The Five Billion Year Story is about how we came to be and our place in the cosmos. It is a story of the emergence out of a sea of change of local islands of form where patterns persist. The Five Billion Year Story is about the formation of the Earth, the development of life and then the development of humanity. 'Before the Beginning' is the story of how the stuff that makes up the Earth came into being.
Y: Is this a true story?M: This is my own understanding, the story I like best, based on the work of other people, mostly scientists of the 20th Century. Parts of it are made up of observations (scientific experiments) but mostly it is made up of theories which link those observations and extend them way beyond the contexts in which they were originally found. I think the important question about the theories is how consistent they are with the observations, and how widely applicable.
The 'Truth' of this or any other story in an absolute sense, is a philosophical issue we will consider very carefully later.[1]
We people, and the other animals, continually re-form ourselves from the food we eat (which comes from other animals and plants) plus water and oxygen from the air. The plants re-form themselves from water, air and trace minerals from the soil.
The air is continually re-formed from gases taken in and given off by life, through exchange from the sea, volcanoes, and now from the by-products of human culture. The waters of the seas, lakes and rivers too are in a state of continual change. Over a much longer time scale, even the land changes. Continents drift about on the surface of the Earth, colliding with one another. Mountain chains rise and are worn away.
All of these forms, living and inanimate, are formed and re-formed from smaller parts. We complex living forms are composed of organs and tissues, which in turn are composed of cells, which in turn are composed of molecules, which in turn are composed of atoms, and so on. Each level of organisation brings with it much structure that comes from the lower levels from which it is made, plus new organising principles specific to its own level. Each level of organisation can form only when the conditions are right for it.
The Five Billion Year Story is about the emergence of the succession of levels that makes up complex life through the history of the Earth. 'Before the Beginning' is about the emergence of the inanimate lower levels, which appeared before the formation of the Earth.
Y: Is this really necessary? Isn't it going rather far beyond the main area of the book?M: If you think of the book as about modern human life and the possibilities for change, then this part seems very distant. But it sets the context for the rest. It shows how we as individuals and as a species are part of a larger whole and shows some of the interconnections.
Also, it is a good story. It is the modern equivalent of the creation myth. And I hope you will find that, unlike many tellings of this story, it does not leave the impression of a mechanical universe dominated by random events.
The Earth formed out of a spinning cloud of dust about 5 billion years ago. It formed from the edge of that cloud, most of which settled at its centre to form the Sun.
The material of the Sun, mostly hydrogen, contracted and became hotter until the Sun ignited in a thermonuclear reaction, like a giant hydrogen bomb, which still continues today. The remainder of the cloud (only a fraction of a per cent of the total), dispersed over thousands of millions of miles, settled into a disk, and then into clumps. The largest of these clumps formed the 9 major planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto, spinning around the Sun in elliptical orbits.
The Sun, the major planets, plus many smaller bodies: asteroids, comets, and dust, are all locked together by their mutual gravitational attraction, circling about each other as our Solar System.
On a much larger scale, our Solar System is one of perhaps 100 billion such solar systems forming the Milky Way Galaxy, again held together by their mutual gravitational attraction. The distances to these other solar systems are so great that we can only see their central stars. We do not know if they too have planets, but if they were formed by the same processes as our Solar System, it is likely that they do.
Galaxies contain far more than stars or solar systems. The space between them, which appears 'empty' compared to the density of material on Earth, actually contains clouds of dust and gas on a vast scale. These clouds are in constant motion within the galaxy.
Within a galaxy, stars form, burn brightly for awhile and then die out. The larger ones have relatively short lives and may end in a massive explosion, a super-nova. These explosions add to the interstellar gases, and create shock waves which blow the gas clouds about in giant bubbles. Where the clouds of gases collide, regions of higher density are created from the impact. Out of these, new stars and solar systems form.
Thus the current picture of the life
of a galaxy is of continual change, continual re-formation of the parts which
make up the galaxy. Stars, clouds of gas, and other structures form and then
dissipate or condense and then collapse into black holes. Later generations
of stars are formed from the debris of earlier ones, in regions where the chaos
throws up sufficient density and quantity of matter. All of what makes up you
and I and the rocks we stand upon was once part of the distant, long-dead stars
out of whose fragments our Sun and Solar System formed.
Metaphor 1 - The WhirlpoolThis image of a galaxy composed of stars and other structures which form and re-form has the character of a Whirlpool. Picture a swirl of water, perhaps in a river near an outcrop of rock. The whirlpool appears when the flow of the river is at certain levels. The form of the whirlpool is clear, as it dances about, changing slightly about a general shape. Take a snapshot of the whirlpool and you will see the drops of water which make it up at that instant. Perhaps a small twig or leaf will mark some drops. Another snapshot, a minute later, will show a similar form, some of the same drops of water but in different places, and many new drops of water. The drops become part of the whirlpool and then leave it. Through its lifetime, the whirlpool is continually re-formed from the water of the river. (Drawing of The Whirlpool) A galaxy is the same kind of form, continually re-forming. I have alluded earlier in this section to animals and plants as continually re-forming from their parts and will develop that image further later in the book. This image of a form which is continually re-formed rather than fixed and static will appear in many places later in the book. I shall refer to it as 'the whirlpool metaphor'. I find it to be a very useful conceptual tool. |
Y: What about the Big Bang? Isn't that part of this story?M: The Big Bang theory really is getting very far from the main ideas of this book. Also, I think it is possible that over the next few years quite different ideas may come to replace it. But, since you ask, I will include a brief summary of it.[2]
On a still larger scale, the Milky Way Galaxy is only one of perhaps 100 billion galaxies in the Universe. There appears to be structure at these larger scales too: clusters of galaxies and even clusters of clusters of galaxies.
The galaxies all appear to be flying apart from one another. Those farthest away from us appear to be moving away at the greatest rate so that they all seem to be moving away from each other. This image of an expanding Universe has been developed greatly in recent decades, and has developed into the 'Big Bang' theory. According to the Big Bang theory, if we work backwards from the expansion we can observe, there was a time when all the galaxies were much closer to each other. Still further back, there was a time when all the matter in all the galaxies was in one region. Ultimately, before that, everything started together, in a single original moment that was the Big Bang.
In the Beginning was the Big Bang... and in that original moment there was no form: no matter, no time, no space. As the Universe began to expand, the smallest forms we know about appeared from this chaos.
Y: What are the smallest forms? How far down can you go?M: I am reasonably comfortable with molecules, which make up all the common substances we know and which in turn are made up of atoms. Some substances are made up of only one kind of atom, like hydrogen, helium, iron, copper, gold, carbon, oxygen, nitrogen, etc.
I'll go below that to atoms as made up of a central nucleus surrounded by a cloud of electrons. The atoms in a molecule are bound together by sharing some of the outer electrons in the cloud. (That is what Chemistry is all about.)
The nucleus of each atom is made up of protons and neutrons. The kind of atom it is (i.e. iron, copper, hydrogen, helium, oxygen, etc.) depends upon the number of protons in the nucleus.
I think that's all we need to know for the formation of the Earth and later for the formation of Life. Anyway, my understanding of the other subatomic particles and below that, of quarks, isn't worth writing about.
By about 100 seconds after the big bang, the new universe had expanded and cooled to the temperature now found only in the hottest stars, around one thousand million degrees. Under these conditions electrons, protons and neutrons could stabilise as well as some of the simpler combinations of them. Thus the only materials which were around then were hydrogen (one proton), and some deuterium (a form of hydrogen with one proton and one neutron), helium (two protons and two neutrons formed from two deuteriums), and a little of some of the next heavier elements: lithium (3 protons and 3 or 4 neutrons), and beryllium (4 protons and 5 neutrons).
Conditions for the formation of these elements lasted only a few hours. A million years or so passed before conditions were right for the next stage, when out of this sea of particles, the galaxies and first stars were formed.
As the sea of first particles swirled around, clusters appeared: whirlpool-like-forms which condensed under their mutual gravitational pull. These clusters were the first galaxies. Within the galaxies, smaller clusters formed, local contractions within the overall expansion of the Universe.
As these clusters grew smaller and hotter, the particles in them were forced closer to each other. Eventually, they reached conditions in which hydrogen atoms could combine frequently with each other to form helium. Hydrogen into helium is the reaction of a hydrogen-bomb, but here it was on the scale of a star. The first stars lit up.
In those reactions in the centre of the first generation of stars, not only helium nuclei were formed, but also a small proportion of somewhat larger and heavier elements, like carbon, nitrogen and oxygen. However, the necesssary conditions for the formation of much heavier elements, like iron, copper, on to lead and uranium, are far more extreme. They only occurred in the death throes of the largest of those early stars, which exploded as supernovae. The conditions were then set for the formation of second and third generation stars, like our Sun.
1
There has been a lot of work in the philosophy of science on how to interpret
the 'truth' of scientific
theories, especially since new
theories regularly displace old ones. The seminal book by Thomas
Kuhn, The structure of scientific
revolutions led to much discussion and debate. A more recent
book by Stegmuller, The Structure
and Dynamics of Theories, offers much more clarity: it is wide
scale coherence and consistency which
are significant, not 'absolute truth'.
2
I recommend Stephen Hawking's A Brief History of Time, Bantam,
1988, for a good current
description of the Big Bang
theory. It was my principle source.