This project aims to make it easy to extract meaningful predictions from some of our most important physical theories. We first encounter the so called strong force as it holds protons together at the center of atoms against all the electric repulsion struggling in vain to pull them apart. Whereas the electric field is transmitted by particles which classically ignore each other called photons, the strong force is transmitted by particles which even classically attract and repel each other called gluons. Much of the fascinating physics we learn from high energy particle colliders like the LHC at CERN is indeed from the scattering of gluons. The theory governing their scattering has special properties which makes it easier to predict the outcome as we scatter with higher energies, yet the calculations involved in making these predictions can still be incredibly laborious. Calculating predictions in gravity using traditional methods, such as how the orbits of spinning black holes decay by emitting gravitational waves, turns out to be even more horrendously complicated, not to mention the factorially more complicated quantum corrections.
Spectacularly we have found structure within all these predictions which may be exploited for tremendous simplicity. We call this structure a "double-copy" structure, metaphorically reminiscent of the double-helix of DNA. Instead of containing the information describing how varied life can be, this double-copy structure in theoretical predictions describes how varied different theories can be -- but also in terms of a small number of building blocks. Indeed this structure not only relates graviton predictions to much simpler gluon predictions, but finds a theoretical web weaving its way between many of our most important models for how nature behaves. With an improved ability to calculate we can answer questions in a few minutes by hand on a blackboard that took large supercomputers weeks and weeks to approach just a few years ago. We realize that we only need to calculate a few core predictions, and then we can combine them in various ways to accurately describe what would seem to be vastly different phenomena, exploiting this surprising universality. These methods suggest the possibility of insight across a huge range of scales: from the smallest interactions imaginable to the largest cosmological scales describing the formation of structure at the beginning of our universe.
Our field of scattering amplitudes bridges many communities allowing us to leverage ideas and insights for mutual benefit. Ultimately the most important achievement of this project will be seen as strengthening these connections in surprising new ways.
