Sunday, 26 March 2017

Week 25: (20th March to 26th March 2017) or 'Dating the Past'

Those who are successful in conquering the fortress of time by flying vessels back to the past and reacquainting with the tides of history, have often found themselves sitting on shelves marked Science Fiction or planated into large screens, surveyed by faces stuffed with popcorn. Those who proclaim to be time-travellers are quickly netted up from the streets of reality and pressed into the pulped fibres of books and comics to be sold as a fantasy. Little do those who govern book stores know that time travel is indeed achievable and that a vessel to ship one back to distant times already exists. It's called the 13:41 to Oxford. It looks awfully like a train.

The thrill that one imagines a ride through the time vortex must stir, sadly is never realized. Not only does the machine look like a train, but the excursion back into spent time progresses at a similarly dispiriting speed. One might step aboard and prepare to be hurled through the carriage, upon the great regurgitated projectiles of gravity, but such a flurry of commotion never transpires. When I took a trip on the machine last week, my fellow time-travellers seemed in no way elated by the journey; indeed, many were slipping in and out of a doze. Perhaps they were dreaming of the places, dates and events they wished to travel to. Perhaps they were on the way to rekindle a friendship or repair a dropped stitch in the tapestry of their marriage. But, alas, history is upholstered with impregnable strength and as much as one may desire to re-fashion events, we travel back in time only as shadows.

Alight from the time machine, and at first you curse yourself for forgetting to select a year of the past. You are in Oxford but newspapers still flash colour and crowds still roam the platforms with their gaze glued to glassy gizmos. But persevere with these mere echoes of the future, and proceed out of the station. A short stroll across the concourse and there you find that cul-de-sac of English history; the road to the beating heart of a forgotten heritage. Shavings of the 11th century furnish the thick ragstone walls, and the mind - medicated into dream-state by gothic spires - turns to imagine the depths of Oxford's lierne vaults that lie below the streets. Baroque porches and timber-frames decorate facades and Georgian terraces wrap themselves around the Bath stone. Ivy is maypole dancing around the cast iron balconies. Wander on further, along tree-lined avenues and under the gables of tall villas, and eventually emerge out the other side as if abseiling back towards the future; there spacious gardens await you in one of England's finest Victorian suburbs. You pull hard on the rope that is still knotted to the battlemented walls of medieval Oxford and climb back into a bubble of deep history.

Be warned! The pursuit through the great spindle of Saxon lanes that wrap around the cloisters of Oxford's past is likely to draw attention. I had the distinct feeling that a college proctor had tunnelled through the dust towards a small window in the attic of one of the towers and was eyeballing me, occasionally shaking his head in disapproval. I imagine him seeing me clutching my crumpled paper map and wondering how I managed to get so far without someone informing me that only neatly laminated maps adorned with Royal gold lace were allowed by Oxford's pedestrian traffic. How he must have exclaimed "By Jove" out loud when I boarded a public bus to travel to my budget hotel! How could one not afford to travel in a private chariot?  How could one survive without the cock-a-hoop formality of a luxury hotel? If only he really knew 'what a hoot' a Travelodge can sometimes turn out to be...

A trip to Oxford is to attend a date with the past. You walk through Oxford and become embraced by the comforting arms of antiquity. You pat the Portland stone facades of buildings with affection. Perhaps you stand and stare romantically towards handsome inns and bell towers. You want to buy a drink for the great founders of these icons: William Waynflete, Duke Humphrey, Christopher Wren, Charles Robert Cockerell. In many of the colleges, musicians robed and gowned are rehearsing for the night ahead and you believe that if you peer through the glass, Handel and Haydn are there too, each of them inking the final corrections onto their manuscripts.

Dating the past in Oxford.


In many ways, I had travelled to Oxford specifically to 'date the past' this week. For a few days, I would attend the NERC Radiocarbon Workshop, and join a corpus of archaeologists and environmental scientists, each working on separate ideas but linked by a common interest: being able to put a date to an artefact using Radiocarbon Dating. Let me explain.

You would have thought that the cosmos, infinitely large as it may be, would be the last place to experience a collision. But trillions of collisions are occurring in Space, notably between Nitrogen atoms and cosmic rays. The result is the production of radioactive carbon which then gets absorbed into plants on the Earth's surface. Last night, you (hopefully) had at least one vegetable and so in consuming that celery, that Kale, that lettuce you too transferred the radioactive carbon into your own body. When humans die (and please permit this brief encounter with morbidity), we stop eating vegetables, and the radioactive carbon that we have already absorbed starts to decay. It decays at a slow and steady rate. Because we know that rate (the half-life is 5730 ± 40 years) it is possible, through measuring the radioactive carbon still left in the human, to say how much time has passed since they died. This can be achieved with anything that once lived. However, beyond 50,000 years, the radioactive carbon left in a sample is so minute that measuring it becomes a haphazard business.

Archaeologists may appear slightly amateur with their shovels and toothbrushes, but delve into their work deeper and you will be amazed at the precision by which they are able to date the once-living artefacts they find. A small brush in the field turns into a large, and multi-faceted complex of machines and laboratories. Samples of bone, paper, seeds and tree are often contaminated, so have to undergo thorough cleaning. The cleaning is often completed using strong acids and alkali, often resulting in a loss of the carbon itself. With cleaning out of the way, the carbon is often converted to Carbon Dioxide, then into graphite, which is then compressed into a capsule as I have photographed below.

The hole at the top of this aluminium tube is little more than a millimetre wide but the process from here invests in scales that makes a millimetre seem Herculean in size. The procedure now is to take these tubes of graphite for a walk across the Oxford cobbles and into the AMS (Accelerated Mass Spectrometry) laboratory. In a room no larger than perhaps a small hotel lobby sits a complicated sprawl of wires, pipes, tubing and buttons. You stand, at first, in amazement that such a ridiculously small sample of graphite requires a machine so major in size and complexity. You try and follow just one pipe on a journey from one end of the machine to the other; it coils around the laboratory like a metallic snake and you lose it in the jumble of unfathomable convolution. You wonder what might happen if 'this' button was pressed, or 'this' knob was turned, or 'this' wire was cut. The technician simply walks past as if the machine is as ordinary as the public phone box or the cement mixer.

I have tried, and failed, to write about how the graphite is plugged in at one end and the process by which a radiocarbon date is acquired at the very end. It is a recipe involving some very technical ingredients (ions, molecules, electrons and isotopes) and each ingredient would warrant a separate volume of additional information. So allow me to reassure you that by some miracle that the technicians call 'straightforward science', a radiocarbon date is churned out eventually.

Back across the road, in the laboratory where samples are cleaned, are five people. All of them bar one wear white coats and safety googles. All of them bar one are busy with their potions; stirring, mixing, decanting, filtering. All of them bar one are whirring with the excitement that I imagine stems from working in an Oxford laboratory. All of them bar one. You are told that this 'one' sits in a corner, and will refuse to speak to you. You are told that he doesn't even move, and yet he is oldest in the room. So why, you ask, doesn't he take charge and offer mouthfuls of wisdom and experience, as the old so often relish the chance to do? You ask to be taken to him and then you learn why. He sits, almost 3000 year old, in a cardboard box on a laboratory work bench.

If ever a seminal case of mistaken identity is needed, walk into the Department of Earth Sciences and ask about the skull. A brown tag stapled to the box reveals the words: Norfolk Constabulary. The skull alone was enough to grasp my attention, but a wave of overwhelming curiosity suddenly emerged when I read those very familiar words. The narrative goes that in the 1970s, a headless body - the remains of a brutal murder, although most murders are brutal - was found in Lowestoft. Years passed until a head was found; a skull unearthed by the dutiful ploughing of a nearby field. The police sent the skull to the Oxford Radiocarbon Laboratory, to check that the life which had once bustled inside the skull, had terminated in 1970. A month or two later, the Norfolk Constabulary received a telephone call from a laboratory in Oxford. The person had not died in 1970, but 900BC. The skull, now "eliminated from their enquiries", has resided in the laboratory ever since.

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