## Kinetic theory

Gases and fluids are made up of gazillions of atoms or molecules, yet when we observe them they appear to us as a whole. They have features such as temperature or pressure, which we can easily measure without looking to see what every individual particle is doing. The kinetic theory of gases goes back to the 19th theory and bridges the gap between the microscopic world of molecules and atoms and the macroscopic world we can easily observe, explaining phenomena such as temperature and pressure in terms of the motion of the individual particles.

Today, ideas from this theory can be used in many situations that involve a multitude of mobile individual components — be they people, biological cells, or Big Data. The field is so relevant that the Isaac Newton Institute for Mathematical Sciences in Cambridge is currently hosting the KineCon 2022 research programme, bringing together some of the best minds in the area. Find out more with these articles.

Kinetic theory: Taming multitudes — Kinetic theory bridges the gap between the big and the small to understand systems made up of many components: from plasmas to people.

Living Proof: Anita Layton – one of Canada’s most powerful women — In this episode of the INI's *Living Proof* podcast, we join Dan Aspel to talk to the irrepressible Anita Layton about her career and research in kinetic theory.

Maths in a Minute: Statistical mechanics — Meet the theory that bridges the gap between the microscopic and the macroscopic using statistics and probability.

Maths in a Minute: The second law of thermodynamics — Thermodynamics describes phenomena such as heat and temperature, and can be formulated in terms of microscopic particles. The second law states that heat always flows from warmer objects to colder ones, never the other way around. But it also has a much less mundane formulation. Find out more with this article.

Maths in a Minute: Entropy — Entropy is a central concept in kinetic theory. You can think of it in terms of thermodynamics, in terms of disorder, and even in terms of information. Here's a brief introduction.

Satanic science — There's no doubt that information is power, but could it be converted into physical energy you could heat a room with or run a machine on? In the 19th century, based on insight of how gases behave, James Clerk Maxwell invented a hypothetical being, a "demon", that seemed to be able to do just that. The problem was that the little devil blatantly contravened the laws of physics. What is Maxwell's demon and how was it resolved?

*This article was produced as part of our collaboration with the Isaac Newton Institute for Mathematical Sciences (INI) – you can find all the content from our collaboration here.
The INI is an international research centre and our neighbour here on the University of Cambridge's maths campus. It attracts leading mathematical scientists from all over the world, and is open to all. Visit www.newton.ac.uk to find out more. *