Write a prompt for a piece of speculative fiction: In a world where time travel is possible, a group of scientists discover a way to manipulate the past in order to create a utopian society

Write a prompt for a piece of speculative fiction:

In a world where time travel is possible, a group of scientists discover a way to manipulate the past in order to create a utopian society. However, as they delve deeper into changing history, they uncover dark secrets and realize that their actions may have unintended consequences. Write a story exploring the ethical dilemmas and consequences of altering the past for the greater good.