Assume this was done on Earth in a sort of collision facility.
I'm working on story about two scientists who are researching temperatures, and how they would affect the world. In an advanced society, I didn't know what the impact of the collision would mean (and have since found out Absolute Hot on Earth is a REALLY bad idea). It would determine how hot my "mutants" will be, and the sort of cancelling out I would need to make them equal (one is evil, the other is good).
Note: I have no idea what to tag this as.