CASPER

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the String Landscape, the Multiverse
the Anthropic Principle
Dr. Gerald B. Cleaver
Baylor University
UNT 13 Nov 07
CASPER
www.baylor.edu/CASPER
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500 Physicists seeking Einsteins final
goal? the Theory of Everything (Physical)
Realized in String/M-Theory
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• Science Fiction has become Science
• Extra Dimensions (7 to be exact)
• Parallel Universes (at least 1 maybe a few
  more)
  
• Multiple Universes (perhaps 10100 to 500)
• Warped Spacetime
• Time before Time
• End of the Universe Predicted
• ? Anti-Gravity is pulling apart our universe
• in Trillion yrs even atoms torn apart

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• String Theory
  implies
• nature of reality existence is
• more complex
• more beautiful
• yet more simple
• then ever imagined before!

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Outline

• Brief Intro to Strings/M-Theory
• String Cosmology
• Destiny of the Stringy Universe
• Landscape of String Theory

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Visible Universe
13.7 billion light years In diameter 8 x1022 mi
trillion galaxies, trillion stars per galaxy
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All Matter Forces in the UniverseUnified by
String Theory
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Particles ForcesLike Notes on a Violin String
B
A?
??
??
C?
D
G?
??
??
??
??
E?
F?
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String Interactions consistent w/ Relativity
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Quantum MechanicsRequires String Theory w/9 1
Dimensional Spacetime
Astronomy, OFotU
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Strings have two vibrations CW CCW Spin
of Vibrations in our 31 Dim. Spacetime
Gravitons Spin 2 Particles
Strings w/ both vibes in 31 Dim S-T Photons,
Gluons, W,-, Z (non-grav. force part.)
Spin 1 Particles
Strings w/ 1 vibe in 31 Dim S-T
1 vibe in 6 Dim Comp
Space SUSY- Matter Spin 0 Particles
Strings w/ both vibes in 6 Dim Comp
Space
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Too Simple
Circular
Spherical
Toroidal
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too simple to result in Either the matter
particles that exist
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Or the force carrying particles So
more complex shapes investigated
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RequireCalabi-Yau Compactification for all 6
Compactified Dimensions
2 Dim Surface C-Y SurfaceNeed to extend to 6 Dim
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Energy Modes
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String Duality
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Finite Initial Size and Temperature of Universe
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Nagging Problem for 1st Decade (1985-95)Not
Just 1 10-Dimensional String Theory But 5!
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Solution Duality (Equality) of All 5 String
Theories
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Each Theory is SAME THEORY IN
DIFFERENTMATHEMATICAL LANGUAGE
?
O
O
?
?
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Membrane
String
?
?
w/ 10 Dim
w/ 11 Dim
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Two 9-brane Universes Us Themand extra
dimension between
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Compactify 6 of the 9 Spatial Directions of each
Brane as Before
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Effective 5-Dimensional Theory
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Size of 5th Dimension?

• 10-33 cm lt ?y lt 0.1 mm

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Tests for sub-mm.directions

• Fgrav -Gm1m2/r2 ? -Gm1m2/r2n
• 1/r2 form of gravity being tested.
• Standard gravity verified down to 0.15 mm
• at Univ. of Wash. with 97 confidence level

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Manufacturing of Stringy Blackholes!

• If sub-mm. dimension then it may be possible to
  produce gravitons and mini-black holes (with
  peco-second half-lives) at Fermilab CERN this
  decade!
• Mini-black holes have distinct decays
• easily identifiable!
• Black Holes Detectors for
• Fermilab and CERN

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Proposed Explanation for Big BangImplying Time
Before Time!
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Astronomy, OFotU
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The colliding Branes would not remain perfectly
flat as they approach each other due to quantum
effects. Big Bang Inflations occurs in bumps on
Branes that collide first. Multiple,
separated, Big Bang regions might have been
formed from distinct collision points of Branes!
Multiple universes on our Brane besides 1
Parallel Branes along an extra spatial direction
?
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CMB
CMB Temp 2.73 Degrees above absolute
Zero
Temp variations of 1 part in 100,000 denoted by
color variations Blue is hottest, Red is
coldest
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Recent Observation of Earliest GalaxiesFormed 1
billion years after Big Bang
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OBSERVATION Eight distant infant galaxies --
essentially giant globs of hydrogen with a few
hot young stars -- lie inside a thin filament,
visualized with a computer overlay. The hot stars
make the hydrogen glow. Other objects in the
image are nearer galaxies or stars.
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You are here ?
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New Scientist, 5 Feb 2005
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String Landscape
C.C.
1
10-120
10100 to 500 Models in M-Theory
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String Landscape
C.C.
1
10-119
10-120
Anthropic Principle of String Theory
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Examination of the State of the Universe from
Anthropic Principle and Fine Tuning
Weak anthropic principle (WAP) "The observed
values of all physical and cosmological
quantities are not equally probable but they take
on values restricted by the requirement that
there exist sites where carbon-based life can
evolve and by the requirements that the Universe
be old enough for it to have already done so."
(Barrow and Tipler 1986 16). The
Merriam-Webster dictionary defines WAP as
conditions that are observed in the universe must
allow the observer to exist. Strong anthropic
principle (SAP) "The Universe must have those
properties which allow life to develop within
it at some stage in its history." (Barrow and
Tipler 1986).

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Barrow and Tipler then proposed three
(overlapping) elaborations of the SAP (i)
"There exists one possible Universe 'designed'
with the goal of generating and sustaining
'observers.' " This implies that the purpose of
the universe is to give rise to intelligent life,
with the laws of nature and their fundamental
constants set to ensure that life as we know it
will emerge and evolve. Fine tuning of constants
in nature result as necessities for life. (ii)
"Observers are necessary to bring the Universe
into being." Barrow and Tipler believe that
this can be validly inferred from quantum
mechanics. (iii) "An ensemble of other
different universes is necessary for the
existence of our Universe." This interpretation
sympathizes with the many worlds interpretation
of quantum mechanics. We will see a possible
reemergence of this in string theory
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Fine-Tuning The premise of the fine-tuned
universe assertion is that any small change in
the twenty or so physical constants would make
the universe radically different and therefore,
unsuitable for life If, for example, the
electron's charge were slightly different, or if
the strong nuclear force were only 2 stronger,
di-protons would be stable and hydrogen would
fuse too easily, making stars as we know them
impossible and prevent the universe from
developing life as we know it. Or, if the
cosmological constant had been greater than it is
by a factor of 10, the universe would have
expanded to fast for galaxies to ever form.
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Eternal Inflationary Universe
Each later universe has lower cosmological
constant than did the universe from which it
came.
String Cosmology implies physical creation is
likely eternal. Gods creative act never ceases.
Each universe produces an infinitude of
universes.
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Understanding of String Landscape and our
Universe in relation to it Controversial topic at
the momente.g. papers of the last two
months Domain walls, near-BPS bubbles, and
probabilities in the landscape, A. Ceresole et
al., hep-th/0605266. On the Geometry of the
String Landscape and the Swampland, H. Ooguri
and C. Vafa, hep-th/0605264. Cosmological
Landscape From Nothing Some Like It Hot, A.
Barvinsky and A. Kamenshchik, hep-th/0605132. The
Supersymmetric Vistas of the Supergravity
Landscape, T. Ortin, Annalen Phys. 15 (2006)
252. Inflation, dark matter and dark energy in
the string Landscape, A. Riddle and L
Urena-Lopez, astro-ph/0605205. Eternal observers
and bubbler abundances in the Landscape, The
Landscape 'avant la lettre'. V. Vanchurin and
A. Vilenkin, hep-th/0605015. The Landscape
'avant la lettre, A. Schellekensilen,
physics/0604134
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Role of Anthropic Principle? Hotly debated in
String/M-Theory e.g., On making predictions in
a multiverse Conundrums, dangers, and
coincidences, A. Aguirre, astro-ph/0506519. The
Anthropic principle and the duration of the
cosmological past, M. Cirkovic,
astro-ph/0505005. Supersymmetry breaking in the
anthropic landscape, L. Susskind,
hep-th/0405189. Is there a string theory
landscape Some cautionary notes, M. Dine,
hep-th/0405189. Multiple universes, cosmic
coincidences, and other dark matters, A.
Aguirre and M. Tegmark, hep-ph/0409072 Is there
a string theory landscape? T. Banks et al.,
hep-th/0309170. Can the universe experience many
cycles with different vacua? Y. Piao,
hep-ph/0407258.
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String/M-Theory as presently understood has a
large parameter space of variables (angles
between each compactified direction, lengths of
each, plus things called fluxes and torques) each
leading to universes (observable, hidden, or
both) with differing properties. On the order of
gt 10100 different universes all seem equally
possible. Why our particular String/M-Theory
universe? Some scientists (e.g. Stephen Hawking)
are suspicious that determination of a particular
choice of ALL of the M-Theory parameters might
not be totally determinable, based on Gödels
Theorem, which says that one cannot formulate a
finite system of axioms to prove every result in
mathematics. This means that inconsistencies or
indeterminacies can arise if one tries to prove
statements that refer to themselves. A physical
theory is a mathematical model. So if there are
mathematical results that cannot be proved, there
are physical problems that cannot be solved. We
do not live outside of the universe, but instead
we and our theories are both part of the universe
we are describing. Hence our theories are also
self-referring. And thus we might suspect that
any Theory of Everything determined by a finite
number of known parameters or variables might
ultimately be incomplete or undetermined!
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String/M-Theory

• Provides unified explanation of all 4 forces
  matter particles.
• Develops deeper understanding of nature of
  spacetime and gravity.
• Presents our universe with a simplicity, order
  and beauty never before imagined. Simultaneously
  provides for complexity of universe.
• Suggests more to our universe than ever of
  dreamed prior.

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Interesting String (Cosmology) Web Sites (also
image sources)
http//www.superstringtheory.com/ John Schwarz
"The Official String Theory Web Site"
http//www.sukidog.com/jpierre/strings/ String
Tutorial with glossary, refs links http//www.s
uperstring-theory.com/EnglishVersion.html another
excellent intro http//www.superstringtheory.com/
cosmo/index.html http//www.ba.infn.it/gasperin/
http//feynman.princeton.edu/steinh/ Great
string cosmology sites http//www.nuclecu.unam.mx
/7Ealberto/physics/string.html
http//dmoz.org/Science/Physics/Quantum_Mechanics
/ http//pages.wooster.edu/bboroson/clinks.html
worthwhile collections of links to other major
string sites http//pancake.uchicago.edu/carr
oll Several slides in the presentation
borrowed from this site!