The podcast introduces DreamGym, a novel framework designed to overcome the challenges of applying reinforcement learning (RL) to large language model (LLM) agents by synthesizing diverse, scalable experiences. Traditional RL for LLMs is constrained by the cost of real-world interactions, limited task diversity, and unreliable reward signals, which DreamGym addresses by distilling environment dynamics into a reasoning-based experience model. This model uses chain-of-thought reasoning and an experience replay buffer to generate consistent state transitions and feedback, enabling efficient agent rollout collection. Furthermore, DreamGym includes a curriculum task generator that adaptively creates challenging task variations to facilitate knowledge acquisition and improve the agent's policy. Experimental results across diverse environments demonstrate that DreamGym substantially improves RL training performance, especially in settings not traditionally ready for RL, and offers a scalable sim-to-real warm-start strategy.