Wonders of the Universe. Andrew Cohen

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.

      The work of the space programmes across the world cannot be viewed as a luxury, but rather as a necessity. It is through the missions of space shuttles such as Atlantis

      The cosmos is about the smallest hole that a man can hide his head in.

      —G.K. Chesterton

      Care is in order, because the very beginning – by which we mean the events that happened during the Planck epoch – the time period before a million million million million million million millionths of a second after the Big Bang, is currently beyond our understanding. This is because we lack a theory of space and time before this point, and consequently have very little to say about it. Such a theory, known as quantum gravity, is the holy grail of modern theoretical physics and is being energetically searched for by hundreds of scientists across the world. (Albert Einstein spent the last decades of his life searching in vain for it.) Conventional thinking holds that both time and space began at time zero, the beginning of the Planck era. The Big Bang can therefore be regarded as the beginning of time itself, and as such it was the beginning of the Universe.

      There are alternatives, however. In one theory, what we see as the Big Bang and the beginning of the Universe was caused by the collision of two pieces of space and time, known as ‘branes’, that had been floating forever in an infinite, pre-existing space. What we have labelled the beginning was therefore nothing more significant than a cosmic collision of two sheets of space and time.

      It may be that the question ‘Why is there a Universe?’ will remain forever beyond us; it may also be that we will have an answer within our lifetimes, but the quest has to date proved more valuable than the answer because the ancient search for origins lies at the very heart of science. Indeed, it lies at the heart of much of human cultural development. The desire to understand events beyond the terrestrial seems to be innate, because all the great civilisations of antiquity have shared it, developing stories of beginnings, origins and endings. It is only recently that we have discovered that this quest is also profoundly useful in a practical sense. When coupled with the scientific method, this quest has allowed us not only to better understand nature, but to manipulate and control it for the enrichment of our lives through technology. The well-spring of all that we take for granted, from medical science to intercontinental air travel, is our curiosity.

      THE VALUE OF WONDER

      The idea that a journey to the edge of the Universe is deeply relevant to our everyday lives lies at the heart of Wonders of the Universe. I cannot emphasize enough my strong conviction that exploration, both intellectual and physical, is the foundation of civilisation. So whilst building rockets to the Moon and telescopes to capture the light from the most distant stars may seem like an interesting luxury, such a view would be superficial, incorrect and downright daft – to borrow a phrase from my native Oldham. We are part of the Universe; its fate is our fate; we live in it and it lives in us. How can anything be more important, relevant and useful than understanding its workings?

      When we began to think about the series, we wanted to make programmes that were more than a simple tour of the wonders of the Universe. Of course black holes, colliding galaxies and stars at the edge of time are fascinating, and we see them all, but to characterise the ancient science of astronomy as a spectator sport would be to miss the point. The wonders we see through our telescopes are laboratories where we can test our understanding of the natural world in conditions so extreme that we will never be able to recreate them here on Earth. With this in mind, we decided to base the programmes around scientific themes rather than the wonders themselves.

      When you set sail for Ithaca, wish for the road to be long, full of adventures, full of knowledge.

      —C. P. Cavafy

      Endeavour that we can truly begin to understand the origins and the workings of the Universe and use this information to plan for our future on Earth.

      ‘Messengers’ is about light – our only connection with the distant Universe that may lie forever beyond our reach. But it is also about the information stored within light itself, and how that information got there; the fingerprints of the chemical elements are to be found in the most distant starlight, enabling us to know with certainty the composition of the most distant star.

      ‘Stardust’ asks an ancient question: what are the building blocks of the Universe? And also, how was the raw material of a human being assembled from the debris of the Big Bang? – a searingly hot, yet beautifully ordered fireball with no discernable structure.

      ‘Falling’ tells the story of the great sculptor of the Universe: gravity. For some reason that we do not understand, gravity is by far the weakest of the four fundamental forces in the Universe, but because it has an infinite range and acts between everything that exists, its influence is all-pervasive. Our most precise theory of gravity, Einstein’s General Theory of Relativity, dates from 1915, which makes it the oldest of the modern theories of the forces. The theory of the electromagnetic force, Quantum Electrodynamics, dates from the 1950s, while the theory of the Strong Nuclear Force from the 1960s and 70s. Our description of last of the four, the Weak Nuclear Force, resides in the Standard Model of particle physics. This theory, a product of the 1970s, unifies the description of the Weak Nuclear Force with Quantum Electrodynamics, although there is a missing piece of the theory known as the Higgs Boson that is currently being searched for at the Large Hadron Collider at CERN in Geneva. Until the Higgs Boson, or whatever does its job, is found, we cannot claim to have a working description of the Weak Nuclear Force and its relationship with electromagnetism.

      However despite the long pedigree and beautiful accuracy and elegance of Einstein’s theory of gravity, it is known to be incomplete. Our description of the Universe breaks down in the heart of its most evocatively named wonders. Black holes are known to exist at the centre of galaxies such as the Milky Way, and are dotted throughout the cosmos; the carcasses of the most massive stars in the Universe. We see them by their influence on passing stars and by detecting the intense radiation emitted by gas and dust that has the misfortune to venture too close to their event horizons. We have even seen their formation in the most violent cosmic events – supernova explosions. These events mark the destruction of stars that once burned brightly for millennia, completed in a matter of minutes.

      The final chapter, ‘Destiny’, delves into the distant past and the far future; following the inevitable ticking of the universal clock. It is also the chapter that most directly touches on the great contribution of engineering to our story. The science of thermodynamics, which has become our guide to the ultimate fate of the Universe, arose from considerations of the efficiency of steam engines in the nineteenth century and not a desire to peer out towards a possibly infinite future. In ‘Destiny’ we describe thermodynamics in detail, and show how this quintessentially nineteenth-century science allows us to speculate with some grounding in reality about events that will happen 10,000,000,000,000,000,000,000,000,000,000,000,

      000,000,000,000,000,000,000,000,000,000,000,000,000,000,

      000,000,000,000,000,000,000,000 years from now. Not bad for the pioneers of the age of steam.

      So as we look to the future and survey the wonders of our universe, we discover that Einstein’s theory of gravity, our best description of the fabric of the Universe, predicts its demise inside black holes. The collapsing remnants of the most luminous stars represent the edge of our understanding of the laws of physics and therefore the edge of our understanding of the wonders of the Universe. This is exactly where every scientist wants to be. Science is a word that has many meanings; one might say science is the sum total of our