N-body linear force law allowing analytic solutions

TL;DR

This paper introduces a novel N-body force law that allows for exact analytic solutions by effectively reducing the complex system to independent harmonic oscillators, enabling efficient simulations of many-particle dynamics.

Contribution

The authors propose a new pair-wise force law in N-body systems that yields analytic solutions, simplifying the analysis of complex many-particle interactions.

Findings

Particles behave as if interacting with the system's center of mass.

The effective interaction follows Hooke's Law with a common frequency.

Analytic solutions enable efficient simulation of many-particle systems.

Abstract

We present a pair-wise force law in a system of N particles that produces analytic solutions for arbitrary number of particles, masses, and initial conditions. Each pair of particles interacts via a force that is proportional to the product of their masses and their separation distance, with the force directed radially. We show that, despite the N-body interaction, each particle behaves as if it interacts only with the center of mass of the system. This effective two-body interaction behaves as Hooke's Law with a common frequency for all particles, with the familiar analytic solutions for the trajectories. With these analytic solutions, it is possible to efficiently simulate a collection of these particles and incorporate other external forces. As an example, we simulate the particles within an adiabatically expanding container and calculate pressure and temperature in both the attractive and repulsive cases.