Knocking on Heaven's Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World - Lisa Randall (2011)


When I first looked at translations of German media reports on my physics research or my book, Warped Passages,75 I was surprised by the repeated presence of the words “edge of the universe.” The explanation of the plausible but seemingly random appearance of the phrase wasn’t quite obvious at first—it turned out to be the computer’s German translation of my last name.76

Yet we are indeed at the edge of the universe, both on small scales and on large ones. Scientists have experimentally explored distances from the weak scale of 10-17 centimeters to the size of the universe, 1030 centimeters. We can’t be sure what the scales that demarcate true paradigm shifts in the future will be, but many scientific eyes are now focused on the weak scale, which the LHC and dark matter searches are experimentally exploring. At the same time, theoretical work continues to investigate scales ranging from the weak to the Planck energies, and to larger scales as well, as we attempt to fill in gaps in our understanding. It’s hubris to think that what we’ve seen is all there is. New discoveries almost certainly await.

The era of modern science represents a mere blip on the timeline of history. But the remarkable insights gained through advances in technology and mathematics since its birth in the seventeenth century have taken us an impressively long way toward understanding the world.

This book has explored how high-energy physicists and cosmologists today determine their course and how a combination of theory and experiment could shed light on some deep and fundamental questions. The Big Bang theory describes the universe’s current expansion, but it leaves open the questions of what happened earlier—and what is the nature of dark energy and dark matter. The Standard Model predicts elementary particle interactions, but leaves unresolved questions about why its properties are what they are. Dark matter and the Higgs boson could be around the corner—as could evidence for new spacetime symmetries or even new dimensions of space. We could be lucky and have answers soon. Or—if the relevant quantities are too heavy or too weakly interacting—it could take a while. We’ll only know if we ask and look.

I’ve also presented speculations about some even more difficult-to-test ideas. Though they expand the imagination and might eventually connect to reality, they could also remain in the domain of philosophy or religion. Science won’t disprove the landscape of multiple universes—or God for that matter—but it’s unlikely to verify them either. Even so, some aspects of the multiverse—such as those that could explain the hierarchy—do have testable consequences. It’s up to scientists to ferret these out.

The other major element of Knocking on Heaven’s Door has been the concepts—such as scale, uncertainty, creativity, and rational critical reasoning—that inform scientific thought. We can believe that science will make progress toward reaching answers and that complexity can emerge over time even before we have a fully fleshed-out explanation. The answers might be complicated, but that doesn’t justify abdicating faith in reason.

Understanding nature, life, and the universe poses extraordinarily difficult problems. We all would like to better understand who we are, where we came from, and where we are going—and to focus on things larger than ourselves and more permanent than the latest gadget or fashion. It’s easy to see why some turn to religion for explanations. Without the facts and the inspired interpretations that demonstrated surprising connections, the answers scientists have arrived at so far would have been extremely difficult to guess. People who think scientifically advance our knowledge of the world. The challenge is to understand as much as we can, and curiosity—unconstrained by dogma—is what is required.

The line between legitimate inquiry and arrogance might be an issue for some, but ultimately critical scientific thinking is the only reliable way to answer questions about the makeup of the universe. Extremist anti-intellectual strands in some current religious movements are at odds with traditional Christian heritage—not to mention progress and science—but fortunately they don’t represent all religious or intellectual perspectives. Many ways of thinking—even religious ones—incorporate challenges to existing paradigms and allow for the evolution of ideas. Progress for each of us involves replacing wrong ideas and building on the ones that are right.

I appreciated the sentiment when at a recent lecture, Bruce Alberts, former president of the National Academy of Sciences and current editor in chief of Science magazine, highlighted the need for the creativity, rationality, openness, and tolerance that are inherent to science—the robust combination of qualities that Jawaharlal Nehru, India’s first prime minister, called “the scientific temper.”77 Scientific ways of thinking are critical in today’s world, providing essential tools for dealing with many tough issues—social, practical, and political. I’d like to close with a few further reflections about the relevance of science and scientific thinking.

Some of today’s complex challenges might be addressed with a combination of technology, information about large populations, and raw computing power. But many major advances—scientific or otherwise—simply require a lot of thought by isolated or small groups of inspired individuals working on hard problems for a long time. Although this book has focused on the nature and value of basic science, pure, curiosity-driven research has—along with advancing science itself—led to technological breakthroughs that have completely changed the way we live. In addition to giving us important ways of thinking about hard problems, basic science can lead to technological tools today that—when combined with more scientific thinking that absorbs the creativity and principles we’ve discussed—will help find solutions tomorrow.

The question now is how to address bigger questions in that context. How do we take technology beyond mere short-term goals? Even in a world of technology, we need both ideas and incentives. The company that makes a must-have gadget may be very successful, and it’s easy to get caught up in the pursuit of a new one. But this can distract from the real issues we’d like technology to address. Although iPods are fun, the iPod lifestyle isn’t going to solve the big problems of today’s world.

Kevin Kelly, one of the founders of Wired magazine, said when we were on a panel together at a conference about technology and progress: “Technology is the greatest force in the universe.” If that is indeed the case, science is responsible for the greatest force, since basic science was essential to the technology revolution. The electron was discovered with no ulterior motive, yet electronics has defined our world. Electricity too was a purely intellectual discovery, yet the planet is now pulsing with wires and cables. Even quantum mechanics, the esoteric theory of the atom, turned out to be the key to Bell Labs’ scientists developing the transistor—the underlying hardware of the technology revolution. Yet none of the early investigators of the atom would have believed that the research they were doing would ever have any application, let alone one as grand as the computer and the information revolution. Both basic scientific knowledge and scientific ways of thinking were needed for the deep insights into the nature of reality that ultimately led to these breakthroughs.

No amount of computing power or social networking would have helped Einstein develop the theory of relativity any faster than he did. Scientists probably wouldn’t have understood quantum mechanics any more rapidly either. This is not to deny that, once there is an idea or some new understanding of a phenomenon, technology expedites advances. And some problems simply do require sifting through large amounts of data. But usually a core idea is essential. The insights into the nature of reality that the practice of science gives us can ultimately lead to transformative breakthroughs that affect us in unpredictable ways. It is vital that we continue to pursue it.

It is now a given that technology is central. This is true in the sense that most new developments critically employ technology. But I would add that it is central in the sense of being neither the beginning nor the end, but rather a means of getting things done and communicating and connecting developments. What we want to use it for is our choice. And the insights that go into solving problems or new developments can arise from many forms of creative thought.

Technology also makes each of us the center of our own universe, as we see physically in MapQuest or metaphorically on any social networking site. But the problems of the world are far more extensive and global. Technology can enable solutions, but they are more likely to come when also prompted by clear and creative thinking—the kind we see in the best scientific work.

In the past, our nation’s attention to science and technology—along with the recognition that we need to make long-term commitments and stick to them—has proved to be a successful strategy that kept us in the forefront of new developments and ideas. We now seem to be in danger of losing these values that have worked so well for us before. We need to recommit to these principles as we seek not just short-term advances but also to understand the costs and benefits for the long term.

Rational inquiry about the world deserves more credit, so that we can use it to address some of the serious challenges that lie ahead. Bruce Alberts in his lecture also advocated scientific thinking as a way of arming people against rants, simplified TV news, and overly subjective talk radio. We don’t want people to drift away from the scientific method, since that method is essential to reaching meaningful conclusions about the many complex systems that societies today must deal with—among them the financial system, the environment, risk assessment, and health care.

One of the key elements in making advances and solving problems—whether scientific or otherwise—has been and will be an awareness of scale. Categorizing what has been observed and understood by scale has taken us very far in our understanding of physics and the world—whether the units are physical scales, population groups, or time frames. Not only scientists, but political, economic, and policy leaders too need to keep such concepts in mind.

Supreme Court Justice Anthony Kennedy, in a speech to the Ninth Judicial Circuit, referred not only to the significance of scientific thinking, but also to the important contrast between “micro” and “macro” thinking—words that apply as much to the small-scale and large-scale elements of the universe as to the detailed and global ways we think about the world. As we have seen in this book, one of the factors in addressing issues—scientific as well as practical and political—is the interplay between the two scales of thought. The awareness of both is one of the factors that contributes to creative ideas.

Justice Kennedy also noted that among the elements of science that he likes are “the ridiculous solutions [that] often turn out to be the ones that are true.” And this is indeed sometimes the case. Nonetheless, good science, even when it leads to superficially far-fetched or counterintuitive conclusions, is rooted in measurements that show these conclusions to be true, or in problems that call for the apparently crazy solutions we conjecture might be real.

Many elements combine to form the foundation of good scientific thinking. In Knocking on Heaven’s Door, I have attempted to convey the significance of rational scientific thought and its materialist premises, as well as the ways in which scientific thinking tests ideas through experiments and discards them when they don’t measure up. Scientific thought recognizes that uncertainty isn’t failure. It properly evaluates risks and accounts for both short- and long-term influences. It allows for creative thinking in the search for solutions. These are all modes of thought that can lead to advances—both in and out of the laboratory or office. The scientific method helps us understand the edges of the universe, but it can also guide us in critical decisions for this world that we now live in. Our society needs to absorb these principles and teach them to future generations.

We shouldn’t be afraid to ask big questions or to consider grand concepts. One of my physics collaborators, Matthew Johnson, got it right when he exclaimed, “Never before has there been such an arsenal of ideas.” But we don’t yet know the answers and are waiting for experimental tests. Sometimes answers come more quickly than expected—as when the cosmic microwave background taught us about the early exponential expansion of the universe. And sometimes they take longer—as with the LHC, which still has us waiting.

We should soon know more about the makeup and forces of the universe, as well as why matter has the properties it does. We also hope to learn more about the missing stuff that we call “dark.” So, as our “prequel” ends, let’s return to the line from the Beatles song that accompanied the introduction to my earlier book, Warped Passages: “Got to be good-looking ’cause he’s so hard to see.” New phenomena and understanding might be challenging to find, but the wait and challenges will be worth it.