Member of Technical Staff, Staff Physicist at FirstPrinciples (Ontario, Canada)Member of Technical Staff, Staff Physicist

FirstPrinciples is building AI to accelerate scientific discovery. Our core product is the Theo Platform, a research environment built to help researchers iterate faster, validate rigorously, and reach verified results they can trust. 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 are building an AI Physicist, but there is no established way to define, evaluate, or measure high-quality research when AI is part of the system. This role exists to bring deep domain expertise to shape how the system learns, what “good” looks like, and how we benchmark progress, ensuring the outputs are scientifically rigorous, meaningful, and advance the field.

What You’ll Do:

• Review and critique the model's reasoning in physics, identifying subtle conceptual errors and invalid assumptions.
• Provide clear corrections, alternative derivations, and minimal counterexamples to shape what “good” scientific reasoning looks like.
• Translate domain expertise into actionable improvements for model behaviour, reasoning patterns, and tool usage.
• Create gold-standard solutions and reference outputs for training and fine-tuning.
• Rank and evaluate model outputs to improve scientific reasoning through expert feedback loops.
• Help build and operate our external Collaborators program, coordinating expert review cycles and integrating feedback into training and evaluation.
• Contribute to high-quality research outputs (benchmarks, datasets, technical reports, preprints) that meet publishable standards.

Who You Are:

• PhD in Physics, or a closely related field, with postdoctoral-level research maturity.
• Proven ability to reason at a research level in physics and rigorously critique proofs, derivations, and scientific arguments.
• Strong scientific programming skills (Python) and experience with research tooling (Git, LaTeX).
• Clear, precise communicator with a strong ability to translate complex ideas into sharp critiques, guidance, and evaluation frameworks.
• Comfortable working in a fast-moving, cross-functional environment with researchers and engineers.
• Mission-driven, with an entrepreneurial mindset and interest in tackling foundational problems in science.

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 contribute to work aimed at advancing fundamental science.