This week, we discuss a short important article written by Jim Baggott about the lack of evidence in theoretical physics. The problem, according to Baggott, is that much of theoretical physics has crossed the line from physics to metaphysics. Theoretical physicists are sometimes eager to try answer the big questions concerning the origins of the universe, the underlying structure of reality and the meaning of life. The theories that emerge from this pursuit are often speculative; they are not based on any observable and measurable evidence. This is precisely where lies the danger! Baggott rightly notes that "the purpose of science is to seek rational explanations and ultimately an understanding of empirical reality by establishing a correspondence between the predictions of scientific theories and the results of observations and measurements."