The universe is a fascinating place, constantly evolving towards greater entropy, or disorder, as described by the Second Law of Thermodynamics. This might make you wonder how organized structures, like living beings, can exist if everything is moving towards chaos. The key lies in understanding the difference between entropy and complexity.
Entropy measures the number of ways you can arrange small-scale particles while maintaining the same large-scale properties, like temperature or color. Complexity, however, is about how difficult it is to describe a system’s large-scale properties. Simple systems are easy to describe, while complex systems require more detailed information.
Imagine a cup filled with half coffee and half milk. Initially, it has low entropy because swapping coffee molecules with each other or milk molecules with each other doesn’t change much. However, swapping coffee with milk molecules would be noticeable. This setup is simple, with milk on top and coffee on the bottom.
As the milk and coffee mix, entropy increases. The system becomes more complex as you need to describe the intricate swirls of milk and coffee. Eventually, entropy continues to rise until the mixture reaches equilibrium, where swapping molecules doesn’t make a difference. At this point, the system is simple again, just a homogeneous mixture of coffee and milk.
This principle applies to the universe as well. The early universe was smooth and dense, characterized by low entropy and simplicity. In the distant future, the universe will be smooth again but very dilute, with high entropy and simplicity. Currently, we are in the middle, where entropy is moderate, and complexity is at its peak. Stars, galaxies, and life forms like humans exist in this exciting phase of complexity.
However, just like the coffee and milk, the universe will eventually simplify again, and complex structures like us will fade away.
This exploration of entropy and complexity is part of a series on time and entropy, created in collaboration with physicist Sean Carroll. Supported by Google’s Making and Science initiative, the series aims to inspire people of all ages to engage with science. The videos are based on Sean Carroll’s book, “The Big Picture: On the Origins of Life, Meaning, and the Universe Itself,” available online and in bookstores worldwide.
Engage with an online simulation that allows you to manipulate particles in a closed system. Observe how changes in particle arrangement affect entropy and complexity. Reflect on how this relates to the universe’s evolution.
Form small groups and discuss the coffee and milk analogy. Consider how this analogy helps explain the concepts of entropy and complexity. Share your insights with the class and explore any questions that arise.
Research how entropy and complexity manifest in biological systems. Prepare a short presentation on your findings, focusing on how living organisms maintain order despite the universe’s tendency towards disorder.
Write a short story from the perspective of a particle in the universe. Describe its journey through different states of entropy and complexity, incorporating scientific concepts discussed in the article.
Participate in a debate about the future of complexity in the universe. Argue whether complex structures will continue to evolve or if the universe will inevitably return to simplicity. Use evidence from the article to support your position.
Entropy – A measure of the disorder or randomness in a system, often associated with the second law of thermodynamics. – In a closed system, entropy tends to increase over time, leading to a state of maximum disorder.
Complexity – The state or quality of being intricate or complicated, often used to describe systems with many interconnected parts. – The complexity of biological systems can be analyzed using principles from physics and chemistry.
Universe – The totality of known or supposed objects and phenomena throughout space; the cosmos. – The study of the universe involves understanding the fundamental forces and particles that govern its behavior.
Thermodynamics – The branch of physical science that deals with the relations between heat and other forms of energy. – Thermodynamics provides essential insights into energy transfer processes in chemical reactions.
Particles – Small localized objects to which can be ascribed several physical or chemical properties such as volume or mass. – In quantum physics, particles like electrons and photons exhibit both wave-like and particle-like properties.
Systems – A set of interacting or interdependent components forming an integrated whole, often studied in physics to understand complex interactions. – The solar system is a classic example of a gravitationally bound system studied in astrophysics.
Equilibrium – A state in which opposing forces or influences are balanced, often used to describe physical systems. – Chemical equilibrium occurs when the rate of the forward reaction equals the rate of the reverse reaction.
Galaxies – Massive systems of stars, stellar remnants, interstellar gas, dust, and dark matter, bound together by gravity. – The Milky Way is one of billions of galaxies in the observable universe.
Humans – Members of the species Homo sapiens, known for their advanced cognitive abilities and use of complex tools. – Humans have developed technologies that allow them to explore the fundamental laws of physics.
Science – The systematic study of the structure and behavior of the physical and natural world through observation and experiment. – Science has enabled us to understand the principles governing the natural world, from atomic particles to cosmic phenomena.
