Molecular Adhesion and Its Applications : The Sticky Universe At the beginning of the twentieth century engineers and technologists would have recognized the importance of adhesion in two main aspects: First in the display of friction between surfaces — at the time a topic of growing importance to engineers; the second in crafts requiring the joining of materials — principally wood—to form engineering structures. While physical scientists would have admitted the adhesive properties of glues gels and certain pastes they regarded them as materials of uncertain formulation too impure to be amenable to precise experiment. Biological scientists were aware also of adhesive phenomena but the science was supported by documentation rather than understanding. By the end of the century adhesion and adhesives were playing a crucial and deliberate role in the formulation of materials in the design and manufacture of engineering structures without weakening rivets or pins and in the use of thin sections and intricate shapes. Miniaturization down to the micro and now to the nano level of mechanical electrical electronic and optical devices relied heavily on the understanding and the technology of adhesion. For most of the century physical scientists were aware that the states of matter whether gas liquid or solid were determined by the competition between thermal energy and int molecular binding forces. Then the solid state had to be differentiated into crystals amorphous glasses metals etc. so the importance of the molecular attractions in determining stiffness and strength became clearer. to Molecular Adhesion and Fracture: The Adhesion Paradox Phenomenology of Adhesion: Fracture Stranger than Friction Theories and Laws of Molecular Adhesion: All Molecules Adhere Evidence for the First Law of Adhesion: Surface Leap into Contact Intermolecular Forces: The New Geometry of Computer Modeling Evidence for the Second Law of Adhesion: Contamination Reduces Adhesion Influence of the Adhesion and Fracture Mechanism: The Third Law More Intricate Mechanisms: Raising and Lowering Adhesion Adhesion of Particles: Deformation Friction and Sintering Adhesion of Colloids: Dispersion Aggregation and Flocculation Pastes and Gels: Effects of Adhesion on Structure and Behavior Adhesion of Biological Cells: The Nature of Slime Nano adhesion: Joining Materials for Electronic Applications Films and Layers: Adhesion of Coatings Fracture and Toughness of Engineering Adhesive Joints Composite Materilas: Held Together by Adhesion at Interfaces The Future of Molecular Adhesion.