Here’s what you’ll learn when you read this story:Researchers have made a breakthrough in applying the first law of thermodynamics to complex systems. The first law of thermodynamics is undergoing a huge renovation. The first law of thermodynamics is one of the bedrock laws of physics. “The first law of thermodynamics tells you how much the balloon expands and how much hotter the gas inside the balloon gets. “Out of equilibrium, the first law of thermodynamics continues to only describe energy conversion during a process that changes the density and temperature,” Cassak tells Popular Mechanics.