The Universe and Me: On the Origin of Everything

By Bob Murphy

The Universe and Me is his most ambitious work to date. A tour de force, this book represents a synthesis of at least a dozen separate scientific disciplines, including cosmology, physics, chemistry, microbiology, paleobiology, paleoclimatology, paleontology, botany, optics, mammology, primatology, anthropology and the history of science. All of these skillfully and woven together into a fabric of great charm. This is, literally, the greatest story ever told. It is our story. The story of creation, and in the hands of this story-teller, this great adventure, has never been more understandable and available to all.

• Language: English
• Publisher: Xlibris US
• Release date: Apr 14, 2009
• ISBN: 9781469118888

Bob Murphy

Bob Murphy played for the Western Bulldogs for 17 years and was their captain from 2015 to 2017. In 2015 Murphy was named captain of the year at the AFL Players Association awards and was also captain of the All-Australian team. The following year, the Bulldogs won their first premiership in 62 years. Murphy has written regularly for The Age, and his first book was Murphy’s Lore.

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Copyright © 2009 by Bob Murphy.

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Contents

1

Birth Pains

2

Heaven and Hell

3

The Genesis

4

The Age of Aquarius.

5

The Beginning of Tomorrow

6

From Fins to Fingers

7

From Fangs to Feathers

8

The Fine Art of

BeingUp-close and Personal

9

Children of Snow and Ice

To Viviane Leventhal

Plate 1: Earth and all the life on it are merely products of great forces intrinsic to the Universe. © Lynette Cook, 2003. Reproduced with permission.

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1

Birth Pains

Nothing comes from nothing

(LUCRETIUS:The Nature of Things)

I recently bought myself something I had wanted all my life—a telescope. Now that I am in my sixth decade, I seem able to make room for many things in my life that had previously been forgotten or neglected. That is the beauty of becoming aged, unlike one’s youth, one can enjoy it.

Why I had never got around to buying a telescope before, was not just due to the simple and common neglect of childhood ambitions when in the prime of life, but also to the geography of Sydney. To use a telescope to its full advantage when close to city lights is unrealistic—they compete with the faint light from the distant stars. I have lived in the suburbs of Sydney most of my life, but about ten years ago I moved to the foothills of the Blue Mountains, where I was far enough away from the city lights to get a good view of the stars. So now, a telescope is a feasible acquisition.

Our beautiful blue planet as seen from NASA shuttle orbiter taken 11/27/1989 Note the storm in the Pacific. Copyright ©1989 NASA Reproduced with permission.

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Looking at the stars is awesome, in the real sense of that latterly abused word. The more one learns about the stars, the more reverent one becomes when considering them. It is also romantic. Perhaps that is why sitting under the stars has been a favourite pastime for lovers, and perhaps, there were other reasons as well. Looking at the stars is romantic for me. I am often transfixed by the night sky. Fascination with the stars has characterized humans throughout recorded history. I would like to entertain, the perhaps quixotic notion, that the reason why we have always found star-gazing to be so fascinating, is that somewhere deep down in our collective psyche, we can appreciate that we are looking at our own past—seeing the face of our mother, if you will, because, truly, we are children of the stars.

I get the same filial feeling, and the same sense of awe, when near the sea. I think that many people do. Certainly, most Australians do, that is why most of them live on the coastal fringe of that great continent, and why most of them plan to spend their retirement, if not their working life, in a house or apartment within walking distance, or, at the most, a short drive from the beach. Perhaps it is that Australians, understand their primordial relatedness to the sea—so they go there to live. On the other hand, maybe it is just that Aussies like water sports. Whatever the reason, almost all Australians can all agree on one thing—it’s nice to live close to Mum.

As we shall see in Chapter 3, 370 million years ago (370 Mya), some of our ancestors, the first tetrapods, gingerly climbed out of the maternal nursery of the ocean, and took their first unsteady steps on the land. This was the time when we said goodbye to Mum—our great mother—the sea, but, now that we are grown-ups, it is nice to visit her from time to time. By the way, we are still technically tetrapods like our ancient ancestors, which is why we find it comfortable to swing our arms when walking—we are assuming the same motion that any other tetrapod would when walking.

Wherever we look, in sea or sky, we can’t avoid this sense of relatedness, and yet so often we see ourselves as separate—separate from nature—separate from the Universe itself—separate from our fellow creatures, and separate from each other.

This illusion of separateness is largely responsible for many of the problems in which we find ourselves. It is time for us to consider the things that unite us to the rest of creation, rather than the fraudulent idea that we are in some way unique and separated from it.

‘Creation’ is a word I will be using often (as well as its derived relative, creature—which derives from creatura meaning ‘a thing created’). The word creation, of course, implies a creator, just as the existence of a watch implies the prior existence of a watchmaker, as the nineteenth century cleric William Paley argued. So who was the ‘creator’? All the evidence suggests that the creator is the Universe itself. That is why I have capitalized the first letter of that word—in the manner of Judeo-Christian literature when referring to the fundamental source of everything.

In this book we will explore the origins of all life, and explode the myth of our separate creation. This has been very destructive, not only to human beings, but to just about every other living creature with whom we have shared this world. I will also discuss how it seems that our Universe has been programmed to ever more complexity, ultimately and inevitably to result in creatures such as ourselves. I shall use the term ‘meaningful complexity’, meaning complexity which itself leads to the development of further complexity. A thunderstorm is complex, but it is not meaningfully complex.

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The late Fred Hoyle

According to the best understanding we have today, all the atoms in you and me and everything else, had their origins in the most phenomenal explosion of all time, to which the late British astronomer, Fred Hoyle (he died in 2001) gave the name The Big Bang in a BBC radio broadcast of the 1940s. Actually Fred gave it this name because he was trying to make fun of the idea. He did not really believe in the concept at all—along with Thomas Gold and Hermann Bondi, he was one of a triumvirate of British astronomers who were proponents of the opposing ‘Steady State Hypothesis’. So ironically, the name which Hoyle used sarcastically to refer to the theory became perhaps the best known name in cosmology.

Evidence for the Big Bang was first accumulated by a drop-out lawyer and boxer, and his colleague, a mule-team driver.

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Edwin Hubble, Astronomer

Edwin Powell Hubble was a brilliant student and a good amateur boxer. He acquired degrees in mathematics and astronomy from the University of Chicago in 1910. While at Chicago he met and was inspired by the great American astronomer George E. Hale. Hale was a good scientist, but a better fund-raiser. While at Chicago with Hubble, he founded the Mount Wilson Observatory, near Los Angeles, with the assistance of the Carnegie Institute.

For a while, Hubble turned his back on astronomy and studied law at Oxford University as a Rhodes Scholar. Graduating, he practiced law for a short time, until the stars called once again.

In the days before widespread use of the motor vehicle, most heavy carrying was performed by teams of mules or oxen. The 100 inch concave mirror, and the rest of the astronomical paraphernalia associated with the building of the Mount Wilson Observatory were carted up the mountain by mule train, and one of the mule-train drivers was Milton Humason. When the building was completed in 1917, Humason stayed on, first as a janitor, then as a night assistant, and finally as an astronomer, even though he had never gotten beyond the eighth grade at school. Together, Hubble and Humason collected the evidence for what became known as the Big Bang.

Apart from discovering many distant objects, which had to be other galaxies (at the time it had been thought by the scientific establishment that the Milky Way was the only galaxy in the Universe), Hubble and Humason made another important discovery—they found that when they looked at a spectrograph of light from any distant object, that the markings denoting elements were shifted to the red end of the spectrum. This was the discovery for which they will be most remembered, because although they didn’t immediately realize it, they were night after night patiently accumulating the evidence for the Big Bang.

When Hubble and Humason saw that these distant galaxies were red-shifted what exactly did it mean? For generations students were taught that what they were seeing was ‘red-shift’ due to the Doppler Effect? So what is the Doppler Effect? When an electromagnetic wave, of which light, sound, radio, and television broadcasts are examples, is moving away from an emission source, it travels in all directions as concentric circles—like the circles you see when you toss a pebble into a still pond. Incidentally, the idea that our television broadcasts are moving into space in all directions is, for me at least, a bit of a worry. By about now, intelligent life on a planet near the star Beta Pictoris, if there is any, is just receiving our broadcasts of I Love Lucy. If this is the way that they are getting their information about our species, is it any wonder then that no-one has come?

So much for waves from a stationary source. Let us now consider waves from a moving source. When a train emitting a whistle passes you, what you hear is a shift in pitch. You can hear the same phenomenon when a motorcycle passes—the sound from the motor is in one pitch as it approaches, and a different one as it moves away. This is called the Doppler Effect (named after the Austrian mathematician, Christian Doppler, who first described it, and who was born in the same city as Mozart). The change in pitch occurs because although the sound waves emitted are moving away from the source in all directions and at a constant speed, the source itself is moving, and those sound waves ahead of it get compressed or pushed together by this movement, while those behind it get stretched. When sound waves are compressed, the outcome is a sound which has a higher pitch, and when they are stretched, the resulting sound has a lower pitch. So to an observer near the track as the train rushes past, it seems that the train’s whistle changes in pitch as it passes. This same effect occurs with all electromagnetic waves.

The Mount Wilson 100 inch Hooker Telescope

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Colour is to light what pitch is to sound. So when light waves get squashed together because the emission source is moving, the light changes colour depending on whether the emitting object is approaching or moving away from the observer. If it is approaching, then the light coming from it has a shorter wavelength and tends to be in the blue end of the spectrum. If it is moving away, the light from the object tends to have a longer wavelength, and lies in the red area of the spectrum. We call the former situation ‘blue-shifted’ and the latter ‘red-shifted’ light. I will explain this phenomenon in more detail a little later.

You might expect then, that if you stand in the same position, with the train coming towards you, that the train should appear bluish. Why this doesn’t occur is because the train is moving about one-million-times too slow for the Doppler Effect to show up, but galaxies are moving at just about the right speed.

Hubble and Humason certainly saw a red-shift in all the distant galaxies in their spectrographs. Everywhere that they looked seemed to show the same effect. For decades it was thought that what caused this phenomenon was the Doppler Effect, but was it? Well, actually it wasn’t. For generations astronomy students have been taught the wrong thing. The red-shift that Hubble and Humason observed was not a Doppler red-shift, but a cosmological red-shift. The Doppler red-shift is not the same as the cosmological red-shift, although astronomers often, and inaccurately, treat it as such (because they themselves were given the wrong information). The former is governed by special relativity, and refers to what happens within the Universe, while the latter is governed by general relativity, and describes what Universes do. The Hubble and Humason red-shift was caused not by the motion of the emitting body, as is the case in the classical Doppler Effect, but by the expansion of space-time itself.

As light from a distant galaxy travels through space, it travels through space which is itself expanding, and a beam of light in an expanding Universe tends to get stretched. If a light beam travels through space that doubles in size, then the wavelength of that beam of light experiences a doubling of its wavelength. That is why the galaxies are red-shifted, and that is why those that are furthest away are the most red-shifted, because they are experiencing a greater stretching of their wavelengths. That is cosmological red-shift, and although, over relatively small distances it seems to have the same effect as the Doppler Effect, it is actually a world away from the Doppler Effect (no pun intended).

Whether the effect was attributed to Doppler or cosmological red-shift, this observation of Hubble and Humason established the reality of the Big Bang concept. All of these distant galaxies were red-shifted, meaning that they were moving away from the observer at great speeds, as well, the further away these celestial objects were, the more red-shifts they were, meaning the faster they appeared to be moving (away). Since the observer was not in a privileged position, it must be the case, that every galaxy was moving away from every other galaxy—space-time itself was expanding. Through their painstaking and tedious observations, Hubble and Humason had accumulated the evidence for the Big Bang. It was one thing to suggest the Big Bang, as Hubble and Humason’s data did, and yet another to confirm it. This confirmation came from a most unexpected quarter—this cornerstone of cosmology was verified by two guys tuning an antenna.

In 1965 Arno Penzias and Robert Wilson, employees of Bell laboratories, were given the task of finding out what was causing the annoying hiss in early satellite telecommunications. To do this they were trying to tune a very sensitive antenna. What they found when they were doing this work, in Holmdel, New Jersey, was that they were picking up background microwave radiation that seemed to be coming from everywhere. They concluded that they must be picking up the background radiation ultimately attributable to the Big Bang. Since it had been expanding outwards from a single point, some 13.7 billion years (5 x 10¹⁷ seconds) ago, it now seemed to be present everywhere, in every direction they pointed the antenna. This is the grainy ‘static’ that you see on a television set not properly tuned into a channel.

For their contribution to cosmology, German-born Penzias and American-born Wilson were awarded a Nobel Prize in 1978.

The idea that the whole Universe once started from something very small indeed, seems to have first been proposed by a Belgian priest, Georges Lemaitre in 1927. He took the red-shifted galaxies of Hubble and Humason as evidence for the expansion of the Universe as predicted by Einstein’s theory of relativity.

Einstein had predicted either an expanding or a contracting cosmos, and being a theoretical physicist rather than an astronomer, in 1917, he went to the leading astronomers of his day and said to them something like this: My equations predict either an a universe which is expanding or contracting. Please tell me whether or not you think that the universe is expanding. The learned men of his day thought that the Universe was the Milky Way, which, of course, is only a galaxy, and a very small part of the Universe as a whole. The Milky Way was not expanding, so they replied to Einstein’s enquiry along these lines: Don’t worry about it! The Universe certainly is not expanding. Our universe is a static universe.

Now this may appear true for the Milky Way (and in fact, it, along with the rest of space-time is actually expanding, but on such a small scale that it is hard to detect), but it was certainly not true for the Universe as a whole. Nevertheless, Einstein then went away and tried to make his calculations fit with this ‘Steady State Universe’ that the learned men of his time had assured him correctly described the Universe in which he was living. In the first couple of decades of the twentieth century, the accepted view was that Universe was infinite, and that the galaxies followed no particular pattern of movement, neither expansion nor contraction. In order to make his theory compatible with this received ‘wisdom’, Einstein had to introduce what today we might call a ‘fudge factor’, something that made his calculations comply with observations, or at least what he was told were observations. This he called the cosmological constant.

Physicist George Gamow, in an autobiography called My World Line, and written much later when recollections can get muddled, said that Einstein had said to him that his cosmological constant was the "the greatest blunder of my life." We do not know if Einstein actually said that, but we do know that he did describe his cosmological constant in the following way: Since I introduced this term I had always a bad conscience. I am unable to believe that such an ugly thing should be realized in nature. Gamow by the way, used to see Einstein on a fortnightly basis, when they were both doing secret work for the US government. Einstein was employed by the US Navy evaluating ideas for new weapons submitted by members of the public. Einstein was good at this because he had years of experience as a patent clerk in Switzerland, and Gamow was his courier, bringing the applications to Einstein in Princeton from the US Navy headquarters in Washington DC.

But that was years later, we were talking about what Einstein was doing early in the twentieth century. He had to adjust his ideas that the Universe might be expanding to meet the incorrect advice he was given that it was in a steady state. It might come as no surprise when I say that Einstein was right, the learned men were wrong, and the cosmological factor seems to represent dark energy—a mysterious force—which tends to make the Universe expand, rather than acquiesce to the otherwise ineluctable force of gravity, and collapse. More about dark energy later!

In 1931 Einstein met Edwin Hubble, who convinced him of the truth of the Big Bang idea. As a result, Einstein ultimately rejected his original concept of introducing a cosmological constant to explain a ‘static’ Universe.

This same George Gamow, along with his colleague Georges Lemaitre, was amongst the first influential physicist to have nothing to do with the Steady State or Static Universe. They threw the idea out, to their credit, and proposed instead that all the matter currently in the Universe, originated in an incredibly dense super-atom (literally, the primeval atom). According to their theory, this object exploded, releasing all the matter and energy which we see around us. Lemaitre and Gamow’s theory went further than this. They further proposed that this Primal Atom or Cosmic Egg, which brought about all of the matter and energy in the Universe today, was only about 30-times the diameter of the Solar System. In fact, it was much smaller still. In 1970, Roger Penrose, in collaboration with Stephen Hawking, did calculations which show that the way the Universe is expanding today proves that it began as something extremely small—a point even smaller than the smallest things we know—smaller in fact, than the proton or the neutron found in the nucleus of an atom.

At this miniature level of existence—the zero point, just prior to the Big Bang, Einstein’s theory of relativity breaks down, and can no longer predict events. Everything is a singularity—smaller than a sub-atomic particle—and no theory can describe what happens there. It is important to understand that not only did matter and energy start with the Big Bang, but so too, did time and space. The expansion of the Universe is actually the expansion of the very fabric of space-time itself, with all the galaxies and other material objects embedded in it, like coins in a baking Christmas pudding. As Stephen Hawking, the theoretical physicist who currently holds Newton’s old job, the Lucasian Chair of Mathematics at Cambridge University puts it, since time started with the Big Bang, it is meaningless to ask the question what happened before the Big Bang? Before the Big Bang time didn’t exist. What he means is that before the Big Bang time could not really be defined, because the space-time continuum only began to exist just after the Big Bang. There is, however, much about the Big Bang that we do not know. Big Bang theory can tell us nothing about time zero (the actual bang of the Big Bang). At best, Big Bang theory leaves out the bang. As Brian Greene so aptly puts it: It tells us nothing about what banged, why it banged, how it banged, or, frankly, whether it ever really banged at all¹

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Not only is the Universe expanding, but different parts of it are expanding at different rates. As a rule (Hubble’s Law), the speed of the recession is directly proportional to the distance. If a galaxy is, for example, speeding away from us at 1000 kilometres per second, then one that is twice the distance is speeding away at 2000 kilometres per second. According to Hubble’s Law, some galaxies beyond a certain distance away (Hubble’s distance—14 billion light years) seem to be running away from us with a velocity greater than the speed of light. But hang on! I hear you say, isn’t that impossible? Didn’t Einstein say that nothing could move faster than the speed of light? So wouldn’t that mean a violation of the special theory of relativity? Yes, it would if it were motion, but this is not motion. This is an expansion of space-time itself. Cast your mind back to the analogy of the coins in the baking (and therefore expanding) Christmas pudding. As the pudding expands the coins are changing their position in space, but they are not moving around the pudding. Their motion is due to the expansion of the pudding itself. Now, imagine if you can, a pudding which is expanding faster than the speed of light, and you might get some idea of what seems to be happening in the far parts of the Universe. The galaxies there have an apparent motion which is greater than the speed of light, but actually they are not really moving (if you ignore small local movement caused by gravity), they are being carried by the fabric in which they are embedded. The special relativistic speed limit does not apply to the Universe as a whole. It obeys the general theory of relativity. What this means is that light leaving these galaxies and travelling in our direction will never reach us. Indeed, it will never go anywhere, because although like light everywhere else, it is travelling at 186 000 miles (300 000 kilometres) per second, it can never catch up to the expansion of the Universe. Like the Queen of Hearts in Alice in Wonderland, it is running as fast as it can just to stay in the same place

As far as we can go back, and still maintain our normal concept of time, is to the era of Planckian gravitation—that first flash (or bang) lasting 10-43 seconds, which gave birth to the Universe. Here, in this era of enormous density and temperature, time had not yet gained its definition. Some version of space-time must have existed before 10-43 seconds, but we do not know what form it took. At this time, called Planck Time, all that we now see around us, and much that we don’t see—the entire known Universe—could have been one-billion-times smaller than a proton. The beginning of the beginning, started with a favourable fluctuation in the background foam of space-time, which resulted in a sudden and rapid expansion. At zero time everything was very hot, about 100 billion degrees Kelvin [°K] (the Kelvin scale of temperature starts at absolute zero—273.15°C. The Kelvin degree is the same size as the Celsius degree, hence the two reference temperatures for Celsius, the freezing point of water [0°C], and the boiling point of water [100°C], correspond to 273.15K and 373.15K, respectively). This is one-billion-times hotter than the boiling point of water. At this temperature, all the energy in the Universe was in the form of electromagnetic radiation, with protons and neutrons being transiently created and destroyed, as described by Einstein’s famous equation E = mc².

The initial inflation of the Universe produced something which was essentially empty. For the first 10-37 seconds, there was neither matter nor energy in the Universe, just a rapidly expanding vacuum, in which all the potentialities of the current Universe were mysteriously locked up. There was no light and there was no matter.

About one tenth of a second after zero time, matter began to form as the temperature cooled to only 30 billion degrees K. At this moment, the density of the Universe was 30-times the density of water, and all the energy in the Universe was still in the form of radiation. Freezing out of this energy were, at first, equal numbers of protons, neutrons, and electrons. However, because neutrons which were not part of an atomic nucleus, tended to decay into a proton and electron, eventually the numbers of the charged particles began to increase. The temperature dropped still further, and when it reached 13.8 billion degrees K, one proton and one neutron began to stick together, if only temporarily, to make a nucleus of heavy hydrogen, or deuterium. They formed in this transient way, because almost as soon as they were produced, they were bombarded by other particles, and knocked apart again. All this time, the neutrons which had formed initially, were decaying into protons and electrons, but, by the time the temperature reached an atomically comfortable 1 billion K, at three minutes and two seconds after zero time, with the proportion of neutrons to protons having fallen to only 14 per cent, and it was cool enough for nuclei of deuterium and other light nuclei to stick together. In this way, some of the neutrons were saved from oblivion.

Over the next few seconds of the existence of everything, nuclear reactions took place everywhere, safely saving the remaining neutrons inside the nuclei of helium-4. After this stage, the Universe consisted of about 25 per cent helium and almost 75 per cent hydrogen nuclei in terms of mass, with a trace of other light elements.

This creation of elements (nucleosynthesis) by the Big Bang, stopped at 3 minutes 46 seconds after zero time, and for all of this time, while nuclei were being created, the Universe was entirely dark. Three to five hundred thousand years after zero time, the Universe had cooled to about the temperature of the surface of our Sun (about 6000 °K). At this temperature atoms could form for the first time, because the electrons had slowed down sufficiently to enable the nuclei of the light elements to capture them. When this happened, matter was coupled with energy, and light streamed through the Universe for the first time. The Universe took only 0.000000000000 1 (10-12) seconds to expand from the size of a subatomic particle to the size of our Solar System, and it has been expanding ever since.

How were the elements formed? Immediately after the Big Bang, the Universe consisted mostly of neutrons compressed to an extremely high density. These started to decay ( beta decay) producing electrons and protons (or hydrogen nuclei). Some of the hydrogen nuclei (protons) captured a neutron to produce hydrogen’s heavy isotope, deuterium. Two deuterium nuclei then collided to form the other heavy isotope of hydrogen, tritium (producing hydrogen in the process). Then a collision between tritium and deuterium resulted in a helium-4 nucleus, and the result of two colliding deuterium nuclei produced helium-3 nucleus. Most of the helium in the Universe today, as well as most of the lithium, was produced in this ancient alchemist’s crucible.

About one second after zero time, protons and neutrons bound together as nuclei of hydrogen, helium, lithium, and deuterium. Three minutes after zero time, matter and radiation coupled together, and the first stable nuclei began to form. About 300 000 years after zero time, stable atoms formed, and the Universe lit up, as fusion began. Then, one thousand million years after zero time, matter clustered to form stars and proto-galaxies. The stars began to synthesize heavier nuclei, and the Universe as we know it, then became recognizable. But how, you might ask, did all the elements common today, come to be? Where did the iron in our motorcars come from? Or the gold in our banks? The answer is that all these elements were forged in stellar furnaces.

So the Big Bang—a great expansion of everything—started from something extremely small, and produced everything we know today. At the level of the very small, the physics of quantum mechanics predominates, and at the level of the very large, Einstienian relativity predominates. This is why Einstein’s relativity cannot comment on what happens just after the Big Bang—things on this scale are too small for relativity to be relevant. In between relativity and quantum mechanics lies Newtonian physics, which applies when things are not too big or too small, or moving too fast—the world of Newtonian physics is the world with which we are familiar—the one of planets, solar systems, beings, and the things of this world.

To those that have, more will be given seems to be a universal theme because those areas of the Universe in which matter is concentrated are expanding slowly, compared to those areas in which it is not. Such dense areas became more densely packed with matter. These are the places, where today we see galaxies, clusters of galaxies, and the like. What about the other parts of the Universe? That part which represents most of it, which seems to be empty. Is it really so empty? Perhaps now, it is time to talk about the dark side of matter and energy, that is, dark matter, and dark energy.

But first let me ask the question: will the cosmic expansion go on forever, or will we reach a point where the expansion stops, and perhaps, then contraction starts, resulting ultimately in an infinitely shrinking Universe—another Primal Atom—the Big Crunch? It seems from current scientific knowledge that the Universe will expand forever. There simply does not appear to be nearly enough matter in the Universe to precipitate a Big Crunch. This expansion of the Universe seems to be powered by dark energy, and the current state of the Universe is a balance between the cosmic force which wants to cause the Universe to expand—dark energy, and the force which wants to cause it to contract—dark matter. Dark energy is a mysterious form of universal energy, which is not well understood, but seems to be what Einstein was referring to, when he spoke about his ‘cosmological constant’. So, it wasn’t a ‘fudge factor’ at all, nor was it a ‘great blunder’. Einstein was right all the time, and his cosmological constant represents the force of dark energy acting to inflate the Universe, now at ever increasing speed. In addition to dark matter and dark energy, the Universe is filled (even the empty bits) with force fields, but more about them later.

The Universe was not always expanding so rapidly. At about 7 billion years ago (7 Gya), the expansion which had been taking place since the Big Bang began to slow down. It did so, because at the time the Universe was dense and hot, and the dark matter in the then smaller Universe was sufficient to slow the cosmic expansion, but since then, the expansion has sped up markedly, and, indeed, is speeding up more and more with time. The reason for the change is that because of cosmic expansion, dark energy is much more common in the Universe than dark matter. It might surprise you to know, that all that we can see in the visible Universe represents less than 1 per cent of the total stuff of the Universe. Seven billion years ago the Universe was composed of two thirds dark matter and one third dark energy. Now the situation is reversed. It is now composed of one third dark matter and two thirds dark energy.

Ordinary matter—protons, neutrons, and electrons—the stuff that makes us up, and everything around us that we can see—represents a mere 5 per cent, and all the rest is made up of that mysterious dark energy. We, and everything we know, are like impurities floating on a vast sea of dark energy. All the visible reality is no more than flotsam left over from the creation of the Universe.

The current preponderance of dark energy can be expected to increase as time goes by, and the expansion of the Universe is set to continue forever, indeed at increasing rates. Eventually, everything in the Universe will become more and more isolated, as its contents just fly apart. We will have the Big Rip, and the Universe will end its days as a cold carpet of fundamental particles reaching forever. But don’t worry, that will not be for a few hundred billion years, by which time, the Earth will have long ago disappeared, the Sun also, will long ago have become a cold, dark White Dwarf star, and humans will have long ago ceased to exist—they would have become extinct, or rendered themselves extinct, or they would have evolved into something