Thought experiments are “what if” scenarios that invite us to look carefully at how we think and view the world. They’ve been used throughout history by philosophers and other thinkers to explore our intuitions and ways of reasoning, to find solutions to problems, and to expand our knowledge of ourselves and the world. In these 24 eye-opening lectures, Professor Breyer takes you deeply into the historical tradition of thought experiments, shining a light on both the purpose and the outcomes of these compelling mental voyages.

What is our species' greatest invention? Medicine, computers, space travel? Not even close. The innovation that underlies each of our past achievements and those we still aspire to is language. Language is the ultimate invention of Homo sapiens - one that has allowed us to change the physical and social world around us in every conceivable way, and an invention that has fundamentally changed us, as well.

"It doesn't take an Einstein to understand modern physics," says Professor Wolfson at the outset of these 24 lectures on what may be the most important subjects in the universe: relativity and quantum physics. Both have reputations for complexity. But the basic ideas behind them are, in fact, simple and comprehensible by anyone. These dynamic and illuminating lectures begin with a brief overview of theories of physical reality starting with Aristotle and culminating in Newtonian or "classical" physics.

Philosophers have long puzzled over the nature of space, time, and matter. These inquiries led to the flowering of physics with the Scientific Revolution in the 17th century. Since then, the spectacular success of modern physics might appear to have made philosophy irrelevant. But new theories have created a new range of philosophical concerns: What is the shape of space? Is time travel possible? Is there a grand unified theory that unites all of physics?

Conventional wisdom suggests there is a sharp distinction between emotion and reason. Emotions are seen as inferior, disruptive, primitive, and even bestial forces. These 24 remarkable lectures suggest otherwise-that emotions have intelligence and provide personal strategies that are vitally important to our everyday lives of perceiving, evaluating, appraising, understanding, and acting in the world.

The Spanish Civil War was a local conflict on the margins of Europe—a short yet bloody series of battles in a lull between the great World Wars—but the conflict was a microcosm of war in the 20th century. Not only did the Spanish Civil War foreshadow the global conflagration to come, but it also had its roots in the modern era’s central divides: urban versus rural, religion versus secularization, rich versus poor, progress versus tradition, democracy versus fascism and communism.

Chemistry and Our Universe: How It All Works is your in-depth introduction to this vital field, taught through 60 engaging half-hour lectures that are suitable for any background or none at all. Covering a year’s worth of introductory general chemistry at the college level, plus intriguing topics that are rarely discussed in the classroom, this amazingly comprehensive course requires nothing more advanced than high-school math. Your guide is Professor Ron B. Davis, Jr., a research chemist and award-winning teacher at Georgetown University.

Understanding our humanity - the essence of who we are - is one of the deepest mysteries and biggest challenges in modern science. Why do we have bad moods? Why are we capable of having such strange dreams? How can metaphors in our language hold such sway on our actions? As we learn more about the mechanisms of human behavior through evolutionary biology, neuroscience, anthropology, and other related fields, we're discovering just how intriguing the human species is.

Recent years have seen the introduction of concepts from the new and exciting field of complexity science that have captivated the attention of economists, sociologists, engineers, businesspeople, and many others. These include tipping points, the wisdom of crowds, six degrees of separation (or Kevin Bacon), and emergence. Complexity science can shed light on why businesses or economies succeed and fail, how epidemics spread and can be stopped, and what causes ecological systems to rebalance themselves after a disaster.

No skill is more important in today's world than being able to think about, understand, and act on information in an effective and responsible way. What's more, at no point in human history have we had access to so much information, with such relative ease, as we do in the 21st century. But because misinformation out there has increased as well, critical thinking is more important than ever. These 24 rewarding lectures equip you with the knowledge and techniques you need to become a savvier, sharper critical thinker in your professional and personal life.