CONCLUSION: LOOKING UP

I have had the good fortune to be invited to conferences with leaders in diverse fields—ranging from business, law, and foreign policy, to the arts, media, and of course science. Even when I have a different perspective from that of the other panelists or speakers, the discussions invariably stimulate fresh thinking about a wide spectrum of important topics. But the best questions—especially about my research—don’t always come from the conference participants. A particularly gratifying exchange about physics at one recent event took place right after the conference had ended, when Jake—the young driver who was taking me to the local Montana airport—surprised me with his thoughtful interest.

Upon learning that I’m a physicist, many people feel compelled to tell me their attitude toward the subject—whether it’s love or hate or fascination or confusion. I find this a bit funny. After all, most of us don’t feel the need to inform lawyers, for example, about our thoughts on jurisprudence. But these curiously confessional physics conversations sometimes pay off. Jake explained to me how a few years back, he had relished college-level physics in his Oregon high school and how he was now eager to keep learning more. Although he was no longer taking classes, he wanted to hear more about the many advances that physicists have made since then toward our understanding of the Universe.

But Jake didn’t ask only about recent developments. He also wanted to know about the place of the physics he had studied in light of later progress. So I explained to him that advances of the twentieth century taught us, for example, that Newton’s Laws—though they remain an extremely accurate approximation in familiar environments—cease to apply when applied to high velocity, small distance, or high density environments in which special relativity, quantum mechanics, or general relativity take over.

After pondering this for a while, Jake posed an off-beat, but profound question. He asked me what I would do with my knowledge if I could go back in time, wondering if I would tell the people I met there about the more recent developments that we know about only now.

Jake recognized the two important aspects of this dilemma. The first was whether anyone would believe me—or if they would just assume I was nuts. After all, without the supporting experimental evidence that was obtained only through much more advanced technology, the remarkable phenomena and connections that scientists discovered and deduced in the last century might seem crazy. They violate the intuitions formulated in more commonplace surroundings.

But the second facet of his quandary was perhaps even more compelling. Jake wondered whether, even if people did listen and believe the new insights, they would be scared and ignore them or—at the other extreme—rush to apply them too hastily. His first instinct was to think I should keep the information to my imagined time-traveling self, reasoning that the world would be better off if it were allowed to evolve the way it had—with no shortcuts to scientific knowledge.

Given society’s usual resistance to long-term thinking, Jake was worried that a sudden burst of information might be dangerous. He didn’t think that change was bad. But he was apprehensive when he saw his younger siblings trapped by video games and smartphones—forgoing exercise and the outdoors and the sense of exploration which he had so enjoyed at their age. He also worried about the example of his home town, where he had seen industries rush to grab resources once new technologies were introduced, without regard for either the local or the global implications. Once Jake had reflected on the irreversible consequence—to the landscape and to his family’s way of life—that he had seen take place during his short lifetime, he reasoned that society probably would be better off with sufficient time to adjust to major scientific discoveries or technological changes by more thoughtfully developing comprehensive, long-term strategies.

This book has explored how several major, uncontrollable perturbations in the Earth’s past have profoundly disturbed the stability of our planet. One such disturbance with an extraterrestrial origin occurred 66 million years ago when a speeding comet—which might have been triggered by dark matter—precipitated a major extinction. Perhaps in another 30 million years or so, another one will do so again. Such events are fascinating to decipher, which is why I have focused on them in this book and continue to study them in my current research.

But understanding their impact on the planet and on life might have further benefits—helping us anticipate the consequences of some of the perturbations that we are making to our environment today. On the time scales relevant to civilization and the diversity of current life on Earth, a deviant comet is not our most pressing concern. But the changes that an exploding human population makes when it too hastily exploits the Earth’s resources might well be. The impact might even be compared to that of a slow-moving comet—but this time the impact is of our own making. In contrast to an impact triggered at the farthest reaches of the Solar System—with the changes that are occurring now, we have the potential to exercise some control.

The study of dark matter is hardly the most obvious avenue to such concerns. Dark Matter and the Dinosaurs is a book about our surroundings in the largest sense—our cosmic environment and the remarkable insights that scientific advances have already brought us—and what future advances may come to reveal. But thinking about dark matter led me to think about our galaxy, which led me to learn more about the Solar System, which led me to consider comets, which led me to a better understanding of the extinction of the dinosaurs, which led me to contemplate the delicacy of the balance that allows life—meaning the life that exists on Earth today—to thrive. If we mess with that balance, we might survive and the planet certainly will. But it’s less clear that the species we live with and rely on will survive any consequent radical changes.

The Universe has been around for 13.8 billion years and the Earth has taken some four and a half billion orbits around the Sun. Humans have graced the planet for a mere two million years and civilization for less than twenty thousand. Yet in my lifetime, the human population has more than doubled, adding more than four billion people to the planet. When we are too hasty in exploiting the Earth’s resources—significantly influencing the planet and its life—we are very rapidly undoing the cosmic work of millions or even billions of years. The threats might escape ready notice in the short span of a human life. But exercising caution when moving forward could help us figure out more optimal ways to utilize new information and advances in the future.

We like to think we are resilient, but most likely the current state of the world is less stable than we think. Altering and destroying habitats and the atmosphere at the current rate is affecting biodiversity, and might even be precipitating a sixth extinction. Although humans certainly won’t disappear any time soon, important aspects of our way of life might. The modifications we are making—or even our attempted solutions—threaten our environment, not to mention our social and economic stability. Though the consequences might ultimately be beneficial in some global sense, they won’t necessarily be so for the species on Earth who live here now.

We can try to engineer some aspects of our environment but the world is an enormously complicated system that employs many miraculous-seeming features—only some of which we currently understand. Even if technology can solve some problems, it will be difficult in any case for it to keep up with the ever-increasing rate of change. Without repeated innovations to substantially alter the equation, the result will inevitably be an unsustainable expansion in which something has to give. A supportive political, social, and economic climate in which technology can be integrated into a more comprehensive strategy is essential if we are to achieve the optimal response. The challenges are clearly daunting but shouldn’t prevent our making some headway towards this very worthwhile goal.

Exponential growth starts relatively slowly but then shoots up dramatically. The resources required to sustain this new status quo swamps anything we’ve encountered in the past. In our delicately balanced ecosystem and with our complex and fragile infrastructure, even relatively small disturbances have the capacity to generate large effects. It’s important to ask ourselves whether we should plan our growth differently or at least anticipate the conceivable changes in a more deliberate manner. Even Pope Francis in his 2015 Encyclical warns about the faster and more intense human activity of what he calls “rapidification.” Though some aspects of coming changes will be beneficial, the potentially detrimental consequences are worth anticipating too. Viewed from outside—or inside—we can seem pretty shortsighted.

Don’t get me wrong. I believe in progress. After all, knowledge is a wonderful thing. But I also believe in taking responsibility for applying advances wisely, which sometimes means taking the long term view. An intelligent species shouldn’t predicate its existence on competing for and destroying scarce resources that have taken billions or at least millions of years to emerge. Although technological applications can be useful or harmful—sometimes inadvertently so—increased knowledge gives us the ability to create desirable machinery, make better predictions, find workable solutions to potential problems, and evaluate the limitations of our current understanding. It’s up to us to use our knowledge well.

We should remember that the full scope of applications of scientific discoveries is rarely apparent at first. Yet scientific advances can surreptitiously change our world, as well as our worldview. If applied well, they can yield tremendous benefits. Even many insights rooted in abstract theory—basic research that no one initially thought would ever have practical applications—has had a profound impact on our world.

Genetic studies, which today aim to treat cancer, are rooted in DNA research that initially was focused on purely theoretical questions. Medical tools such as MRIs grew out of our understanding of the atomic nucleus. Nuclear energy, which has been used for good and ill, emerged from knowledge of the structure of the atom. The electronics revolution grew out of transistor development, which developed from quantum physics. The Internet was a byproduct of the computer scientist Tim Berners-Lee’s work at CERN—the particle physics accelerator center that now hosts the Large Hadron Collider—to improve communication and coordination among scientists in different nations,. GPS systems—ubiquitous today—incorporate Einstein’s theory of relativity. No one even knew electricity would be important when it was first discovered, yet it is crucial to our current way of life.

When first starting his studies, the geologist Walter Alvarez, whose father was a Nobel-prize winning physicist, thought geology was routine compared to physics. Geologists were reconstructing relatively prosaic river and land patterns, while twentieth century physicists were radically changing the way people thought about the world and how it works. But as plate tectonics, stratigraphy, and geological evolution became better understood, oil reserves and mineralogical deposits were discovered and exploited. What started off as idle curiosity developed into tools for searching for oil and minerals. The transition began in the 18th century, but geology escalated in importance in the 20th. Geology provided great dividends to our world. It literally fueled the modern industrial complex—and with it, our economy and lifestyles—but many of our current environmental troubles too.

However, as the legacy of Alvarez and others demonstrates, not just industrial applications, but basic research goals as well, have fueled important advances in our understanding of geology. Connecting the meteoroid and the Solar System to a wider context—the structure of the galaxy—seems like the right progression in this expanding intellectual adventure of grasping the connections between our world and the surrounding Universe.

I like to think of the research this book describes as a continuation of the appreciation of other sciences that Alvarez’s work precipitated with its intertwining of geology, chemistry, and physics. That dark matter might complete the set of known relationships reinforces this continuity. Not only can we use geology to understand a cosmic event, but maybe with a detailed understanding of the nature of dark matter will we come to understand the dynamics that threw a comet into our path in the first place.

Though most people’s interest in meteoroids—astronomers and asteroid-mining-investors aside—derives from their potential consequences for life, the imminent danger presented by these flying objects is fairly minimal. Asteroids and comets are mostly in stable orbits and those that do deviate to hit the Earth are usually pretty small. Only rarely do big objects digress enough to leave the Solar System or strike the Earth. Based on the information I’ve presented, I hope you now have a better sense of what extraterrestrial bodies could hit in the future and how dangerous their impact is likely to be.

This book has explained the multiple threads of evidence establishing the one solid example of such a connection, which is the K-Pg extinction 66 million years in the past. In some global sense, we are all descendents of Chicxulub. It’s a part of our history that we should want to understand. If true, the additional wrinkle presented in this book would mean that not only was dark matter responsible for irrevocably changing our world, but also that some of it played a crucial role in allowing for our existence. In this scenario, from the dinosaurs’ perspective, dark matter was evil after all and the name scientists gave it was apt. But from a human perspective, this newly proposed type of dark matter was the instigator of one of the central accidents that changed the course of the Earth’s development to the point where you could be sitting here reading this book.

In Dark Matter and the Dinosaurs, I’ve tried to give a taste of the nature of scientific investigations—how we pin down what we know and advance beyond to uncharted realms. On the other hand, the history of the Universe and of the Earth takes us on an exciting but challenging voyage into our past. If you think family history is difficult to trace—even when people are still around to tell the tale—think of the obstacles to extricating a past preserved only in inanimate rocks, many of which have eroded over time or been subducted back into the mantle below or the complexity of understanding how dark substances, which we can’t even see, created structure.

Yet progress in science has revealed some of the remarkably intricate connections between the most fundamental matter’s physical makeup and the features of the world that we see. Particles of dark matter collapsed to form galaxies, heavy elements created inside stars have been absorbed into life, the energy released by decays of radioactive nuclei deep inside the mantle have driven the movements of the Earth’s crust that have created mountains. I find our ability to make progress in understanding these deeper connections in the Universe truly inspiring. Every time scientists have explored the boundaries of the known world, unanticipated discoveries have emerged.

Our world is rich—so rich that two of the most important questions particle physicists ask are, “Why this richness?” “How is all the matter we see related?” In my research, I am aware that what I am investigating may or may not ultimately connect directly to our experience of the world around us but hoping that, no matter what, the results will contribute to further progress. I concentrate on the task at hand, aware that anything that doesn’t fit into our standard picture and calculations could either indicate an inadequate understanding of conventional models or it could be a sign of something new.

Dark matter and its role in the Universe’s evolution are some of the most exciting scientific topics today. We will truly understand all forms of matter—as with any culturally complex society—only when we recognize and value the ways in which the diverse populations together contribute to the richness of our environment. The best way to advance our understanding will be to determine the most elegant and reliable table setting of matter that fits with observations. The dark matter proposal I’ve presented might be a thought experiment for now, but it’s one that will be validated or invalidated by actual future measurements. Data and theoretical consistency together are the uncompromising arbiters of what is right.

The speculative influence on a comet for which this book is titled is not the only possible implication of the new type of dark matter we’ve proposed. A dark matter disk could affect the motions of stars, the makeup of dwarf galaxies, and the results of experiments and observations in laboratories and in space. Though understanding dark matter has been even more elusive in many respects than exploring the Earth and the Solar System, scientists are finding novel ways to track it down. The results will tell us about the make-up of our galaxy and of our Universe.

Our planet probably doesn’t contain the only forms of life in the cosmos. But our existence required and still requires a universe and a planet with a number of remarkable properties. Forces we are only beginning to understand have been essential to how we got here. Understanding the galaxy and our origins within it yields a wider perspective on the felicitous accidents as well as the more predictable evolutionary processes that got us to this point. The amount that we already grasp is remarkable, as are the many more connections we aim to reveal. The progress of the last 50 years is nothing short of astonishing.

Though we are often faced with discouraging headlines and disappointingly cyclical patterns in world events, expanding scientific knowledge has the potential to enrich our lives and guide our actions in ways that preserve what we most value as we continue to advance. As research continues to uncover still more of the bridges that link our lives to our surroundings and our present to our past, we should appreciate the many features of our world that have been so long in the making and take care to use our acquired wisdom and technological advances well.

I always find it heartening to remember our amazing cosmological context. The petty squabbles of the world and short-term concerns shouldn’t distract us from the enormous scope of what science can teach us about the world. The words I’m about to say might not always sound like the most practical advice. But look up. And around you. A fascinating Universe is out there for us to cultivate, cherish, and understand.