Lab leader

William Fedus

William Fedus, also known as Liam, is a Periodic Labs co-founder. His research has examined generative model training, experience replay in reinforcement learning, and sparse expert networks. With Barret Zoph and Noam Shazeer, he introduced Switch Transformers, which route inputs to selected model components. He later co-authored work on stable expert models and the SimpleQA factuality benchmark. His GPT-4 credit concerns data work within reinforcement learning and alignment. Periodic was founded in 2025 to build AI scientists and laboratories for physical experiments. This connects model training and evaluation with an effort to produce and study measurements from the physical world.

• Sparse models
• Factuality
• Scientific AI