Knocking on Heaven's Door (3 page)

Along with presenting specific hypotheses, this part explains how physicists go about constructing models and the efficacy of guiding principles such as “truth through beauty” and “top-down” versus “bottom-up.” It explains what the LHC is searching for, but also how physicists anticipate what it might find. This part describes how scientists will try to connect the seemingly abstract data the LHC will produce to some of the deep and fundamental ideas that we currently investigate.

Following our tour of research into the interior of matter, we’ll look outward in Part V At the same time as the LHC probes the tiniest scales of matter, satellites and telescopes explore the largest scales in the cosmos—studying the rate at which its expansion accelerates—and also study details of the relic radiation from the time of the Big Bang. This era could witness astounding new developments in
cosmology
, the science of how the universe evolved. In this section, we’ll explore the universe out to larger scales and discuss the particle physics–cosmology connection, as well as the elusive dark matter and experimental searches for it.

The final roundup in Part VI reflects on creativity, and the rich and varied elements of thought that enter into creative thinking. It examines how we attempt to answer the big questions through the somewhat smaller seeming activities we engage in on a day-to-day basis. We’ll conclude with some final thoughts on why science and scientific thinking are so important today, as well as the symbiotic relationship between technology and scientific thinking that has produced so much progress in the modern world.

I am frequently reminded how tricky it can be for non-scientists to appreciate the sometimes remote ideas that modern science addresses. This challenge became apparent when I met with a class of college students following a public lecture I gave about extra dimensions and physics. When I was told they all had the same pressing question, I expected some confusion about dimensions, but instead learned that they were eager to know my age. But lack of interest isn’t the only challenge—and the students actually did go on to engage with the scientific ideas. Still, there is no denying that fundamental science is often abstract, and justifying it can be difficult—a hurdle I had to face at a congressional hearing about the importance of basic science that I attended in the fall of 2009 along with Dennis Kovar, director of High Energy Physics at the
U.S.
Department of Energy; Pier Oddone, director of the Fermi National Accelerator Laboratory; and Hugh Montgomery, director of Jefferson Lab, a nuclear physics facility. This was my first time in the halls of government since my congressman, Benjamin Rosenthal, took me around when I was a high school finalist in the Westinghouse Science Competition many years before. He generously provided me with more than the mere photo op that the other finalists had received.

During my more recent visit, I again enjoyed observing the offices where policy is made. The room dedicated to the House Committee on Science and Technology is in the Rayburn House Office Building. The representatives sat in the back and we “witnesses” sat facing them. Inspirational plaques hung above the representatives’ heads, the first of which read “W
HEN THERE IS NO VISION THE PEOPLE PERISH
. P
ROVERBS
29:18.”

It seems American government must refer to scripture even in the congressional room explicitly dedicated to science and technology. The line nonetheless expresses a noble and accurate sentiment, which we all would like to apply.

The second plaque contained a more secular quote from Tennyson: “F
OR
I
DIPPED INTO THE FUTURE, FAR AS MY EYES COULD SEE
/ S
AW THE VISION OF THE WORLD AND ALL THE WONDER THAT WOULD BE
.”

That was also a nice thought to bear in mind while describing our research goals.

The irony was that the room was arranged so that we “witnesses” from the science world—who already were sympathetic to these statements—faced the plaques, which hung directly in our line of view. The representatives, on the other hand, sat underneath the words so they couldn’t see them. Congressman Lipinski, who in opening statements said that discoveries inspire more questions—and large metaphysical inquiries—acknowledged that he used to notice the plaques but they were now all too easy to forget. “Few of us ever look up there.” He expressed his gratitude for being reminded.

Moving on from the decor, we scientists turned to the task at hand—explaining what it is that makes this such an exciting and unprecedented era for particle physics and cosmology. Although the representatives’ questions were occasionally pointed and skeptical, I could appreciate the resistance they constantly face in explaining to their constituents why it would be a mistake to stop funding scientific work—even in the face of economic uncertainties. Their questions ranged from details about the purposes of specific experiments to broader issues concerning the role of science and where it is heading.

In between the absences of the representatives, who periodically had to leave to vote, we gave some examples of the side benefits accrued by advancing fundamental science. Even science intended as basic research often proves fruitful in other ways. We talked about Tim Berners-Lee’s development of the World Wide Web as a means of letting physicists in different countries collaborate more readily on their joint experiments at CERN. We discussed medical applications, such as PET scans—positron emission tomography—a way of probing internal body structure with the electron’s antiparticle. We explained the role of the industrial-scale production of superconducting magnets that were developed for colliders but now are used for magnetic resonance imaging as well, and finally the remarkable application of general relativity to precision predictions, including the global positioning systems we use daily in our cars.

Of course significant science doesn’t necessarily have any immediate benefit in practical terms. Even if there is an ultimate pay-off, we rarely know about it at the time of the discovery. When Benjamin Franklin realized lightning was electricity, he didn’t know electricity soon would change the face of the planet. And when Einstein worked on general relativity, he didn’t anticipate it would be used in any practical devices.

So the case we made that day was focused primarily not on specific applications, but rather on the vital importance of pure science. Though the status of science in America might be precarious, many people currently recognize its worth. Society’s view of the universe, time, and space changed with Einstein—as the original lyrics of “As Time Goes By” quoted in
Warped Passages
attest to.
³
Our very language and thoughts change as our understanding of the physical world develops and as new ways of thinking progress. What scientists study today and how we go about this will be critical both to our understanding of the world and to a robust and thoughtful society.

We are currently living in an extraordinarily exciting era for physics and cosmology, with some of the edgiest investigations ever proposed. Through a wide-ranging set of explorations,
Knocking on Heaven’s Door
touches on our different ways of understanding the world—through art, religion, and science—but chiefly with a focus on the goals and methods of modern physics. Ultimately, the very tiny objects we study are integral to discovering who we are and where we came from. The large-scale structures we hope to learn more about could shed light on our cosmic environment as well as on the origin and fate of our universe. This book is about what we hope to find and how it might happen. The journey should be an intriguing adventure—so welcome aboard.

SCALING REALITY

WHAT’S SO SMALL TO YOU IS SO LARGE TO ME

Among the many reasons I chose to pursue physics was the desire to do something that would have a permanent impact. If I was going to invest so much time, energy, and commitment, I wanted it to be for something with a claim to longevity and truth. Like most people, I thought of scientific advances as ideas that stand the test of time.

My friend Anna Christina Büchmann studied English in college while I majored in physics. Ironically, she studied literature for the same reason that drew me to math and science. She loved the way an insightful story lasts for centuries. When discussing Henry Fielding’s novel
Tom Jones
with her many years later, I learned that the edition I had read and thoroughly enjoyed was the one she helped annotate when she was in graduate school.
⁴

Tom Jones
was published 250 years ago, yet its themes and wit resonate to this day. During my first visit to Japan, I read the far older
Tale of Genji
and marveled at its characters’ immediacy too, despite the thousand years that have elapsed since Murasaki Shikibu wrote about them. Homer created the
Odyssey
roughly 2,000 years earlier. Yet notwithstanding its very different age and context, we continue to relish the tale of Odysseus’s journey and its timeless descriptions of human nature.

Scientists rarely read such old—let alone ancient—scientific texts. We usually leave that to historians and literary critics. We nonetheless apply the knowledge that has been acquired over time, whether from Newton in the seventeenth century or Copernicus more than 100 years earlier still. We might neglect the books themselves, but we are careful to preserve the important ideas they may contain.

Science certainly is not the static statement of universal laws we all hear about in elementary school. Nor is it a set of arbitrary rules. Science is an evolving body of knowledge. Many of the ideas we are currently investigating will prove to be wrong or incomplete. Scientific descriptions certainly change as we cross the boundaries that circumscribe what we know and venture into more remote territory where we can glimpse hints of the deeper truths beyond.

The paradox scientists have to contend with is that while aiming for permanence, we often investigate ideas that experimental data or better understanding will force us to modify or discard. The sound core of knowledge that has been tested and relied on is always surrounded by an amorphous boundary of uncertainties that are the domain of current research. The ideas and suggestions that excite us today will soon be forgotten if they are invalidated by more persuasive or comprehensive experimental work tomorrow.

When the 2008 Republican presidential candidate Mike Huckabee sided with religion over science—in part because scientific “beliefs” change whereas Christians take as their authority an eternal, unchanging God—he was not entirely misguided, at least in his characterization. The universe evolves and so does our scientific knowledge of it. Over time, scientists peel away layers of reality to expose what lies beneath the surface. We broaden and enrich our understanding as we probe increasingly remote scales. Knowledge advances and the unexplored region recedes when we reach these difficult-to-access distances. Scientific “beliefs” then evolve in accordance with our expanded knowledge.

Nonetheless, even when improved technology makes a broader range of observations possible, we don’t necessarily just abandon the theories that made successful predictions for the distances and energies, or speeds and densities, that were accessible in the past. Scientific theories grow and expand to absorb increased knowledge, while retaining the reliable parts of ideas that came before. Science thereby incorporates old established knowledge into the more comprehensive picture that emerges from a broader range of experimental and theoretical observations. Such changes don’t necessarily mean the old rules are wrong, but they can mean, for example, that those rules no longer apply on smaller scales where new components have been revealed. Knowledge can thereby embrace old ideas yet expand over time, even though very likely more will always remain to be explored. Just as travel can be compelling—even if you will never visit every place on the planet (never mind the cosmos)—increasing our understanding of matter and of the universe enriches our existence. The remaining unknowns serve to inspire further investigations.

My own research field of particle physics investigates increasingly smaller distances in order to study successively tinier components of matter. Current experimental and theoretical research attempt to expose what matter conceals—that which is embedded ever deeper inside. But despite the often-heard analogy, matter is not simply like a Russian matryoshka doll, with similar elements replicated at successively smaller scales. What makes investigating increasingly minuscule distances interesting is that the rules can change as we reach new domains. New forces and interactions might appear at those scales whose impact was too tiny to detect at the larger distances previously investigated.

The notion of scale, which tells physicists the range of sizes or energies that are relevant for any particular investigation, is critical to the understanding of scientific progress—as well as to many other aspects of the world around us. By partitioning the universe into different comprehensible sizes, we learn that the laws of physics that work best aren’t necessarily the same for all processes. We have to relate concepts that apply better on one scale to those more useful at another. Categorizing in this way lets us incorporate everything we know into a consistent picture while allowing for radical changes in descriptions at different lengths.

In this chapter, we’ll see how partitioning by scale—whichever scale is relevant—helps clarify our thinking—both scientific and otherwise—and why the subtle properties of the building blocks of matter are so hard to notice at the distances we encounter in our everyday lives. In doing so, this chapter also elaborates on the meaning of “right” and “wrong” in science, and why even apparently radical discoveries don’t necessarily force dramatic changes on the scales with which we are already familiar.