Contributor(s): Professor Ricardo Hausmann | The difference between rich and poor countries is mostly explained by differences in “technology”. But what is technology and why does it not diffuse more quickly? This lecture will clarify the importance of collective know-how in technology diffusion and the importance of a sense of us in creating the needed cooperation to support the implementation of technology. Ricardo Hausmann (@ricardo_hausman) is Director of Harvard's Center for International Development and Professor of the Practice of Economic Development at the Kennedy School of Government. Previously, he served as the first Chief Economist of the Inter-American Development Bank (1994-2000), where he created the Research Department. He has served as Minister of Planning of Venezuela (1992-1993) and as a member of the Board of the Central Bank of Venezuela. He also served as Chair of the IMF-World Bank Development Committee. He was Professor of Economics at the Instituto de Estudios Superiores de Administracion (IESA) (1985-1991) in Caracas, where he founded the Center for Public Policy. His research interests include issues of growth, macroeconomic stability, international finance, and the social dimensions of development. He holds a PhD in economics from Cornell University. Riccardo Crescenzi (@crescenzi_r ) is a Professor of Economic Geography at LSE. The LSE Department of Geography & Environment (@LSEGeography) is a centre of international academic excellence in economic, urban and development geography, environmental social science and climate change.