Published covertly in Leiden in 1638 while Galileo was living under house arrest by the Inquisition, the Discorsi e dimostrazioni matematiche intorno a due nuove scienze is the foundational treatise of modern kinematics and structural engineering.
Written as an engaging philosophical dialogue between Salviati (Galileo’s voice of reason), Sagredo (the educated gentleman), and Simplicio (the traditional Aristotelian), the work treats two distinct fields:
1. The resistance of solid bodies to fracture (strength of materials, scaling laws, and why giant animals cannot maintain bone proportions of small creatures).
2. The science of motion (kinematics): demonstrating that freely falling bodies accelerate uniformly regardless of mass, formulating the distance law (d ∝ t²), and proving that projectile motion combines uniform horizontal velocity with accelerated vertical fall to trace a parabola.
This book replaced qualitative Aristotelian physics with quantitative, mathematically described physical laws, directly preparing the ground for Isaac Newton.
