More than half a mile under the earth, in a laboratory set into a band of translucent silver rock salt left behind by the evaporation of an epicontinental northern sea some 250 million years earlier, a young physicist is trying to look into a void.
He sits watching a computer screen, close to a large silver cube. The cube’s name is DRIFT and it is a breath-catcher. The young physicist is trying to catch the faint breath of a particle wind sent blowing across space from a constellation called Cygnus, the Swan, many light years distant from Earth.
The young physicist is searching for evidence of the shadowy presence at the heart of the universe: a presence so mysterious that it has thus far engulfed almost all of our attempts either to investigate or to represent it. The name we have given to this presence – which refuses to interact with light, which may not even exist – is ‘dark matter’. And the only place the young physicist can conduct his enquiry is down here in the underland, shielded from the surface by 3,000 feet of halite, gypsum, dolomite, mudstone, siltstone, sandstone, clay and topsoil.
It is a paradox of his work that in order to watch the stars he must descend far from the sun. Sometimes in the darkness you can see more clearly.
In the early 1930s a Swiss astronomer called Fritz Zwicky was studying galaxy clusters through the telescopes of the California Institute of Technology when he noticed an anomaly of extraordinary implications. Clusters are groups of gravitationally bound galaxies, and Zwicky’s work involved measuring the speeds of revolution of individual galaxies in their orbits around the core of the cluster, in order to weigh the cluster as a whole. What Zwicky observed was that the galaxies were revolving much faster than expected, especially towards the outer reaches of the cluster. At such speeds, individual galaxies should have broken their gravitational hold on one another, dispersing the cluster.
There was, Zwicky determined, only one possible explanation. There had to be another source of gravity, powerful enough to hold the cluster together given the speeds of revolution of the observable bodies. But what could supply such huge gravitational field strength, sufficient to tether whole galaxies – and why could he not see this ‘missing mass’? Zwicky found no answers to his questions, but in asking them he began a hunt that continues today. His ‘missing mass’ is now known as ‘dark matter’ – and proving its existence and determining its qualities is one of the grail-quests of modern physics.
How, though, to hunt for darkness in darkness? How to seek a substance that has mass and therefore exerts gravity, but that does not emit light, reflect it or block it? Since Zwicky, the evidence for the existence of dark matter has been gathered largely by inference: the detection not of the matter itself, but of its presumed influence on luminous entities, observable objects. To perceive matter that casts no shadow, you must search not for its presence but for its consequence.
It is now known, for instance, that dark matter affects the rotation curves of spiral galaxies, causing all bodies within such a galaxy to revolve at comparable rates, regardless of their distance from the galaxy’s gravitational centre. It is also known that dark matter bends light as it passes around a galaxy, causing what is referred to as ‘gravitational lensing’. Mass curves space, Einstein showed in his General Theory of Relativity, and light follows those curves of space – as when it passes around a massive entity such as a galaxy. But just as Zwicky’s galaxies rotated too fast, so light also bends too greatly to be due only to the visible components of a given galaxy. There must again, therefore, be more mass than that which can be seen. This imperceptible, space-curving, light-lensing massive presence that surrounds a visible galaxy is known to astrophysicists as a ‘dark-matter halo’.
What these observations and others like them suggest is that only around 5 per cent of the universe’s mass is made of the matter we can touch with our hands and witness with our eyes and instruments. This is the matter of stone, water, bone, metal and brain, the matter of which the ammoniacal storms of Jupiter and the rubble rings of Saturn are made. Astronomers call this ‘baryonic matter’, because the overwhelming share of its mass is due to protons and neutrons, known to physicists as ‘baryons’. A little over 68 per cent of the universe’s mass is presumed to be made of ‘dark energy’, an enigmatic force that seems to be accelerating the ongoing expansion of the cosmos. And the remaining missing 27 per cent of the universe’s mass is thought to be made up of dark matter – the particles of which almost wholly refuse to interact with baryonic matter.
Dark matter is fundamental to everything in the universe; it anchors all structures together. Without dark matter, super-clusters, galaxies, planets, humans, fleas and bacilli would not exist. To prove and decipher the existence of dark matter, writes Kent Meyers, would be to approach ‘the revelation of a new order, a new universe, in which even light will be known differently, and darkness as well’.
Dark-matter physicists work at the boundary of the measurable and the imaginable. They seek the traces that dark matter leaves in the perceptible world. Theirs is hard, philosophical work, requiring patience and something like faith: ‘As if’ – in the analogy of the poet and dark-matter physicist Rebecca Elson – ‘all there were, were fireflies / And from them you could infer the meadow’.
Presently, the particle thought most likely to be the constituent of dark matter is known wryly as a WIMP – a weakly interacting massive particle. What we know of WIMPs suggests that they are heavy (up to more than a thousand times the weight of a proton), and that they were created in sufficiently vast quantities in the seconds after the birth of the universe to account for the missing mass.
WIMPs – like neutrinos, nicknamed ‘ghost particles’ – have scant regard for the world of baryonic matter. WIMPs traverse our livers, skulls and guts in their trillions each second. Neutrinos fly through the Earth’s crust, mantle and solid iron-nickel core without touching a single atom as they go. To these subatomic particles, we are the ghosts and ours the shadow-world, made at most of a diaphanous webwork. The great challenge faced by physicists has been how to compel such elusive particles to interact with experiments; how to weave a net that might catch these quick fish. One of the solutions has been to go underground. Subterranean laboratories have been established around the world, dedicated to the detection of evidence that a WIMP or a neutrino has briefly interacted with baryonic matter. The experiments under way in these deep-sunk laboratories are all forms of ghost hunting, and they are located far underground because the surrounding rock shields the experiments from what physicists call ‘noise’.
Noise is the trundle of everyday particles through the air, the din of the ordinary atomic world going about its business. Radioactivity is deafening noise. Cosmic-ray muons are noise. If you wish to listen for sounds so faint they may not exist at all, you can’t have someone playing the drums in your ear. To hear the breath of the birth of the universe, you must come below ground to what are, experimentally speaking, among the quietest places in the universe.
Half a mile underground in an abandoned mine in Japan, set in a chamber of 250-million-year-old gneiss, a stainless-steel tank holds 50,000 tons of ultra-pure water. Watching the water are 13,000 photomultiplier tubes, forming a compound eye. The eye is looking for tiny flashes of blue light. These flashes are Cherenkov radiation, produced when an electron moves faster than the speed of light in water. Electrons reach such speeds when an atom is – occasionally – struck by a neutrino, the impact scattering the atom’s electrons at velocities in excess of the speed of light. These scattered electrons are called ‘annihilation products’, and if those electrons are scattered in water then they briefly create a luminous blue cone around them as they move. The compound eye of the photomultiplier tubes therefore watches for trebly displaced evidence of the ‘ghost particles’: not the neutrino itself, or the atom it has struck, or the electrons it has dispersed, but the blue aura left by that ghost-struck atom – annihilation’s afterglow. This buried chamber of gneiss is called an ‘observatory’, for although it is deep underground it is in fact scrying the stars: among its many other tasks is keeping watch for supernovae in the Milky Way.
Deep in a worked-out open-cut gold mine in South Dakota, super-cooled xenon is held in a six-foot-tall vacuum vessel, surrounded by 71,600 gallons of deionized water contained in a welded steel tank and watched by photomultiplier tubes for the displacement of a single photon and a single electron brought about by the strike of a WIMP. Xenon, a noble gas, has large atoms. When xenon is very cold it is very dense; those large atoms huddle together, thus presenting a greater cross-section to incoming particles and optimizing the chances of WIMP strikes. In a landscape where the earth was once raked and gouged in search of a highly valued rare metal, the search is now ongoing for a substance that is plentiful beyond imagination and of no worth at all.
And near the little village of Boulby on the Yorkshire coast, in a salt cavern far below the headworks of a potash and rock-salt mine that commenced operation in 1973, a dark-matter detection experiment is presently under way that is known by the acronym DRIFT: directional recoil identification from tracks.
~
Neil Rowley unrolls his map of the underland on his desk, and places four chunks of rock on its corners to keep it flat, naming each as he puts it down: sylvite, halite, polyhalite, boracite. He smooths the map out with his hands, working from the centre to the edges. Neil is a mine-safety specialist. He has worked in coal; now he works in potash. He likes W. H. Auden, he likes maps and he loves mining.
Neil’s map records the roadways and refuge chambers of the Boulby mine. At first glance, it looks to me like the wings of a dragonfly, intricately veined and structured. Slowly my eyes key into its codes.
The north-east coastline of England is present as a faint grey line running across the map from north-west to south-east: a surface irrelevance, shown chiefly for purposes of orientation. At Boulby itself, two circles signify the two shafts that plunge into the bedrock, giving access to the tunnel network. From that centre point the tunnels fan out to the north-east and the south-west, forming the wings of the dragonfly. To the south-west, they spread under moor and dale, deep into North Yorkshire. To the north-east they spread under the North Sea, running out beyond the shipping lane and into open ocean.
This network of tunnels and roadways is collectively known as ‘drift’. There are more than 600 miles of existing drift burrowed into the soft bands of halite (salt) and sylvite (potash) that stretch below sea and land, out to the mining faces where – every hour of every year – men and machines claw tons of potash from the seams, duct the potash onto hoppers and start the journey of this buried residue of a Permian sea up to the world’s crop fields, where it will be spread as a fertilizer in both of the Earth’s annual two springs, returning vital potassium to the growing cycle.
As the land below the Mendips holds a water-made labyrinth, so the land below Boulby holds a human-made maze. I have come from rift to drift.
On Neil’s map, red lines signify drift cut through salt, black lines signify drift through potash. Yellow squares mark refuge chambers, dug into the side walls of the tunnels and armoured against heat by polyfoam outer walls. In the case of collapse or fire at depth, these are the fall-back sites.
At the tips of the wings – far under the sea and far under the moors respectively – thin green threads lick out. These are the lateral boreholes being drilled by mine geologists to test the lie and integrity of the deposits ahead of the workface. The information they return will determine the future directions of the mining, the future spread of the wings.
‘You need to understand that the tunnel network is on a tilt,’ says Neil, drawing his finger across the map, from one end of the dragonfly’s wing to the other. ‘The drift tilts because the deposit tilts. The tunnels follow the potash, and the potash strata are inclined.’
Inland the potash deposit runs deeper, reaching a maximum depth of around 4,500 feet at the outermost limit under the moors. Seawards, it rises to a minimum depth of around 2,600 feet at the outermost point beyond the shipping channel. A temperature gradient follows the depth gradient. At 2,600 feet the air temperature is 35°C. At 4,500 feet it’s 45°C. In both places the geothermal heat is so intense, and the moisture content of the air so low, that sweat evaporates before it can even be seen. Dehydration is rapid. For the miners it is like labouring in the Sahara at noon, in darkness.
‘The men all carry cool-boxes with four litres of chilled water per shift,’ Neil says. ‘They have rehydration timetables throughout their shifts. Got to keep drinking. Much safer.
‘Come on – let’s see if we can catch a lift down there, find some dark matter, then we’ll make the long drive out to the mining face under the sea.’
Ear defenders on. Respirator hooked at the belt. Numbered bronze triangle in pocket as proof of entrance: Don’t lose it now, you won’t be allowed out . . . Yellow cage door clangs shut, cage starts its drop, steady but still stranding the stomach. Roar of the fan-house fading away, cage speeding up. Halfway down a shudder and blast as the other cage crosses on its way up, squeezing air between cages with a crash-whoosh like two trains passing in opposite directions. Slow, slow, slow, bump, stop, cage door clangs open – and voices are yelling, ‘Ears off, lights on! Ears off, lights on!’
Rock dust swirls in the air, thick enough to taste, salty on the tongue.
Black mouths of drift lead away under the ocean, into the Permian.
An airlock in a wall opens into a laboratory.
~
The young physicist sits at his computer, watching for signals from Cygnus. His name is Christopher Toth, and his white lab coat is too big for him. Christopher speaks with calm clarity. His manner is modest, gracefully gentle, and I wonder if this comes in some way from spending your days thinking through time so deep it stretches to the birth of the universe.
Along the walls of the laboratory, at intervals of every fifteen feet or so, black-and-yellow warning tape marks the outlines of what look like potential doorways, rising only to thigh level. Above each taped outline, a long-handled axe with a splitter blade is held in two hooks.
Salt has very low gamma radiation. Salt is a good insulator. Salt is radio-pure. Salt is an excellent substance in which to encase yourself if you want to study weakly interacting massive particles. But salt is also highly plastic. Salt flows over time. It creeps around. It sags. If you cut a chamber out of a seam of halite with 3,000 feet of bedrock above it, that chamber will slowly distort. The ceiling will dip, the sides will bulge. Gravity wants that space back. So the scientists working in the Boulby laboratory know they are operating in a temporary zone, with limited years of safe life. Deep time must be studied fast.
‘Those are your emergency exits in case of a sudden slump in the halite,’ says Christopher, mimicking the hand gestures of a flight attendant explaining the safety protocols, and pointing to the doorways marked with warning tape, ‘here, here . . . and here. If the lab begins to collapse, you grab an axe, hack your way through the lab wall, then hack your way out through the salt to safety.’
He pauses, smiles. ‘Well, that’s the theory, at least.’
Several different kinds of underground experiment are presently taking place in the laboratory. One assays rock samples in order to research techniques for the long-term burial of radioactive waste. Another investigates a technology known as ‘muon tomography’, which makes use of highly penetrating charged particles (muons) produced by cosmic rays from space. Because of their ability to pass deep into rock, muons allow sunken structures such as the interiors of volcanoes and the hollow hearts of pyramids to be perceived. Muons offer a way of seeing through stone. These are all remarkable experiments. But the jewel in the experimental crown of the Boulby laboratory is DRIFT.
Christopher walks me towards a large object located at one side of the laboratory. ‘This is my underground crystal ball,’ he says – flourishing his hands like a magician revealing a trick – ‘also known as the Time Projection Chamber.’
From the outside, the magnificently named Time Projection Chamber is disappointing to look at. Black bin liners are taped scruffily around a large metal-clad box.
‘I see that bin bags make up the vital outer layer of your crystal ball,’ I say.
‘You mock,’ replies Christopher, ‘but duct tape and bin bags have proved crucial to more scientific breakthroughs than you’d imagine.’
He explains the experiment to me. ‘We know dark matter is massy. Massively massy. So its particles, even though they’re invisible to us, have mass, and if they have mass then they must at least occasionally collide with particles we can see. These collisions send nuclei scattering. Our first goal with DRIFT is to detect these collisions, and follow the nuclei as they scatter.’
He pauses. I wait. Trillions of neutrinos pass through our bodies and on through the Earth’s bedrock, its mantle, its liquid innards, its solid core.
‘Imagine watching a game of billiards in which the red balls are visible but the white isn’t. Suddenly you see the red ball – an electron – move across the baize. By plotting the red ball’s path, you might be able to backtrack, as it were, the path of the invisible white ball – the WIMP – that struck it. And from this, you might be able to learn more about the direction, mass and qualities of that white ball. We’re looking to do this enough times, and with enough precision, to provide the signature of a dark-matter halo.’
At the core of the DRIFT device is a steel vacuum vessel a cubic metre in volume, criss-crossed by a meshwork of ultra-thin, highly charged wires spaced a millimetre apart. If a WIMP collides with the nucleus of an atom of ordinary matter inside the chamber, it causes an ionization track, which the meshwork of wires both intensifies and records. The track can therefore be reconstructed in three dimensions, providing information about the type and origin of the colliding particle. The wires are held within a low-pressure gas, the low-pressure gas within a conductive chamber, the conductive chamber within a steel neutron shield – and the whole unit is held in a band of halite left by the evaporation of an ancient sea.
I will learn over the years ahead that many such Chinese-box structures, with their multiple containment protocols, characterize storage procedures in the underland, from the falcon-headed Canopic stone jars of ancient Egyptian burial practice – into which were placed the vital organs of the dead, and which were themselves encased in a painted wooden chest, itself encased in a tomb, itself encased in a pyramid – to the concentric sheathing of spent uranium pellets from nuclear reactors; the pellets placed within rods of zirconium, the rods encased in a copper cylinder, the copper cylinder encased in an iron cylinder, the iron cylinder encased in bentonite clay rings, and the rings encased in the bedrock of a deep geological storage facility, sunk thousands of feet into gneiss, or granite, or salt.
Christopher leads me to his desk. The screensaver image on his computer is of the turquoise waters of Lake Louise in the Canadian Rockies. He shows me a diagram representing data returns from the Time Projection Chamber. It has lines of different bright colours, across which a fine black streak runs at an angle.
‘This diagonal line is the path of an alpha particle,’ Christopher says, following it with his little finger. ‘He’s a bludgeoning, portly gentleman who comes barrelling through our experiment, making a lot of noise as he goes. He’s not of interest to us, except insofar as identifying his signal helps us know what we’re not looking for.
‘What we’re trying to hear, instead, are the quiet whispers behind his boisterousness. Not even whispers, in fact; more like the faintest of breaths – of breathing. Down here in the salt is about the only place you could hear such breath. That breath is the sound of a weakly interacting massive particle passing through – and it leaves a fine trace. What we think is a WIMP-collision looks more like two small blips, one on each of two channels.’
With his fingernail he picks out two dots: one on a yellow line, one on pink. He pauses. His screensaver changes to an over-saturated image of a white-sand beach with palm trees, lapped by a lapis-lazuli sea. The WIMP wind from Cygnus blows through our bodies.
‘This data is very beautiful once you get used to it,’ he says. I nod in agreement.
‘Right now,’ Christopher says, ‘you are looking into the absolute smallness of the universe with pinpoint accuracy, peering down at the most minute of scales. Those coloured lines are our magnifying lens.’
Then he says – as if the phrase has just entered his head without warning, scoring a trace as it passes through – ‘Everything causes a scintillation.’ He pauses.
‘Why are you searching for dark matter?’ I ask.
‘To further our knowledge,’ Christopher replies without hesitation, ‘and to give life meaning. If we’re not exploring, we’re not doing anything. We’re just waiting.’
He pauses again. I wait. The screensaver on his computer changes to Yosemite in the autumn, with early snow on the top of El Cap. Christopher does not speak.
‘Is the search for dark matter an act of faith?’ I ask him.
He waits for me to elaborate – he has heard the question before, wants more before he answers. His screensaver changes to the desert dunes at Sossusvlei in Namibia.
I think of Rievaulx Abbey west of Boulby, where in a fertile river valley Cistercian monks founded and built a space in which to hold Mass. Out of ironstone they made an airy structure of soaring buttresses and vaulted ceilings. Their abbey was one among a network of such sites spread around the world, in which prayers were offered to a presence disinclined to disclose itself to the usual beseechings.
On the hillsides above the abbey geological forms known as ‘slip-rifts’ slowly open and close in the rock, emitting warm air from deep within the earth, such that on cold days the hillside itself appears to be breathing – as if the land itself were alive. Thousands of years before the Cistercians arrived in those valleys, Neolithic and Bronze Age peoples entered the darkness of the slip-rifts to carry out rituals that may have been sacrificial and were surely devotional, interring body parts amid the stones of the rifts; another kind of annihilation product.
I remember the Wind Cave system in the Black Hills of South Dakota, sacred to the Lakota Sioux people and close to the American dark-matter detection laboratory set deep in the worked-out gold mine. From the opening to Wind Cave, which extends for more than 130 miles below ground, air rushes or is drawn with such force that it can strip hats from heads. In the Lakota creation stories it is from Wind Cave that humans first emerge into the upper world, where they are astonished by colour and space.
‘My sense,’ I say to Christopher, ‘is that the search for dark matter has produced an elaborate, delicate edifice of presuppositions, and a network of worship sites, also known as laboratories, all dedicated to the search for an invisible universal entity which refuses to reveal itself. It seems to resemble what we call religion rather more than what we call science.’
‘I grew up as a very serious Christian,’ Christopher says. ‘Then I lost my faith almost entirely when I found physics. Now that faith has returned, but in a much-changed form. It’s true that we dark-matter researchers have less proof than other scientists in terms of what we seek to discover and what we believe we know. As to God? Well, if there were a divinity then it would be utterly separate from both scientific enquiry and human longing.’
He pauses again. It is not that this thinking is hard for him – he has moved down these paths before – but that he is picking each word with care.
‘No divinity in which I would wish to believe would declare itself by means of what we would recognize as evidence.’ He gestures at the data read-out. ‘If there is a god, we should not be able to find it. If I detected proof of a deity, I would distrust that deity on the grounds that a god should be smarter than that.’
‘Does it change the way the world feels?’ I ask him. ‘Knowing that 100 trillion neutrinos pass through your body every second, that countless such particles perforate our brains and hearts? Does it change the way you feel about matter – about what matters? Are you surprised we don’t fall through each surface of our world at every step, push through it with every touch?’
Christopher nods. He thinks. His screensaver changes to the limestone towers at Guilin, seen near dusk such that they are backlit in ways that are considered widely appealing on Instagram and other large-scale image-sharing platforms.
‘At the weekends,’ Christopher says, ‘when I’m out for a walk with my wife, along the cliff tops near here, on a sunny day, I know our bodies are wide-meshed nets, and that the cliffs we’re walking on are nets too, and sometimes it seems, yes, as miraculous as if in our everyday world we suddenly found ourselves walking on water, or air. And I wonder what it must be like, sometimes, not to know that.’
He pauses, and it is clear that he is thinking now beyond the confines of the salt cavern, beyond even the known limits of the universe.
‘But mostly, and in several ways, I’m amazed I’m able to hold the hand of the person I love.’
~
Neil wanted to drive the Paris–Dakar Rally back in the day. Neil is steering a stripped-down doorless Ford Transit van in a subterranean desert maze more than 600 miles in extent, Neil is a matter of weeks from retirement, and Neil doesn’t give a shit.
We take the ramps fast enough to lift up as we come over them. We leave the tunnels behind us clouded with dust. Instead of slowing down for the corners, Neil just leans on the horn. Paaaaarp! He’s a man passionate about mine safety; he’s also a man passionate about fun. I like him a lot.
I hang off the roof handle with my left hand, lean forwards and brace myself with my right hand against the dashboard. I clench my jaws to stop my teeth clattering.
‘Between the main shaft, where the lab sits, and the production districts, there’s barely anyone except at shift change,’ says Neil. ‘If they’re coming our way, we should see their lights from a long way off.’
The roadways are cut from the halite, with ramps leading up into the potash seams. The sides of the roadways glimmer a little in the light, like ice. We’re trucking through pure salt. The tunnels are of standard dimensions – 3.8 metres high, 8 metres wide – and their ceilings are regularly reinforced with bolts the length of a man, to slow the slump.
‘The potash is more fissile,’ says Neil. ‘Cracks more easily. You don’t want to run roadways through it unless you have to. Halite tends to sag rather than shatter. Much safer.’
Thump! Paaaaarp!
‘These main roadways have two years or so in them before they start to scrunch up. We prop them up with wood stacks. Wood’s better than steel: it squishes rather than snapping. Much safer. Still, sometimes we lose a district before it’s mined out. So it goes.’
Neil has a disconcerting habit of turning to me as he talks, keeping one hand on the top of the wheel but no eyes on the road. Sometimes he rotates the steering wheel with his palm, as though he is buffing a car’s panel work in small arcs. Wax on, wax off. ‘It’s not like a coal mine, where you’re always worried about combustion of the coal dust in the air,’ he says. ‘Here the salt dust acts like a dry-powder fire extinguisher. Much safer.
‘The last death down here was in the 2000s, caused by a low-velocity explosion at the production face: 500 tons of rock came down in a recently mined roadway, pushed the machine back, and the machine crushed a man to death. No one’s died down here this decade.’
A few months later a popular miner called John Anderson will be killed in a gas blowout.
We ramp up into a potash seam. Neil brakes the van to a halt in a swirl of dust, jumps out, cracks a fat flake of potash off the tunnel wall and hands it to me. It is pink as meat and flecked with silver mica. It is surprisingly light, almost buoyant in the hand.
‘Lick it,’ says Neil. It fizzes on my tongue. It tastes of metal and blood. I want to eat it all.
A stream of water runs down a wall of the tunnel from a crack in the ceiling. Neil points upwards. ‘We’ve just crossed the coastline! We’re under the sea now!
‘Halite and sylvite are both soluble in water,’ says Neil. ‘This poses problems when you mine below the ocean. We have to pump the mine continuously to keep it workable: 1,000 gallons a minute, giving us an electricity bill of about £3 million per year. The Russians and the Canadians have both lost potash mines to flooding in the past.
‘We had a big flood not so long back: 3,500 gallons a minute, running for eight weeks. We thought we’d lost the mine for a while. Then it slowed as it self-sealed; don’t quite know why. Nothing to say it won’t start up again.’
‘How reassuring.’
We get back into the Transit. ‘How’s this for a job, eh?’ Neil asks no one in particular. ‘I get paid to do this!’ He slams the pedal to the metal, we lurch back in our seats and hammer on down the drift.
Neil’s navigational powers impress me. He has no map, there are no signs, but he shows no hesitation at any of the dozens of junctions we meet.
‘If you were to die,’ I say, ‘just hypothetically speaking, how would I get out of here?’
‘If in doubt, follow the wheel tracks,’ he yells. ‘And if I cop it, just keep the wind in your face and you’ll find the way out!’ He points up again. ‘We’re out beyond the shipping lane now. Imagine those captains in charge of their boats, with never a clue we’re careering about below them!’
It takes us another twenty minutes to reach the production face. Neil parks at the side of a tunnel, behind two other transits, straightening up the wheels as neatly as if he is on a suburban street.
Dust smogging the air; the tunnels ahead forking out; flickering lights and shadow-movement. The walls of the tunnels are inscribed with gouged patterns: spirals, cross-hatchings. They look like the cuts of a creature trying to claw its way out of a trap, or the ritual petroglyphs of a tribe.
‘Production District 887 – the limits of the seam,’ says Neil. ‘The test-probes suggest the seam exhausts itself more or less here. Once this district is mined out, there’ll be no more north-westwards progress; we’ll look to the eastern and south-eastern edges of the undersea drift.’
Two teams of men are sitting at tables, drinking and eating. In the blackness I can see only the glowing strips of their hi-vis jackets. It’s a scene from Tron. The men look up, nod a greeting, get back to their food. There are dozens of penises scrawled in biro and marker pen on the white wipe-clean PVC of the tabletop.
Left down one tunnel, right down another. Noise increasing; dust increasing. Halogen light-beams slice through choking air. Screaming noise of metal on mineral.
A huge red-black machine, low-slung and sharp-toothed as a Komodo dragon, is feeding at a face of rock. The dragon is controlled via a thick black rubberized cable, as if on a dog leash. From the lizard’s arsehole extrudes a long thin stream of potash ore on a conveyor belt, ducted back towards a hopper to begin its journey to the world’s fields.
The lizard-machine feeds at the face, the conveyor belt continues to trundle ore towards the hopper, and I am struck by a sense of the creatureliness of the mining operation: the avid clawing at the rock, the tunnel network that has been created. I remember cross-sections I have seen of the interiors of termite mounds and ants’ nests, rabbit warrens and mole runs. Neil’s map of the mine, with its hundreds of miles of intersecting drift, is just the plan of another animal’s burrow-complex, bored out in search of resources.
What curious partners they have become in the darkness, the mine and the laboratory, oddly echoic of each other’s operations. The geologists sending their probes out into the rock ahead, hoping to detect and pursue the most remunerative seams. The physicists watching for the arrival of knowledge, pure knowledge, the sylvite of knowledge, hard to reach, worth nothing, hoping to detect the missing portion of the universe: dark matter, a yield that cannot be sold.
Neil leans close again, cups his hands to shout into my ears above the noise of extraction. ‘Those face-mining machines? They cost £3.2 million each. The engines are modified, obviously, to prevent sparking. We bring them down in sections in the lift shaft, assemble them in build-up bays, and then drive them out to the production face, towing a generator behind them. It takes them three days to trundle the seven or so miles out here to where they begin work.’
The strains of the work are intense, the lifespan of the machines short. ‘When one of them reaches the end of its useful days,’ says Neil, ‘it’s not cost-effective to bring it back up. It’d take the place of ore in the upshaft, and that’s too expensive. So instead the machine gets driven into a worked-out tunnel of rock salt, and abandoned there. The halite will flow around it as the tunnel naturally closes up.’
It is an astonishing image: the translucent halite melting around this cybernetic dragon – the fossilization of this machine-relic in its burial shroud of salt.
I remember the pit ponies about which Emile Zola had written, brought down as foals into France’s great nineteenth-century coal mines. The foals would not see daylight again. They grew in the mines, were fed there, were worked to death there, and their stunted bodies were left in side tunnels, awaiting the burial of collapse.
In the halite strata that underlie the New Mexico desert, an underground facility known as the Waste Isolation Pilot Plant has been excavated, designed for the long-term disposal of transuranic radioactive waste arising from the research and production of nuclear weapons. More than 2,000 feet below the desert surface, a burial site has been created for thousands of silver steel drums packed with nuclear waste. Because the waste remains radioactive for thousands of years, it generates heat. This heat will increase the plasticity of the halite – and so once each chamber is replete, the warmed halite should creep around the barrels, securing them for the deep time future.
I am briefly filled with a longing to step into a side tunnel myself, lie down and let the halite slowly seal me in for five years or 10,000 – to wait out the Anthropocene in that translucent cocoon.
~
In 1999, at a conference in Mexico City on the Holocene – the epoch of Earth history that we at present officially inhabit, beginning around 11,700 years ago – the Nobel Prize-winning atmospheric chemist Paul Crutzen was struck by the inaccuracy of the Holocene designation. ‘I suddenly thought this was wrong,’ he later recalled. ‘The world has changed too much. So I said, “No, we are in the Anthropocene.” I just made the word up on the spur of the moment. But it seems to have stuck.’
The following year, Crutzen and Eugene Stoermer – an American diatom specialist who had been using the term informally since the 1980s – jointly published an article proposing that the Anthropocene should be considered a new Earth epoch, on the grounds that ‘mankind [sic ] will remain a major geological force for many millennia, maybe millions of years to come’. As the Pleistocene was defined by the action of ice, and the Holocene by a period of relative climatic stability allowing the flourishing of life, so the Anthropocene is seen to be defined by the action of anthropos: human beings, shaping the Earth at a global scale.
The scientific community took the Crutzen-Stoermer proposal seriously enough to submit it to the rigours of the stratigraphers. In 2009 the Anthropocene Working Group of the Subcommission on Quaternary Stratigraphy was created. It was charged with delivering two recommendations: firstly, whether the Anthropocene should be formalized as an epoch and if so, secondly, when its ‘stratigraphically optimal’ temporal limit should be located, i.e. when it could be said to have begun. Among the baselines considered by the group have been the first use of fire by hominins around 1.8 million years ago, the start of agriculture around 8,000 years ago, the Industrial Revolution, and the so-called ‘Great Acceleration’ of the mid twentieth century, when the nuclear age dawned, massive increases occurred in terms of resource extraction, population growth, carbon emissions, species invasions and extinctions, and when the production and discard of metals, concrete and plastics boomed.
What signatures our species will leave in the strata! We remove whole mountain tops to plunder the coal they contain. The oceans dance with hundreds of thousands of tons of plastic waste, slowly settling into sea-floor sediments. Weaponry tests have dispersed artificial radionuclides globally. The burning of rainforests for monoculture production sends out smog-palls that settle into the soils of nations. A nitrogen spike, indicated in ice-cores and sediments, will be one of the key chemical insignias of the Anthropocene, caused by the mass global use of synthetic nitrogen-rich fertilizers and by fossil-fuel burning. Biodiversity levels are crashing worldwide as we hasten into the sixth great extinction event, while the soaring number of a small number of livestock species ensures the geological posterity in the fossil record of sheep, cows and pigs. We have become titanic world-makers, our legacy legible for epochs to come.
Among the relics of the Anthropocene, therefore, will be the fallout of our atomic age, the crushed foundations of our cities, the spines of millions of intensively farmed ungulates, and the faint outlines of some of the billions of plastic bottles we produce each year – the strata that contain them precisely dateable with reference to the product-design archives of multinationals. Philip Larkin famously proposed that what will survive of us is love. Wrong. What will survive of us is plastic, swine bones and lead-207, the stable isotope at the end of the uranium-235 decay chain.
There are many reasons to be suspicious of the idea of the Anthropocene. It generalizes the blame for what is a situation of vastly uneven making and suffering. The rhetorical ‘we’ of Anthropocene discourse smooths over severe inequalities, and universalizes the site-specific consequences of environmental damage. The designation of this epoch as the ‘age of man’ also seems like our crowning act of self-mythologization – and as such only to embed the technocratic narcissism that has produced the current crisis.
But the Anthropocene, for all its faults, also issues a powerful shock and challenge to our self-perception as a species. It exposes both the limits of our control over the long-term processes of the planet, and the magnitude of the consequences of our activities. It lays bare some of the cross-weaves of vulnerability and culpability that exist between us and other beings now, as well as between humans and more-than-humans still to come. Perhaps above all the Anthropocene compels us to think forwards in deep time, and to weigh what we will leave behind, as the landscapes we are making now will sink into strata, becoming underlands. What is the history of things to come? What will be our future fossils? As we have amplified our ability to shape the world, so we become more responsible for the long afterlives of that shaping. The Anthropocene asks of us the question memorably posed by the immunologist Jonas Salk: ‘Are we being good ancestors?’
But to think ahead in deep time runs against the mind’s grain. Try it yourself, now. Imagine forwards a year. Now ten. Now a century. Imagination falters, details thin out. Try a thousand years. Mist descends. Beyond a hundred years even generating a basic scenario for individual life or society becomes difficult, let alone extending compassion across much greater reaches of time towards the unborn inhabitants of worlds-to-be. As a species, we have proved to be good historians but poor futurologists. While we have devised abbreviations for marking out deep time in the past – BP for ‘before present’; MYA for ‘million years ago’ – we have no equivalent abbreviations for marking out deep time in the future. No one speaks of AP for ‘after present’, or MYA for ‘million years ahead’.
The Anthropocene requires us to undertake a retrospective reading of the current moment, however – a ‘palaeontology of the present’ in which we ourselves have become sediments, strata and ghosts. It asks that we imagine a single figure: a hypothetical posthuman geologist who – millions of years into the future, long after the extinction of our species – will examine the underland for what it reveals of the epoch of anthropos. This imaginary figure – our archivist, our analyst, our judge – is the contemporary version of the ‘last man’ presence that haunted nineteenth-century extinction narratives, or of Thomas Macaulay’s ‘New Zealander’, sitting by the banks of the Thames in a London that has been overwhelmed by nature, ruminating on ruination.
Down at the chaos of the mine’s production face, I think of the puzzles we are creating for our future geologist. I wonder how, millions of years on, she will interpret the fossil presence of the lizard-like mining machines of Boulby, manufactured in the Anthropocene and embedded in the strata of a 250-million-year-old seabed. How will she distinguish them as machines rather than as organisms? And what of the drift itself – the faint impress that this 600-mile maze will leave in the layers of halite and sylvite?
Geologists and palaeobiologists speak of ‘trace fossils’. A trace fossil is the sign left in the rock record by the impress of life rather than life itself. A dinosaur footprint is a trace fossil. The enigmatic doughnut-shaped flints called ‘paramoudra’ are thought to be the trace fossils of a burrowing worm-like creature that lived vertically in the seabed during the Cretaceous, its breathing organs just above the level of the silt. Boreholes, funnels, pipes, slithers and tracks are all trace fossils – stone memories where the mark-maker has disappeared but the mark remains. A trace fossil is a bracing of space by a vanished body, in which absence serves as sign.
We all carry trace fossils within us – the marks that the dead and the missed leave behind. Handwriting on an envelope; the wear on a wooden step left by footfall; the memory of a familiar gesture by someone gone, repeated so often it has worn its own groove in both air and mind: these are trace fossils too. Sometimes, in fact, all that is left behind by loss is trace – and sometimes empty volume can be easier to hold in the heart than presence itself.
~
The return from the production face is a madcap rally-drive. Neil works the van even harder. Dust in the mouth, hitting the ramps at speed – whump – stomach in the mouth, then slam down onto the halite floor. We approach a corner. Neil hammers the horn. Paaaaarp! He hammers it again. Silence. Hammer. Silence.
‘I must have shaken a circuit loose,’ Neil says.
‘That’s been evident for a while now,’ I say.
‘Not to worry. We’re coming back out. We’ve got right of way, at least in theory. I’ll slow down a bit.’
He doesn’t slow down at all.
‘Watch out for oncoming headlights on the side walls! If I knock myself out, take over the wheel and head south-west!’
We pass two wrecked Transits in side tunnels, their bonnets crushed from unknown impacts, waiting to be absorbed by the halite. On we pummel through miles of tunnel, back at last to the yellow cage of the upshaft.
Soft whoosh and air-squeeze halfway up as the down-cage passes us. Jolt and slow as we near the surface. The shuffle of men readying themselves for the exit, thinking of shower, home, family, food, drink. Rattle of the door opening. Block-squares of light through steel gate lock-hatches. Smell of the sea, smell of the sun. Into the airlock, counted out one by one. Miners first. Respirator back on the peg. Check. Push the bronze triangle in at the window desk. Check. Clear.
Out through the door and into burning white day, blue billowing sky, sun glinting off windscreen and chain-link, tarmac and grass blade, dark matter nowhere and everywhere around me – and surfacing into this blinding light seems like stepping into ignorance.
~
Later I drive west over the moors for hours, winding home. The ling is in bloom and pollen glitters in the air. Marks of mining are everywhere I look, left by thousands of years of human boring into this northern landscape in search of materials: slate, lead, iron, copper, ironstone, silver, coal, fluorspar. Marks of burial too, left by thousands of years of humans interring their dead in the same terrain: medieval church cemeteries, burial mounds from the Neolithic, the Bronze Age, the Iron Age.
Near dusk I am in the ridge-and-fold limestone valleys of the North Pennines. The easterly breeze of the morning has grown in force to a gale. At Rookhope I park and walk the mile or so up onto the moor above the village.
The wind at that height is chilling, though the late sun is still strong. Cottontails of bog-grass thrum in the wind, glowing like gas mantles. Four kestrels, strung in a ragged low line above the moor to my west, hold their positions with grace against the wind. I gorge on the glut of light, the fetch of space. Reaching a jumble of boulders I stand on the highest stone, face east and lean a little into the wind, feeling the push of its hand on my chest – holding me in part-flight, kestrelling me.
Time feels differently reckoned after the mine: further deepened, further folded. My sense of nature feels differently reckoned too: further disturbed, further entangled. Somewhere to my east, men are at work a mile below the moors, half a mile under the sea, cutting tunnels through the salt-ghost of an ocean to harvest its energy for crops as yet ungrown. A Time Projection Chamber is waiting for signals from Cygnus, the Swan, that might tell something of the birth of the universe, 13.8 billion years earlier. A labyrinth of drift is slowly closing up, lizard-machines and Ford Transits are being sealed into their tombs of salt – and through it all is passing a particle wind of WIMPs and neutrinos, to which this world is as mere mist and silk.
‘At night, according to their accustomed watches, the stars traverse a path beneath the earth,’ Bede had written in The Reckoning of Time, 1,300 years earlier, as he calculated the six ages of the Earth, and the seventh age to come. I think of the miners who worked the underland of these Pennine valleys through the nineteenth century, following seams holding metallic ores of silver, magnesium, lead and zinc. Where galena coated the sides of a rift, it could gleam as brightly as a mirror. The same veins held wondrous blossoms of fluorspar, crystals of which shone blue in ultraviolet light. Occasionally the miners hacked their ways into geodes the size of rooms, walled and roofed in crystals and metals. The flames of their lamps glittered off quartz, aragonite, dolomite, fluorspar, iron pyrites and galena – as if they had broken into a buried star-chamber down there in the crust.
A full moon has begun to rise. The sky is darkening to red and black, the moor is sinking to browns and silvers, and the valley is suddenly off-planet.
The first star shows, then others glimmer into view. I step off the boulders, begin the walk down off the ridge, when a skylark shoots up a yard or so from me, shocking my heart, and I put a hand down in the hollow from which it has flown in time to catch the trace warmth of its body before the cold steals it away. The lark rises up into the sky, its cascading song clear and present in the moment.
~
A long night drive on high moors and down over coastal plains, headlights sweeping heather on the corners, coning the sky on the uphills, and home at last after midnight to a house at the foot of a mountain. The sky is salted with stars.
I pad into the room where my youngest son, Will, is sleeping. The moonlight pouring through the thin curtain casts my shadow across the floor.
I stand over Will and he is lying so still that panic sluices coldly through me, my heart thumps in my ears and I reach my hand towards his mouth to feel for his breath, to search for proof of life in the darkness.
Nothing, no breath, no breath – and then there it is, on the exhale, drifting faint and warm on my skin, and I rest the back of my fingers for a few seconds on his cheek, feel the mass of his body.
Still there, my love?
Breathe.
Breathe again.
My heart slowing back down. Starlight silvering the fine down on the edge of his skin. Everything causing a scintillation.