Bear with me a while because yours is a long story but it's a story very much worth telling.
About 13.7 billion years ago the universe came into existence as a singularity. We know this because the universe is expanding in all directions at a measurable rate. Projecting this backwards leads to a time when the entire universe occupied a single point of nearly infinite density; a black hole or singularity.
We also know that time and space are part of the universe and do not exist independently of it, so there is no sense in which we can talk of where and when this singularity occurred in some pre-existing space-time dimension.
Quantum mechanics tells us that a single particle takes all possible paths through space-time. What we see as a wave is the resultant sum over histories for that particle. The shape of the wave is the probability distribution of that particle occupying any single point in space-time.
So it was for the singularity. It was not a single universe which came into existence but all possible universes, each with its own set of initial conditions – what scientists call quantum foam.
Some of these universes would have decayed immediately; some may have existed for a few milliseconds; some maybe for longer, and some, like our universe, would have had initial conditions which allowed it to expand rapidly under the outward pressure of forces from which gravity had been stripped.
We know that there is a minimum unit of space, (the Planck length). There is also a minimum length of time (the Planck time) 10-43 seconds (10 to the power of -43 or 0.0000000000000000000000000000000000000000001 of a second). This means that immediately the universe came into existence it was already 10-43 seconds old. This time, for our universe, was enough for gravity to be stripped off from the other three forms of energy – weak and strong nuclear forces and electromagnetic force – which are the forms of energy of which, in one manifestation or another our universe is composed.
Why did all this happen? Why did quantum foam form in the first place and so a universe in which we can ask questions arise? The answer need be nothing more complicated than a quantum fluctuation. At the quantum level there is no such thing as an absolute; all things fluctuate within a range of probabilities which is actually unbounded. At the quantum level all possible events will occur. If it is possible it WILL happen. And of course, in order for us to be asking these questions in the first place there MUST be a universe in which to ask them, and this universe MUST be capable of containing intelligent life capable of asking such questions.
In this universe all observations confirm that gravity is equal to the sum of the other three forms of energy and that, if gravity is the opposing form of the other three, the grand total of energy in the universe is zero. In total energy terms the universe is nothing.
And here we have answered three question which are often thrown at science by those who have never tried to understand it; by theologians and philosophers who struggle to understand why there is a universe instead of nothing, how a universe could come from nothing and why it appears to be 'fine tuned' for the existence of life.
Quantum foam explains all these things and removes any gaps in which those seeking to include one in the explanation can fit their favourite god. There is no need for a 'prime cause' and so no need for a prime causer.
Creationists may wish to breathe a huge sigh of relief at this point because it removes the obligation on them to explain the origins of their assumed creator without invoking a sub-prime cause, ad infinitum, so rendering absurd their prime cause hypothesis. Something which has caused them huge embarrassment and lead to all manner of increasingly ludicrous attempts to work around the problem and still retain the prime-cause hypothesis whilst simultaneously destroying it.
But let's leave creationists to come to terms with the destruction of their favourite hypothesis and the simultaneous relief from the embarrassment of it. Your story now moves on to what happened to all that energy which was made available.
About one ten thousandth of a second after the Big Bang, energy was electromagnetic radiation in the form of high-energy photons. At this stage the universe’s density would have been about a hundred trillion times as dense as water with a temperature of about 1 trillion degrees Celsius. In these extreme conditions, photons would have been moving with enormous energy but would hardly travel any distance before smashing into each other. The collision force would have been enough to create more elementary particles such as neutrons which would then have been smashed again to produce protons and electrons. But things were changing rapidly.
When the universe was just one second old its density had fallen to about 380,000 times that of water, its temperature was down to about ten billion degrees. The number of neutrons now being destroyed exceeded the number being created since photons were still powerful enough to smash them but lacked the energy to create new ones.
At about three minutes old the temperature was down to about a billion degrees (seventy times as hot as the sun) and the rate of change was also slowing.
If the universe had remained in that state for just a few more minutes, all the neutrons would have decayed to protons and electrons, and that would have been that. In some of the universe’s histories in the quantum foam, this is indeed what will have happened, but in this particular history, the one in which we live and ask questions about its origins, and maybe in an unknown number of other histories, the temperature cooled enough for some neutrons to stick to protons to form helium nuclei (or alpha particles). Neutrons had become stabilised and your universe entered its next phase.
We were just a few minutes away from never having existed!
This phase lasted for several hundred thousand years during which it was still too hot for the electrons to stick to the protons and alpha particles to form atoms. Instead they were free to zig-zag about in the expanding and slowly cooling universe, interacting with the electromagnetic radiation which still filled the universe. This final phase of the Big Bang continued until the next major change which occurred some 300,000 to 500,000 years after the beginning when the universe had cooled to a mere 6,000 degrees, or about the same temperature as the surface of the sun. At this temperature, negatively charged electrons become captured by positively charged protons and alpha particles to form electrically neutral atoms of hydrogen and helium respectively. Your universe had given birth to atoms.
The birth of atoms marks the end of the Big Bang and the beginning of atomic matter as we know and understand it. Moreover, since these neutrally charged particles hardly interact with electromagnetic radiation, the universe had become transparent. Photons were now free to stream almost uninterrupted through the universe and atoms were free to clump together under the influence of their own gravity, undisturbed by photons continually stirring them up and knocking them into different paths so ensuring a chaotic distribution of atoms. So clouds of gas could form in an otherwise amorphous universe. The universe was becoming grainy as centres of gravitational attraction were forming; structure was beginning to form under the influence of nothing more complicated than gravity.
Order was forming out of chaos and the whole process was inevitable. And now we have answered another question frequently asked of science, especially by Creationists pursuing a religious agenda. How did order come from chaos? The answer is quite simple - gravity.
Your story now moves on to the story of stars which are the end-point of collapsing clouds of hydrogen and helium, then the only atoms which exist in your still young universe. Under gravity, the gas clouds collapse and release some of the energy stored up in gravity to produce heat, so the collapsing gas clouds heat up. The rate of collapse increases as more and more atoms of gas are pulled towards the centre and, as more and more mass is added, so the gravity increases.
Clusters of stars form into galaxies of billions or trillions of stars which begin to spiral inwards towards a centre of gravity and, as the rate of collapse increases so the rate of rotation also increases until the centrifugal force tending to push bodies outwards equals the gravitational (centripetal) force tending to pull them inwards. Once again a degree of order is emerging in your universe from the chaos of unevenly distributed balls of collapsing gas clouds. A new structure is inevitably being imposed on the universe by the action of a simple forces on chaos and that force is once again gravity. And a third level or order is also emerging as galaxies form super-cluster.
But your story is still being written in the centres of these young suns. The precise details will depend on the size of the original gas cloud out of which the sun was formed. All suns will follow more or less the same process but what happens at the end of their life, and how quickly that end is reached will vary. Let us take a sun rather like our own in size and about which we know rather a lot and which is known to be a rather average sun. Gravity here has produced a temperature of around fifteen million degrees Celsius and hydrogen nuclei (or protons) are being forced together to form helium nuclei and releasing energy as they do so in a huge nuclear fusion reactor.
This process will continue until the star has used up all the hydrogen in its core, where the temperature is hot enough for the fusion reaction to proceed. At that point, with no energy being produced and so nothing pushing the helium outwards, the core will undergo a further collapse forcing helium atoms to fuse together to form carbon, and the temperature will rise to one hundred million degrees Celsius. The outer layer will swell enormously and dim so that the sun will become a red giant.
Eventually the helium supply will run out too and, in a final cataclysm, the core will collapse in one more time and carbon atoms will fuse to form larger atoms in a final, short-lived burst of activity, and a release of energy so violent it will force the sun to fly apart to form a super nova, the products of its reactor being thrown out into space to form interstellar dust and, together with hydrogen and helium, a new cloud out of which second generation suns will form, but clouds which now containing heavier elements than the hydrogen and helium out of which first generation stars were formed.
Not all suns have this ending. If they are large enough they will continue to collapse under their own gravity eventually forming a singularity with a gravity field so powerful that not even photons can escape it. They will form black holes and, at that local level, gravity will have regained control and that part of the universe will again be nothing. And it will be a suitable place for another quantum foam of universes to arise, each with its own space and time existing outside our universe.
Some stars may be too large to form red giants and supernovae and too small to become black holes. These will collapse to a density in which all atoms again break down and all electrons and protons are forced together to form neutrons. The neutron stars.
But your story continues not in a super-massive star destined to be a black hole or a massive star destined to become a spinning ball of super-dense neutrons. Your sun is a second or maybe third generation sun. It was formed from a collapsing cloud of gas and interstellar star dust formed in earlier suns and containing the elements with which you will be made; the carbon, nitrogen, sulphur and oxygen in your proteins; the iron in your blood, the phosphorus and calcium in your bones; the sodium and potassium in your cells. You are made of stardust, formed in nuclear fusion reactors and exploding supernovae out of the elementary particles formed out of pure energy during the Big Bang.
But we still have a few chapters of your story to tell. Your story now moves to the formation of this solar system centred on a rather ordinary star in an outer arm of an unremarkable galaxy in a cosmos containing perhaps a trillion galaxies each with maybe a trillion suns. This chapter begins about 4 billion years ago by which time the universe was about 10 billion years old.
|Relief Map of the Moon Showing Impact Craters|
One collision involving Earth early in the life of the solar system was with a very large object, possibly a small planet, which tilted Earth on its axis of rotation and threw enough material out of Earth's gravity to give rise to a small accretion disc of its own. The relatively large Moon was formed out of this debris. For all practical purposes the Earth and Moon form a twin planet, formed out of the remains of these two earlier planets.
This event had huge significance for your story. The tilt of Earth’s axis has produced seasons and the close proximity of another relatively large body has produced tides. It is probable that both these contribute to Earth being a suitable place on which life could exist. But we still have another chapter in your story to tell.
About 3.5 billion years ago, on this little planet orbiting a very ordinary sun situated on an outer arm of a very ordinary galaxy, something quite extraordinary happened. We don’t know exactly how, though we have several theories, and we don’t know if it was unique. It might well have happened on other planets in other galaxies maybe a trillion times but, as the distances between galaxies and even across galaxies are so vast, we may never find out.
Here on our tiny bright blue dot, a replicator arose. A replicator is a chemical which can produce copies of itself. We don’t know exactly what the first replicator was; one theory is that it may have been crystalline structures in clay; another is that it may have been ribonucleic acid (RNA). It is generally agreed that RNA came into it fairly early on, maybe from the outset, maybe riding on the back of some other chemical in an evolutionary process in which those replicators better at replicating will produce more descendants. There are still some organisms like viruses which depend on RNA and RNA is certainly still involved even where the main genetic material is deoxyribonucleic acid (DNA). However this replicator started, it seems to have fairly quickly evolved into a DNA-based one.
For a general outline of what probably happened, see How Did Life Originate.
Each of your cells, with the exception of your red blood cells, contains DNA which contains all the instructions for making you and making the protein enzymes which control your body’s metabolism. DNA is organised into genes which carry instructions. Without going into detail (whole books are devoted to how DNA works as a store for information and how it is organised into genes, but the details are very well understood), these genes are the basic building blocks of life and are the replicators which carry your information from your parents, through you and into your children. Your story is the story of your genes which, over billions of years have built survival machines for replicating themselves through time. You are a gene survival machine with a body superbly fashioned to survive and reproduce and so pass on your genes to the next generation.
Consider again that dot. That’s here. That’s home. That’s us. On it, everyone you love, everyone you know, everyone you ever heard of, every human being who ever lived, lived out their lives. The aggregate of all our joys and sufferings, thousands of confident religions, ideologies and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilizations, every king and peasant, every young couple in love, every mother and father, every hopeful child, every inventor and explorer, every teacher of morals, every corrupt politician, every superstar, every supreme leader, every saint and sinner in the history of our species, lived there on a mote of dust, suspended in a sunbeam.Replicators are very good at replicating but occasionally they produce slightly different copies of themselves and these slight differences give rise to slight variations between individuals. Some of these will make the individual less fitted to survive and some will make it more fitted; the vast majority however will make no noticeable difference as they take place in the accumulated redundant DNA which all organisms contain.
Where the variation makes a difference, however, the environment will determine whether it gives an advantage or a disadvantage, or, in fact makes no difference in terms of success, even where there is a difference. It will tend to select for individuals carrying genes which make it more able to survive and against those less able. Those which tend to survive will tend to produce more descendants, in that environment, and those descendants will inherit the advantageous genes. Natural selection acts like a sieve at each generation tending to filter out those characteristics which act against survival and allowing through those which enhance it. In this way the gene pool of a species tends to adapt to its local environment and, where the gene pool is split amongst several different environments, tends to produce diversity. Diversity will eventually lead to speciation if separation is maintained for long enough.
So what does this mean for you and your story? You are the end-point of your own genes' evolution. You are the descendant of survivors, each of whom bred successfully and never once failed – for 3.5 billion years!
Think about that for a moment. In a world in which, for very many individuals, an early death and failure to breed were by far the most likely outcome, not one single one of your ancestors failed to produce at least one offspring. If they had failed, your gene-line would have ended there and then.
You are the product of billions of passes through the sieve of selection and at every pass your gene-line passed the fitness test. You are good at surviving; and you are unique in the history of the cosmos. The likelihood of you being alive at all is almost vanishingly small and yet here you are. Never before has anyone with your individual combination of genes, your individual collection of atoms and your history existed.
And you never will again.
Your ancestors were there when Europe and Africa split off from the Americas. They were there as small mammal-like reptiles when dinosaurs ruled the earth. They saw pterodactyls flying overhead. They survived the mass-extinction which ended the dinosaurs reign.
Your ancestors swam in the pre-Cambrian seas and crawled out onto the land as early air-breathing fish destined to become land-based animals. Your ancestors lived through the Carboniferous era when dense forests of tree ferns grew in steaming jungles where dragonflies with meter-wide wings flew. The trees then fell and formed the deposits destined to be coal as the climate changed. They saw the first flowering plants as plants and insects formed their mutual-benefit society.
Your ancestors lived through the first great toxic waste disaster when the blue-green algae produced oxygen and triggered a mass extinction; and they learned to turn it to their advantage by evolving aerobic respiration.
Your ancestors were bacteria; they were arcae; they may have been the strange edicarans which were the earliest known multi-cellular organisms. In almost every one of your cells, in your genes, you carry a record of your evolution, of the entire human evolution story, and of a great deal of the evolution story of every other living thing.
Your journey through space and time has been an adventure of disasters, adaptation, survival and recovery, many, many time you will have been on the brink of extinction - the fate of 99% of all known ancient species - yet your ancestors survived and because they were good at surviving you are here and now.
You will live for a mere flash in the time-scale of the universe but in the vast darkness of the cosmos there can surely be few flashes as bright as your bright spark of consciousness.
Be proud. Be very proud. But at the same time be humbled by the enormity of the events which produced you and the fragility of it all.
Stars died and because they died, you live. You are made by stars out of stardust and in a very real sense, because you are made of the same stuff the universe is made of and are a part of it, there is something even more wonderful about you. Through you, though not just through you, and maybe not just here on this small planet, the universe has gained self awareness and can begin to understand itself. Through you it can stand on the surface of this beautiful little jewel in the cosmos, can look up in awe at itself and think "Wow!"
You’re special. You are unique and you were nearly 14 billion years in the making.
That’s your story. Enjoy it while it lasts.
And please bear in mind also that every other human being; every mammal; every bird, insect, spider, fish, or worm; every plant; indeed, every other living thing, has made the same journey you have made. Each is unique and the descendant of survivors. Each has an unbroken gene-line going right back to the first replicator. They are your relatives. Like you they are part of the whole web of interdependent things we call life on earth.
To end their life will end their gene-line for the first and only time in the history of the universe. Something which has taken nearly 14 billion years to produce and 3.5 billion years to perfect will have been extinguished forever.
Each of them is worthy of respect and each of them deserves the one opportunity to experience life that chance has given them.
Life is too rare, precious and wonderful a thing to take lightly.