Daniel Whiteson says global energy conservation breaks down in an expanding universe

What was said

""Conservation of energy. As you say, like energy can't be destroyed or created. But actually, we've discovered that's not true, right? that conservation of energy is something people assume and talk about and it seems obvious but what we've discovered is the expansion of the universe tells us that energy can be created and destroyed and it's happening all the time.""

Daniel Whiteson tells the show that the common slogan “energy can’t be created or destroyed” does not hold in a simple global sense for the universe as a whole, and he points to expansion-related effects in cosmology—such as dark energy’s constant density and the redshifting of photons—as examples where the total energy budget does not behave like a closed system.