“Do you want to hear the most epic story ever?”
So begins The Zoomable Universe (October 2017, Scientific American/FSG), a new book from astrophysicist Caleb Scharf and artist Ron Miller that is a tour of, well, almost everything. The “epic story” is the tale of how atoms made in the immediate aftermath of the big bang 13.8 billion years ago came together from the hearts of distant, long-dead suns scattered across our galaxy to coalesce into our familiar Earth—into toadstools, trilobites, trees and, of course, dear reader, into you.
Just as our planet itself is but one of hundreds of billions likely to exist in the Milky Way, this opening story is just one small part of Scharf and Miller’s greater, grander aim: condensing the sum total of our knowledge about the natural world into one illustrated 200-page volume. Of course, this doesn’t mean copying the entirety of Wikipedia onto glossy paper in microscopic print; they take a more elegant path, crafting a cosmic travelogue that jumps through all of existence’s known scales in order-of-magnitude leaps, ranging from the outer limits of the observable universe to the quantum worlds of fundamental particles. It’s a timeworn formula, tracing at least as far back as Charles and Ray Eames’s seminal 1977 film Powers of Ten—but updated for the 21st century with new findings from the far frontiers of science at all scales.
Scientific American spoke to Scharf about his book, his research process and what it really means to appreciate the universe’s vast scales.
[An edited transcript of the interview follows.]
What is this book about, fundamentally?
It’s not just about scales, for starters. It’s about all that we’ve learned about the cosmos in the last hundred years or so—and not just things like planets, stars and galaxies, but also the fundamental physical underpinnings of reality. It’s a highly visual and accessible presentation that is meant to bring a reader right up to date: all that we know, in a nutshell, about everything. But in a more ambitious sense, I feel this book is a jumping-off point for stories yet to be told, a starter for codifying what we do not know. It’s not a tidy wrap-up by any stretch of the imagination. The story of physical reality could be written differently, and it can and will be rewritten in the future. I hope that this book will help prompt those next sets of questions in readers somewhere, and lead to this tale being revised and retold.
What most interested you about this project?
There were lots of things. There’s the minutia and the mechanics of the project itself: How do you choose where this tour of the entire universe takes you, across 63 orders of magnitude, from the very large to the very small? Then, on what is really a meta-level, there is something intriguing about the idea of gathering together a summation of our knowledge of the physical world into a few words and pictures on some pages. These days I think most people have heard about how amazingly big a galaxy is or the incredibly small sizes of the quantum realm. But to have it all laid out in one place—maybe that isn’t so usual. There’s something special about that. And I like the idea of laying the right bread crumbs, clues—for talking about all the things we don’t know.
Given the breadth of the material covered, some of it must have fallen outside your expertise in physics and astronomy. Were you ever surprised by anything you learned while writing this?
There definitely were those moments. Here’s a rather extended example: One of the big decision points for The Zoomable Universe was to choose where to set the zoom’s midpoint, where we show things that we as humans are most familiar with. So, the original Powers of Ten presentation from Charles and Ray Eames zoomed in and out from a couple lying on a picnic blanket in a park in Chicago. And that’s great, but I wanted to get away from a Western-centric view and pick somewhere else on Earth, and I didn’t want to focus so strictly on humans. So I ended up making the midpoint a family of elephants walking in the Great Rift Valley in Africa, zooming in on a bird on one elephant’s back eating a louse out of the elephant’s skin, and then to the cells in a grain of pollen on a whisker near the louse’s compound eye, and so on. But we don’t just talk about multilayered biosystems here—this is also a place to talk about minds and consciousness, because elephants are incredibly intelligent creatures. So one of the breakout graphics we decided to do was a two-page spread on “Brains of the World,” showing different species’ brains to scale with each other and some information about how many neurons each contains and how we associate all this with cognitive abilities.
It was surprising to me how difficult it was to assemble that information. We don’t really know exactly how many neurons there are even in a human brain. When I started putting together the data, I took the number that appears nearly everywhere: A hundred billion neurons. It turns out that isn’t true—it’s more like 86 billion neurons—but even that number is constantly being revised, and that’s not even addressing the brains of other species! At heart, I am a physicist, and physicists want to quantify and count fundamental things: ”Okay, we’ve got a brain. How many neurons are in it? How many cells?” And it became apparent to me that, to some extent, many biologists don’t find that approach useful.
I ended up being obsessed with this for a week or two, trying to find the right numbers to have data for the graphic; and then wondering whether the numbers, exact or not, actually tell us anything useful—how meaningful is it to compare the number of neurons in a bee to the number in a mouse or in a human?
Right, so when you’re trying to sum up all our knowledge, you end up better appreciating the gaps—not only in what we know, but in how different scientific disciplines see and study the world. It’s interesting that these tensions came up for you, in this book about scale. Many people might think a book like this would just be about space and physics. But you’ve just described how it encompasses more than that.
Well, as I was developing the narrative of the book, I was very aware I had to link a huge diversity of topics together, and I knew that a way to do this might be to appeal to the different physical forces operating at each scale, and also to appeal to a reader’s preexisting knowledge. So at the big-picture scale of the universe, gravity is the thing to talk about—it’s what pulls mass together, and people are familiar with its effects and, of course, it operates at every scale, although other forces become more important further down. But gravity probably isn’t the best or only way to talk about planets or about life, right? So, for example, maybe talking about how energy moves and dissipates in the universe is better there. The Earth formed more than four and a half billion years ago, and it’s been trying its hardest to cool down ever since. Except it’s being blasted by solar radiation all the time, and by talking about that I could discuss how life exists as part of that global thermodynamic process. A book like this allows you to explore all these little side streets and alleyways that branch off from the main streets and highways of our knowledge. Do all those branches reflect enough of reality? I don’t know, but they definitely reflect how we’ve constructed our pictures of it.
Speaking of side streets, here’s one to go down: Sometimes an apparent “gap” in our knowledge is actually just showing us the true, fundamental absence of something rather than our ignorance. For example, in the section of the book where you zoom into an atom, it seems like there is an awful lot of empty space down there between an atom’s electrons and its nucleus. And so one might wonder—does this void reflect something we don’t know? Or is there really just nothing there to see?
I noticed this as I was writing the book and planning the illustrations with my collaborator Ron Miller, thinking about the linear progression of scales. The first chapter we handled was about planets, because we wanted to begin the collaborative process with a visually rich topic. That part came naturally to us. But later, as we went further down and got to the scale of the interior of atoms, we reached this place where, as you say, you’re in an atom. And now you’re scaling down, down, down through this void toward the atomic nucleus, the protons and neutrons, and there’s just nothing much to say. And nothing much to illustrate, either!
This highlights a counterintuitive statement you might have heard before, which is that in a very real physical sense we are mostly emptiness. And that is definitely driven home when you’re sitting there looking at what are essentially blank pages for the illustrations, saying, “Okay, well, can we put a little dot in the middle just to give readers the idea that something is coming next?”
You asked whether this is just a gap in our knowledge, or is this instead just how things are. It does seem sad in an aesthetic sense if that’s all there is, but the atomic emptiness also mirrors other voids that seem to exist at even smaller scales. In the book, as we zoom down through the quantum realm, we eventually reach a page that marks 10-18 meters, which is the scale where we find ourselves well within a proton, deep down into even more fundamental particles—quarks and gluons. Then you turn the page, and we have suddenly jumped further down by 17 orders of magnitude, to 10-35 meters, to what we call the Planck scale. Based on our understanding of the laws of physics, this is where uncertainty causes the concepts of location and duration to lose all meaning, where spacetime itself may break down into a probabilistic “quantum foam” of virtual particles and fields popping in and out of existence. But we really can’t say much more about it—or all those orders of magnitude we skipped—because we simply don’t know.
We thought about including those additional orders of magnitude at one per page—so 17 additional pages. But we didn’t know what to fill those pages with except for abstract, speculative visualizations. Then we considered just including 17 blank pages. You know, just turn, turn, turn, turn, to kind of pound home the emptiness. In the end, we just skipped these scales. There’s a big chart toward the end that shows all the scales the book covered. Those last scales are there, but they’re blank. We don’t make a big deal out of it in the book. But it’s there. And maybe some readers will see that and react to it, which is precisely what I’d like to have happen. Maybe an astute 12-year-old somewhere will read it and think, “Hang on, these idiots left the most important parts out!” The book does leave some clues lying around about what we might be missing.
Thinking about that big chart that shows all of the book’s scales, from the quantum foam to the outer limits of the observable universe, it’s already impressive that we can plot out 63 orders of magnitude like that in a unified diagram. But can anyone actually grasp it all? Can you hold all those scales together simultaneously as a construct in your mind and get an idea of what they all add up to in any meaningful sense?
I have to admit I can’t grasp it all—no. It’s a struggle to even comprehend small parts of it. There are moments in life when you might discern a superposition of more than one order of magnitude scale, but those experiences are few and far between—standing under the Eiffel Tower, hiking through the Grand Canyon, looking up at a total solar eclipse and seeing the stars come out. But, yeah, most of the time I don’t feel it in a visceral sense—I just see numbers on the page or on the screen. In a very selfish way, I guess the whole book was kind of an experiment to see if I could collect all this information to somehow get that feeling of awe, of perspective, and hopefully to create a way for other people to have that feeling, too.
Other than awe, how do you think contemplation of these scales should make us feel, as human beings, as little sparks of consciousness and quasi-emptiness adrift in a cosmos steadily sliding deeper into entropy? Are we meant to feel apathetic and insignificant in a vast and meaningless universe? Can you just think about quantum foam and multiverses, and suddenly it doesn’t matter that you stepped in a big wad of chewing gum on your way into the office in the morning?
Wow! Well, I can see our insignificance in terms of scale, and I can see my own insignificance there, too. But I guess I’d rather be a microscopic speck in a vast and fascinating universe than to be some bloated, central lump around which everything else revolves.[ That kind of puts you in a box, right? Being so small—being surrounded by things that are so much bigger, and other things that are so much smaller—it just means there’s so much more to explore. For me it’s actually affirming to think that in all this unfathomable vastness we have somehow managed to be here at all. So what if our existence is just due to some quantum fluctuation? Why should that change how we feel? Sure, on a truly grand scale we’re not even really here—we have borrowed something from somewhere else, and someday that something will be gone and we will be gone with it.
But, you know, we are still here, now. We can write books like this. We can construct stories, and that as a cosmic phenomena may be quite unique. I mean, life might exist all over the place in the cosmos. We don’t know yet. But this capacity to not just communicate but to imagine and to dream, maybe that is a bit special, even for intelligent life. Bees and ants communicate with each other in a language of sorts. In some ways they are collectively very intelligent. But I don’t think they tell each other epic fantasies or debate their interpretations of reality the way humans do. It could be, in that sense, we fall in a pretty special category. Which, I guess, can be a comforting thought.