Understanding how solid materials break is a major issue, with challenging physics. Slow loading leads to creep or catastrophic rupture. Despite the major risks, no physics-based model predicts Earthquakes, and engineered structures require high safety margins. These difficulties are linked to heterogeneities and thermal vibrations. The physics of fracture concentrates energy stored at a large scale, to dissipate it locally around the fracture tip, which can lead to significant heating. We will analyse the mechanical behaviour, the associated energy flux, the heat source and transport, temperature and stress around the crack tip, and the ruptures of molecular bonds. We will compare numerics to experiments, breaking different materials (polymers, glass, elastomers) with detailed local temperature measurements. This will allow testing and extending the theory and its predictive character. The temperature around crack tips will be measured by several techniques, at different spatial and temporal scales. These measurements will be compared to the theoretical computations. We will also explore different types of heterogeneities and material heat conduction to analyse the mechanical impact. This has ambitious applications, such as the design of high-performance materials.