1. The Origin and Fate of the
Universe
Alberto Mulero

2. Preface

3. Preface
• The general theory of relativity, predicts that
space-time began at the big bang singularity and
that it will come to an end either at the big
crunch singularity (if the whole universe
recollapsed), or at a singularity inside a black hole
(if a local region, such as a star, were to collapse).
• However when quantum effects are taken into
account in the study of these singularities results
vary.

4. “Hot Big Bang Model”
• First put forward by:
– George Gamov & Ralph Apher (in 1948).
• States that:
– The universe expanded from a singularity and that it is still
expanding today.
• It’s supported by:
– Hubble's law and the expansion of space
– Cosmic microwave background radiation
– Abundance of primordial elements
– Other

5. “Hot Big Bang Model”

6. Questions Left Unanswered
• Why was the early universe so hot?
• Why is the universe so uniform on a large scale?
• Why did the universe start out with so nearly the critical
rate of expansion?
• Why, despite the fact that the universe is so uniform and
homogeneous on a large scale, it contains local
irregularities, such as stars and galaxies?
• What were the universe’s initial “boundary conditions”?

7. Chaotic Boundary Conditions
• Assume that:
– Either the universe is spatially infinite or that
there are infinitely many universes.

8. Anthropic Principle
• “We see the universe the way it is because we
exist.”

9. Fundamental Numbers
(Ex. from “Martin Rees's Six Numbers”)
• N≈1036 - ratio of the fine structure constant to the gravitational coupling constant. N governs the
relative importance of gravity and electrostatic attraction/repulsion in matter.
• ε≈0.007 - the fraction of the mass of four protons that is released as energy when fused into
a helium nucleus.
• Ω ≈ 0.3 - the ratio of the actual density of the universe to the critical (minimum) density required
for the universe to eventually collapse under its gravity.
• λ ≈ 0.7 - The ratio of the energy density of the universe, due to the cosmological constant, to
the critical density of the universe.
• Q ≈ 10– 5 - The energy required to break up and disperse an instance of the largest known
structures in the universe, namely a galactic cluster or supercluster, expressed as a fraction of the
energy equivalent to the rest mass m of that structure, namely mc2
• D = 3 - the number of macroscopic spatial dimensions.

10. Inflation
• First put forward by:
– Alan Guth (in 1980)
• States that:
– The universe underwent extremely rapid exponential expansion at an early
stage.
• Factor of at least 1078 in volume.
• It lasted from 10−36 seconds after the Big Bang to sometime between 10−33 and
10−32 seconds.
• It’s supported by (it accounts for):
– A model of the universe in which many different initial configurations could
have evolved to something like the present universe
– The homogeneity and isotropy of the observable universe.
– The amount of matter and energy in the universe.
– Observations in the cosmic microwave background.
– Other

11. Cosmic Microwave Background

12. Corrections to some misconceptions
about Inflation
• Inflation is not necessarily driven by dark
energy.
– Guth proposes, it can be driven by a strong
energetic state caused by the symmetry of the
fundamental forces in the early space-time.
• Inflation does not begin or stop with the
formation of our universe.

13. Inflation
(Multiverse)

14. The search for a unified field theory
• Some features it should incorporate:
– Feynman’s proposal to formulate quantum theory
in terms of a sum over histories.
– Einstein’s idea that the gravitational field is
represented by curved space-time

15. Hawking’s Proposition
• “maybe time and space together form a
surface that is finite in size but that does not
have any boundary or edge”

16. Hawking’s Proposition

17. New findings
• 1988 – “A Brief History of Time” is published
• 1998 – Adam Riess, Saul Perlmutter and others
discover the cosmic acceleration.
• 2003 – Full-sky detailed pictures of the cosmic
microwave background radiation confirm Inflation.
• Present – String Theory (notably M-Theory) is being
researched and developed.

18. Current model debate
• Inflationary Big Bang Model
• The Steinhardt–Turok model

19. Inflationary Big Bang Model

20. The Steinhardt–Turok model

21. The Steinhardt–Turok model
• For more info. check
– “Inflationary Cosmology on Trial” – in YouTube
• http://www.youtube.com/watch?v=IcxptIJS7kQ&featur
e=g-like&context=G250e6fbALT2EwdgADAA
– “The Endless Universe: Beyond the Big Bang” by
Paul Steinhardt and Neil Turok