Astrobiologist Michael Russell once remarked that “the purpose of life is to hydrogenate carbon dioxide,” while Nobel laureate Albert Szent-Györgyi famously said, “life is nothing but an electron looking for a place to rest.” Although these statements may not provide the existential meaning of life we often seek, they highlight a fundamental truth: living organisms play a crucial role in the universe’s tendency to increase entropy.
At first glance, it might seem contradictory that life, which is highly organized, contributes to entropy, a measure of disorder. However, complexity does not equate to order. Every living organism, simply by existing, contributes to the increase of entropy in the universe.
Consider a photon from the Sun, which is full of useful energy. When a plant or microorganism captures this photon through photosynthesis, it stores the energy as sugar. However, the sugar contains less useful energy than the original photon because some energy is lost as heat.
When an animal, like a human, consumes the sugar, it uses the energy to produce ATP (adenosine triphosphate), a molecule that acts as a small energy pack. Yet, ATP holds less useful energy than the sugar, as some energy is expended in cellular processes. This pattern continues as ATP fuels muscle contractions or repairs cells, with energy gradually degrading into heat and noise.
This degradation of energy is a consistent pattern: energy transitions from useful to less useful forms, increasing entropy. Interestingly, life itself may have emerged due to entropy. Early Earth had low-entropy environments rich in energy, such as warm alkaline vents on the ocean floor. While simple chemical reactions couldn’t harness this energy, complex reaction networks could.
Under the right conditions, these networks might have sustained themselves by utilizing environmental energy. Some of these networks could have become enclosed in molecular membranes, forming the first living organisms. Thus, life might have begun as a series of chemical reactions that learned to exploit otherwise inaccessible energy.
A similar story can be told about stars. Hydrogen nuclei contain vast amounts of low-entropy nuclear energy, which can be released through fusion into helium. Although fusion is challenging, stars accomplish it efficiently, contributing to the universe’s entropy increase.
Our Sun transforms low-entropy fuel into higher-entropy energy, which life then uses as a fuel source, further increasing entropy. In essence, life continues the mission of the stars by perpetuating the flow of energy and entropy throughout the universe.
This exploration of life and entropy is part of a series on time and entropy, created in collaboration with physicist Sean Carroll. The series is inspired by Carroll’s book “The Big Picture: On the Origins of Life, Meaning, and the Universe Itself,” available on Audible. You can explore these concepts further by listening to the book with a free 30-day trial at Audible.com/minutephysics.
Engage in a seminar where you will discuss and debate the paradox of life and entropy. Prepare a short presentation on how living organisms contribute to the universe’s entropy. Use examples from the article to support your arguments and be ready to engage with your peers in a lively discussion.
Participate in a computer-based simulation that models energy flow from the Sun to plants and animals. Observe how energy degrades at each step and how entropy increases. Reflect on how this simulation mirrors the concepts discussed in the article and write a brief report on your findings.
Analyze a case study on the origin of life in low-entropy environments, such as warm alkaline vents. Work in groups to explore how these environments might have facilitated the emergence of life. Present your group’s hypothesis on how early life forms could have exploited environmental energy, as described in the article.
Write a short story or essay that creatively explores the relationship between stars and life as partners in entropy. Use the narrative to illustrate how stars and living organisms contribute to the universe’s energy flow, drawing inspiration from the article’s discussion on the Sun and life.
Listen to a podcast episode featuring physicist Sean Carroll discussing “The Big Picture: On the Origins of Life, Meaning, and the Universe Itself.” Afterward, participate in a group discussion to explore how the podcast’s insights align with the article’s themes on entropy and life’s role in the universe.
Entropy – A measure of the disorder or randomness in a system, often associated with the second law of thermodynamics, which states that the total entropy of an isolated system can never decrease over time. – In thermodynamics, the entropy of a closed system will increase until it reaches equilibrium.
Energy – The capacity to do work or produce change, existing in various forms such as kinetic, potential, thermal, and chemical energy. – The energy stored in glucose molecules is released during cellular respiration to fuel cellular processes.
Life – A characteristic distinguishing physical entities with biological processes, such as signaling and self-sustaining processes, from those that do not. – The study of life encompasses various fields such as biology, ecology, and genetics to understand living organisms and their interactions.
Organism – An individual living entity that can act or function independently, consisting of one or more cells. – Bacteria are single-celled organisms that can thrive in diverse environments, from soil to the human gut.
Photosynthesis – The process by which green plants, algae, and some bacteria convert light energy, usually from the sun, into chemical energy stored in glucose. – Photosynthesis is crucial for life on Earth as it provides the oxygen we breathe and the food we consume.
ATP – Adenosine triphosphate, a molecule that carries energy within cells, often referred to as the energy currency of the cell. – During cellular respiration, glucose is broken down to produce ATP, which powers various cellular activities.
Hydrogen – The lightest and most abundant chemical element, consisting of one proton and one electron, playing a crucial role in chemical reactions and energy production. – Hydrogen ions are essential in the process of ATP synthesis during oxidative phosphorylation in mitochondria.
Fusion – A nuclear reaction in which atomic nuclei combine to form a heavier nucleus, releasing energy in the process. – The sun generates energy through the fusion of hydrogen nuclei into helium, providing the heat and light necessary for life on Earth.
Universe – The totality of all space, time, matter, and energy, including galaxies, stars, and planets. – The study of the universe involves understanding the fundamental forces and particles that govern the cosmos.
Reactions – Processes in which substances interact to form new products, involving the breaking and forming of chemical bonds. – Enzymes catalyze biochemical reactions in the body, allowing metabolic processes to occur efficiently.
