So, Andrew collaborated with special effects supervisor Scott R. Fisher to visualize subatomic activity onscreen. 

After much trial and error, they developed a chain reaction using thermite.

Andrew told the LA Times, “When you set fire to thermite, it starts a chemical reaction that burns at 2000 degrees Celsius [3632 degrees Fahrenheit] and turns into molten iron. To contain the reaction, we set a flower pot on a stand and covered the hole at the bottom. Once the thermite turned into molten iron, it burned through that hole and poured into a sandbox below, so you had droplets of molten iron hitting the surface and exploding. It was magnificent and incredibly bright. We were all blown away.”

The camera department, led by cinematographer Hoyte van Hoytema, created a special camera rig that filmed tiny bits of metal swirling in water for another sequence. The lens was immersed in the water.