YA (pre-1990) novel: Student writes simulation in which time travel drains prehistoric natural resources, needs to stop from occurring for real

Question

I recall a novel in the mid-'80s about a (high school or college) student assigned to write simulation code. He develops a virtual world in which the inhabitants use time travel to bring natural resources from the past to the present. However, the simulations inevitably fail because overuse of this method results in a barren early Earth that could not initially support life.

At some point, the student realizes that his time-travel equations aren't just hand-wavy but valid in the real world and that the same resource-stripping and resulting consequences might occur in reality. The third act involves escaping from government agencies trying to obtain the simulation code.

Anyone remember this?

Answer 1

Borrowing from my edit of this answer:

"The Gadget Factor" by Sandy Landsman, 1985.

Two college freshmen create the ultimate computer game, a universe built to their own specifications, but complications arise when their formulas for time travel also work in the real world.

It's a professor who steals the research, the person whose data the equations were based upon. He tries to get Mike to share the credit and only publishes on his own when Mike refuses.