Humans compartmentalize. We group ideas and concepts together, perhaps to help us better comprehend the world, or perhaps simply for comfort. The world of science is no exception. We tend to separate the social sciences from the natural sciences, chemistry from physics, and biology from psychology. Important for this report, the life sciences are rarely included in the same academic department as the physical sciences,¹ and it is not uncommon for these fields to be taught in separate colleges. And even within the broad categories of life sciences or physical sciences, microbiologists are likely to be in separate departments from ecologists, while physicists may rarely interact with their chemist colleagues.

To be sure, there are different approaches and methods of analysis in the different disciplines. For example, physicists are accustomed to seeking those few grand, foundational laws that describe all physical behavior and then using those laws to divulge the inner workings of the world. Constrained by these laws, and the limits of mathematical and computational capabilities, they are able to describe with rigor only systems that are, for the most part, very simple (elementary particles, atoms and molecules), very ordered (crystalline material in its many forms), or very disordered (those systems containing incomprehensibly large numbers of particles whose general characteristics and phase transformations are described using thermodynamics). As physical scientists, chemists are equally constrained

by a small number of fundamental laws. They seek to understand how small bits of matter—atoms and molecules—are internally composed, and how they absorb and transmit energy and react with each other.

In contrast, the life sciences seek to understand a natural world that is multifaceted—perhaps even messy—and almost never in the steady state. Whereas fundamental laws drive the physical sciences, diversity and complexity are the key characteristics of the life sciences. This latter world begins at the smallest scales, with the biomolecules of which all living matter is made, and then extends to cells, tissues, and organs, to complete organisms, and then to their interactions with each other and with their environments, first on a local level and then globally. Biologists have traditionally pursued their studies without feeling the need to trace the complexities of those systems to the atomic and subatomic levels, although molecular approaches by now have assumed an enormous influence on most fields of biology.

While the distinctions between disciplines are traditional, they are fast becoming less applicable as science crosses the boundaries that once existed. Are efforts to understand biomolecules, the smallest of biological constructions, a facet of chemistry or biology? Are attempts to understand the environmental effects of greenhouse gases a concern of physical science or of biology? It is becoming increasingly irrelevant whether a particular research topic fits neatly into one discipline or another; in fact, many of the most interesting scientific questions and pressing societal issues will require the collective expertise from multiple fields. These areas of overlap are the focus of this report, where the events being studied cannot unambiguously be described as solely contained within the life or physical sciences.

How, then, to best describe the science of the intersection in terms that may be familiar to those working within the constituent fields? Physical scientists might describe it as a composite, a combination of materials (in this case, concepts, tools, and worldviews) with significantly different properties that, when combined, produce something neither could provide separately. Life scientists might describe it as a hybrid, an attempt to produce something new and different through the cross-breeding of ideas and techniques. All would say these intersectional areas of research require expertise and training outside the traditional scope of their disciplines, resulting in new ways of addressing existing problems or new approaches to emerging topics of study. Along with the novelty, though, comes the possibility of frustrations from falling outside the norm of either canonical discipline, such as difficulties in obtaining funding, finding an academic home, or earning tenure.

This report explores both the promises and obstacles associated with research at the intersection of the life and physical sciences. Chapters 2 and 3 examine, in broad terms, the potential opportunities arising from such research for both scientific communities and society in general. Some of the most promising scientific gains at this intersection are explored in Chapter 2, in the form of five Grand

Challenges—areas that have the potential to transform our understanding of the natural world. The potential societal benefits that will occur from progress in this area are discussed in Chapter 3. Research at this intersection can help address some of our most urgent societal challenges, from improved sources of food to creative, alternative sources of energy and from improved medical diagnostics and treatments to new, biologically inspired devices that identify and combat biological threats or help to mitigate the effects of climate change.

The next two chapters of this report delve more deeply into research efforts—both now and in the near future—in this intersection of the life and physical sciences. Some intersectional work involves scientists applying concepts developed in one area to issues arising in another. Chapter 4 provides three examples of such crosscutting themes: interactions, dynamics, and pattern formation. Other intersectional efforts involve using tools and techniques originally developed in one arena—principally in the physical sciences—to answer questions in the other. Chapter 5 discusses some of those tools and techniques, including some of the technological advances that will be needed shortly to further research in this area.

Finally, Chapter 6 discusses some of the obstacles that prevent research communities from taking full advantage of opportunities afforded by research at this intersection and proposes a number of recommendations for policy makers, academic institutions, scientists, and others to help reduce those obstacles. Highlighted are new mechanisms for education and training, new models for supporting scientific research, and new means for enhancing coordination between federal agencies.