278622039194945047123713786960956364371917 287467764657573962413890865832645995813390478027590099465764078951269468398352 595709825822620522489407726719478268482601476990902640136394437455305068203496

Further discussion


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


3.141592653589793238462643383279502884197169399375105820974944592307816406286 208998628034825342117067982148086513282306647093844609550582231725359408128481 117450284102701938521105559644622948954930381964428810975665933446128475648233 786783165271201909145648566923460348610454326648213393607260249141273724587006 606315588174881520920962829254091715364367892590360011330530548820466521384146 951941511609433057270365759591953092186117381932611793105118548074462379962749 567351885752724891227938183011949129833673362440656643086021394946395224737190 702179860943702770539217176293176752384674818467669405132000568127145263560827 785771342757789609173637178721468440901224953430146549585371050792279689258923 542019956112129021960864034418159813629774771309960518707211349999998372978049 951059731732816096318595024459455346908302642522308253344685035261931188171010 003137838752886587533208381420617177669147303598253490428755468731159562863882 353787593751957781857780532171226806613001927876611195909216420198938095257201 065485863278865936153381827968230301952035301852968995773622599413891249721775 283479131515574857242454150695950829533116861727855889075098381754637464939319 255060400927701671139009848824012858361603563707660104710181942955596198946767 837449448255379774726847104047534646208046684259069491293313677028989152104752 162056966024058038150193511253382430035587640247496473263914199272604269922796 782354781636009341721641219924586315030286182974555706749838505494588586926995 690927210797509302955321165344987202755960236480665499119881834797753566369807 426542527862551818417574672890977772793800081647060016145249192173217214772350 141441973568548161361157352552133475741849468438523323907394143334547762416862 518983569485562099219222184272550254256887671790494601653466804988627232791786 085784383827967976681454100953883786360950680064225125205117392984896084128488 626945604241965285022210661186306744278622039194945047123713786960956364371917 287467764657573962413890865832645995813390478027590099465764078951269468398352 595709825822620522489407726719478268482601476990902640136394437455305068203496

Further discussion


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!


10001000111101010

10001000101001010

10001000101101010

11011000101001010

10001010111101010

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


10001000111101010

10001000101001010

10001000101101010

11011000101001010

10001010111101010




Further discussion

Std. thinking about classical

probabilities


10001000111101010

10001000101001010

10001000101101010

11011000101001010

10001010111101010




Further discussion


probabilitiesSee digits of

discussion


10001000111101010

10001000101001010

10001000101101010

11011000101001010

10001010111101010




Further discussion


probabilitiesSee digits of

discussion

My claim: • The real world does not have

these sorts of solid classical ties to initial conditions.

• If it did, that would be a counterexample to my claim

• Quantum prob. enters randomness on a real computer via IC’s


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






Further discussion






Further discussion


Outline






Outline






Central message:

• “Randomness is (quantum) physics”• Counting may or MAY NOT have a role in

inferring or representing physical randomness

Heads


Central message:


inferring or representing physical randomness• Example: Flip a coin and choose a ball:

Heads

Tails

Results


Central message:



Heads

TailsCounts of red & green

balls here can be related in very

concrete terms to the probability of heads

vs tails


Central message:



Heads

TailsCounts of red & green

balls here can be related in very

concrete terms to the probability of heads

vs tails

107

Now ask: What is the probability that a ball drawn from the “Results” bowl is red?

HeadsA. Albrecht Prob. Lectures for Phy 262

Results

108

Now ask: What is the probability that a ball drawn from the “Results” bowl is red?• Different physical “completions” of this question are

possible which give different answers. (≈ measures)

Heads

Tails

A. Albrecht Prob. Lectures for Phy 262

Results

Results Results

109


possible which give different answers. (≈ measures)• Counting is NOT enough.

Heads

Tails


Results

Results Results

110



Heads

Tails


Results

Results ResultsIn a multiverse with many copies

of you, there simply is *no* physical completion for the

question “which observer am I?”. Future data may address this, but not in time to make predictions.

111



Heads

Tails


Results




112



Heads

Tails


Results




This is where things go wrong in the

standard treatment of the multiverse

113



Heads

Tails


Results






In many cases counting observers has no predictive

value

114



Heads

Tails


Results






In many cases counting observers has no predictive

value

No point in counting for these

cases


Outline






Outline






Outline






Pocket A with quantum amplitude so

118

118

118

1) No “volume factors”2) Boltzmann Brain problem reduced3) No “youngness/end of time” problem

Implications for eternal inflation

Pocket B with quantum amplitude so


Pocket A with Ap

Pocket B with Bp

119

119

119



(from quantum branching ratio)


Pocket A with Ap

Pocket B with Bp

120

120

120


Implications for eternal inflationOne semiclassical universe having many more possible observers in it than another (often counted

by volume), does *not* give that universe greater statistical weight. Quantum branching ratio into one

vs the other ( ) does count/A Bp p


Pocket A with Ap

Pocket B with Bp

121

121

121




Pocket A with Ap Pocket B with Bp







This model has no “Boltzmann Brain” problem as long as

Is not too small/A Bp p





This model has no “Boltzmann Brain” problem as long as

Is not too small/A Bp p

Boltzmann brains are observers which look good vs current data but which

quickly go bad









Are there additional amplitudes hidden in this picture?

If so, they may provide a more detailed (and well defined) measure




More pocket universes produced later vs earlier (due to more inflation)




More pocket universes produced later vs earlier (due to more inflation) & experience any time cutoff

Time cutoff regulator










Time cutoff regulator See also Guth & Vanchurin






Wavefunction cannot give probabilities for which pocket you are in.

Time cutoff only there as (wrong) attempt to determine which pocket

The youngness/end of time problem is asking a question the theory cannot answer




2|A Ap

Quantum Branching

A

B2|B Bp

Eternal inflation




2|A Ap

Quantum Branching

A

B2|B Bp

ABB

A

B

BB

A

ABA`

Eternal inflation

Answer given by these

No need to worry about counting infinite A’s and B’s (if sufficient symmetry)


1) All practically applicable probabilities are of physical (quantum) origin.

2) Counting of objects may or MAY NOT be a way of accessing legitimate quantum probabilities

3) Standard discussions of probabilities in cosmology often make errors re 2)

4) 1) and care about 2) allow us to introduce better discipline into cosmological discussions (just say “no”). Implications so far:

a) No (counting based) volume factorsb) Reduced Boltzmann Brain problemc) No youngness/end of time problemd) Measure problems apparently resolved

Conclusions


1) All practically applicable probabilities are of physics (quantum) origin.




a) No (counting based) volume factorsb) Reduced Boltzmann Brain problemc) No youngness/end of time problem

Conclusions I still have other concerns about eternal inflation that

makes me prefer finite theories, but this “probability

discipline” may resolve what I used to think was the most

troubling issue










troubling issue

Landscape OK too










troubling issue

Landscape OK too

In a systematic treatment the

classical probabilities will reappear as

“priors”. Same math but very different

role.






a) No (counting based) volume factorsb) Reduced Boltzmann Brain problemc) No youngness/end of time problemd) Measure problems appaently resolved

Conclusions

Perhaps related to work by Nomura and

Garriga & Vilenkin and collaborators

I still have other concerns about eternal inflation that



troubling issue

Landscape OK too




role.







Conclusions

Perhaps related to work by Nomura and

Garriga & Vilenkin and collaborators

I still have other concerns about eternal inflation that



troubling issue

Landscape OK too

Clashes with my work on the “clock ambiguity”




role.







Conclusions







Conclusions


3.141592653589793238462643383279502884197169399375105820974944592307816406286 208998628034825342117067982148086513282306647093844609550582231725359408128481 117450284102701938521105559644622948954930381964428810975665933446128475648233 786783165271201909145648566923460348610454326648213393607260249141273724587006 606315588174881520920962829254091715364367892590360011330530548820466521384146 951941511609433057270365759591953092186117381932611793105118548074462379962749 567351885752724891227938183011949129833673362440656643086021394946395224737190 702179860943702770539217176293176752384674818467669405132000568127145263560827 785771342757789609173637178721468440901224953430146549585371050792279689258923 542019956112129021960864034418159813629774771309960518707211349999998372978049 951059731732816096318595024459455346908302642522308253344685035261931188171010 003137838752886587533208381420617177669147303598253490428755468731159562863882 353787593751957781857780532171226806613001927876611195909216420198938095257201 065485863278865936153381827968230301952035301852968995773622599413891249721775 283479131515574857242454150695950829533116861727855889075098381754637464939319 255060400927701671139009848824012858361603563707660104710181942955596198946767 837449448255379774726847104047534646208046684259069491293313677028989152104752 162056966024058038150193511253382430035587640247496473263914199272604269922796 782354781636009341721641219924586315030286182974555706749838505494588586926995 690927210797509302955321165344987202755960236480665499119881834797753566369807 426542527862551818417574672890977772793800081647060016145249192173217214772350 141441973568548161361157352552133475741849468438523323907394143334547762416862 518983569485562099219222184272550254256887671790494601653466804988627232791786 085784383827967976681454100953883786360950680064225125205117392984896084128488 626945604241965285022210661186306744278622039194945047123713786960956364371917 287467764657573962413890865832645995813390478027590099465764078951269468398352 595709825822620522489407726719478268482601476990902640136394437455305068203496

Origin of probabilities and their application to the multiverse Andreas Albrecht UC Davis Phy 262 lectures Adapted from a U. Penn Seminar April, 2014 1A.

Documents

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