# Presentation: 008384

## Slide 1

## Endless Universe

***The***
***Endless Universe***

**w/Neil Turok (Cambridge)**
**feynman.princeton.edu/~steinh**

**Notes:**
According to the standard model of cosmology, our universe began in a big bang about 15 billion years ago filled
gas of infinite temperature and density.  A few instants later, it underwent a tremendous burst of exponential expansion, known as
inflation, which made the distribution of energy nearly uniform, which flattened the curvature of the universe; and
created small inhomogeneties that eventually led to the formation of galaxies.  

Over the past decade, this model has been carefully put to the test through a host of new observations. And the model
has passed all the tests, agreeing with each observation with exquisite detail. No wonder so many cosmologists believe that 
the correct cosmological has been idenitified??

But maybe, just maybe, we have been fooled.  Maybe the truth is a radically different model, but one which happens to give
very similar predictions.  This is the issue we are considering today.

In particular, we will be talking about a model which claims that the big bang is not the beginning. Rather, the bang is 
really a period of transition to an earlier, pre-existing phase of expansion and cooling in the universe.  Furthermore, the key events that
fixed the large scale structure of the universe did not occur after bang, but rather, before the bang, or BEFORE THE BEGINNING...

Yet, despite these radical differences, this new model seems capable of reproducing all the successful predictions of the standard
model to date with the same exquisite detail.  

This new theory, developed with Neil Turok of Cambridge University, is a cyclic model of the universe,
reminiscent of cyclic of the models discussed in the 1920’s, 30’s and 40’s.  Those earlier models had some intriguing and appealing 
aspects, but also had some major flaws that make them untenable today.  The new cyclic model is a 21st century version,
using many novel ideas that enable it to circumvent the old flaws, especially  recent advances drawn from so-called  superstring theory.
Thus, after decades of disappearing from the scene, we have the return of the cyclic in a new and exciting version.

Today I will try to give you a brief introduction to the model.  This will be a descriptive introduction, but I want to emphasize 
that it is a fully developed, quantitative picture – a detailed, predictive scientific model in the same sense as the standard
picture.  Not just a conceptual idea.  If you want to read more about it, here is a website. 

## Today’s Standard Model

- (big bang + inflation)

- big bang

- inflation

## Today’s Standard Model

- (big bang + inflation)

- big bang

- inflation

## Today’s Standard Model

- (big bang + inflation)

- big bang

- inflation

## Wilkinson Microwave Anisotropy Probe

## Today’s Standard Model

- matter

- dark energy ??

- _Today’s Standard Model_
- (big bang + inflation)

- big bang

- inflation

## Slide 8

## Slide 9

## Today’s Standard Model

- matter

- dark energy ??

- _Today’s Standard Model_
- (big bang + inflation)

- big bang

- inflation

- ???

## A Cyclic Universe

## George Lemaitre

- Albert Einstein

## t

- a(t)

## Richard Tolman

## Superstring theory

- “branes”

## V

- Y

- Y

- Superstring theory

- Field theory

- “branes”

## Consensus

- (big bang + inflation)

- big bang

- inflation

- radiation

- matter

- dark energy ??

- ???

- _Cyclic_
- PJS & Neil Turok

- “bang”

- radiation

- matter

- dark energy

- “contraction”

- “crunch”

**Notes:**
The model is actually much more subtle than advertized so far.  The early phases are all rather standard, but the contraction, crunch and bounce are anything but what we you may have been accustomed to before. That is because the model is based on novel ideas inspired by string theory.

## Consensus

- (big bang + inflation)

- big bang

- inflation

- radiation

- matter

- dark energy ??

- ???

- _Cyclic_
- PJS & Neil Turok

- “bang”

- radiation

- matter

- dark energy

- “contraction”

- “crunch”

- Reproduces successful predictions

**Notes:**
The model is actually much more subtle than advertized so far.  The early phases are all rather standard, but the contraction, crunch and bounce are anything but what we you may have been accustomed to before. That is because the model is based on novel ideas inspired by string theory.

## Consensus

- (big bang + inflation)

- big bang

- inflation

- radiation

- matter

- dark energy ??

- ???

- _Cyclic_
- PJS & Neil Turok

- “bang”

- radiation

- matter

- dark energy

- “contraction”

- “crunch”

- Fewer ingredients: no need for inflation

**Notes:**
The model is actually much more subtle than advertized so far.  The early phases are all rather standard, but the contraction, crunch and bounce are anything but what we you may have been accustomed to before. That is because the model is based on novel ideas inspired by string theory.

## Consensus

- (big bang + inflation)

- big bang

- inflation

- radiation

- matter

- dark energy ??

- ???

- _Cyclic_
- PJS & Neil Turok

- “bang”

- radiation

- matter

- dark energy

- “contraction”

- “crunch”

- Dark energy given a purpose

**Notes:**
The model is actually much more subtle than advertized so far.  The early phases are all rather standard, but the contraction, crunch and bounce are anything but what we you may have been accustomed to before. That is because the model is based on novel ideas inspired by string theory.

## Consensus

- (big bang + inflation)

- big bang

- inflation

- radiation

- matter

- dark energy ??

- ???

- _Cyclic_
- PJS & Neil Turok

- “bang”

- radiation

- matter

- dark energy

- “contraction”

- “crunch”

- Avoids infinities (?)

**Notes:**
The model is actually much more subtle than advertized so far.  The early phases are all rather standard, but the contraction, crunch and bounce are anything but what we you may have been accustomed to before. That is because the model is based on novel ideas inspired by string theory.

## Consensus

- (big bang + inflation)

- big bang

- inflation

- radiation

- matter

- dark energy ??

- ???

- _Cyclic_
- PJS & Neil Turok

- “bang”

- radiation

- matter

- dark energy

- “contraction”

- “crunch”

- More complete theory of cosmic history

**Notes:**
The model is actually much more subtle than advertized so far.  The early phases are all rather standard, but the contraction, crunch and bounce are anything but what we you may have been accustomed to before. That is because the model is based on novel ideas inspired by string theory.

## Consensus

- (big bang + inflation)

- big bang

- inflation

- radiation

- matter

- dark energy ??

- ???

- _Cyclic_
- PJS & Neil Turok

- “bang”

- radiation

- matter

- dark energy

- “contraction”

- “crunch”

- Empirically distinguishable: e.g., gravitational waves

**Notes:**
The model is actually much more subtle than advertized so far.  The early phases are all rather standard, but the contraction, crunch and bounce are anything but what we you may have been accustomed to before. That is because the model is based on novel ideas inspired by string theory.

## E-modes

- (energy fluctuations)

- B-modes
- (gravitational waves)

## CAPMAP 

- CAPMAP

- the Cosmic Anisotropy
- Polarization
-  MAPper

**DASI, WMAP, Boomerang**
**...****. Planck, .... CMBPOL**

## FAQs:  feynman.princeton.edu/~steinh/

- Violates conservation of energy?

- Tolman problems?

- What happens at the bounce?

**Notes:**
Perpetual motion?
Is it stable?
What about Tolman:
	potential energy rather than mass density
	no infinities
	no entropy problem
Could there be remnants left over from previous cycles?
Combination model