Universe

The story of the Universe, from earliest times to our continuing discoveries

Peter Grego

• Éditeur: Collins
• Année: 2014
• ISBN:
  9780007563500
• Sujet: Sciences physiques
• Sous-sujet: Cosmologie

An introduction to the universe covering everything from the big bang and our understanding of the universe over time, to the earth's formation, the Sun and how it affects us, the Moon and planets, black holes and galaxies.

The companion volume to ‘Need to Know? Stargazing’ and by the same author, this book focuses on the basic history and science of the universe, rather than on the practical skywatching aspects. It includes information on:

• Outrageous philosophy: weird notions and early ideas about the Universe including ancient Egyptian and Greek cosmology
• How the universe began: creation theories and the expanding Universe, from the Big Bang to the formation of the Sun and the appearance of life and humans
• The Earth's formation and the origin of the Moon
• The structure and composition of planet and the atmosphere, volcanoes, mountain formation and geological catastrophes; past, present and future
• The Solar System
• Star types and their formation, development and demise
• Types of galaxy
• Professional instruments, research and space observatories

In particular, ‘Collins Need to Know? Universe’ also asks what we know about the future: the future of man, and space travel. Will we be able to colonize planets? Will the universe expand or crunch, and could there be alternative universes out there?

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1 A big Universe

Ever since our ancestors were first struck by the majesty of the heavens and pondered its meaning, human beings have felt a profound curiosity about realms beyond the Earth. Unimaginably distant and seemingly untouchable, the wider cosmos – from our closest planetary neighbours to the stars beyond – has inspired humans in countless ways through the centuries.

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Splendour of the heavens

Although science has provided incredible insights into the Universe, our feelings of awe at viewing a star-spangled sky are the same as those experienced by our prehistoric ancestors.

Inklings of the infinite

Throughout history, everyone with the slightest degree of curiosity about the world around them has looked up at the sky and asked questions about it – seeking answers by questioning others, formulating their own theories and by arriving at their own answers through observation.

Galaxies in their thousands – a deep view of the Universe, captured by the Hubble Space Telescope.

Eternal musings

How far away are the stars and what’s the furthest thing in the Universe that our eyes can see? Does it all go on forever? Are there other planets like the Earth, inhabited with beings intelligent enough to question who they are, and how they, their world and the Universe itself came into being? If the Universe is infinite, could there be another person like me wondering exactly the same things at that very same moment in time? Will they reach the same conclusions as me? These sorts of questions have been asked by people of all ages ever since our ancestors developed the mental capacity to lay aside their basic survival instincts for a moment or two and view the world around them – and the skies above them – with a genuine curiosity and a desire to know more about the cosmos.

Cosmic connection

The cosmos includes everything – the Earth included – and while science has amassed a great deal of knowledge about the physical nature of our home planet, the intricate processes at work on its living surface, and in its oceans and atmosphere, remain only partly understood. In modern times, living in a polluted big city where the Sun itself competes for attention amid the concrete canyons, it is easy for an individual to feel utterly detached from the Earth and the rest of the Universe – spiritually, mentally and physically. In the pre-industrial age, our ancestors were much more aware of the cycles of the heavens and the Earth. However, plant any 21st century urbanite beneath a dark, star-studded night sky, away from light pollution and the trappings of ‘civilisation’, and all those hardwired visceral feelings soon return.

Our physical bodies, our clothing and jewellery, the book you’re holding right now and the chair you’re sitting on – everything around you, including the planet beneath your feet – is all made from material produced inside long-dead stars. Knowing that we are made of ‘star-stuff’ allows us to feel more intimately connected with the Universe.

Viewing the awesome cosmos.

Sunshine and starlight

Without the stars, the night skies would lose much of their splendour; without the Sun, there would be nobody around to appreciate the stars. The Sun may not be the most important star in the cosmos, but it is critical to the existence of the Earth.

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must know

Cosmic speed limit

Light travels at the staggering speed of around 300,000km per second. The Moon is 1.3 light seconds away and sunlight is around nine minutes old. Light from the nearest stars in our galaxy takes more than four years to reach us, and light from the most distant galaxies is billions of light years old. Nothing in the Universe can travel faster than light.

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Stellar energy, cosmic distances

That blindingly brilliant object that illuminates the daytime sky – our nearest star, the Sun – appears to be the single most important object in the heavens. If it emitted less heat and light than it currently does, humans would struggle to survive; our species would face the bleakest of prospects as the Earth’s oceans froze and most plant and animal life on our planet became extinct. If its heat and light were switched off, human life could not survive at all. If the Sun were a solid lump of coal, it would burn itself to a cinder within a few thousand years. After millennia of speculation, the source of the Sun’s prodigious output of energy (and that of all the stars visible in the sky) was finally explained in 1926 by the British scientist Arthur Eddington. Something far more powerful than simple chemical combustion powers the Sun. We rely on the thermonuclear processes elegantly encapsulated within Einstein’s formula E=mc² for our continued existence.

As the skies gradually darken after sunset, stars begin to appear. It may seem ironic that the starlight upon which such hopes and dreams for the future are made actually set out on its journey across the galaxy in the remote past – its light may be just over four years old or more than 3,000 years old. Rigil Kent, a star in the constellation of Centaurus, is 4.4 light years away, and the bright star Deneb in Cygnus is 3,200 light years distant. Starlight takes 2.9 million light years to reach us from the nearest big galaxy to our own, the great spiral in Andromeda.

With the exception of the Sun, the stars are too far away to perceive as globes of glowing gas; even when viewed through a powerful telescope, they appear as mere pinpoints of light. Slight variation in colour can be noticed between the stars – some appear white, others bluish, some slightly red. A star’s colour tells us a lot about its physical status – blue stars have intensely hot surfaces, while red stars have comparatively cool surfaces.

Examples of light travel time to the Earth for various objects visible with the unaided eye.

6.5 billion terranauts

We are all separated from the vacuum of space by just a few kilometres of breathable atmosphere. Earth spins on its axis once every 24 hours and revolves around the Sun once a year at a speed of more than 107,000 km/hour, accompanied by the Moon.

A crescent Earth rises over the rugged lunar surface, photographed by the crew of Apollo 17.

Big blue marble

From his vantage point in the command module of Apollo 8 above the Moon in December 1968, astronaut Jim Lovell described planet Earth as a ‘grand oasis in the big vastness of space’. This grand oasis, a beautiful blue globe, two-thirds of whose surface is covered with water, measures 12,756km across. Our planet is the only place in the Universe known to have life. The fossil record shows that life has clung tenaciously to the Earth’s surface for billions of years, surviving the devastating effects of numerous major geological and cosmic catastrophes. Although mass extinctions of many species of animals have occurred, life – in one form or another – has carried on. Just a few dozen kilometres beneath the Earth’s solid crust is a hot mantle – a zone of molten rock which hasn’t cooled down since the Earth was born some 4.5 billion years ago. The Earth’s crust occasiona...