The Big Questions series enables renowned experts to tackle the 20 most fundamental and frequently asked questions of a major branch of science or philosophy. Each 3000-word essay simply and concisely examines a question that has eternally perplexed enquiring minds, providing answers from history’s great thinkers. This ambitious project is a unique distillation of humanity’s best ideas. In Big Questions: The Universe, Dr Stuart Clark tackles 20 key questions of astronomy and cosmology, including: What is the universe? What are stars made from? What is dark energy?  Are there other intelligent beings? Can we travel through time and space? Can the laws of physics change? Are there alternative universes?