Personal reflections on the history of aperiodic crystals from early days to the state of the art

International audienceAperiodic crystals occur as modulated, intergrowth and quasicrystal structures. Their characterization in terms of symmetries possibly requires not only a higher-dimensional description, but also non-Euclidean transformations (like scaling). These crystallographic symmetries, observed in nature, have been investigated but only partially classified. Turning points in the structure determination of aperiodic crystals are presented in historical perspective up to the present time, together with methods and programs. The WEB allows to get more information on all that, on additional tools and on databases. An attempt to present challanges towards lines of future research concludes the review

Communicating Certainty and Uncertainty in Science in Out-of-School Contexts

This chapter addresses the importance of understanding certainty and uncertainty in relation to scientific evidence, risk in decision-making, and trust in science and scientists. Following a museum-based story about certainty and scientific evidence, two significant international events are described to demonstrate the consequences of failing to understand uncertainty in science. Research into people’s perceptions about the nature of scientific knowledge is revisited to reveal that adults may think less scientifically after a science-related experience, and examine how values and beliefs relating to the certainty/uncertainty of scientific knowledge are inherent in how science is communicated in public places like museums. It is argued that if people are to be encouraged to think more scientifically about the nature of science and its processes, a greater effort is needed to present science in ways that may be interpreted as controversial, and also communicate uncertainty in scientific evidence. The chapter concludes by exploring how a balanced exhibition might be achieved in this difficult process