A little over a year ago I was in a great church – the Basilica of St Mark in Venice. Its predecessor was raised in the year 832 to house the mortal remains of St Mark the Evangelist which had supposedly been brought to Venice from Alexandria four years earlier by two Venetian merchants. They are alleged to have hidden the remains of the martyred Saint under layers of pork so as to avoid the attentions of Muslim customs officials.
The present Byzantine style Basilica with its distinctive cluster of low domes was begun in 1063 and consecrated in 1089. Today, it sits next to the Doge’s Palace on the edge of St Mark’s Square, attracting tourists and pigeons rather than pilgrims with a façade to launch a thousand postcards.
I arrived at the church in the early evening with a small group of other scientists for a guided tour after it had closed to visitors for the day. When we entered it was almost in total darkness. There are few windows and those are small and far from transparent. We were asked to sit in the centre, allowing just a few faint floor lights and an occasional electric candle to guide us to our seats. Above us there was only darkness.
Then, very slowly, the light levels slowly rose, above us and around us, and the interior began to be illuminated by a discreet system of hidden sodium lights. The darkness around us gave way to a spectacular golden light. The arching ceilings above us were covered in a spectacular gleaming mosaic of glass and gold. Between the 11th and the 15th centuries nearly 11,000 square feet of gold mosaic was made, square by square, mixing gold with glass by a delicate process that it still not fully understood, to produce this sparkling golden sanctuary. Appearances can be deceptive.
But, on reflection, what was more striking to me was the realisation that the hundreds of master craftsmen who had worked for centuries to create this fabulous sight had never seen it in its full glory. They worked in the gloomy interior aided by candlelight and smoky oil lamps to illuminate the small area on which they worked but not one of them had ever seen the full glory of the golden ceiling. For them, like us, 500 years afterwards, appearances were deceptive.
Our Universe is a bit like that too. The ancient writers who celebrated the heavens’ declaration of the glory of the Lord saw only through a glass darkly. Unbeknown to them and countless others who followed them, the Universe has revealed itself by the instruments that modern science has made possible to be far bigger, more spectacular, and more humbling than we ever imagined it to be.
The Universe appears big and old, dark and cold, hostile to life as we know it, dangerous, and costly to explore. Many a philosopher of the past concluded that the Universe was meaningless and antithetical to life: a bleak and black realm in which our little planet is a temporary outcome of the blind forces of Nature. Yet, appearances may again be deceptive.
Over the past 75 years, astronomers have illuminated the vault of the heavens in a completely unexpected way. The Universe is not only big but it is getting bigger. It is expanding. Great clusters of galaxies are moving away from each other at increasing speeds. This means that the size of the Universe we can see is inextricably bound up with its age. It is big because it is old.
These huge periods of time are important for our own existence. We are made of complicated atoms of carbon, nitrogen and oxygen, along with many others; maybe one day other forms of terrestrial intelligence will be made of silicon atoms. The nuclei of all these atoms do not come ready-made with the Universe. They are put together by a long slow-burning sequence of nuclear reactions in the stars. It takes almost 10 billion years for this stellar alchemy to burn hydrogen to helium, and on to beryllium, and carbon and oxygen and beyond, before the dying stars explode in supernovae and spread their life-giving debris around the Universe where it finds its way into grains of dust, planets, and ultimately into people. The nucleus of every carbon atom in our bodies has been through a star. We are closer to the stars than we could ever have imagined.
So you begin to understand why it is no surprise that the Universe seems so big and so old. It takes nearly ten billion years to make the building blocks of living complexity in the stars and because the Universe is expanding it must be at least ten billion light years in size. We could not exist in a Universe that was significantly smaller.
The vastness of the Universe is often cited as evidence for the extreme likelihood of life elsewhere. While there may be life – even conscious life – elsewhere, sheer size is not compelling: we see that the Universe needs to be billions of light years in size just to support one lonely outpost of life. An economy-sized Universe, just the size of our Milky Way Galaxy, with its 100 billion stars and possible planetary systems, seems room enough for all we hold dear. But it would be little more than a month old. Barely enough time to pay off your credit card bill, let alone evolve complexity and life from sub-atomic simplicity.
Any Universe that is a home for life must be big and old. But this means that it must also be dark and cold. As time passes, the expanding Universe gets cooler and cooler, and energies fall as space is stretched. The inferno of the past “big bang” must, after billions of years, be replaced by the dark night sky we see around us containing just a faint glimmer of microwaves, echoing its hot beginnings, just three degrees above absolute zero of cold, but still detectable in the snow of white noise on an untuned TV screen in our living rooms. The dark night sky that provoked so many human responses to our place in the Universe is a necessary part of a life-supporting Universe.
Life can only arise and persist in a Universe that is big and old, dark and cold, with its planets and stars and galaxies separated by vast distances. These are necessary features of a life-supporting Universe. Astronomy has transformed the simple-minded, life-averse, meaningless Universe of the sceptical philosophers. It breathes new life into so many religious questions of ultimate concern and never-ending fascination. Many of the deepest and most engaging questions that we grapple with still about the nature of the Universe have their origins in our purely religious quest for meaning. The concept of a lawful Universe with order that can be understood and relied upon emerged largely out of religious beliefs about the nature of God. The atomistic picture of matter arose long before there could have been any experimental evidence for or against it. Out of these beliefs came confidence that there was an unchanging order behind the appearances that was worth studying. Great questions about the origin and end of the Universe, possible the sources of all observed complexity, and the potential infinity of space grew out of our religious focus on the great questions of existence and the nature of God. And, like all great questions, they can turn out to have answers that take us down unexpected paths, further and further away from the familiar and the everyday: multiverses, extra dimensions, the bending of time and of space – all may reveal a Universe than contains more than is needed for life, more even than is needed for speculation. We see now how it is possible for a Universe that displays unending complexity and exquisite structure to be governed by a few simple laws – perhaps just one law – that are symmetrical and intelligible, laws which govern the most remarkable things in our Universe – populations of elementary ‘particles’ that are everywhere perfectly identical.
It is to this simple and beautiful world behind the appearances, where the lawfulness of Nature is most elegantly and completely revealed, that physicists look to find the hallmark of the Universe. Everyone else looks at the outcomes of these laws. The outcomes are often complicated, hard to understand, and of great significance – they even include ourselves – but the true simplicity and symmetry of the Universe is to be found in the things that are not seen. Most remarkable of all, we find that there are mathematical equations, little squiggles on pieces of paper, that tell us how whole Universes behave. For there is a logic larger than Universes that is the more surprising because we can understand a meaningful part of it and thereby share in its appreciation.
Once we thought everything in the Universe was made of the things material that we find on Earth. We have now discovered that this too was only a first guess. More than 70 per cent of the Universe is composed of a form of dark energy whose precise identity is unknown. It reveals it presence by its dramatic effect upon the expansion of the Universe. Unlike all other known forms of matter, which exert gravitational attractive forces on other forms of matter and amongst themselves, this dark form of energy responds repulsively to gravity, causing all material to accelerate away from it, creating an acceleration in the expansion of the Universe that began to occur when it had reached about 75 per cent of its presence extent. This discovery about our Universe was a surprise – like discovering something totally unexpected about an old friend. Again, appearances were deceptive.
So, with the Universe, as it was that evening in St Mark’s, things are not always as they seem when we look upwards. The whole is so much more than the sum of its parts. The architects of our religious and scientific pictures of the Universe, and the many commentators on their meanings that followed them, could see only a small part of what there is, and knew only a small part of what it has to teach us about our place in the Universe. We begin to see afresh the extraordinary nature of our local environment and the link that attaches life to the vastness of space and time. Appearances can indeed be deceptive
There are some who say that just because we use our minds to appreciate the order and complexity of the Universe around us that there is nothing more to that order than what is imposed by the human mind. That is a serious misjudgement. Were it true then we would expect to find our greatest and most reliable understanding of the world in the everyday events for which millions of years of natural selection have sharpened our wits and prepared our senses. And when we look towards the outer space of galaxies and black holes, or into the inner space of quarks and electrons, we should expect to find few resonances between our minds and the ways of these worlds. Natural selection requires no understanding of quarks and black holes for our survival and multiplication. And yet, we find these expectations turned upon their heads. The most precise and reliable knowledge we have about anything in the Universe is of events in a binary star system more than 3000 light years from our planet and in the sub-atomic world of electrons and light rays, where it is accurate to better than nine decimal places. And curiously, our greatest uncertainties all relate to the local problems of understanding ourselves – human societies, human behaviour, and human minds – all the things that really mattered for human survival. But that is because they need to be complex – were our minds simple enough to be understood they would be too simple to understand.
In all the science we pursue we are used to seeing progress. Our first attempts to grasp the laws of Nature are often incomplete. They capture just a part of the truth or they see it through a glass only darkly. Some think that our progress is like a never-ending sequence of revolutions which overthrow the old order, condemned never to converge upon anything more definitive than a more useful style of thinking. But scientific progress doesn’t look like that from the inside. Our new theories extend and subsume old ones. The former theories are recovered in some limited situation – slow motions, weak gravitational fields, large sizes, or low energies – from the new. Newton’s 300-year old theory of mechanics and gravity has been superseded by Einstein’s which will be succeeded by M theory or its unknown successor in the future. But in a thousand years time schoolchildren will still study Newton’s theories, and engineers will still rely upon them, just as they do today. They will be the simple limiting form for slow motions and weak gravity of the ultimate theory, whatever it turns out to be. So, in our religious conceptions of the Universe, we also use approximations and analogies to have some grasp of ultimate things. They are not the whole truth but this does not stop them being a part of the truth: a shadow that is cast in a limiting situation of some simplicity. Our scientific picture of the Universe has revealed time and again how blinkered and conservative our outlook has often been, how self-serving our interim picture of the Universe, how mundane our expectations, and how parochial our attempts to find or deny the links between scientific and religious approaches to the nature of the Universe.
Sir John Templeton has sought to encourage this impartial dialogue in the firm belief that religion and science can supply mutual illumination and appreciation of the wonders of our Universe and inspire us to seek out and comprehend the truth in new ways – a truth that is unfailingly unexpected and so often not at all like it first appears.