Why now?

The Show HN post for 'What if the speed of light was 5 km/h?' earned 585 points, demonstrating strong resonance with a technical audience. This traction indicates a timely appetite for intuitive, human-scale physics visualizations, but it is a single data point and does not prove sustained demand.

The gap

Existing physics education tools like PhET and YouTube videos often present relativity abstractly or at cosmic scales. This project's novel angle—scaling the speed of light to human speeds—fills a pedagogical gap for intuitive understanding, but no evidence suggests users are actively seeking or willing to pay for such a tool.

Main competitor

PhET Interactive Simulations (University of Colorado Boulder) offers free, research-based physics simulations, including relativity, and is widely used in education.

Execution plan

1. Refine the existing visualization based on HN feedback, adding adjustable parameters (e.g., speed of light, object speeds) and clear explanations.
2. Package it as a standalone web app with a memorable domain, ensuring it works offline and on mobile devices.
3. Publish a write-up on physics education blogs and forums (e.g., Physics Forums, Reddit r/Physics) to drive initial traffic and gather user feedback.
4. Add interactive challenges or quizzes to encourage repeat visits and deeper engagement, and track usage analytics to measure retention.
5. Explore integration with existing learning management systems (e.g., as an embeddable widget) to reach classrooms, while monitoring for any willingness to pay.

Monetization

Monetization is not yet proven. Potential paths include a freemium model with advanced features (e.g., custom scenarios, classroom tools) or donations, but given the free alternatives and one-shot nature, revenue is uncertain and likely minimal without significant additional value.