Andrew Cohen: Wonders of the Universe

For Mum, Dad and Sandra – none of this would have been possible without you

Brian Cox

For my dad, Geof Cohen (1943–2007)

Andrew Cohen

HarperCollins Publishers

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WONDERS OF THE UNIVERSE. Text © Brian Cox and Andrew Cohen 2011. All rights reserved under International and Pan-American Copyright Conventions. By payment of the required fees, you have been granted the non-exclusive, non-transferable right to access and read the text of this e-book on-screen. No part of this text may be reproduced, transmitted, down-loaded, decompiled, reverse engineered, or stored in or introduced into any information storage and retrieval system, in any form or by any means, whether electronic or mechanical, now known or hereinafter invented, without the express written permission of HarperCollins e-books.

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Ebook Edition © MARCH 2011 ISBN: 9780007413379

Version 2017-02-03

Copyright

Introduction

The Universe

Chapter 1

Messengers

The Story of Light

Our place in the Universe

Our galactic neighbourhood

Mapping the Milky Way Galaxy

The shape of our galaxy

A star is born

What is Light?

Young’s double-slit experiment

Messengers from across the ocean of space

Chasing the speed of light

The search for a cosmic clock

Speed limits

Time Travel

To the dawn of time

Finding Andromeda

The Hubble Telescope

Hubble’s most important image

All the colours of the rainbow

Hubble expansion

Redshift

The Birth of the Universe

Visible light

Picturing the past

First sight

Chapter 2

Stardust

The Origins of Being

The cycle of life

Mapping the night sky

Stellar nurseries

How to find exoplanets

The orgins of life

The Periodic Table

The universal chemistry set

What are stars made of?

The Early Universe

El Tatio Geysers, Chile

The Big Bang

Sub-atomic particles

Timeline of the Universe: The Big Bang to the present

Matter by numbers

The most powerful explosion on Earth

From Big Bang to Sunshine: The First Stars

Red giant

Star death

Planetary nebulae

The rarest of all

Supernova: life cycle of a star

The beginning and the end

The orgin of life

Chapter 3

Falling

Full Force

The invisible string

The apple that never fell

The grand sculpture

The geoid

The Tug of the Moon

The false dawn

The Blue Marble

Galactic cannibals

Collision course

When galaxies collide

Feeling the Force

The gravity paradox

The land of little green men

What is gravity?

Einstein’s Theory of General Relativity

Into the darkness

The anatomy of a black hole

Chapter 4

Destiny

The Passage of Time

The cosmic clock

The galactic clock

Ancient life

The arrow of time

The order of disorder

Entropy in action

The life cycle of the Universe

The life of the Universe

The Destiny of Stars

The demise of our universe

The death of the Sun

The last stars

The beginning of the end

A very precious time

Searchable Terms

Picture credits

Acknowledgements

About the Author

Credits

About the Publisher

THE UNIVERSE

At 13.7 billion years old, 45 billion light years across and filled with 100 billion galaxies – each containing hundreds of billions of stars – the Universe as revealed by modern science is humbling in scale and dazzling in beauty. But, paradoxically, as our knowledge of the Universe has expanded, so the division between us and the cosmos has melted away. The Universe may turn out to be infinite in extent and full of alien worlds beyond imagination, but current scientific thinking suggests that we need it all in order to exist. Without the stars, there would be no ingredients to build us; without the Universe’s great age, there would be no time for the stars to perform their alchemy. The Universe cannot be old without being vast; there may be no waste or redundancy in this potentially infinite arena if there are to be observers present to gaze upon its wonders.

The story of the Universe is therefore our story; tracing our origins back beyond the dawn of man, beyond the origin of life on Earth, and even beyond the formation of Earth itself; back to events – perhaps inevitable, perhaps chance ones – that occurred less than a billionth of a second after the Universe began.

AN ANCIENT WONDER

On Christmas Eve 1968, Apollo 8 passed into the darkness behind the Moon, and Frank Borman, Jim Lovell and William Anders became the first humans in history to lose sight of Earth. When they emerged from the Lunar shadow, they saw a crescent Earth rising against the blackness of space and chose to broadcast a creation story to the people of their home planet. A quarter of a million miles from home, lunar module pilot William Anders began:

‘We are now approaching lunar sunrise and, for all the people back on Earth, the crew of Apollo 8 has a message that we would like to send to you.

In the beginning God created the heaven and the Earth.

And the Earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.

And God said, Let there be light: and there was light.

And God saw the light, that it was good: and God divided the light from the darkness.’

The emergence of light from darkness is central to the creation mythologies of many cultures. The Universe begins as a void; the Maori called it Te Kore, the Greeks Chaos. The Egyptians saw the time before creation as an infinite, fathomless ocean out of which the land and the gods emerged. In some cultures, God is eternal: He created the Universe out of nothing and will outlast it. In others, such as some Hindu traditions, a vast primordial ocean predates the heavens and Earth. Lord Vishnu floated, asleep, on the ocean, entwined in the coils of a giant cobra, and only when light appeared and the darkness was banished did he awake and command the creation of the world.

We still don’t know how the Universe began, but we do have very strong evidence that something interesting happened 13.75 billion years ago that can be interpreted as the beginning of our universe. We call it the Big Bang. (We must be careful with our choice of words here, because this is a book about science, and the key to good science is the separation of the known from the unknown.) This interesting thing that happened corresponds to the origin of everything we can now see in the skies. All the ingredients required to build the hundreds of billions of galaxies and thousands of trillions of suns were once contained in a volume far smaller than a single atom. Unimaginably dense and hot beyond comprehension, this tiny seed has been expanding and cooling for the last 13.75 billion years, which has been sufficient time for the laws of nature to assemble all the complexity and beauty we observe in the night skies. These natural processes have also given rise to Earth, life, and also consciousness, which in many ways is harder to comprehend than the mere emergence of the seemingly infinite stars.