How many universes are there, anyway

http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015John Ashmead Anyway?
Just how many universes
are there,

http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015
• Rainbow gravity
• Gravity leaking
into nearby
dimensions
• Miniature black
holes

• The multiverse
today
• The problem of
ﬁne-tuning
• A scientiﬁc
hypothesis?
• What are the odds?

The Multiverse Today
• A brief history of the
multiverse
• The edge of the known
• From the Big Bang to now

A brief history of the
Multiverse
• Eratothenes’s Earth
• Kepler’s Moon
• Galileo’s Jupiter
• Wright’s Galaxies
• Bessel’s Star

• Chief Librarian at
Alexandria at 245 BC
• Sieve of primes
• Beta/Pentathelete
• Camel-Days
• Right order of
magnitude
Eratothenes’
Earth

Kepler’s
Somnium
(1608+)
• Autobiographical
• Revised thru his life
• Copernican theory
• The view from the
moon

• Careful reasoning
• Notebooks
• Time series
• A lot to love here
Galileo & The Moons
of Jupiter(1610)

Wright’s Galaxies
(1750)
• Milky way as galaxy
• Nebulae as galaxies
• An indifferent universe

Bessel’s Star
(1838)

Cosmic
Distance
Ladder
• Parallax (Blue)
• Standard Candles
(Light Orange)
• Supernovae (Red)
• The red shift (Dull
green)

• 30 billion years away
• But only 13.7 billion
years since start?
• Space has been
expanding!

Finite but no edge!
• Finite but no edge
• It’s getting bigger
every minute
• Now is a good time for
observers

Big Bang Theory
(De Luce)
• Only theory with a TV
show
• Robert Grossteste, 1175
- 1253.
• The Big Bang theory is
not about the Big Bang

• Why is the
universe so
ﬂat?
• With matching
temperature
• & curvature?

Too Hot to Shine
• Only ionized
particles
• The
unfortunate
photon no
sooner escapes
from one
particle
• Than it is
absorbed by
another!

Tri-Alpha Process
• Helium
stable
• Beryllium
(next) is
NOT
• But there is
a resonance
with Carbon
• Tunnel thru!

The problem of fine-
tuning
• Just six numbers
• Quantum
ﬂuctuations
• String theory

Anthropic testsCurious when you
think about it that the
universe is perfectly
adapted for
velociraptors
What if there are lots
of universes & we
just got lucky?
I see dinner!

Vulcan Science
Directorate Thinks not
A parallel
universe.
The science
directorate has
examined all these
theories.
They've found no
evidence of
alternate realities.

Quantum
Fluctuations
• Quantum
ﬂuctuations
• Fractals
• Led to universe
• And galaxies

Eternal Inflation
• Parts of the mega
universe suddenly cool
out
• Creating a bubble
universe
• That inﬂates with speciﬁc
values of the fundamental
physical constants

Live, Die, Repeat
• Origin of species
• “Generate & test”
• Galaxies, stars, planets,
& us
• Universes & their
observers
• And theories of the
multiverse, e.g. String
Theory

String theory
• Most popular today
• Gets rid of some
inﬁnities
• Lets us combine
particle physics &
gravity
• 10 dimensions for
superstrings

Compactification

Calabi-Yau Manifolds
• The “extra”
dimensions are
curled up into
complex structures
• Many possible
ways to do this

String-scape
• 10^500
possibilities
• Most are
uninteresting
• A few “Happy
Valleys”

Fringe Science?
• Hot scientists?
• Equations?
• Intense but
puzzled
expressions?
• Fate of the
universe at
stake?

How to think about
WeirdThings
• Testability
• Fruitfulness
• Scope
• Simplicity
• Conservatism

Testability

Cosmological
Microwave Background

Bubble universes

Bubbles in the CMB?
• Nearby
parallel
universe
• Leaves
smudge on
the CMB
• Sister
universes?

Gravitational waves
• Distant
universes
• Remnants of
collisions
• From before
the Big Bang

Fruitfulness
• Gives you something
to look for at small
scales
• And at large
• Can rock the mind
loose from hard-
wired assumptions

Scope
• Largest possible
scope
• See as far as possible
• And then drive
imagination a bit
further than that

Simplicity
• # of hypotheses
• not number of parts, but
the kinds of parts
• is a Calabi-Yau manifold
simple or complex?

Wheeler’s Radical
Conservatism
• The combination of Eternal Inﬂation
& String theory gives the multiverse
as a straight forward prediction
• Gellmann’s totalitarian principle +
the 30 odd constants also imply
multiverse
• And Many Worlds Interpretation
implies that the multiverse a natural
implication of quantum mechanics

The universe whisperer

• Shift your
assumptions to match
those of your target
world
• Absurd
• And profound
Syllogismobile

one universe or many?

Thanks!
• Balticon & Miriam Kelly
• Ferne Welch
• Brenda Welch & Jamie Laird
• Other quasi-willing ears

• Stenger - God & the Multiverse -
2014
• Greene - Hidden Reality - 2011
• Barrow - The Book of Universes -
2011
• Clegg - Before the Big Bang - 2009
• Susskind - The Cosmic Landscape -
2006

How many universes are there, anyway

Recomendados

Recomendados

Más contenido relacionado

Destacado

Destacado (16)

Más de John Ashmead

Más de John Ashmead (20)

Último

Último (20)

How many universes are there, anyway