Science has been extraordinarily successful in making sense of natural phenomena, and it is a force for good in the modern world. We would not have clean water, bountiful food, good health care, cars, and iPhones without it. However, we also do well to recognize not only its strengths, but also its limitations. I would like to contribute three themes to this discussion:

1. At its heart, science is about observation, and where the field of interest allows direct observation, the results of science are compelling. Our own profession of chemical engineering, for example, depends on scientific principles, together with physical and chemical properties such as phase equilibria and reaction kinetics, that are measured in laboratories and demonstrated in practical applications. In other areas, however, notably the origin of life and the beginnings of the universe itself, and also in fields like plate tectonics, we have no way to make direct measurements of many of the phenomena of interest – especially those that are historical and unrepeatable. All we can do is collect data and make measurements today, and draw inferences. This process employs some very powerful tools, including multi-billion-dollar space telescopes and particle accelerators, highly sophisticated mathematics and data analytics, and supercomputers. This allows us to develop plausible explanations of what might have happened in the distant past; but the level of validation can never match that of repeatable experiments.