Wang Miao visits Ding Yi at Ding's new but nearly empty apartment, where Wang immediately notices Ding's heavy drinking and grief over Yang Dong's death. Ding speaks bitterly about having bought the apartment in hopes of a future with Yang, then tells Wang that the police and military are mistaken to tie the physicists' deaths directly to the Frontiers of Science. He says some of the dead, including Yang Dong, had no connection to that organization, but warns Wang that understanding more will pull him in more deeply.

To explain, Ding turns to the pool table that he and Yang once enjoyed together. He repeatedly sets up a simple shot with a white ball striking a black ball into a pocket, and each time Wang easily reproduces the same result even after they move the table around the room. Ding frames this as an experiment and pushes Wang to explain why the outcome stays constant. Wang gives the standard physical answer: because the masses, relative positions, and momentum transfer remain the same, the result should remain the same regardless of place or time.

Ding then reveals the point of the demonstration. He says modern high-energy particle accelerators in North America, Europe, and Liangxiang have produced the opposite kind of result: when physicists run the same ultra-high-energy collision experiments under the same conditions, they do not get the same outcomes. Results differ between machines and even at different times on the same machine, with no stable pattern. Because fundamental physics depends on the assumption that natural laws are invariant across space and time, these contradictory results have thrown the field into panic.

When Wang asks what this implies, Ding forces him to state the conclusion himself. Wang realizes that if the laws of physics are not universal and stable, then physics as a coherent science collapses. Ding connects this directly to Yang Dong's suicide note, saying Wang has now stumbled onto the first half of the message and should better understand why the discovery would devastate someone devoted to theoretical physics. Ding adds that work at the frontiers of theory requires something like religious faith, making the fall into despair even more dangerous.

As Wang leaves, Ding gives him the address of Yang Dong's mother, explaining that Yang had been the center of her life and that she is now alone. Wang presses Ding for a clearer answer about whether he truly believes the laws of physics are not invariant across time and space. Ding refuses certainty and ends only by saying that this is the question, leaving Wang with a deeper sense of the intellectual and existential crisis behind the deaths.