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Cyclic Multiverse. 朴云松 中国科学院研究生院. Cyclic Universe Tolman 1934. Cyclic Universe There is only single universe in each cycle or each spacelike slice. ” Cyclic multiverse ” The number of independent universes increases cycle by cycle.

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cyclic multiverse

Cyclic Multiverse

朴云松

中国科学院研究生院

slide2
Cyclic Universe

Tolman 1934

slide3
Cyclic Universe

There is only single universe in each cycle

or each spacelike slice.

”Cyclic multiverse”

The number of independent universes increases cycle by cycle.

there are lots of independent universes in each cycle or each

spacelike slice.

slide4
The perturbation in collapse phase

The spectrum of primordial

perturbation can be scale

Invariant during contraction.

Starobinsky 1979,

Wands 1999,

Steinhardt, Turok et.al 2001

However, different from that in inflation,

the amplitude of perturbation modes are increased

after their leaving the horizon.

slide5
The perturbation in collapse phase

The reason is

D is the constant mode

S is the increasing mode for

slide7
On the generation of primordial perturbation

expansion

contraction

Piao, Zhang, PRD70, 043516 (2004)

slide8
On the generation of primordial perturbation

inflation

Steinhardt,

Turok

Piao, PRD68, 083515 (2003)

Starobinsky, Wands

slide9
Steinhardt, Turok et.al (01)

Starobinsky (79), Wands (99)

slide14
The numerical results

J. Zhang, Piao, in preparation

slide15
The perturbation in cyclic universe

Thus in general, after several cycle,

on super horizon scale

In this case, it is obviously impossible that the different regions of global universe will

evolve synchronously, even if they are synchronous

in previous cycle.

slide16
The perturbation in cyclic universe

if a region with super horizon scale has the

density perturbation on corresponding scale larger than 1, such a region will correspond to a separated close universe.

Carr, Hawking, 1974

The separate universe method for large scale

curvature perturbation

Wands, Malik, Lyth, Liddle 2000

slide17
The perturbation in cyclic universe

J. Zhang, Piao, in preparation

slide18
The cyclic miltiverse

Thus the global universe after several cycles will be inevitably separated into many different parts, each of which actually corresponds to a new universe and will evolve independently of one another, up to separation again.

slide19
The cyclic miltiverse

However, in these case, the universe will

be possibly split into smaller and smaller fragments, which will renders the cycle ultimately.

slide20
Design of a cyclic miltiverse

inflation

inflation period

slide22
Design of a cyclic miltiverse

Penrose Diagram

Piao, arXiv:1001.0631

slide23
Summary

1. The super large scale structure of cyclic universe

is generally not homogeneous, the reason is that

perturbation on super horizon scale is increased

during the contraction of each cycle.

2. Thus the global universe after several cycles will

be inevitably separated into many different

``universe”, each of them evolves independently.

This leads to a cyclic multiverse scenario.

3. In principle, the implementing of cyclic multiverse

requires a period of accelerated expansion, which

might provide an alternative motivation for the

existence of dark energy.

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