Into the Unknown, page 1
Copyright © 2024 by Kelsey Johnson
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Library of Congress Cataloging-in-Publication Data
Names: Johnson, Kelsey, author.
Title: Into the unknown : the quest to understand the mysteries of the cosmos / Kelsey Johnson.
Description: First edition. | New York : Basic Books, 2024. | Includes bibliographical references and index.
Identifiers: LCCN 2024002952 | ISBN 9781541604360 (hardcover) | ISBN 9781541604384 (ebook)
Subjects: LCSH: Cosmology—Popular works.
Classification: LCC QB982 .J64 2024 | DDC 523.1—dc23/eng/20240509
LC record available at https://lccn.loc.gov/2024002952
ISBNs: 9781541604360 (hardcover), 9781541604384 (ebook)
E3-20240905-JV-NF-ORI
CONTENTS
Cover
Title Page
Copyright
Dedication
Prologue
Chapter 1: A Little Perspective Interstition
Chapter 2: What Is Knowledge? Interstition
Chapter 3: What Caused the Big Bang? Interstition
Chapter 4: Does Extraterrestrial Life Exist? Interstition
Chapter 5: What Are Dark Matter and Dark Energy? Interstition
Chapter 6: What Happens Inside Black Holes? Interstition
Chapter 7: What Is the Nature of Time? Interstition
Chapter 8: Are There Hidden Dimensions? Interstition
Chapter 9: What Determines the Laws of Nature? Interstition
Chapter 10: Is the Universe Fine-Tuned? Interstition
Chapter 11: What Is Our Place in the Universe?
Acknowledgments
Discover More
About the Author
Further Reading
Notes
To all who gaze at the night sky and wonder
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Prologue
One day while walking home from elementary school, two apparently contradictory facts came together in my head at the same time, and I was both confused and mad.
“So, if fire needs air to burn, and there is no air in space, how do stars burn?”
Either I was too stupid to understand how these “facts” could make sense together, or one of these things had to be wrong, which meant the universe didn’t make sense. I asked my mom this question later that night, and she responded, “I don’t know, I’m not smart enough. I wish your dad were around, I bet he could answer it.” (My mom was smart, but she didn’t have an education past high school.) That night I knew there were things about the universe that were a mystery to me. I also knew that I had to try to understand them. At the time, I also believed that everything must ultimately be understandable, even if I didn’t understand it.
In middle school my science teacher (thanks, Mr. Sackett!) took our class to visit the local state university. We sat in on several classes, which included an astronomy lecture on asteroids causing the extinction of dinosaurs. I’d never really thought about why the dinosaurs went extinct. I just took it at face value as “a thing that had happened that maybe someone understood.” I was shocked that no one had ever told me about asteroids killing dinosaurs. We also sat in on a physics class that day, during which the professor did amazing demonstrations of angular momentum and magnetism, and I realized there were real things in the physical world that I could not see that were extremely powerful and tantalizingly mysterious to me. I didn’t fully know what it meant, but I came home from school that day and declared to my mom that I was going to be an astrophysicist.
In high school, one of my teachers took us to the library at the nearby state university, which made my local library seem quaint and provincial by comparison. I literally had no idea that so much was known about so many things. Maybe here I could find answers to the mysteries of the universe. I checked out books from the university library on black holes, time travel, and other dimensions. I couldn’t understand them and the strange symbols and math they used, but that just made the mysteries seem even more enticing.
When I got to college, I was primed to learn everything I could possibly learn about the universe. Sheer momentum kept me on my quest for understanding for a long time, but after several semesters of learning the detailed math and physics necessary to understand the universe, it became clear to me that the smallest details took center stage. Shockingly few professors engaged with the deep mysteries of the universe that I thought the course material was supposed to be preparing me for. While it may be hard to “see the forest for the trees,” it is at least equally hard to see the cosmos for the stars.
At the time, I assumed that all my professors knew the answers to the big questions I had, but I just didn’t have enough background knowledge yet to understand if they tried to share the answers with me. In hindsight, I think they avoided talking about the big questions because they didn’t know the answers either, instead keeping their focus on the details and challenges of their particular studies: How massive is that black hole? Will those galaxies collide? When will the next supernova explode? These are all good and valuable questions in our quest to understand the universe, but they are a step removed from the beautiful existential questions that impel so many of us to study astrophysics to begin with.
The more I learned, the more I realized just how limited our understanding of the cosmos is. So many fundamental questions remained: What caused the Big Bang? What is the nature of time? What is dark matter? And not least of all, what is knowledge? I packed up my quest for real understanding and tucked it away for later—perhaps after I got my PhD, I could unpack it again with some hope of making progress.
After ten years of college and graduate school, and now many years of teaching at one of the top public universities in the world, I have honed my understanding of what is known and what may be unknowable. Through transdisciplinary work, particularly with colleagues in religious studies, I have also gained valuable experience and insight into diverse epistemological perspectives.
Over these years, I’ve developed a passion for trying to help people understand the foundations of the great mysteries of the cosmos—without needing years of math and science. Yes, of course, knowing advanced math and science will help your intuition, but I believe there is a lot you can understand without a PhD in astrophysics. I just have this crazy belief that it would do humanity good if we all had a better understanding of the universe we are part of.
If you are hoping for a good read on “solved mysteries,” you may wish to look elsewhere. There is no shortage of mysteries in the universe, which is great job security for scientists like me, but presents a bit of a challenge when deciding what makes the cut for a book. I did what any normal human might do and picked my absolute favorites to think about; these are the topics that keep me ruminating well past normal sleeping hours.
The quandaries we will encounter in this book reside at the boundary of human knowledge and understanding. The unknown—and potentially unknowable—nature of each topic sits at the convergence of science, philosophy, and theology. We will encounter question after question to which the answer could be “God.” To be clear at the outset, I don’t dismiss the possibility of a higher power of some sort. In fact, my exposure to astrophysics and the unsolved mysteries of the universe has led me to conclude through purely logical means that there must be things about the universe and its origin that we don’t understand, and possibly never will. Is there room for a higher power? Sure. However, I am also highly sensitized to the brainwashing that takes place in our society, and the extent to which people are taught not to think for themselves. Any belief system too fragile to permit people to reach their own conclusions is inherently flawed and unstable. When we hit the limits of our understanding in each chapter of this book, I will do my level best to offer a buffet of possible solutions, many
The topics of this book are entwined in complex ways—it turns out the universe didn’t evolve to have nice, tidy, and separate categories for humans to write nice, tidy books with clear-cut chapters. As you go on this journey with me through these baffling topics, the deeper we get into the landscape of the mysteries, the more actively connections between topics will multiply. If you are so inclined, you might even consider reading this book twice—building your knowledge of the landscape on the first pass and making deeper connections between chapters on the next go round. Then again, finding time to read at all can be a luxury, and I’m grateful for your curiosity about the universe, whether you just read a single chapter, or the whole book. Twice.
I hope your journey through this book will inspire you to think—for yourself—about the great mysteries of the universe, and by the last page you are even more perplexed and curious about the cosmos we are lucky enough to find ourselves in.
1
A Little Perspective
Often when we astronomers mention that we are astronomers (or “astrophysicists” if we are feeling antisocial), we get a response along the lines of,
“Cool! I loved learning constellations. But don’t we already pretty much know everything?”
The answer is absolutely, conclusively, no.
We’ve barely scratched the tip of a single ice crystal on the tip of the iceberg. In fact, the iceberg itself may even be an illusion. One of the (many) reasons I have trouble at parties is that small talk and the actual nature of reality don’t play well together.
You may go about your normal life and feel things just work. The microwave heats your frozen meal (if not uniformly). Cars drive (and are even starting to drive themselves). Computers calculate all kinds of things—some of which are even useful. We’ve sent spacecraft all over the solar system, and we’re on the verge of sending actual living people on similar escapades to places like Mars. To be sure, we humans have learned a lot, and we seem to have more-or-less understood the world of our everyday lives. So, you can be forgiven if you think we already know pretty much everything. But I’m writing this book with the hope of dislodging that comfy notion from your brain. Considering how limited and provincial our experiences are, I find it astounding that we’ve even figured out as much as we have about the universe.
One of the reasons our world seems to make sense is simply that we are used to it. It is easy to go about normal daily life and take basic things for granted. They just are. For example, right now you may be sitting on a chair, or standing on the floor (or sitting on the floor—but hopefully not standing on a chair). That’s just about the most everyday kind of experience you might have. Take a generous moment and think about gravity holding you down, literally pulling your mass toward the mass of the Earth. Why does gravity do that? “Just because it does” is not a very satisfying answer, and if you’ve had the pleasure of interacting with kids, they might let you know just how unsatisfying “Just because” is, as far as answers go. While we’re on the topic, what even is mass? To be fair, we do know a bit about what is under the hood as far as mass and gravity go, but just because I know there is an engine under the hood of a car, that doesn’t mean I know how it works (which is factually true in my case).
Coming to terms with our unfathomable insignificance in the cosmos may be impossible—the scale of the universe in space and time extends so far beyond our ability to comprehend that sometimes I feel the best we can do is try to comprehend that we don’t comprehend. Even for astronomers who think about these concepts daily, the full scales of time and space are largely abstractions many of us have become desensitized to—perhaps out of necessity to keep our sanity. Staring into the abyss every single day can take a toll if one doesn’t get a touch habituated to it.
Yet here we are on this tiny little speck of a planet trying to understand not just this tiny speck we call home, but the whole universe. It is a monumental task to try to understand the cosmos, and there is no doubt that we have barely scratched the surface. The fact that we have sent relatively infinitesimally tiny little tin cans of spacecrafts successfully to all the other specks we call planets in the solar system and gotten data back from them is an astounding testament to human ingenuity. So, despite our mind-blowing insignificance in the cosmos, you can take a beat and be a little proud of humanity (but not too proud—we’ve screwed up a lot of stuff, too).
To be clear, we only have a limited set of tools at our disposal. Astronomers are effectively scavengers: aside from a few crumbs of information we gather from within the solar system, pretty much the only information we receive from the universe comes from light. So, we’ve gotten really good at scavenging light and squeezing out every last bit of information it can give us. If you were to decide to become an astronomer, you would spend a lot of time learning how to analyze light. Other than light,1 we are largely limited to what we can do with our own brains and logic.
Still, I think it is essential to try to convey at least an impression of the universe we live in. The catch is that this is hard to do on the scale of a book—presumably the book you are reading is smallish on the scale of the universe. Just by seeing things in this smallish book, your brain does a neat trick when you see, for example, a picture of a galaxy. Yup, the galaxy fits on the page, which is totally in the realm of “normal.” This is a very different experience than, say, standing (or more likely floating) on the edge of a galaxy and trying to comprehend its vastness extending in every direction as far as you can see.
Humanity has now taken some astounding images of the universe. We even have images recording light that left its source almost 13 billion years ago and traveled across the entire visible universe before hitting one of our telescopes.2 In other words, we can look back in time almost 13 billion years. How does that make you feel? Like you’re standing on the edge of a dark and unfathomably deep abyss? Good. Because you are.
To provide even an inkling of a sense of scale, let’s start with something closer to home. If you could take a road trip to the Moon on an imaginary superhighway that still had normal Earthly speed limits, how long do you think it would take? Answer: about half a year (without stopping, so maybe stock up on diapers). But you can at least fathom half of a year—that is a timescale you have experienced many times unless you are an exceptionally young and precocious reader. As a reality check, the Moon is the farthest we have ever sent people. To be clear, this is not necessarily a bad thing. I am not a fan of unfettered human colonization. Our ethical understanding of the implications is alarmingly far behind current corporate aspirations. Still, to date we have only managed to get to the moon a couple times in the middle of last century. That’s it.
The farthest that we routinely have people living today is the International Space Station, which might understandably give you the idea that we humans are actually going to space. If you could drive to the space station when it is overhead it would take something like a mere four hours. Leave after breakfast and get there for lunch (hypothetically).
We are not going to zoom out to the entire scale of the universe, but I want to take one tiny step out to the scale of the solar system to make a point. If the Sun were the size of a grapefruit, the Earth would be roughly the size of one of those little round sprinkles you might put on cupcakes. Imagine holding them up next to each other for comparison (or if you have grapefruit and sprinkles on hand, you could actually hold them up for comparison and invite inquisitive looks from your family, roommates, or cat). As a fun fact, you could fit about a million Earths inside the Sun (if you were so inclined, had superpowers, and didn’t care about getting toasted). My experience is that the true relative scale of the Earth and the Sun is radically underappreciated, and for understandable reasons; to illustrate the solar system, many books don’t show things to scale—in part because they can’t show things to scale if you want to see anything. The standard presentation of not-to-scale images can leave an unwary reader with the misimpression that the Earth is a heck of a lot bigger and closer to the Sun than it is. If this is the visualization we grow up with engrained in our minds as reality, our opinion of ourselves and our place in the universe is surely distorted.
