The Beginning and the End of Everything

From the Big Bang to the End of the Universe

Paul Parsons

• Publisher: Michael O'Mara
• Year: 2018
• Print ISBN: 9781782439561
• eBook ISBN: 9781782439660
• Topic: Physical Sciences
• Subtopic: Astronomy & Astrophysics

'Prepare to have your mind blown! A brilliantly written overview of the past, present and future of modern cosmology.' – DALLAS CAMPBELL, author of Ad Astra The Beginning and the End of Everything is the whole story as we currently understand it – from nothing, to the birth of our universe, to its ultimate fate. Authoritative and engaging, Paul Parsons takes us on a rollercoaster ride through billions of light years to tell the story of the Big Bang, from birth to death. 13.8 billion years ago, something incredible happened. Matter, energy, space and time all suddenly burst into existence in a cataclysmic event that's come to be known as the Big Bang. It was the birth of our universe. What started life smaller than the tiniest subatomic particle is now unimaginably vast and plays home to trillions of galaxies. The formulation of the Big Bang theory is a story that combines some of the most far-reaching concepts in fundamental physics with equally profound observations of the cosmos.From our realization that we are on a planet orbiting a star in one of many galaxies, to the discovery that our universe is expanding, to the groundbreaking theories of Einstein that laid the groundwork for the Big Bang cosmology of today – as each new discovery deepens our understanding of the origins of our universe, a clearer picture is forming of how it will all end. Will we ultimately burn out or fade away? Could the end simply signal a new beginning, as the universe rebounds into a fresh expanding phase? And was our Big Bang just one of many, making our cosmos only a small part of a sprawling multiverse of parallel universes?

CHAPTER 1

Our Place in the Universe

‘We are an impossibility in an impossible universe.’

RAY BRADBURY

Before science emerged as a tool for explaining the world, early cosmological theories were driven largely by religious ideas. Some 3,200 years ago, the Mesopotamian people, who lived in what is now Iraq, Kuwait and Saudi Arabia, believed that the god Marduk cleaved the body of the primeval mother, Tiamat, in two – one half formed the Earth; the other the heavens.

The ancient Chinese believed that our universe began as a chaotic, amorphous cloud that, for tens of thousands of years, slowly coalesced into a cosmic egg, from which hatched Pangu, the first living being. Pangu fashioned the Earth and the sky and spent the next 18,000 years driving them apart. After this, Pangu died and his remains became embodied in the universe – his left eye became the sun, his right eye the moon, and his hair became the stars.

Some religious cosmologies resonate with more modern, scientific ideas. For example, Buddhists believe that the universe is eternal, having neither a beginning nor an end – which is reminiscent of the Steady State theory, an idea that was a serious competitor to the Big Bang model until as late as the 1960s. While Hindus advocate a cyclic cosmology, similar to modern theories in which the universe goes through alternating phases of expansion and contraction, Buddhism is possibly unique among religions in that its picture of the universe does not feature an omnipotent creator.

Many early religions, particularly in Egypt, Ancient Rome and North America, idolized the sun. In Britain, historians believe the megalithic monument at Stonehenge may have served as a primitive astronomical observatory, from which pagan worshippers could gauge the timings of the winter and summer solstices.

As our understanding of the natural world grew during the Renaissance, so science came to challenge many religious ideas, and this has made the relationship between science and religion an often difficult one. Some scientists were persecuted for their ideas. Others were more wily – not having their work published until after their deaths. Some expressed religious beliefs openly. British physicist Isaac Newton, for example, held strong religious views that would have counted in his favour, and he was cunning enough not to speak publicly about his more radical opinions.

It’s an uneasy alliance that continues to this day, with some hardliner atheists insisting that religion damages science while others believe the two can coexist. Perhaps most prominent is the dispute between advocates of evolution by natural selection (Charles Darwin’s theory for how species develop and adapt to their environment) and those who believe in creationism (the modern name for the idea that the heavens and the Earth were forged by a supreme being). Creationism is a view still adhered to by some followers of Christianity, Islam and Judaism, among others. For example, in the biblical book of Genesis, God is said to have created the universe and everything in it in six days. Creationists defy all the evidence to the contrary – for instance, young-Earth creationists believe that the universe came into existence just 10,000 years ago, despite there being clear evidence (from rocks, ice cores and even the oldest living trees) that the Earth alone is a lot older than this – before any recourse is made to the astronomical evidence, which, as we’ve seen, and will discuss more later, suggests that the universe was born many billions of years earlier.

And that’s the core difference between science and religion. Religious statements are taken on faith, whereas scientific theories must be vindicated by hard evidence. In science, facts are paramount – be they simple accounts of our everyday experience, evidence gathered by geologists, observations of distant galaxies collected by astronomers, or experimental data teased from the fabric of reality by a multi-billion-dollar particle accelerator. Scientific theories are attempts to explain the world in a logical, systematic way, crucially in a way that makes hard and fast predictions that can be tested against facts – be they existing observations, future observations, or those observations for which an experiment can be devised and carried out. Sometimes the facts may be uncomfortable or unexpected, or may challenge our preconceptions. In science, that’s just tough. If the facts are at odds with the theory then the theory goes in the bin, and the scientists return to their drawing boards – or, as is more likely the case, their notebooks and computers.

Rejecting a theory isn’t disastrous. In fact, it’s a good thing. This is how science really moves on. It’s how we know, for example, that the Earth is spherical not flat, that our planet orbits the sun and not vice versa, and that the Earth most definitely isn’t merely 10,000 years old (the best estimates we have today put the true figure closer to 4.543 billion years). Making the observation that proves a theory wrong is one of the most powerful things a scientist can do – and also one of the most painful when the theory they’re disproving is their own.

The first scientist that we know of was the Greek philosopher Thales of Miletus, who lived between the sixth and seventh centuries BCE. Thales was the first person, at least in recorded history, to shun the notion that the heavens and Earth were created by mysterious and unfathomable gods. Instead he tried to link effects with their observable causes in the real world. Among his achievements were geometrical techniques for calculating the dimensions of pyramids and for triangulating the positions of ships. He also correctly predicted a solar eclipse in 585 BCE, and reportedly used his scientific knowledge for weather forecasting.

An illustration of the Greek theory of the celestial spheres taken from the 1539 book Cosmographia by German astronomer Peter Apian.

Despite Thales’s pioneering talents, the prevailing cosmological view to emerge from Ancient Greece was that of the celestial spheres, which held that the moon, the planets and the sun were each embedded in one of a set of nested, concentric spheres centred on the Earth. Each sphere’s unique rotation around the Earth determined the observed motion of its associated heavenly body. The outermost sphere held the distant stars and rotated to explain the rising and setting of the stars in the night sky.

We now know that this theory is about as wrong as it’s possible to be. Modern observations show that the sun lies at the centre of our solar system and is orbited by the Earth and the other planets. Our moon circles the Earth while the distant stars move independently of the sun and its retinue of worlds.

Interestingly, the Greeks had the evidence to prove that the celestial bodies weren’t quite behaving as the theory of the spheres dictated. Different orbital speeds of the planets mean that, when viewed from Earth, some can appear to speed up or slow down, and sometimes even to move backwards in their orbits. This backward or retrograde motion is quite at odds with the Greek view of them following a smooth circular path around the Earth. One Greek astronomer, Aristarchus of Samos, did make the connection and suggested that the planets circle the sun, not vice versa. Aristarchus’s original work has been lost, but the theory is reported by Archimedes in his book The Sand Reckoner.

Sadly, Aristarchus’s theory fell into obscurity, while the retrograde motion of the planets was misinterpreted. The Greek philosopher Ptolemy endeavoured to explain it within the celestial-spheres theory by supposing that planets didn’t occupy fixed points in their respective spheres but instead underwent small orbits around them, known as epicycles. When the epicycle carried the planet in the same direction as its sphere was rotating, the planet appeared to speed up, and when moving in the opposite direction it seemed to slow down or move in retrograde.

Ptolemy tried to explain the retrograde motion of the planets within the Greek celestial spheres theory by introducing ‘epicycles’ into their orbits around the Earth.

The idea of epicycles was at best a patch on an already broken theory but it was enough to ensure that the celestial-spheres model staggered on until the beginning of the Renaissance. It was here, during the early sixteenth century, that the Polish astronomer Nicolaus Copernicus realized the observed motions of the planets could all be explained far more naturally if they orbited around the sun rather than the Earth. This heliocentric view became a turning point in astronomy and indeed science in general.

Copernicus is believed to have shared early drafts of his theory with close acquaintances in or around the year 1514. It would become the central pillar of his book De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), which Copernicus completed in the early 1530s – although, fearing persecution at the hands of the Catholic Church for defying the established dogma, he didn’t dare publish it until the year of his death, 1543.

Although a gargantuan stride in the right direction, Copernicus’s heliocentric theory still supposed that the sun was at the centre of the entire universe. In 1576, British astronomer and mathematician Thomas Digges put forward the bold suggestion that the universe is actually infinite, and that the stars are objects much like our sun which are evenly distributed through it. He was motivated to rethink the nature of the stars by a supernova – a violent explosion marking the death of a massive star – which he had observed in 1572. This event was in blatant contradiction of the Greek view of the spheres, which held that the distant stars are fixed and unchanging.

Digges’s suggestion that the stars lay at varying distances from the Earth was lent additional weight in the early seventeenth century by the Italian thinker Galileo Galilei. Throughout his life, Galileo made seminal contributions to mathematics, physics, engineering – and astronomy. In 1609, he had learned about the invention, by a group of Dutch spectacle-makers the previous year, of the refracting telescope – a device using a pair of glass lenses to magnify the image of a distant object. Intrigued, and seeing immediately the potential benefits for astronomy, Galileo set about constructing his own version. His first telescope had only 3x magnification, but that was enough to transform his view, not to mention human understanding, of the heavens.

Just half a century after Digges’s initial suggestion that the stars are distributed through space, Galileo discovered that more stars were visible when he squinted through his telescope than when he looked with the unaided eye. Although some of the new stars that he was seeing must naturally have been intrinsically fainter, their sheer numbers meant that some must appear fainter because they are further away. In other words, the stars don’t all lie at the same distance away from us as the celestial-spheres theory requires.

Galileo wasn’t done yet. The following year, he turned his telescope on the planet Venus, finding it to have phases, much like the phases of the moon (full moon, new moon, gibbous and so on). The moon’s different phases are caused as it’s illuminated by the sun from different directions while moving in its month-long orbit round the Earth. In the celestial-spheres theory, Venus must always lie between the Earth and the sun – and that means that we should only be able to see it with new and crescent phases. However, Galileo saw that Venus displayed the full range of phases, supporting the idea that both planets circled the sun.

Galileo set down these conclusions in his book Dialogo sopra i due massimi sistemi del mondo (Dialogue Concerning the Two Chief World Systems), published in 1632. In this text, and in conversation, he was quite open about his belief in Copernicus’s heliocentric theory – and this would ultimately prove to be his undoing (vindicating Copernicus’s earlier decision not to publish the theory until his death). In 1633, Galileo was tried for heresy by the Catholic inquisition and found guilty. Publication of his work was subsequently prohibited and Galileo spent the final years of his life under house arrest. He was reportedly spared torture and a grisly death only because his scientific achievements had earned him allies in powerful places. Galileo died from natural causes in 1642.

But his insights lived on. In 1750, English astronomer Thomas Wright built upon another of Galileo’s findings – that the Milky Way, the pale, diffuse band of light that’s visible across the sky on a dark, clear night, is in fact a vast swarm of stars. In his book An Original Theory or New Hypothesis of the Universe, Wright suggested that the Milky Way is a disc of stars, and that our sun and solar system are embedded within the disc. Rather than being dotted liberally throughout space, as Digges had suggested, Wright imagined that stars are clustered into a multitude of cosmic islands, each resembling the Milky Way – and which would later be dubbed galaxies. What we were seeing in the Milky Way, he asserted, was the edge-on plane of our own galaxy, as viewed from the inside.

By this time, the Church’s stance against the heliocentric view had begun to wane, and the true nature of the solar system as a collection of planets all circling the sun was gaining acceptance. In 1755, the German philosopher Immanuel Kant suggested that the disc of our galaxy, identified as such by Wright, could be rotating – with the stars held in orbit around the galaxy by gravity, just as it holds the planets in their orbits about the sun. Indeed, Newton’s law of gravity (see Chapter 2) requires the stars to be orbiting – else they would all simply fall radially inwards to the galaxy’s centre.

The evidence that there really are celestial objects lying outside the Milky Way was found by astronomers studying comets. These are chunks of ice and dirt, now known to be leftovers from the formation of the sun and planets, which wander the outer reaches of the solar system. It might seem strange that a family of objects living on our cosmic doorstep could have led to a breakthrough in the understanding of the universe at large. But when a comet passes near to the sun, its surface vaporizes into a cloud of steam and other gases that reflect back sunlight to create a fuzzy glowing patch on the night sky. Comet hunters scour the skies looking for these telltale smudges of light – quite distinct from the bright pinprick of a star. Because comets are part of the solar system and orbit the sun just like planets, their positions change significantly with time as they move along their orbits. And as a comet’s orbit carries it nearer to the sun, so the heat increases the amount of gas boiling off from its surface, causing it to brighten.

At least, that’s what they’re supposed to do. During the late eighteenth century, some astronomers began to find faint, fuzzy objects that resembled comets but which didn’t seem to be moving or changing in brightness. These baffling objects became known as nebulae – after nebula, the Latin word meaning ‘cloud’. French comet hunter Charles Messier, working with his assistant Pierre Méchain, drew up the first systematic list of these nebulae. The opening edition of the so-called Messier Catalogue was published in 1774, and contained 103 Messier objects, designated by their characteristic ‘M’ numbers. Today the list has grown to 110, and it’s considered a significant badge of honour among amateur astronomers to successfully spot them all in a single night’s observing (a feat known as the ‘Messier Marathon’). But back in the late eighteenth century, the puzzle remained: what exactly are they?

Answering that question took almost fifty years and involved a new field of experimental science called spectroscopy – splitting white light up into its spectrum of colours and measuring the brightness of each colour. When we look at a rainbow, each colour is made of light with a particular range of wavelengths. For example, red light has a wavelength centred on 700 ...

Table of contents

• Cover
• Title Page
• Copyright
• Dedication
• Contents
• Timeline
• Introduction
• 1: Our Place in the Universe
• 2: The Theory Within the Theory
• 3: The Expanding Cosmos
• 4: Two Smoking Barrels
• 5: Most of Our Universe is Missing
• 6: A Quantum Interlude
• 7: Into Darkness
• 8: The Even Bigger Bang
• 9: The Birth of Galaxies
• 10: From Out of Nowhere
• 11: Worlds in Parallel
• 12: Crunch Time
• 13: The Long Dark Eternity
• 14: Into the Unknown
• Acknowledgements
• Index