Quantcast

«

»

Dec 11 2009

The age of the Earth-7: The Earth starts getting younger again

(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.)

For previous posts in this series on the age of the Earth, see here.

Darwin and Wallace published their theory of natural selection at a time when it seemed that they had all the time they needed for their theory of natural selection to work. But that window of freedom of long geological times was soon to close and, starting around 1860, newer estimates of the age of the Earth started to shorten it considerably. Part of the reason was undoubtedly a backlash to the success of Darwin’s theory of evolution that, within a decade of the publication of Origins in 1859, had persuaded almost the entire scientific community that evolution was a fact and that its basic idea that all organisms arose from descent with modifications from common ancestors was true.

Acceptance of evolution did not mean that people had given up on god altogether. Most people, including many in the scientific community, were still religious and sought to find ways to preserve a role for god. While they accepted evolution as a fact, what these people found difficult to stomach was Darwin and Wallace’s mechanism of natural selection as the driving force for the process, because this implied that evolution is directionless. Especially troubling was its implication that humans were an accident, not guaranteed to appear, and thus could not be part of any original design plan that god would have had.

There were competing models that preserved this idea of design and thus had a potential role for god and these were the ones favored by religious scientists. Theistic evolution (in which god guided the process of evolution in unspecified ways), orthogenesis (in which it was postulated that organisms contained within themselves a directional mechanism that resulted in continuous improvement), and Lamarckism (in which the acquired characteristics of an organism were somehow transmitted to its progeny) all had the possibility of a role for god, or at least had some directionality that implied that humans were the inevitable result of a grand plan. Natural selection offered no such consolation.

What religious scientists realized was that the smaller the value arrived at for the age of the Earth, the more unlikely it was that natural selection could be the mechanism for evolution. A younger earth implied the need for some agency to speed up the process of evolution and what could that agency be other than god? (In this respect, they were much like modern day intelligent design creationists.) And so there was a strong motivation to lower the upper limits on the age of the Earth and thus strengthen the case for the alternatives to natural selection.

But it must be emphasized that even this was a far cry from the efforts of present day creationists to resurrect a 6,000 year-old Earth. Even the religious scientists of that earlier time had by then rejected that idea with its supernatural catastrophes as absurd and no serious scientist for the past 200 years has even considered that possibility (Burchfield, p. 37). Anyone who argues for such a young Earth has rejected science altogether. These religious scientists accepted evolution as a fact. What they were hoping for is that their methods of estimating the age of the Earth using purely scientific methods would yield results that were of the order of a hundred million years or less, which would be too tight a timescale for natural selection to work.

It was the physicist William Thomson (1824-1907), better known by his later title of Lord Kelvin, who seriously threatened to overthrow the natural selection mechanism for evolution. Kelvin was opposed to evolution by natural selection because it seemed to rule out design in nature and thus left no role for god (Burchfield, p. 33). Kelvin had already established a reputation as one of the foremost physicists of his day, pioneering important work in the study of thermodynamics, especially with the first law (that dealt with the conservation of energy) and the second law (that dealt with the dissipation of heat energy and the consequent directionality of heat flow). So his words were taken seriously, since physics was seen as the most well-established of scientific disciplines.

What Kelvin did was to apply the laws of physics to three different kinds of calculations for the age of the Earth: calculating the age of the Sun to set an upper limit, examining the role that tidal friction played in shaping the Earth, and treating the Earth as a solid cooling body, all of which gave him similar results, persuading him that he was on the right track (Jackson, p. 200).

In the most important of those methods, the cooling method, what Kelvin did was similar to the idea of Buffon in 1778, except that the laws of physics, especially thermal physics, had advanced considerably since Buffon’s time, and Kelvin himself had played a major role in that advancement. Kelvin assumed that all the Earth’s (and Sun’s) energy originated as gravitational and mechanical energy in the particles and possibly meteors that preceded its formation, and that as they coalesced to form the Earth, this gravitational energy was transformed into heat energy that made the Earth into a hot molten ball. The Earth then gradually cooled and solidified as this heat was slowly radiated away into space.

Knowing the mass of the Earth and the Sun and making various assumptions about the initial kinetic energy of the particles, the state of the Earth’s core, and the rates of conductivity of heat from that core to the surface and radiation into space, in 1862 Kelvin came up with upper limits for the ages of both, captured in his statement that the Sun “has not illuminated the earth for 100,000,000 years, and almost certain that he has not done so for 300,000,000 million years.” He also estimated that the Earth was somewhere between 20 million and 400 million years old, with the likely figure being 98 million (Burchfield, p. 36). In 1868, he revised his calculations and made an even stronger statement, that the Earth was no more than 100 million years old (Burchfield, p. 43). He thus flatly contradicted Darwin’s calculations of 300 million years for the time taken for the denudation of the Weald.

Kelvin had thrown down the gauntlet to the geologists and biologists and the next fifty years would result in a struggle to see which side would emerge the winner: the young Earthers of that time (which meant ages of less than 100 million years, not the ridiculous 6,000 years of the present-day creationist young Earthers) or the old Earthers.

(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: Playing dumb

If there is anything more annoying than people who pretend to be smarter and more knowledgeable than they are, it is people who pretend to be stupider than they are.

What is particularly sad is that Fox News must think their viewers don’t like people who actually know stuff and would prefer the stereotypical dumb blonde.

<td style='padding:2px 1px 0px 5px;' colspan='2'Gretchen Carlson Dumbs Down
The Daily Show With Jon Stewart Mon – Thurs 11p / 10c
www.thedailyshow.com
Daily Show
Full Episodes
Political Humor Health Care Crisis

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>