Executive Summary
Biological physics, or the physics of living systems, brings the physicist’s style of inquiry to bear on the beautiful phenomena of life. The enormous range of phenomena encountered in living systems—phenomena that often have no analog or precedent in the inanimate world—means that the intellectual agenda of biological physics is exceptionally broad, even by the ambitious standards of physics.
For more than a century, the contrast between the complexity of life and the simplicity of physical laws has been a creative tension, driving extraordinarily productive interactions between physics and biology. From the double helical structure of DNA to magnetic resonance images of our brain in action, results of this collaboration between physics and biology are central to the modern understanding of life, and these results have had profound impacts on medicine, technology, and industry. Until recently, however, these successes were codified as parts of biology, not physics.
As the 20th century drew to a close, this began to change: Members of the physics community came to see the phenomena of life as challenges to our understanding of physics itself, challenges that are as profound and revolutionary as those posed by phenomena of the inanimate world. This wide range of explorations is united by the search for underlying physical principles, leading to the major conclusion of this study: A new field has emerged.
Conclusion: Biological physics now has emerged fully as a field of physics, alongside more traditional fields of astrophysics and cosmology, atomic, molecular and optical physics, condensed matter physics, nuclear physics, particle physics, and plasma physics.
Reacting to the emergence of this new discipline, the Committee on Biological Physics/Physics of Living Systems: A Decadal Survey of the National Academies of Sciences, Engineering, and Medicine was appointed to carry out the first decadal survey of this field, as part of the broader decadal survey of physics. Hundreds of scientific community members from a wide range of institutions and career stages provided valuable input to the committee, in addition to the funding agencies themselves. This report aims to help federal agencies, policymakers, and academic leadership understand the importance of biological physics research and make informed decisions about funding, workforce, and research directions.
Although the field is intellectually broad, unifying conceptual questions, in the physics tradition, help to organize exploration of the field.
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What are the physics problems that organisms need to solve?
To survive in the world, living organisms must convert energy from one form to another, sense their environment, and move through the world. Exploration of these functions has led to surprising new physics, from the interplay of classical and quantum dynamics in photosynthesis to hidden symmetries in the dynamics of macroscopic animal behavior.
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How do living systems represent and process information?
Understanding the physics of living systems requires us to understand how information flows across many scales, from single molecules to groups of organisms. From harnessing energy dissipation for more reliable information transmission on the molecular scale to using novel network dynamics as a neural code in the brain, life has found unexpected realizations of the physics of information.
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How do macroscopic functions of life emerge from interactions among many microscopic constituents?
From the ordered structure of a folded protein to the ordered flight paths of birds in a flock, much of what fascinates us about life involves collective behavior of many smaller units. Theory and experiment have combined to show how these collective behaviors can be described in the language of statistical physics, while pointing to new kinds of order that have no analog in the inanimate world.
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How do living systems navigate parameter space?
The numbers describing the mechanisms of life change in time through the processes of adaptation, learning, and evolution. The biological physics community has brought new perspective to these problems, envisioning life’s mechanisms as drawn from an ensemble of possibilities. The char-
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acterization of these ensembles—from the repertoire of antibodies in the immune system to the range of synaptic connections that are consistent with brain function—provides new physics problems.
These general physics questions are illustrated by many different biological systems, and answers will have concrete consequences. Details on each of these “Big Questions” appear in Part I of the report.
No healthy scientific field exists in isolation. Biological physics has drawn ideas and methods from neighboring fields of physics, but also has been a source of inspiration for new problems in these fields. Historical connections to many different areas of biology and chemistry continue to be productive, and results from the physics of living systems reach further into medicine and technology. The biological physics community has provided new tools for scientific discoveries, new instruments for medical diagnosis, new ideas for systems biology with applications in synthetic biology, new methods and theories for exploring the brain, and new algorithms for artificial intelligence. Results and methods from the biological physics community have been central in the world’s response to the COVID-19 pandemic. More on these connections can be found in Part II.
Finally, the report addresses what must be done to realize the promise of biological physics as a field. Building a new scientific field is a multigenerational project, and the emergence of biological physics prompts rethinking of how we teach physics, biology, and science more generally. Funding structures, currently fragmented, need revision to respond to the full breadth and coherence of activity in the biological physics community. Fully realizing the potential of the field requires welcoming aspiring scientists from all over the world, and from all segments of our society, managing resources in ways that are both effective and just. The committee’s general and specific recommendations in response to challenges in education, funding, and the human dimensions of science can be found in Part III, and are summarized in Appendix B.
The biological physics community is developing new experimental methods that expand our ability to explore the living world, and new theories that expand the conceptual framework of physics. These developments are redrawing the intellectual landscape of science and driving new technology. Ultimately, a mature physics of life will change our view of ourselves as humans.