Download How will the universe end?

How will the universe end?
S. Bernhart
Some say the world will end in fire,
some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
Robert Frost 1920
This is the way the world ends
Not with a bang but with a whimper.
T.S. Eliot 1925
Short Outline on Cosmology
Relativistic cosmology is based on:
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cosmological principle
Weyl's prinicple
general relativity
Robertson-Walker metric:
R(t) scale factor (radius in a closed
universe)
1 closed
0 flat
k curvature constant =
-1 open
{
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Short Outline on Cosmology
Friedmann equation:
H(t) Hubble parameter
Cosmological constant Λ:
introduced by Einstein in order to desribe a
static universe
Reasons for the existence of Λ:
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helpful when Hubble time and astrophysically determined age of the universe lead to different values
quantum field theory: vacuum energy not necessarily zero
Experimental determination of Λ indirectly via deceleration parameter
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Short Outline on Cosmology
Deceleration parameter q0:
q0 is related to the
rate with which the expansion slows down
critical density
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ρ0 observed density
ρ0,crit would lead to a
flat universe
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Short Outline on Cosmology
Classification of Friedmann universes in chronological order:
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1917 Albert Einstein static universe, introduction of Λ, R(t)=const., k=+1
1917 de Sitter, flat solution, k=0, matter free universe, violates Mach's law!
1922 Friedmann, vanishing Λ, k=+/-1, pressure p=0 (interesting: oscillating
universes with negative lambda)
1925 Lemaitre expanding universe, k=+1, lambda positive
1929 Robertson solutions with optional lambda, k=0 and p=0
1932 Einstein-de Sitter universe, flat, k=0
in the aftermath many sub-classifications of Friedmann-Lemaitre models
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Observational Findings
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1998 by observing Type 1a supernovae two teams found that
the universe is speeding up instead of slowing down (Schmidt
group at Mount Stromlo Observatory in Australia and Perlmutter
group of Berkeley Laboratory in California)
WMAP observations of the cosmic background radiation
confirmed that the universe is flat and expanding forever
For an inflationary universe:
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Three alternative scenarios
Big Crunch – eventual collapse
Big Freeze/Chill – expansion forever at a
steady state
Big Crackup/Rip – expansion forever at an
accelerating rate
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Timeline
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10^17 years: white dwarfs will cool to black dwarfs
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10^19 years: galaxies will boil away
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10^20 years: planets knocked off their orbits or spiral into the stars
they are orbiting
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Timeline
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10^23 years: dead stars boiled off from galactic clusters – clusters
disintegrate – CMB radiation cooled to about 10^(-13) K
everything except from black holes will tend to ionize
black holes probably evaporate due to Hawking radiation – solar
mass bhs in 10^66 years and galactic bhs in about 10^99 years
neutron stars either ionize or quantum-tunnel into bhs which radiate
away
eventually all matter turns to iron due to quantum tunneling – will
take 10^1500 years – likely proton decay (10^32 years) will happen
before
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Timeline
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10^23 years: dead stars boiled off from galactic clusters – clusters
disintegrate – CMB radiation cooled to about 10^(-13) K
everything except from black holes will tend to ionize
black holes probably evaporate due to Hawking radiation – solar
mass bhs in 10^66 years and galactic bhs in about 10^99 years
neutron stars either ionize or quantum-tunnel into bhs which radiate
away
eventually all matter turns to iron due to quantum tunneling – will
take 10^1500 years – likely proton decay (10^32 years) will happen
before
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Timeline
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if no ionization or proton decay for black dwarfs and planets, they
may quantum-tunnel into solid iron – it may either evaporate or
quantum-tunnel
into
bhs
which
radiate
away
within
10^100000000000000000000000000 years
particle density will go to zero – each particle will be cut off from
the rest by a cosmological horizon – no interaction possible anymore
A. Loeb: high-redshift sources will only be visible to us until they
reach some finite age in their rest-frame
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Alternative Model: Quintessence
Cosmological constant: fixed
distributed vacuum energy density
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value
of
a
homogeneously
Quintessence: a dynamic, time-evolving and spatially dependent
(inhomogeneously distributed) form of energy with negative
pressure sufficient to drive the accelerating expansion
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Simplest model: a quantum field with a very long wavelength,
approximately the size of the observable universe
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In the quintessence scenario a slow-down of the acceleration
could be possible.
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Brief Story of Eschatology
by Jim Holt, 2004
Freeman Dyson, Princeton:
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“Time Without End” 1979, “a universe growing without limit in richness and
complexity, a universe of life surviving forever...” - humanity should hibernate
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conscious life in form of interstellar dust/plasma clouds
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acceleration might slow down again in the quintessence model as opposed to the
dark energy scenario
Ed Witten, Princeton:
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favors quintessence theory, runaway expansion possibly only temporary
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Protons do decay within 10^33 years or so – dissolution of all matter
Lawrence Krauss, Case Western, Cleveland:
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“We appear to be living in the worst of all possible universes.”
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life is doomed – in any case
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Brief Story of Eschatology
Frank Tipler, Tulane University, New Orleans:
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1994 “The Physics of Immortality”, Big Crunch happiest of all endings
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resurrection in virtual reality
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universe has “no choice” but to expand and then contract, everything else would
violate the quantum law called “unitarity” (probability must be conserved)
Michio Kaku, City College in New York:
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“Lifeboat” scenario: open a “wormhole” through which we escape into a new
universe, needs a unified theory of physics to stabilize the wormhole
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human development may take 100,000 years but still enough time left
J. Richard Gott III, Princeton:
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Copernican Principle 'You are not special'
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humanity will probably die out before 7.8 million years
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A very fast end...
Today's assumption: the universe is in a real vacuum, i.e., the
vacuum in space is of lowest possible energy (ground state)
Coleman and De Luccia: What if today's vacuum is not the real
one but just in a long-lasting metastable state (like a uranium
nucleus)?
The vacuum decay could start with a small bubble of real
vacuum expanding with the speed of light, absorbing larger areas
of false vacuum and turning it into real one annihilating
everything on its way.
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or more likely a slow end ...?