In the forty-three years and ten incarnations of The Doctor, David Tennant is only the second Scottish actor to portray the eccentric adventurer (following Sylvester McCoy). Born in Bathgate in 1971, to a Church of Scotland minister and future moderator of the General Assembly, David grew up in Renfrewshire and was educated at Paisley Grammar School before attending the Royal Scottish Academy of Music and Drama in pursuit of his childhood dream of becoming an actor. As a boy, his passion for acting was partly fuelled by an ambition one day to play the lead in his favourite programme, Dr Who, an ambition he achieved in March 2005 when Christopher Eccleston’s brief stint at the helm of the TARDIS came to an end and David spoke his first line as his boyhood hero, “Hello! New teeth, that's weird.”

With Scotland’s rich tradition of expertise and innovation in science, it is not necessary to look to science fiction to find local heroes who have shaped and challenged mankind’s understanding of the nature of time. Scotland, and the worldwide Scots diaspora have had a striking impact on the history of science, not least in giving us a picture of deep time that we now take for granted, but that was revolutionary when first mooted by radical thinkers and scientists.

Prior to the nineteenth century, most people in Europe accepted the Old Testament account of creation without question. Chronologies compiled based on the Biblical version of events dated the Earth, and indeed the entire universe, as being in the order of 6,000 years old. The most famous Biblical chronology, published in 1650 by Bishop James Ussher, placed the creation of the Earth on the evening of 22 October, 4004BCE. This comfortable understanding of the world was thrown into disarray when the new sciences of geology and paeleontology set out to investigate the age of the Earth by studying the Earth itself, rather than ancient texts. This early application of empirical methodology by Scots scholars, set science on the road to our current understanding of the antiquity of the planet we call home.

One of the earliest Scots scientists to call into question the canonical interpretation of the Earth’s age was Edinburgh physicist James Hutton. Emboldened by the inquisitive spirit of the Scottish Enlightenment that transformed first Scotland’s, then the world’s intellectual life in the 18th century, he observed the geological evidence and saw a world in constant flux and of unimaginable venerability. What is now dry land, he reasoned, had once been the ocean floor; and what is now deep seabed would one day be plains and mountains. Hutton saw this as a continuous process, devoid of a single act of creation: in his 1785 work, Theory of the Earth with Proof and Illustrations, he asserted that the Earth had “no vestige of a beginning – no prospect of an end”. Although somewhat contradicted by modern thought, Hutton’s ideas were astonishingly prescient, and went on to influence later thinkers, not least by throwing the question of the age of the Earth open to scientific inquiry, where it had previously been a matter of scriptural dogma.

Another early Scots investigator of deep time was William Thomson, Baron Kelvin of Largs. Lord Kelvin was a giant of the era in physics, and is now best known for devising, and lending his name to, the Kelvin temperature scale, the absolute scale of temperature now used throughout the sciences, but he also applied his keen understanding of heat and temperature to estimate the age of the Earth. Kelvin’s method assumed that the Earth was born of a hot, molten state, and that it had been gradually cooling ever since. Based on the Earth’s current temperature, he initially reckoned the Earth to be between 20 and 400 million years old, although the figure was later revised downward such that he opined in 1862, “we have . . . good reason for judging that [the creation of Earth] was more than 20 and less than 40 million years ago, and probably much nearer 20 than 40.” This figure brought him into conflict with Charles Darwin and his fellow proponents of evolution by natural selection, who realised that their theory on the origin and diversity of life required more time to have passed than Kelvin’s dating allowed.

The missing factor in Kelvin’s equations was first discovered and studied in the late 19th and early 20th centuries: what Lord Kelvin never imagined was that the Earth was being heated from within, by radioactive minerals. The early study of radioactivity, and its invaluable usefulness in dating the Earth, also benefited from Scots’ influence.

Nobel prize-winning physicist Ernest Rutherford was born in New Zealand in 1871, the son of Scottish wheelwright and engineer James Rutherford. In a career that made him one of the world’s best-known and respected scientists, he pioneered the orbital theory of the atom, discovered the concept of radioactive half-life, became known as the father of nuclear physics, and was described by no less a figure than Albert Einstein as “a second Newton”. It was his discovery of half-life (the phenomenon that radioactive elements decay at a predictable logarithmic rate), that proved decisive in determining the true age of the Earth, by its extension to the modern technique of radiometric dating.

This predictable decay allows modern geologists to date rocks with remarkable accuracy. Interestingly, one of the most reliable elements used in radiometric dating, Strontium, is named after the Scottish village of Strontian, in Lochaber, where strontanite (the element from which Strontium is refined) was first mined. Several different radiometric methods are used, and independently agree on an age of around 4,600 million years for the Earth. It is difficult to imagine such a vast expanse of time, but if it were compressed into a single day the entirety of recorded human history would fit into a little over one tenth of one second. Scientists now believe that the entire solar system is of a similar age, thanks in part to the samples of moon rock brought to Earth by another diaspora Scot, Neil Armstrong.

To this day, Scotland is leading the way in Earth science: Scotland’s elite universities, combined with her unique native geology, make her a world leader in both academic and practical research.

Earlier this year, Daniel Campanile and Kate Dobson, PhD student’s with Glasgow University’s Earth Surface Dynamics research group, won first and second prizes respectively for Best Oral Presentations at the quadrennial European Conference on Thermochronology in Bremen, Germany, seeing off competition from all over the world. Following in the footsteps of Lord Kelvin, thermochronology uses the study of heat to measure the age of the Earth.

Also at Glasgow, Dr Tim Dempster is conducting groundbreaking research into the history of the Earth’s crust that will give geologists worldwide an invaluable new tool in researching the movement of the crust, impacting on such diverse fields as the safe disposal of nuclear waste, oil prospecting, and the mining of important minerals. Using samples of the mineral apatite from the Outer Hebrides, Dr Dempster has employed state-of-the-art electron microscopy to study the rocks’ surface in unprecedented detail, allowing the history of their behaviour within the Earth’s crust to be analysed in more detail than ever before.

Of course, not all the learning is done in the rarified and sometimes seemingly impenetrable world of academe. Since 1999, Edinburgh’s Our Dynamic Earth museum has been making Earth science fun and accessible for visitors of all ages. Waggishly dubbed the “Scottish Millennium Dome” by locals due to its striking tented roof, the attraction has enjoyed rather more success than its short-lived southern counterpart. Seven years on, Our Dynamic Earth is still attracting visitors to enjoy interactive learning of the prehistory of the Earth and the life upon it. Visitors can experience a simulated journey to the centre of the Earth; travel back in time to see the beginnings of the universe from their very own TARDIS; marvel at the dinosaurs and other fabulous beasts that once roamed Scotland; trace the meanderings of the land that is now Scotland through the shifting oceans and continents of the ancient world; and be surprised to discover that Scotland was once located near the South Pole. We can only rejoice that it now rests somewhere a little nearer the Equator.

Courtesy of Scotland.org

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