Silas R. Beane, Zohreh Davoudi and Martin J. Savage found the notion of the universe as a computer simulation to be fascinating. They began to think about how it might be possible to determine if our own universe is a numerical simulation. It all begins with lattice gauge theory and quantum chromodynamics (QCD).
We know of four fundamental forces in our universe: strong nuclear force, electromagnetism, weak nuclear force and gravity. Lattice gauge theory and QCD focus on the strong nuclear force, which is the force that holds subatomic particles together. It's the strongest of the four fundamental forces but also has the shortest range.
Quantum chromodynamics is a theory that explains the fundamental nature of the strong force in four space-time dimensions. Using high-performance computing (HPC), it's possible for researchers to simulate an incredibly small universe in an effort to study QCD. It's on the femto scale, which is even smaller than the nano scale. A nanometer is one-billionth of a meter -- a femtometer is one-quadrillionth, or 10-15 meters.
Within this simulation, researchers use a lattice structure to represent the space-time continuum. If we were to somehow shrink down small enough to be inside this universe, we might be able to detect that it's a construct by observing how certain energies interact with the lattice.
In our universe, that energy could be cosmic rays. If scientists could observe cosmic rays behaving as if there is a lattice around our own universe, it would suggest that we are actually inside a computer simulation that uses the same techniques as lattice gauge theory.
We would have to develop technology sufficiently sophisticated and powerful enough to detect these cosmic rays and measure their behaviors to notice a lattice structure. This approach also assumes a few other constraints:
- The entities that designed the simulation followed a practice similar to what researchers are doing with QCD experiments.
- The entities had limited resources with which to work, meaning our universe would also be finite.
- The universe's designers are not actively preventing us from discovering that we're in a simulation.
If your mind isn't spinning already, let's move on to think about what living within a computer simulation would actually mean.