observed features of the universe universe is homogeneous and isotropic on lengths > 100 mpc...
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Observed Features of the Universe• Universe is homogeneous and isotropic on lengths > 100 Mpc
• Universe expanding uniformly
• ordinary matter is more abundant than ordinary antimatter
• chemical composition is roughly 75% H, 25% He, + trace
• thermal background of radiation with T~3K
• nearly scale invariant spectrum of CMB fluctuations
• hierarchy of structure from 1 kpc to 1 Mpc scales
• matter is a minority (1/4x) of all energy
• ordinary matter is a minority (1/6x) of all matter
• universe is spatially flat
• expansion rate accelerating
Observed Features of the Universe• Universe is homogeneous and isotropic on lengths > 100 Mpc
• Universe expanding uniformly
• ordinary matter is more abundant than ordinary antimatter
• chemical composition is roughly 75% H, 25% He, + trace
• thermal background of radiation with T~3K
• nearly scale invariant spectrum of CMB fluctuations
• hierarchy of structure from 1 kpc to 1 Mpc scales
• matter is a minority (1/4x) of all energy
• ordinary matter is a minority (1/6x) of all matter
• universe is spatially flat
• expansion rate accelerating
Why is the Universe homogeneous and isotropic?
Robs (t0) = radius of observable universe today ~ 1/H0 ~ t0
Robs (t) = size of same patch at time t
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Why is the Universe homogeneous and isotropic?
Robs (t0) = radius of observable universe today ~ 1/H0 ~ t0
Robs (t) = size of same patch at time t
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Why is the Universe homogeneous and isotropic?
Robs (t0) = radius of observable universe today ~ 1/H0 ~ t0
Robs (t) = size of same patch at time t
o
e
ecausal
eobs
a
a
tR
tR
~)(
)(>> 1
universe decelerating
HORIZON PROBLEM
Why is the Universe so FLAT?
Recall:
>> 1
universe decelerating
FLATNESS PROBLEM
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MONOPOLE PROBLEM
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if monopolesare stable:
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HORIZON PROBLEM
MONOPOLE PROBLEM
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FLATNESS PROBLEM a
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HORIZON PROBLEM
MONOPOLE PROBLEM
2
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FLATNESS PROBLEM a
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accelerated expansion
INFLATION
inflation = finite period of accelerated expansion
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V
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Planck units
INFLATIONARY MENU
ENTRANCE INFLATION EXIT
phase transition
“chaos”
stochastic
“tunneling from nothing”
defect driven
Slow roll
flat potentials
power-law potentials
two or more fields
tensor (R + R2 +…)
fermi condensate
KE driven
oscillation
extended
scalar field decay
bubble nucleation
de Sitter fluct’s
Density Perturbations
H nearly constant
Density Perturbations
inflation ends, H-1 grows
ijiji
iS
EB
Bg
;;
;)(
2
2
for scalar field, B and E = 0 Newtonian gauge:
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2
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k uUxxd
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1
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ieu
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2)32(
)1(6
w
w
need this to
be small
More generally …
w ~ -1: INFLATION
w >> 1: EKPYROTIC/CYCLIC
AMPLITUDE Strategies
1) Evolve u -equation
2) famous trick '
2 /)1(3
2~
aH
u
awk
k
3) heuristic:
'~~~~~
/1
/~
2/32
2/1
2/3
V
VHHtH
t
t
t
tt
T
T
The Cyclic Universe
w/Neil Turok
with many important contributions from:Justin Khoury (Princeton), Burt Ovrut (Penn)
and Nathan Seiberg (IAS)
Consensus(big bang + inflation)
big bang
Consensus(big bang + inflation)
big bang
inflation
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
V
Y
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
V
Y
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
V
Y
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
V
Y
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
“contraction”V
Y
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
“contraction”
“crunch”
the “b
ou
nce
”
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
“contraction”
“crunch”
the “b
ou
nce
”
Reproduces successful predictions
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
“contraction”
“crunch”
the “b
ou
nce
”
Fewer ingredients: no need for inflation
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
“contraction”
“crunch”
the “b
ou
nce
”
Dark energy given a purpose
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
“contraction”
“crunch”
the “b
ou
nce
”
Avoids infinities?
Consensus(big bang + inflation)
big bang
inflation
radiation
matter
dark energy ??
???
CyclicPJS & Neil Turok
“bang”
radiation
matter
dark energy
“contraction”
“crunch”
the “b
ou
nce
”
More complete theory of cosmic history
V
Y
Y
M-theoryField-theory
“branes”
The Cyclic Universe
V
Y
The Cyclic Universe
THE BOUNCE