At the cutting edge of theoretical physics, it was common to throw a particle into an unpredictable chaotic system.
Then, the system could be observed indirectly by the motion of the particle.
In fact, Lu Zhou's experiment proposal idea came from his earlier work at CERN.
The whole system of plasma could be treated like a pool table where playing a shot could tell you where the balls were.
As for the particle that would play the role of the "white ball", there wasn't a better option than helium-3.
First of all, its atomic diameter was small. It consisted of two protons and one neutron, which was close to the atomic mass of helium-2, and the nuclear structure was stabler than helium-2! Not only could it avoid indistinguishable multi-atomic collisions, but it could also pass through plasma easier.
