'MINIMAL' MODEL CAPTURES NEURONS, FLOW OF OPINIONS, EXOTIC MATTER

A new study has introduced a new form of the classic Ising model that, by incorporating non-reciprocal interactions, can recreate many properties of one-way networks

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Biologists have the fruit fly. Botanists have the thale cress. Neurologists have the roundworm. These are model organisms: plants and animals that scientists in each of these fields study to make sense of almost all other plants and animals in the world.

For example, in the 1990s, Victor Ambros and Gary Ruvkun discovered a new form of RNA called microRNA (miRNA) in the roundworm Caenorhabditis elegans. For revealing that miRNA regulates genes and allows certain physiological processes in all organisms — including humans — to function properly, Ambros and Ruvkun received the medicine Nobel Prize in 2024.

Similarly, scientists studying recombinant DNA have Escherichia coli, toxicologists have rats, anatomists have zebrafish, those studying hepatitis have rhesus macaques, and so on.

In the same vein, condensed-matter physicists have the Ising model. 'Strange' particle found to have mass when moving in one direction, not another

A simple, powerful model

The German physicist Ernst Ising created the Ising model in 1924 following a suggestion by his PhD supervisor Wilhelm Lenz. The Ising model provides a simple way to solve problems involving systems where different types of units interact with each other.

For example, say there's a gas of a few million hydrogen atoms trapped in a chamber and a magnetic field is applied. You need to find out how much the energy of the gas has changed. Since each of these atoms itself is like a tiny magnet and has a north pole (or south pole) pointing in some direction, you can represent it as a grid of atoms: