The hidden physics of life | Nikta Fakhri | TEDxNewEngland

Key Concepts

• Equilibrium: A state of balance, stability, and predictability where a system is unchanging and time loses its direction.
• Non-equilibrium: A dynamic state far from balance, characterized by constant motion, perpetual energy consumption, and continuous change, where life thrives.
• Symmetry Breaking: A physical process where a system transitions from an initial state with no preferred direction or configuration to one with a specific, chosen direction or pattern. In non-equilibrium systems, this is an ongoing, cascading process.
• Emergence: The phenomenon where complex, macroscopic patterns or behaviors arise from the interactions of simpler, microscopic components. In living systems, this is a dynamic and ongoing process with feedback loops.
• Arrow of Time: The irreversible, clear directionality of time, a hallmark of non-equilibrium living systems, mathematically related to energy flow and dissipation.
• Entropy: A thermodynamic concept measuring disorder. In living systems, higher energy flows lead to higher entropy production and more irreversible processes.
• Energy Dissipation: The process by which energy is converted into less useful forms, often heat, driving irreversible processes and contributing to the arrow of time in non-equilibrium systems.
• Self-organization: The process where order and complex structures arise spontaneously from local interactions within a system, driven by energy flow in non-equilibrium conditions.
• Collective Behavior: The coordinated actions of a large group of individuals, such as a murmuration of starlings, resulting in complex patterns that are more than the sum of their parts.

The Physics of Life: Non-Equilibrium Systems

The video explores the fundamental principles of non-equilibrium physics, arguing that these principles govern all of life, from microscopic cells to vast ecosystems. The speaker, a physicist, uses the breathtaking aerial ballet of starling murmurations as a central example to illustrate these concepts.

Equilibrium vs. Non-Equilibrium

The journey begins by distinguishing between two fundamental concepts:

• Equilibrium: This is a state of balance, stability, and predictability. It is illustrated using a simple bar magnet. In an ordinary piece of iron, tiny magnetic domains (like compass needles) point randomly. When an external magnetic field is applied, these domains align, a process known as symmetry breaking. Initially, there's no preferred direction (symmetry), but the alignment breaks this symmetry, choosing a specific direction. Once aligned, the system reaches a stable, predictable, unchanging equilibrium. A key characteristic of equilibrium is that time loses its direction; a video of the magnet's domains played backward would look almost identical to the forward version. Crucially, the speaker states that this equilibrium state is "the antithesis of life."
• Non-Equilibrium: This is the state where life truly thrives, "far from equilibrium." The starling murmuration serves as a complex and dynamic example. Each bird acts as a "flying living compass needle," aligning its velocity with its neighbors. However, unlike the magnet, this alignment is "ever changing," responding moment by moment. The flock is a "dynamic living system" that never settles into a quiet equilibrium, remaining in "constant motion, perpetually consuming energy to maintain its intricate dance." This "perpetual motion" and "ceaseless consumption of energy" define non-equilibrium, which is presented as the "seeds of life's beauty and complexity."

Dynamic Symmetry Breaking and Emergence

The video elaborates on how symmetry breaking operates in non-equilibrium systems:

• Continuous Symmetry Breaking: Unlike the one-time event in an equilibrium system, symmetry breaking in non-equilibrium systems like a starling flock is an "ongoing process driven by the constant flow of energy and matter." This leads to a "cascade of symmetry breaking events," where each break creates "new possibilities, new patterns, new structures," akin to a "neverending game of dominoes." This continuous process enables the "incredible diversity and adaptability of life," allowing living systems to respond, evolve, and create increasingly complex structures.
• Dynamic Emergence: The starling murmuration is presented as a perfect example of emergence in a non-equilibrium system. While the alignment of microscopic domains in a magnet leads to a stable, macroscopic magnetic field, the coordination among individual starlings leads to the "complex and fluid-like behavior" of the flock, which is "dynamic, ongoing." The flock's behavior continuously emerges from individual interactions, yet it also guides those same individuals, creating a feedback loop that maintains the system far from equilibrium. This "dynamic emergence" is a universal feature of living systems, applying from a collection of cells forming a human being to groups of humans forming complex societies. In each case, "the behavior of the whole emerges from yet it also guides the behavior of its parts."

Non-Equilibrium Across Scales: From Murmurations to Cells

The principles of non-equilibrium are not confined to macroscopic phenomena but are "universal," manifesting "across all scales of life."

• Microscopic Life: The speaker zooms in from the murmuration to a single living cell. In the lab, using "advanced microscopes," the speaker's team observes proteins (the building blocks of life) organizing into "waves and spirals of activity" across the surface of a dividing cell. These proteins interact with their molecular neighbors, mirroring the starlings' collective behavior, to create patterns that "guide the development of life itself."
• Research Findings on Protein Patterns: The speaker highlights that the "same principles of non-equilibrium physics" describe these intricate biological processes. For instance, they discovered that these protein spirals behave like "charged particles," with the core of each spiral corresponding to either a positive or negative charge based on its rotation. These "focal points of protein activity orchestrate the developmental processes across an entire oocyte."

The Arrow of Time and Entropy

A profound concept discussed is how life breaks the "symmetry of time itself":

• Irreversible Time: In the equilibrium state of a bar magnet, time loses its direction. However, in the non-equilibrium world of living systems, "time is an an arrow," possessing a clear, irreversible direction. Playing a video of a murmuration in reverse would immediately look "wrong, unnatural." Every biological process, from a starling's wing beat to cell division and heartbeats, is a "step forward in time that cannot be undone."
• Energy Flow and Entropy: The speaker reveals a "remarkable" mathematical relationship: the "arrow of time is mathematically related to the flow of energy in living systems." The direction of time arises from "energy dissipation" or "how far from equilibrium your system is." This is quantified using entropy, a "measure of disorder." In living systems, which continuously exchange energy and matter with the environment, "higher energy flows means higher entropy production and more irreversible processes." The speaker's group's experiments with protein patterns have confirmed this. While living systems create order and complexity, they do so by "adding to the universe's overall increase in entropy."

Implications and Future Perspectives

Embracing this dynamic view of life opens new avenues for inquiry and innovation:

• New Materials: Can non-equilibrium physics principles be used to design "smarter and more adaptable" new materials?
• Sustainable Energy: Could studying energy flows in ecosystems help discover "more sustainable ways to produce and use energy"?
• Origins of Life: Should the search for life's origins focus on places where "fluxes and energy flows create the potential for complexity," potentially leading to the discovery of "new forms of life or lifelike processes"?
• Universal Application: These fundamental processes are evident everywhere: in the "delicate balance" of a coral reef, the coordinated firing of billions of neurons in the human brain creating consciousness, and even the complex economic and social structures of human societies.

Conclusion: The Dance of Existence

The video concludes by revisiting the starlings, now seen through the lens of non-equilibrium physics. Their ballet illustrates how "energy drives matter to self-organize," how "breaking symmetries create diversity," and how "time's arrow arises from the processes that drive life." The speaker shares a personal realization from observing protein patterns in the lab: "life isn't about reaching equilibrium. It's about maintaining this dance far from it." The "constant flux," this "journey of becoming," is where "the true wonder of existence lies," a dance in which "we're all part of every moment."