November 30, 2009
The age of the Earth-1: The history of the search
(My latest book God vs. Darwin: The War Between Evolution and Creationism in the Classroom has just been released and is now available through the usual outlets. You can order it from Amazon, Barnes and Noble, the publishers Rowman & Littlefield, and also through your local bookstores. For more on the book, see here. You can also listen to the podcast of the interview on WCPN 90.3 about the book.)
It has been awhile since I have made the regular readers of this blog suffer through a long multipart series exploring a particular question. But my post on the interconnectedness of scientific theories spurred me to thinking about finding a good example, and the age of the Earth popped into my head as almost perfect. This series will be interspersed with posts on other topics.
The process by which science came to be interconnected can be described as beginning with a transition from 'early modern science' (which I have chosen to date as beginning with Galileo around 1600 CE) to 'modern science', that started around 1800 as new disciplines like geology, chemistry, and biology started to become mature and independent, developing their own theories and research protocols. But starting around 1900 a new trend emerged, which I will call 'late modern science', in which these somewhat independently developing fields began, as they grew, to encroach on each other's territories, and the need to seek consistency among them became apparent. After some initial crises of incompatibility, by around 1930 the theories had started to mesh reasonably well.
The reason modern scientific theories, unlike those of the past, are so robust is that they are now part of an interconnected web of theories that span many disciplines that formerly were separate. The age when each sub-discipline in science could develop on its own with little reference to other sub-disciplines is over. Now they are all linked together with varying degrees of separation. In addition, there are also general, over-arching scientific principles (the laws of thermodynamics, the atomic theory, quantum mechanics, and relativity to name a few) that no one theory can ignore or unilaterally over-ride.
Hence any attempt to reject any one theory in that web and replace it with another without taking into account the impact of this move on other theories is doomed to fail. This is where creationists stumble badly. They tend to view scientific theories and facts as modular units in which any one they dislike or which obviously disagrees with the Bible or Koran or other religious text can be plucked out and replaced with one that is more congenial. Dislike evolution? Remove it from the scientific pantheon and put special creation in its place. Don't want to believe in an old Earth? No problem. Replace it with Ussher's calculation of 4004 BCE as the year of creation.
But hold on a minute there, my creationist friends. You are no longer living in the 17th century and so your freedom to pick and choose is long gone. Determining the age of the Earth is precisely one of those investigations that beautifully illustrate the interconnectedness of science and why efforts to change the scientific consensus in such an ad hoc manner are bound to fail. In fact, estimating the age of the Earth provides a beautiful example of how scientific theories have made the transition from early modern to modern to late modern, and this series of posts will illustrate that sequence.
In his classic book The Structure of Scientific Revolutions, Thomas Kuhn pointed out the important role that scientific textbooks play in our understanding of science. They are usually re-written after each scientific revolution and in addition to elucidating how the latest theory works, their other purpose is to persuade the reader of the worthiness of the new theory, why it should be accepted as the right one and why the previous ones were wrong. So textbooks are also designed to serve at least partly a propaganda purpose. But in doing so, they necessarily distort scientific history. As part of this attempt at persuasion of the worthiness of the latest theory, textbooks often act as if the questions which the current theory addresses successfully are the ones that have always concerned (and baffled) scientists from the beginning of time, and then proceed to explain why each of the earlier theories failed to get the right answer before the current one came along and solved the problem. In reality, the questions that the new theory successfully deals with often came into sharp definition concurrently with the new theory.
This is the case with the age of the Earth. We have now pinned it down accurately (we think) to the current value of 4.55 billion years. This is quite a feat and reflects great credit on the current scientific theories that have converged on that number. We now think that the age of the Earth is such an obviously important question (after all, we have devoted enormous resources to pinning it down) that we cannot imagine that people were not always trying to figure it out. But in fact, the idea that the Earth has a definite age at all, let alone a number that can be actually measured scientifically, is a relatively new idea, that has been taken seriously only within the last 150 years or so.
For a long time in history, although most ancient religions had their cosmogonies, the idea of estimating the age of the Earth and giving it a definite number of years was not an important question. In the early days, it used to be that the age of formation of the Earth, of the universe, and the appearance of humans were not really distinguished but are thought to have all occurred in some distant, unspecified past, perhaps even infinitely far back.
The books, The Chronologers' Quest: The Search for the Age of the Earth (2006) by Patrick Wyse Jackson and Lord Kelvin and the age of the Earth (1975) by Joe D. Burchfield examine some of those early beliefs. Very often they involved elaborate stories about how the universe came into being, such as an egg hatching and giving birth to the Sun, but no indication of when that happened or even if there was an actual starting time. Many of them had cyclical ideas of the universe in which it either oscillated or went through repeated creation and destruction events so that what we currently have is just the latest cycle but the process would have been continuing back into eternity. Hence fixing a creation date did not even make sense.
But things changed with the arrival of Christianity, as I will discuss in the next post in this series.
(Main sources for this series of posts are The Chronologers' Quest: The Search for the Age of the Earth (2006) by Patrick Wyse Jackson and Lord Kelvin and the age of the Earth by Joe D. Burchfield (1975).)
POST SCRIPT: Homeopathy explained!
I discussed homeopathy before but now a homeopathy 'expert', described as an eye doctor, tries to explain how it works, which consists of snowing her audience with scientific jargon. In the process she manages to mangle almost all of physics. Although what she says makes no sense at all, it is an illustrative example of how people will believe what they want to believe, especially if it is presented authoritatively by someone who seems to have some sort of credentials.