About FirstPrinciples FirstPrinciples is a research organization building AI infrastructure for discovery in fundamental science. Currently, our work focuses on building systems like Theo, the AI Physicist, which is a domain-specialized system for research in fundamental physics. We’re a fast-growing, remote-first team of builders, researchers, engineers, and thinkers working across Canada, the US, the UK, and expanding globally. What brings us together is a shared curiosity about how the universe works, and a belief that we can build systems that help us explore it more effectively. We spend our time working on questions that don’t have clear answers, like how to design AI that can reason through scientific problems, and how the scientific process as a whole might evolve. This is work that sits somewhere between creativity and rigorous thinking, and often requires comfort with ambiguity and iteration. If you’re someone who enjoys tackling big, abstract problems and exploring ideas that don’t yet have a defined path forward, you’ll likely find the work here interesting. Why This Role Exists: We’re building the next version of our product and need someone who can own the experience end-to-end, from first concepts to final implementation. This role is not just about refining interfaces, but about inventing new ways for people to work with advanced AI systems: making complex model behaviour understandable, making uncertainty legible, and creating interactions that help users know what to trust, question, and do next. You’ll play a central role in defining how our AI Physicist shows up in the product, translating its capabilities into experiences that are clear, intuitive, and genuinely new. That includes exploring interaction patterns for reasoning traces and explanations, confidence and ambiguity, and steering and guidance controls. We’re looking for someone with strong product taste, sharp interaction instincts, and the ability to bring ideas to life in code, so they can move fluidly from concept to prototype to polished product experience. What You’ll Do: Translate product ideas and AI model outputs into usable, trustworthy, and intuitive interfaces with strong visual and interaction design Explore novel human-AI interaction patterns, designing interfaces for reasoning traces and explanations, AI uncertainty and confidence, and model steering/guiding controls Develop & ship responsive, high-performance frontend code using modern frameworks Work closely with product, engineering, and research to rapidly iterate on ideas and prototypes Establish and evolve design systems, UI patterns, and frontend standards Balance speed and quality, knowing when to prototype quickly and when to refine Talk to users to iterate, continuously improving the product experience based on feedback, usage, and evolving needs Who You Are: Strong builder with proven experience shipping production-quality interactive products in code, using tools like React, TypeScript, and similar modern web frameworks Excellent product and interaction instincts; you have a portfolio that demonstrates thoughtful, high-quality UI/UX work Able to move fluidly between design and code, with a strong sense of ownership over the end-to-end experience Experience working in fast-moving, ambiguous environments where you’ve helped shape the product, not just execute against a spec Deep attention to detail in interaction, layout, and visual polish Comfortable collaborating across disciplines and translating abstract ideas into tangible product experiences Motivated by building something from the ground up and having a visible impact on the product Bonus: Experience building AI or LLM-based products Background or degree in HCI, interaction design, or related field Experience designing products for highly technical users such as researchers, engineers, analysts Experience with data-heavy or workflow-heavy interfaces such as notebooks, IDEs, dashboards What You’ll Get: The opportunity to work on foundational problems at the intersection of AI and physics A high-trust, low-bureaucracy environment with real ownership Remote-first work with flexibility in how you structure your day Exposure to cutting-edge ideas across AI, scientific discovery, and emerging technologies A culture that values curiosity, depth of thinking, and first-principles reasoning The chance to shape how advanced AI systems are used in scientific discovery