Shannon Stirone | Longreads | October 2020 | 16 minutes (4,288 words)
When I was 8, I noticed an atlas on the bookshelf in my room. I had just started amassing large art books from family museum trips but this was the first abnormally sized book in my posession — it was so oddly shaped its pages spilled over the edge of the shelf. One day I used all my strength to wiggle it down off the bookcase. I sprawled on my bedroom floor and began sifting through the long pages. It must have been from the ’50s or ’60s. It smelled old but it was clearly a book that had been cared for over the years. Its pages were a mix of pastels so dizzying and complex; in how pinks separated from light green and the skinniest blue rivers cut across the pages. Once I was old enough to read, my grandpa started ceremoniously gifting me books from his shelves.
One by one, every time I saw him, a piece of his library became mine. He had travelled all over the world and knew how much it could change a person. And whenever I’d visit him, I’d browse the books on the lower shelves and run my fingers along the spines like a car’s wheels over speedbumps, each cover sort of yellowed from years of his cigarette smoke and constant reading. Once this book and I were formally introduced, I began having regular dates with the atlas. Each day I would lay on my stomach and then sit cross-legged hunched over the pages, running my fingers down the rivers in Africa — the Nile, Limpopo, I’d take a trip to France or Chile. I would attempt to pronounce Czechoslovakia and many other long words that threw me into a joyous tizzy. Every mountain range, every body of water, every large city I would look at longingly wondering one day when I got older, how many of these mysterious places I would see with my own eyes. My wanderlust grew as I grew. There was so much to be explored, there was so much space that existed around my little home in Los Angeles. There was so much I didn’t know.
For as long as we have existed, humans have been trying to understand themselves in the context of their physical location. Granted we associate value and identity with where we come from, where we live, and even many times where we know we are going. One of the oldest maps of the world on record in human history comes from the 7th or 6th century in Mesopotamia. The Imago Mundi is a simple clay tablet carved with cuneiform writing. Its eight sections describe a region around the Euphrates River in Babylon. But it is much more than a physical representation of where the Babylonians lived. Surrounding the Euphrates is a circle meant to symbolize the ocean or “bitter river.” The sections outside the circular ocean are called “nagu” or distant regions, some of which are also mentioned in the Babylonian Epic of Gilgamesh. This relationship between the parts of the map shows us that the ancient Babylonians were trying to place themselves and their location into the greater unknown regions beyond their understanding. By this time human civilizations had spent many years examining the stars and planets and marking down the movements of these objects in the sky. But the Imago Mundi is our first record of a map of our direct surroundings. “It’s a really unique text because we have a lot of descriptions of the world, but we don’t have a lot of drawings of it,” says Assyrian scholar Dr. Moudhy Al-Rashid. “We have drawings of buildings, building plans, that sort of thing but not an attempt to explain the world visually,” she says. “There are drawings of stars, there are star maps but not maps of the world.”
Two scissor lifts, with men strapped to the metal banister, flank the side of the telescope. There’s an oil leak near where the 5,000 robots are supposed to move around and they can’t stare at galaxies if there’s an oil leak. My visit to the Mayall 4-meter telescope at Kitt Peak National Observatory in Arizona came on a very regular working day in September 2019. The drive up the mountain started clearly, with no other cars in sight. There is a long narrow highway that drives straight toward the mountain, with two lanes that cut through the middle of the Tohono O’odham National Reservation. At first I could make out the greenery of shrubs and trees and rock layers folded together like neapolitan ice cream with milky chocolate ripples, rosey-tan, and white. These features were formed during the Triassic period, some 200 million years ago.
Each passing minute up the 6,883 foot climb became more and more opaque — I was driving into a cloud. When I parked and got out the wind knocked me onto my car, and when I looked up to stare at the dome, I couldn’t see the top. At 18 stories high, the dome housing the Mayall 4-meter disappeared into the sky above.
The Kitt Peak team were nearly done installing the DESI instrument that would search the universe for dark energy — the elusive force responsible for expanding our universe outward at speeds of tens of thousands of miles per second — 70 kilometers per second per megaparsec, to be precise. DESI, the Dark Energy Spectroscopic Instrument was being attached to the telescope to officially hunt galaxies in the early days of 2020. On October 22nd, 2019, they opened the double doors of the dome and the telescope collected its first official light as the DESI mission officially began. Their goal is an ambitious one — to make the most detailed 3D map of the universe. They will do this by looking back in time as far as 11 billion years ago when the universe was very young, galaxies were just beginning to form, and the contents of the universe were nestled much closer together.
For thousands of years people have climbed mountains and crossed rivers to create maps to understand their place in the context of things. In a way this 3D map of the universe is the last map humans can make. Sure it won’t be the last map of the universe, but we’ve traced the boundaries of land, marked rivers and oceans, countries and species. We’ve mapped Mars, the Moon, the solar system, even our own galaxy. Which means there is only one thing left to understand in this symbolic way and that is the entirety of the cosmos.
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DESI is a conglomerate of 500,000 parts moving in a synchronized ballet. Collected in tubes that run 40 feet from the top of the telescope to the bottom are 5,000 fiber optic cables. These threads of pure glass are as thin as a strand of hair and act as conduits for light. At the top of the telescope all 5,000 strands fan outward where each single cable will be assigned to an individual galaxy. Every 20 minutes the team will point the telescope at a new patch of sky while each one of the 5,000 cables locks onto a different galaxy. It takes only a few seconds for each robot to do-si-do and swivel to a new object. On an average night the team expects to collect the light from 150,000 different galaxies and will rarely look at the same galaxy twice. While this might sound daunting, the tricky element with DESI isn’t mapping nearly 40 million galaxies over five years, but the 5,000 miniature robots that move each individual hair-like strand inside the telescope. “This is a very complicated instrument,” says Michael Levi, DESI Director. “It has a half a million moving parts.” Not unlike the way complex internal clock mechanisms work, DESI’s 5,000 robots are so small that if one thing goes wrong each time they shift, it risks the entire operation, and a setback in data collection.
We’ve mapped Mars, the Moon, the solar system, even our own galaxy. Which means there is only one thing left to understand in this symbolic way and that is the entirety of the cosmos.
DESI’s 5,000 eyes will spend five years looking back in time at ancient light to better understand the story of the universe. By collecting this data they will be able to decode the light’s journey across the void. While we don’t have any functioning DeLoreans just yet, we do have telescopes and telescopes are real time machines. It is easy to forget that the images we see of space are never from the present –– that light has taken billions or millions of years to reach us. When we study deep space, we are studying the past, objects as they once were, not as they are now. We do this by studying photons. A photon is one of the lightest particles in the universe which happens to be responsible for what we know of as light and they play a vital role in how DESI will help us understand dark energy and the expansion of the universe.
Because this light takes so long to reach us, each photon has a story to tell of where it comes from and where it’s been. These photons have spent billions and billions of years traversing the cosmos to get to Earth but when they enter the mirror of the Mayall telescope their journey isn’t quite finished. As the light enters each fiberglass cable, it will travel down the length of the telescope through each individual thread of glass another 40 feet and across the white tile floor into a room that houses 10 identical spectrographs. The instruments will break the light apart sort of like a mail sorting machine, only with the spectrum of light from each galaxy. Depending on the story of each individual collection of photons, it will appear in the instrument as either redshifted or blueshifted. As light travels, the colors within the spectrum appear at different wavelengths — if an object is moving toward us its light is crunched and appears toward the blue part of the spectrum, whereas if an object is moving away, the light is stretched out and appears red. After traveling many billions of years, the journey of the light from all 40 million galaxies will end in a clean room inside of a dome on a mountaintop in Tucson, Arizona.
After traveling many billions of years, the journey of the light from all 40 million galaxies will end in a clean room inside of a dome on a mountaintop in Tucson, Arizona.
In 1929 astronomer Edwin Hubble was studying the light spectra of galaxies and announced that his observations showed that many galaxies were redshifting — they were in fact moving away from us. But what he’d actually discovered was the expansion of the universe. Those galaxies weren’t just speeding away on their own, the very fabric of space-time itself was ballooning outward. He didn’t believe this was evidence of expansion; it would take another 70 years before scientists realized that not only was the universe expanding –– the expansion was speeding up.
Nearly a decade before Hubble took to the telescope, Albert Einstein proposed a theory called the Cosmological Constant in tandem with his theory of general relativity. The idea being that the universe was a static place and the density remained constant. When Einstein saw Hubble’s news about the redshifting galaxies he threw this theory away, except Einstein was sort of right, go figure. The universe is not a static place — we know it’s expanding rapidly, but the density in the universe still remains constant. Think of it like this, imagine you’re in your living room with a table and TV and some books and a cup of coffee. Now imagine if that room began to expand like a balloon and got bigger and bigger. The objects in your living room would not increase in density — they are what they are. This is the same with our universe, as it balloons out the density remains the same, hence, your cup of coffee is the cosmological constant.
This was a tricky thing for astronomers to accept for the longest time because there is a lot of matter in the universe. And because of gravity we know that matter clumps together, so shouldn’t the universe be contracting? Newer estimates by astronomers say that there could be up to two trillion galaxies in the universe which are made up of two types of matter. The matter made of “normal” things like you and me and your cat and desk and iPhone — represents only 5 percent of the matter in the universe. Dark matter, which we cannot see, is about 25 percent. That is a lot of mass, and a lot of mass that is gravitationally attracted to each other; however despite this unfathomable amount of material and density, it is no match for the dominating force in the universe which accounts for 70 percent of everything in existence — dark energy. Ninety five percent of the universe is made of things we cannot see and have no real understanding of. It’s fair to say at this point in history that we and our 5 percent are not “normal” matter –– we are the real anomalies in this universe.
It’s fair to say at this point in history that we and our 5 percent are not ‘normal’ matter –– we are the real anomalies in this universe.
The name dark energy is born out of ignorance — we call it dark because scientists simply cannot see it and they don’t really have any idea what it is. Well, they have some ideas. “The simplest understanding is that it’s a thing called the cosmological constant,” says Dr. Risa Wechsler, an astrophysicist and professor at Stanford University. “This would mean essentially it’s a property of space itself, which is a constant over all space and time.” This is conveniently also the only way Einstein’s density theory works. Score one for the current working model. But it’s a bit of a Catch 22 — the more space there is, the more dark energy there is and the more the universe expands. Therefore the more the universe expands the more space there is and thus more dark energy. “We are at a very interesting stage right now in cosmology,” says Wechsler. “We have had what is essentially a standard cosmological model for the past 20 years. That model is basically still working but there are starting to be some signs that it’s breaking. And I think right now we’re in the stage where we don’t know whether things are going to go away when the data gets better or whether when the data gets better, we’re going to see a real sign that the model doesn’t work anymore.”
The survey data from DESI may show that the current understanding of the universe is wrong — this would not be the first time this happened. At least we know that dark energy is not a particle like dark matter. Some scientists think it could be another dimension leaking into our universe. But more than likely, it might be space itself. This would mean that space wasn’t actually empty, we just can’t see what it really is. But so what does “space itself mean?” We have no idea.
Given how new to the planet humans are on the grand scale, we’ve figured out quite a lot about the cosmos. We know the Earth is about 4 billion years old, we know that 13.8 billion years ago there was nothing and then there was everything. We know absolutely nothing about the first one ten millionth of a trillionth of a trillion of a trillionth of a second but after that we have the timeline worked out to minutes. Very shortly after the universe came into existence it inflated like a balloon and very quickly spread the matter around. But this inflation was brief and the universe continued to expand but not accelerate. So everything is fine, stars are being formed and eventually galaxies begin to coalesce and then galaxies huddled together and made galaxy clusters, and the objects in the version of the universe we know were born. So here is where things get weird.
All of this matter was gravitationally pulled toward each other, just as you’d expect matter to behave. As a result of all of this matter clumping together, the expansion of the universe slowed down. But then suddenly around seven billion years ago, the expansion started to speed up and it’s only gotten faster since. Sometime between 11 billion years and seven billion years ago, dark energy turned on and began dominating the universe. For a sense of scale at how fast this expansion is going –– our universe came into existence 13.8 billion years ago. Without dark energy and expansion, the diameter of the universe would then be 13.8 billion light years wide, but, we do have dark energy and because of this expansion the observable universe is now 91.32 billion light years across.
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Many scientists around the world, both on the DESI team and elsewhere, are desperately trying to understand why this shift suddenly happened. Why did dark energy suddenly turn on? All we know right now is that dark energy is winning.
Today’s task was to rebalance the telescope. Because the DESI cables are so heavy, they’ve thrown the balance of the scope out of whack. I stood with David Sprayberry, my host and onsite manager of the project, while his team strapped themselves into harnesses on a floor elevator 18 stories up. Men my dad’s age slipped their legs into something fit for a person working on the outside of the Empire State Building. Some of these technicians have been working on the telescope since it was built over 40 years ago and have watched it turn over to different scientific endeavors, DESI being the newest. They banter back and forth about their weekend plans and who is starting the elevator and are they all strapped in? Don’t wanna die today! Up they go.
To balance the telescope they have to carry trays of solid lead weights the size of envelopes up into its belly. Two by two they would screw on each weight and then test it, then add more weight to certain spots and test it again. They were just weeks away from collecting what astronomers call “first light.” The lucky first object of DESI’s gaze would be a spiral galaxy called Triangulum, 2.7 million light years away. This particular galaxy has been studied so much over the years that its spectra is very well known, making it a sort of galactic calibrator.
There’s so much laughter despite the mundane part of this work. So here we are, scissor lifts and lead weights on a quest to understand the most mysterious force in the universe. They should all have shirts on that say “Team Heat Death” but I am not in charge.
Before they started to fix the balance issue, we climbed down a thin metal ladder and into the center of the telescope directly below the mirror. At four meters, twice the size of the Hubble Space telescope mirror, the Mayall might be a bit older but it’s a serious telescope, which is good because it has a serious job to do.
The inscriptions on the Imago Mundi map describe some basic features — where the sun rises, where the mountains are. But then there is a line that refers to the four quadrants on the map as “The four quadrants of the entire universe.” A fact they could not have known, but it still remains true that the boundary of the universe is limited by what we can see, even today.
Finally, the last paragraph of writing on the Imago Mundi is a poignant ending, “In all eight ‘regions’ of the four shores (kibrati) of the ea[rth …], their interior no-one knows.” Ancient Babylonians were limited in their knowledge of what existed beyond the mountains to the East –– while they knew the underworld was in one direction and a group of people that were enemies in another. The Babylonians were limited in their scope of understanding, and while our knowledge has grown exponentially, we are in many ways still in the same position –– looking up and out and wondering what lies beyond ourselves.
The Babylonians were limited in their scope of understanding, and while our knowledge has grown exponentially, we are in many ways still in the same position –– looking up and out and wondering what lies beyond ourselves.
For DESI this might seem a bit absurd, making a map of a universe that is constantly changing, forever expanding. There is something striking and a bit ironic about creating a map of a boundary that is constantly moving away from us, like attempting to map grains of sand on a beach while the tide continues to roll in. The “edge” of our universe will continue to expand until everything is gone. But this map of the universe is almost more about understanding our past than our future. In this case, in order to know where we are going, we must first know where we have been.
DESI’s project director Michael Levy likens it to a space MRI. “It’s a little like medicine when they switched from x-rays, which were inherently two dimensional, to MRIs where you could take slices of the body.” DESI will serve a similar purpose but for space, “we will now have time slices or distance slices of the universe.”
By collecting data and slicing the light into periods of time, it will allow scientists to reconstruct the history of the universe. Eventually once the survey is completed we will be able to examine deep astronomical time the same way geologists have used fossils and minerals to tell the story of the Earth. Instruments like DESI allow us to breach the laws of physics. In this case by looking back in time, we can deduce what will happen in the future, even as far forward as the end of the universe.
We use our location as a way to think about our identity. In the case of the cosmos the timescale is well beyond our very short lifetimes or even beyond our comprehension. Some of the answers to these questions won’t be solved while we are still here but will be left to the incoming generations and the truth is there are questions that will simply be passed on and never answered. The quest might seem a bit nonsensical. Why does it matter when or how the universe began? Why does it matter when or how it ends? It matters for the same reason your locations throughout your life carry context for who you are. We exist on a timeline together — we pop into existence and then one day we stop. It matters for the same reason one of the first questions you learn to ask in another language is, “where are you from?” To know where you are at any given time is a frame of reference in which to measure your life in some way and in many ways those locations, those slices of time, hold a great deal of meaning.
To know where you are at any given time is a frame of reference in which to measure your life in some way and in many ways those locations, those slices of time, hold a great deal of meaning.
Before leaving we stopped inside the main office where people pick up keys for their dorms. Many folks were sleeping during the day as astronomers have a tendency to do. A cork board at least 30 years old is hanging from a wall covered in very old sun-faded cartoon clippings from newspapers that all have something to do with astronomy. At the very bottom is a black and white Ziggy cartoon with torn, frayed edges. It shows a person staring into a telescope, and it says, “I read that the universe is racing away from the Earth at over 15,000 miles per second! I wonder if it knows something we don’t.”
I left the telescope and DESI team around 4:00 p.m. that day and by the time I left the dome, the clouds had burned off and I could see all of Kitt Peak. Each ridge had clusters of telescopes all with their own quests for different answers, all of which lied overhead. I could see the roads snaking through the valley below –– I could finally see where I was.
One day, googols and googols of years after you and I have died, the universe will end. Just like us, it is currently in the process of its death. It is expanding outward at unfathomable speeds, so much so that eventually all matter in the universe will begin to separate, growing further and further apart. As a result of this expansion the universe and all the matter in it will cool off until everything is the same temperature. This is one of the most popular theories for the end of the universe called the Heat Death — literally the death of heat. Over time, stars will die, galaxies and their solar systems, globular clusters and everything we’ve ever known will get consumed by black holes — the last things to exist in this universe. Eventually the matter inside of those black holes will evaporate until there is nothing left. (If you could move forward in time when the only thing left were black holes, where average temperatures hover just a fraction of a degree over absolute zero, you would be the hottest thing in existence. The radiation emitted from your body would glow hotter than anything else.) This goes far beyond Sagan’s pale blue dot — everything we’ve ever known will be gone, every human ever born and died, every person we’ve ever loved, every work of art, every book, every planet, every galaxy, every star, every atom that was ever created will cease to be.
Meanwhile, you and I are going about our days on an average rocky planet in just one of trillions of solar systems. Our planet orbits around an average star that moves around the third arm of the Milky Way galaxy, local group Virgo supercluster in an ancient universe that is moving ever outward. Where are we? The answer is always changing.
Shannon Stirone is a writer living in the Bay Area. She covers space exploration, science and culture. Her work has appeared in the New York Times, the Washington Post, Rolling Stone and elsewhere.
Editor: Krista Stevens
Fact checker: Julie Schwietert Collazo