CoursesCourse 15
Openness and evolution
Living things, cities, and societies are not sealed boxes, and that is how they keep their order. This course follows what happens when a system stays open: patterns that exist only while energy flows through, strict rules of scale for animals and cities, copies that make mistakes and so evolve, and cells that swallowed other cells to build a new level of life.
Start lesson 1Lessons
- 1 Order that flowsThe second law says disorder grows, yet cells, cities, and civilizations get more organized. The way out is to stay open, and a dish of liquid heated from below shows what that can build.
- 2 Bigger means slowerA mouse’s heart races and an elephant’s plods, and one rule of scale ties them together. What Kleiber’s law says, why it holds so widely, and where it is contested.
- 3 Bigger means fasterAnimals slow down as they grow, but cities speed up. The same mathematics gives wealth, crime, and a warning about runaway growth, and a famous forecast of a “singularity.”
- 4 Copies, mistakes, and partnershipsIndividuals die, so life copies itself. How a machine can copy itself, how copying errors drive evolution, and how cells that swallowed other cells built the levels of life.
You’ll be able to
- Explain how an open system can build and keep order without breaking the second law of thermodynamics, and describe Bénard’s honeycomb as a dissipative structure.
- Use scaling to explain why an elephant’s heart beats slowly and a big city’s pace quickens, including Kleiber’s law and what is still disputed about it.
- Describe how growth with an exponent above 1 leads to the idea of a finite-time “singularity,” and judge forecasts of a technological singularity as claims, not results.
- Explain von Neumann’s design for a machine that copies itself, how copying with mistakes plus selection produces evolution, and how swallowing and keeping other cells built a new level of life.
About this course
This course covers 开放与进化 (Openness and Evolution), the part of the series on complex systems that asks how order survives and grows. It picks up where Course 5, Energy, entropy, and order, ended: open systems keep their order by taking energy in and sending disorder out. Its last lesson returns to evolution, the story that Course 8, The journey of life, tells from fish to humans.
The argument and examples lead. Around them we add background for readers outside China, the views of other scientists where they differ, and hands-on activities. Where a claim has been disputed or has changed since it was first made, such as the exact exponent in Kleiber’s law or the forecasts of a technological “singularity,” we say so plainly.