Recap the Creation of the Universe

1
Recap the Creation of the Universe

• What is the 3 main experimental observations
  which support the Big Bang model ?
• Explain the effect of the hyperweak force in the
  first fraction of a second of Big Bang
• When did atoms form ?
• When did galaxies form ?

2
Where Did the Universe Come From ?

• The traditional answers God created it (Plato)
  or It always existed (Aristotle) are not
  acceptable for scientists. Not because scientists
  are not religious but because scientists want a
  more complete answer.
• An acceptable scientific answer Although the
  Universe is not eternal it has neither a
  beginning nor an end. (Hawking and the
  Superstrings Theory)
• Another correct scientific answer is The
  Universe started as a microscopic quantum
  fluctuation , possibly in a previously existing
  Universe. The possibility that the Universe
  eternally re-creates itself does not necessarily
  resolve the problem of creation, but pushes it
  back to indefinite past.

3
Self-Reproducing Universes

• Andrei Linde speculated about self-reproducing
  Universes in his chaotic inflationary theory. His
  Model is also known as the Inflationary Model.
• His quantum fields-based theory introduced waves
  of quantum fluctuations which are streched by an
  inflation process. Quantum kicks occuring every
  10-35 sec. can be accumulated and sometimes they
  can double in size every 10-35 sec.
• In some places these waves become stationary and
  lead to the formation of galaxies.
• But occasionally eternal inflation can occur,
  which leads to the formation of a pocket
  Universe. A multitude of types of Universes can
  form, each giving birth to others and although
  some Universes can crush themselves out of the
  existence, the cosmos would go on forever.
• In Lindes theory various Universes can have
  different physics laws. They can probably be
  inherited from the previous Universe and
  mutations can happen. In our Universe these laws
  allow the creation of life, while in others their
  laws might not permit life.

4
The Inflationary Multiverse
5
Where Did Matter Come From ?

• Virtual particles become real
• Quantum uncertainty principle allows for virtual
  pairs of particles-antiparticles.
• In the Inflationary Model quantum fluctuations
  add up in the same place and the
  particle-antiparticle pairs become real.
• Particles from change of dimensions
• 1981 H.Pagels and D.Atkatz at Rockefeller U.
  propose that the Universe might have began with a
  sudden change in the dimensionality of space.
• They showed that a 10-dimensional space could
  create particles during its transition to a
  4-dimensional space-time (similar to the Higgs
  mechanism related to a change in symmetry).

6
The Anthropic Principle

• The Anthropic Principle can be paraphrased as
  We see the Universe the way it is because we
  exist.
• The weak principle says that the conditions for
  life will be met only in some limited space-time
  conditions.
• The strong principle proposes that there are many
  Universes with their own initial configuration,
  history and laws of science. We are in an ideal
  Universe for the creation of life.
• The Anthropic Principle complements well the
  Inflationary Model.

7
Hawkings Baby Universes

• The self-reproducing Universes theory is
  complementary to Hawkings Baby Universes
  model, associated with the study of black holes.
• Hawking proposed that the particles go through
  the black hole into a small self-contained
  universe which branches out of ours. It can join
  later our region of space-time and evaporate
  returning the particles.
• Although not good for space travel, these baby
  Universes can influence observations in our
  Universe. There might be an astronomical number
  of baby Universes and they might influence the
  value of Einsteins cosmological constant.

8
M-Theory Cosmology

• The picture for the Multiverse based on the
  M-Theory (detailed discussion in the last
  lecture)
• Our Universe is a 4-dimensional brane on a
  vibrating 5-dimensional bubble. We see only a
  part of our Universe because of the bubble
  geometry.
• There are other Universes on other 5-dimensional
  bubbles which can be very close to ours
  (fractions of a milimeter)
• Big Bangs are associated with collisions between
  these bubbles. No need for quantum fluctuations
  to justify them !

9
Are There Parallel Universes ?

• The work of Linde, Hawking and the M-theory all
  point to possible parallel Universes, but where
  are they located ?
• A Stanford group in 1998 showed that a 5th
  dimension might be curled with a macro-radius
  (about 1mm). They explained that gravity is weak
  at subatomic scale because it spreads in 5
  dimensions. So far, experiments showed that
  Newtons gravity theory is valid down to
  fractions of a mm.
• The simplest version of the M-Theory based model
  assumes a 10-30 cm gap between the 4-dimensional
  parallel branes on 5-dimensional bubbles.
• These branes interact only gravitationally and
  therefore we cannot see a shadow brane, but we
  can feel it gravitationally. This might explain
  some missing mass in the Universe.

10
The Evolution of the Definition of our Universe

• Greek philosophers Earth, Sun, planets were the
  Universe
• 17th century Sun at the center of our system and
  other stars
• Beginning of 20th century Milky Way is our
  Universe and there are other Universes
  corresponding to other galaxies
• Today we speak about our Universe containing 1011
  galaxies and we started studying the possibility
  of parallel Universes outside our 4 dimensional
  space-time.
• Current pictures of the Universe see it as part
  of a Multiverse.
• The two current competing models are the
  Inflationary and the M-Theory based brane
  model.

11
Does God Really Play Dice ?

• Einsteins famous comment God does not play
  dice.
• But the Universe is clearly indeterminist at
  micro level and current theories about the
  creation of the Universe talk about either about
  quantum fluctuations, or about the M Theory-based
  Multiverse.
• Our Universe becomes deterministic at macro level
  because at this level systems suffer external
  interactions (bombardment with cosmic particles).
  But without these particles the reality would be
  indeterminist.
• Even when we described the evolution of life
  through chemical and then biological processes
  (again) randomness was a key feature.