Faith and science 2: cosmological evolution

cosmic_evolution

If science is defined as a method or project based on the assumption that there are laws of nature that can be defined mathematically and discovered experimentally then what it produces is a steadily richer set of descriptions of aspects of what exists. These descriptions themselves are modified as new theories replace discredited ones but the observations that enable them are preserved and re-thought rather than abandoned. Thus our basic model of the solar system has a lot in common with that of Newton even as its theoretical underpinning has been totally transformed. We still plot orbits of the planets around the Sun even as the nature of gravity has been totally rethought and the idea of the Sun as stationary been replaced with one in which the Sun itself is part of a complex galactic system in motion both around its own centre of gravity and with respect to other galaxies.

This second part of our series on faith and science touches on two domains of contemporary scientific description, cosmology and biological evolution, and attempts to integrate them into a single “story of everything” before reflecting on the implications of this story for Christian faith.

It is now thought that everything we can observe (the Universe) had its origins in a single event 13.8 billion years ago usually called the Big Bang. At that point there was a single undifferentiated point in which all the matter-energy that now exists (remembering that matter and energy are convertible into one another by the formula {\displaystyle E=mc^{2}} where E is energy, m is mass and c is the speed of light). The space into which this was compressed, which was all the space that then existed, was smaller than the smallest particle. The laws of physics that govern our reality did not yet (could not yet) apply and the forms of matter and energy with which we are familiar could not yet exist.

There was a  rapid expansion and cooling of this initial state and after something like 1 microsecond the energy levels dropped sufficiently so that elementary particles (protons, electrons and neutrons) were able to exist stably and within a few minutes the first nuclei of elements (hydrogen and helium) “condensed” out of the soup of sub-atomic particles so that the expanding universe could be thought of as a gas cloud, although this process was not completed for some hundreds of thousands of years. No more complex structures than that had yet come into being.

There followed a period of structure formation when, over very long periods, slight differences in the density of the gas cloud led to gravitational forces pulling large amounts of hydrogen and helium together into galaxies and stars. The best estimate for how long it took for the first stars to come into existence is 200 million years. Sufficient matter had by then been brought together by gravity for nuclear fusion to begin, releasing energy and creating atoms of a range of elements heavier than hydrogen and helium. These heavier elements are released both during the life of a star and more especially when it comes to the end of its life and explodes as a super-nova.

The galaxy of which our Sun is part is thought to have formed 13.6 billion years ago and our Sun to have ignited within it about 4.5 billion years ago with the earth and the other planets being created as part of the same process which drew together heavy elements from the remnants of an earlier generation of stars within the galaxy.

The first appearance of life on earth is thought to have occurred between 3.8 and 4.1 billion years ago. There is no consensus on how the transition to self-replicating life came about. The chemical building blocks (organic chemicals) are widely dispersed throughout the universe but the processes whereby the complex processes of life appear have not been determined.

The “last common ancestor” of all current living things is thought to have been about 3.5 billion years ago and was probably a single-celled organism most similar to a modern bacterium. Photosynthesis producing oxygen evolved among the bacteria around 3 billion years ago and began to transform earth’s atmosphere. By 1.2 billion years ago sexual reproduction had emerged among the single celled organisms and by 800 million years ago multi-celled organisms had appeared.

At 500 million years ago the first evidence exists for life that could leave the water and shortly after that for vertebrate fish with true bones and then for land-based plants. Before 350 million years ago the earth began to resemble its current state, with plants and animals including insects on the land. At around 250 million years ago a major extinction event wiped out around 90% of then existing species. A second major extinction event before 200 million years ago allowed the rise of the dinosaurs.

At 66 million years ago another large extinction took place that wiped out most of the dinosaurs and made space for the rise of the mammals, birds (and ants!). At 35 million years ago another big change includes diversification of grasses and of mammals with many modern types appearing.

Somewhere between 65 and 55 million years ago the hominims, which include the chimpanzee, modern humans and the totally extinct Australopithecenes first emerged.  The last common ancestor of humans and chimpanzees (our nearest living relatives) is thought to have been 4 to 8 million years ago. The first emergence of the genus Homo sapiens is dated to about 2 million years ago with biologically modern human beings (people genetically identical to us) appearing in Africa about 250,000 years ago. The migration of Homo sapiens out of Africa is thought to have happened 50,000 years ago and the last other human species (Neanderthal) to have become extinct 30,000 years ago.

A distinction is made between biologically modern humans and behaviourally modern humans. Behavioural modernity is a way of life recognisably continuous with all modern humans. This is a controversial and much debated distinction but behavioural modernity is generally thought to include; abstract thought,  planning, trade, cooperative labor, body decoration, control and use of fire. Along with these traits, humans possess a heavy reliance on social learning. Archeological markers of these traits are accepted as; burial of the dead, fishing, figurative art, use of pigments for self-decoration, use of bones for tools, transport of resources over long distances, blade technology, diversity, standardization, and regionally distinct artifacts, hearths, and complex tools.

Whether behavioural modernity emerged suddenly, about 50,000 years ago, or gradually culminating at that time is a matter of debate. In either case it was not present at the first evolution of biologically modern human beings and was present at around the time of the migration out of Africa. It is also generally agreed that some kind of religion was present no later than 30,000 years ago with some scholars claiming to have identified evidence of religious practices even before the evolution of Homo sapiens.

The next major event in this story is the so-called Neolithic Revolution of around 12,000 to 10,000 years ago. At that time human beings began the transition from a hunter-gatherer way of life that involved them getting their food from the existing environment to an agricultural way of life where they controlled and tended their sources of food (primarily wheat and domesticated animals). These first agricultural societies began a process of cultural evolution that brings us to the current day.

Over the next four sessions we will explore the implications of this picture for theology.

  • We will consider what it means for our ideas about a creator God and his relationship to Creation when we recognise that Creation is not and has never been stable. Right down to the most basic physical constitution of the Universe we see processes of change and development within time that still continue.
  • We will think about the nature of human beings and the relationship between the modern scientific view of them and the special place they occupy in Christian theology as the “image of God”. This will involve thinking about modern neuroscience and the puzzle of consciousness.
  • We will think about ideas about the ultimate destination and purpose of the Universe/Creation in light both of scientific projections and of our tradition of thinking about the End
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