One current theory for the origin of the Evolutionary Big Bang is that the emergence of the eye in animals such as the trilobite triggered the Cambrian Explosion. Once a predator possesses eyes which will help it chase its prey, a new force in natural selection is immediately introduced. The animals that survive this selection are those that are best adapted to this new threat; they may camouflage themselves, leading to an increasingly sophisticated visual appearance, or dodge the predators with enhanced sense organs. In other words, once one predatory species develops eyes, there is a powerful selection mechanism in favour of others developing and refining eyes too. In turn, this selects far more sophisticated predators, and so on. This is in a sense an evolutionary arms race, as the pressure of natural selection leads more and more complex life forms to develop.
The Carina Nebula is a large bright nebula that surrounds several clusters of stars. It contains two of the most massive and luminous stars in our Milky Way galaxy, Eta Carinae and HD 93129A. Located 7500 light years away, the nebula itself spans some 260 light years across, about seven times the size of the Orion Nebula, and is shown in all its glory in this mosaic. It is based on images collected with the 1.5-metre Danish telescope at ESO’s La Silla Observatory.
NASA
These early creatures, immortalised in the Burgess Shale, were among the very first to harness the light that filled the Universe. Before they emerged, the rise and fall of the Sun and the stars in the night sky went unnoticed. These creatures are our ancestors, and in fact there is also evidence at Burgess that we humans may only exist because of one particular adaptation in a strange, worm-like creature called a Pikaia. Although the Pikaia looks unimpressive, it may be one of the most important animals ever discovered. It is thought by some, although not all, evolutionary biologists that the Pikaia is the earliest known ancestor of modern vertebrates – the branch of life that we are categorised in – so it could be that this little worm-like creature is our earliest known ancestor. What is also fascinating about Pikaia is that it may have had light-sensitive cells that allowed it to evade predators and survive in the Cambrian seas – cells that may have evolved over many hundreds of millions of years into our eyes. This is all speculative, but it is possible that without Pikaia’s primitive yet remarkable ability to detect the light from the Sun, we humans may never have appeared on planet Earth. Perhaps there would never have been a life form here with the ability to do the one thing that has allowed us to understand our universe more than anything else: to look up.
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We have even been able to capture the light from the beginning of time and we have glimpsed within it the seeds of our own origins.
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Understanding the Universe is like reading a detective story, and the essential evidence we need to solve it has been carried to us across the vast expanses of space and time by light. We have even been able to capture the light from the beginning of time and we have glimpsed within it the seeds of our own origins. We’ve seen things our ancestors wouldn’t believe: stars being born in distant realms, and galaxies lost in time at the very edge of the visible Universe and our cosmos just moments after it all began.
It’s a wonderful thought that these primitive biological light detectors that emerged on Earth half a billion years ago in the Cambrian Explosion have evolved into those most human of things; our green, blue and brown eyes that are able to gaze up into the night sky, capture the light from distant stars and tell the story of the Universe
NASA
CHAPTER 2
STARDUST
THE ORIGINS OF BEING
What are we made of? This is an old question, maybe one of the oldest, and one that thinkers and scientists have been working hard to answer since ancient times. This work continues today, and it may be that by the time you read this book the story of the search for the building blocks of the Universe will have another chapter. Such is the power, excitement and rate of progress of modern science. This chapter is the story of how those building blocks were created in the very early Universe, fused into more complex structures over billions of years in the furnaces of space, and delicately assembled by the forces of nature into planets, mountains, rivers and human beings.
The Large Hadron Collider (LHC) is the highest energy particle accelerator at CERN (the European particle physics laboratory near Geneva, Switzerland). In this huge machine, 27km (17 miles) in circumference, proton beams are accelerated so that they collide head-on. The resultant particles can be detected and recorded so that scientists can then try to understand how they fit together.
DAVID PARKER / SCIENCE PHOTO LIBRARY
The ancient Greeks thought deeply about the question of what we are made of, although they lacked the scientific methodology and technology to arrive at a definitive answer. This led to many competing hypotheses, including some that got close to our modern view: we are all made out of smaller pieces. That there are the smallest building blocks of matter (indivisible basic units that can be fitted together to build the world) was termed the ‘atomic hypothesis’, a theory usually credited to two thinkers – Leucippus and Democritus – in around 400 BC. They held that the world was created from an infinite number of different types of indivisible and indestructible atoms. Each had a different shape, allowing them to fit together neatly to build large objects. So, iron was made of one type of atom, water of another, human flesh of another, and so on. They thought atoms possessed the properties of their real-world substances – water atoms were slippery, while metal ones were shaped so that they locked together to produce very hard substances. We now know that this is not only wrong, but a gross overcomplication. While their hypothesis correctly stated that the world is made from smaller pieces, you don’t need an infinite number of atom types to build the complexity around us. A human is made of the same stuff as a rock; a fish of the same stuff as the Earth; the sky of the same stuff as the oceans. Enumerating the basic building blocks and understanding how they fit together is the province of the science of particle physics, and this quest continues at the Large Hadron Collider at CERN, in Geneva.
By early 2011, we had discovered that the Universe is composed of twelve basic building blocks, only three of which are required to build everything on our planet, including our bodies. These three components, known as the up and down quarks and the electron, can be assembled into the more familiar protons and neutrons – two up quarks and a down quark make a proton, and two down quarks and an up make up a neutron. In turn, the protons, neutrons and electrons make up the chemical elements – ninety-four of which are known to occur naturally – including the basic chemical elements hydrogen, carbon, oxygen, iron, gold and silver
THE CYCLE OF LIFE
Fifteen miles northeast of the Nepalese capital city of Kathmandu, three small streams come together to mark the beginning of one of the holiest rivers in the world. At its source the Bagmati is a fast-running mountain stream, but by the time it winds through the Kathmandu valley and enters the great city of the Himalayas it has become a wide and majestic river.
In the eastern part of the city, where the river’s mythical power is at its greatest, stands the fifth-century Pashupatinath Temple, one of the most sacred sites in the Hindu world. Pilgrims come from all over India and Nepal to worship there and pay their respects to the god Shiva.
I have always found the Hindu faith fascinating; it is rich and complex, a disorientating mix of mythology and philosophy, a continual and jagged juxtaposition of temples, holy sites, rituals and everyday life that produces a joyful assault on the senses. Pashupatinath is no exception. It is at once vibrant and ethereal, a place where the colours and noise of India meet the gentle philosophy of Tibet and the hybrid dissolves into the crystal-clear, high Himalayan air in the smoke of a thousand burning bodies on the funeral pyres lit at this holy place. The scent of burning flesh mixes with incense and tinkling bells, and the sound of chanting Monkey Gods continually interrupts the calls of market traders.
A
central tenet of Hindu philosophy is the concept of the Trimurti – the triad of the three fundamental aspects of the Supreme Being, represented as the great gods Brahma, Vishnu and Shiva. Lord Brahma is the creator of the Universe, Lord Vishnu the preserver, and Lord Shiva the destroyer. Shiva represents darkness, as an angry god who will eventually bring an end to Earth, yet in Hinduism this destruction is seen as an essential part of the cycle of life, because in order for new things to be created, the old order must first be destroyed. Shiva is therefore also a regenerative or reproductive power, part of the endless cycle of death and rebirth that is central to the Hindu belief system. This is why the Pashupatinath Temple and the river it stands beside are revered as places to die.
The Bagmati River is lined with funeral pyres burning the bodies of the deceased.
For Hindus, the passing of a loved one is a stage in the endless cycle of death and rebirth that is central to their beliefs. Cremations are a familiar sight along the holy Bagmati River; the body is dipped in the river three times before cremation, and at the end of the ceremony the chief mourner must bathe in the river’s water, often accompanied by the other attendant mourners.
Hindus believe that the purpose of a soul’s time on Earth is to work through a cycle of rebirth and reincarnation until it becomes perfect. Only then can it be reunited with the Universal Soul and be freed from its material existence. The Bhagavad Gita says: ‘Just as a man discards worn-out clothes and puts on new clothes, the soul discards worn-out bodies and wears new ones’. By having your body cremated on the riverbank beside Shiva’s Pashupatinath Temple, it is believed that your soul will be released from the worn-out body as quickly and easily as possible.
According to the Nepalese Hindu tradition, the dead body must be dipped three times into the Bagmati River before cremation. The chief mourner, usually the first son of the deceased, lights the funeral pyre and must bathe in the waters of the holy river immediately after the cremation. Many of the relatives who join the funeral procession also bathe in the river or sprinkle the holy water on their bodies. This makes the river bank a strange and crowded place. To my British eyes it is somewhat shocking, because death is rarely, if ever, paraded like this; but here in Kathmandu it is not seen to be insensitive to wander between the pyres as the relatives and friends go through their rituals.
In Hindu tradition the human body consists of five elements: air, water, fire, earth and ether. Remarkably, according to modern science, this is overcomplicated, but their belief about what happens to these elements after death parallels our modern understanding of how the world works.
Underlying the cremation ceremony is the conviction that the elements of the body vacated by the soul are returned to Earth to be re-used and recycled. Death is therefore not an end for the immortal soul or the mortal flesh, it is simply the conclusion of one stage of existence and the beginning of another; part of a natural cycle of death and rebirth. As far as the atoms and molecules in our bodies are concerned, modern science is in complete agreement with that idea. When I die my constituents aren’t going to be magically destroyed; they will be returned to Earth and, given enough time, they will become part of some other structure.
Of course, Hinduism isn’t alone in having rich and lyrical stories about the origin and evolution of Man and the Universe. Virtually every society and every religion around the world has at its heart a creation story that explains where we come from, how we came to be here, and what will happen to us when we die. This suggests that curiosity about our origins is an innate, perhaps even a defining part, of the human condition.
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Underlying the cremation ceremony is the conviction that the elements of the body vacated by the soul are returned to Earth to be re-used and recycled… As far as the atoms and molecules in our bodies are concerned, modern science is in complete agreement with that idea.
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In common with the great systems of thought throughout history, modern science has its own creation story to tell – one based on physics and cosmology. It can tell us what we’re made of and where we came from – in fact, it can tell us what everything in the world is made of and where it came from. It also answers that most basic of human needs: to feel part of something much bigger, because to tell this story you have to understand the history of the Universe. It also teaches us that the path to enlightenment is not in understanding our own lives and deaths, but in understanding the lives and deaths of the stars
The Dunhuang star chart dates back to AD 700 and is the oldest existing star chart. It was named after the place where it was found along the Silk Road trade route in northern China (in the twentieth century) and is now owned by the British Library. It depicts the stars in the sky according to the Chinese constellation tradition.
MAPPING THE NIGHT SKY
The moment you leave a city and experience a truly dark night sky, it becomes obvious why our ancestors spent a great deal of time looking up at the stars. They are a bewildering array; a patterned silver canopy self-evidently not devoid of meaning or purpose. For thousands of years ancient astronomers endeavoured to capture and catalogue every light; to observe, log and name as many of these distant suns (for we now know their true nature) as they could. The oldest-known record of a star chart may be over thirty thousand years old. A carved ivory mammoth’s tusk, discovered in Germany in the late 1970s, appears to be imprinted with a pattern that resembles the constellation of stars we now call Orion. In France, cave paintings have been discovered which reveal that humans were mapping the night skies tens of thousands of years before the great civilisations of antiquity began to slowly explore the Universe in more detail.
This celestial map shows a more detailed, highly illustrated view of the constellations according to Dutch cartographer Frederik de Wit in the seventeenth century.
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For thousands of years ancient astronomers endeavoured to capture and catalogue every light; to observe, log and name as many of these distant suns (for we now know their true nature) as they could.
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The Egyptians were one of the first ancient cultures to not only map the night sky but to name some of the stars they observed. They called the North Star the ‘star that cannot perish’, and they also recorded the names of constellations. The Sumerians and Babylonians went a step further by writing down these early names and patterns and creating astronomical catalogues that listed and grouped stars in ever-increasing complexity. Greek, Chinese and Islamic astronomers all continued to build ever more complex systems of classification, with many stars today still being referred to by their original Arabic names.
To the ancients, the stellar backdrop had a deceptive permanence that no doubt motivated them to record and mythologise the patterns they saw. But in AD 185, for the first time in recorded history, a particular type of fleeting addition to the lights in the night sky was observed and documented. Understanding the nature of this rare and spectacular phenomenon eventually led us beyond merely naming the stars and enabled us to tell the story of their births and deaths.
In AD 185, Chinese astronomers witnessed a brightness in the sky comparable to that of Mars, and this remained for eight months. This phenomena was the first recorded occurrence of a supernova explosion, but it was not until late 2006 that the remains of this cosmic event were identified. This picture, taken by the Chandra X-ray Observatory, shows an object now known as RCW 86. The image shows low-, medium-and high-energy X-rays in red, green and blue respectively. It was the study of the distribution of X-rays with energy, combined with measuring the remnant’s size, that enabled scientists to conclude that RCW 86 was created by the explosion of a massive star around 8,000 light years away.
NASA
In late 2006, the remains of the cosmic event of AD 185 that illuminated the skies and minds of Chinese astronomers almost two thousand years ago was identified. The picture above, taken by the Chandra X-ray Observatory, is that of the object known as RCW 86. This object is thou
ght to be the still-glowing remains of one of the most powerful events in our universe – a supernova explosion.
Supernovae are the final act in the lives of massive stars, colossal explosions in which a single star can shine as brightly as a billion suns. If RCW 86 is the remains of the AD 185 supernova, then the ‘guest star’ described by the Chinese astronomers that glowed brightly in the skies for eight months before fading from view was around 8,000 light years away – a quite colossal distance for something to shine so brightly in our skies. The ancient astronomers didn’t know it at the time, of course, but they had documented the first clear evidence that the stars must all eventually die
STELLAR NURSERIES
Above our heads a story of life and death is being told in spectacular fashion. This tale begins in the vast stellar nurseries where new stars burst into life. These fertile areas of star formation are known as nebulae and are among the most beautiful structures in the skies. One of these, the Orion Nebula (pictured far right), is perhaps the most studied astronomical object. It is usually credited as being discovered by Nicolas-Claude Fabri de Peiresc in 1610, but there is evidence from folk tales that the Mayans knew of the faint smudge beneath the stars of Orion’s belt. It can be seen with the naked eye in a very dark clear sky, and it is this complex, ever-changing formation that has taught us most about how stars are born.
Wonders of the Universe Page 8
