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History of Cosmology

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Standard Big Bang (SBB) Cosmology. Other theories. Observations & experiments ... Anisotropy. Jan 2003: MAP results. Silvio Orsi 12-05-2003. Nucleosynthesis ... – PowerPoint PPT presentation

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Title: History of Cosmology


1
History of Cosmology
  • Silvio Orsi
  • 12 May 2003

2
My Talk
  • Cosmologists
  • physicists matematicians
  • Theories models
  • Standard Big Bang (SBB) Cosmology
  • Other theories
  • Observations experiments
  • Unsolved problems in SBB

3
Before Hubble
  • The Universe looks the same in all directions
    (isotropic and homogeneous)
  • Parallax first measured by Bessel, XIX sec.A.C.
  • An infinite homogeneous static Universe is stable
    (well well...)

4
Olbers paradox
  • XIX cent. A.C., traced as far back as Kepler in
    1610

The Sky is dark at night
http//math.ucr.edu/home/baez/physics/Relativity/G
R/olbers.html
5
Modern Cosmology
6
Hubble 1929
7
Einstein
  • General Theory of Relativity (1915)
  • Einstein equation in cosmology gives a relation
    between the energy density and the curvature of
    spacetime
  • Space is not flat!
  • Is the Universe expanding? No, because of the
    cosmological costant...

8
Friedmann
  • On the curvature of spacetime - Zeitschrift für
    Physik, 1922
  • The stationary type of Universe comprises only
    two cases which were considered by Einstein and
    de Sitter. The variable type of Universe
    represents a great variety of cases there can be
    cases of this type when the world's radius of
    curvature ... is constantly increasing in time
    cases are also possible when the radius of
    curvature changes periodically ...

9
Standard Big Bang Cosmology
10
Hoyle the Big Bang
11
Steady State Theory
  • Bondi, Gold, Hoyle 1948
  • The same laws of physics are valid at all times
  • The Universe does not change in time
  • Continuous creation of matter balances the
    expansion of the Universe
  • There are more bright radio sources at greater
    distances gt the Universe is changing
  • The discovery of CMBR killed the idea of a static
    Universe

12
Steady State Universe
  • Bondi, Gold, Hoyle - 1948

The universe is continuously growing, but it is
uniform in space and unchanging in time.
13
CMBR 1948
  • Theoretical prediction of a CMBR by Alpher,
    Ermann paper on Nature
  • When the photon temperature drops below the
    hidrogen binding energy, photons become free
  • electromagnetic decoupling
  • last scattering surface
  • Red-shift Tobs 5-10K

14
CMBR 1965
Isotropy
  • Penzias
  • Wilson

15
CMBR 1992
  • Anisotropy

Jan 2003 MAP results
16
Nucleosynthesis
17
Shape of the Universe
  • Closed
  • Open
  • Flat

18
Problems in SBB
19
The Flatness Problem
  • Observations indicate that the amount of matter
    in the universe is about the critical amount
    needed to stop the expansion
  • Unrealistic initial condition required right
    after the big bang, the density must have been
    equal to the critical density to 50 decimal
    places!

20
The Horizon Problem
  • CMB photons come from causally disconnected
    regions
  • How can they have the same temperature? (10-5
    perturbations)
  • Inflationary hypothesis

21
Large Scale Structure
  • Random nonuniformities in the expanding universe
    are not sufficient to allow the formation of
    galaxies. In the presence of the rapid expansion,
    the gravitational attraction is too slow for
    galaxies to form with any reasonable model of
    turbulence created by the expansion itself.

22
Matter/antimatter asymmetry
  • Antiparticles exist in Nature
  • Tiny Antimatter/Matter ratio
  • Strong connection with particle physics
  • Possible way-ut CP symmetry violation in weak
    interaction

23
Dark Matter
24
Inflation 1981-82
  • 1981 old inflation by Guth
  • 1982 slow-rollover inflation by Linde
  • Quantum fluctuations from the BB epoch are
    increased and made visible (CMBR anisotropies,
    large-scale structure)
  • Scale factor a(t) exponentially increased space
    is now flat (independently on I.C.)
  • Explanation of horizon problem

25
History of the Universe (with Inflation)
26
Inflation (potential)
27
Transplanckian theories
28
Pre Big-bang Scenario
Inflation after BB
Inflation before BB
Figures from http//www.ba.infn.it/gasperin/
29
Ekpyrotic Scenario
  • One visible brane one hidden brane in a 11-D
    space
  • Brane oscillations induce energy transfer (BB in
    our brane)

Figures from http//www.sciencenews.org/20010922
/bob9.asp
30
If there is time
31
Gravitational Waves
BH, quasar, compact binary objects, ...
Interpherometer
SN
32
Gravitational Waves
33
Other Open Issues
  • Age of the Universe
  • Before the Big Bang
  • SUSY (neutralinos, ...)
  • Monopoles, relics from BB (massive particles)
  • Cosmological constant
  • Arrow of time
  • Hidden dimensions
  • Planck length

34
Further reading
  • The Early Universe, Kolb Turner
  • Cosmological Inflation and Large-Scale Structure,
    Liddle Lyth
  • www.
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