Turning Time Travel into a Product: Choosing First Users, Rules and Safeguards

Design a time machine. Approach it as a product design question: decide who it is for, what it lets them do, and how you would launch it. ```hint Set the rules first Agree with the interviewer on what the machine can do: past, future or both, and whether travelers can change events or only watch them. Those rules decide who can safely use it and what can go wrong. ``` ### Clarifying Questions - Does the machine reach the past, the future, or both, and can travelers change events or only observe them? - Are we building it at Google, where it should connect to the company's mission and existing products, or as a standalone business? - Should we treat the technology as working and safe, or must the design account for risks such as a traveler not returning? - Who may use it: anyone who pays, approved institutions, or only the company itself? ### What a Strong Answer Covers - Explicit ground rules for how time travel works, and how those rules shape safety, ethics and scope. - A reasoned choice among user segments and use cases, with the prioritization criteria stated. - A concrete first version and later versions, including what the machine deliberately does not allow. - A north-star metric plus counter-metrics for safety, privacy and misuse. - Risks and a rollout plan proportionate to the stakes. ### Follow-up Questions - A government asks for exclusive access to trips into the future. How do you respond, and what would change your answer? - How would you price a trip, and how does pricing affect who gets to use the machine? - Months after launch, monitoring suggests a mission altered something in the past. What safeguards should have prevented it, and what do you do now?