From the New York Times bestselling author of Clear Thinking and Farnam Street founder, Shane Parrish. The second book in the timeless Great Mental Models series. Time and time again, great thinkers such as Charlie Munger and Warren Buffett have credited their success to mental models–representations of how something works that can scale onto other fields. Mastering a small number of mental models enables you to rapidly grasp new information, identify patterns others miss, and avoid the common mistakes that hold people back. Volume 2 of The Great Mental Models series provides a collection of over twenty important concepts from physics, chemistry, and biology in a clear and accessible style. Not only will you better understand the hidden forces that influence the world around you, you’ll also learn how those forces can work to your advantage. Some of the mental models covered in this book include: Leverage : When the application of a small force to one end results in a larger force at the other end. Inertia : An object (or organization) at rest will stay at rest unless acted upon by an external force. Activation Energy : The minimum amount of energy required to incite a chemical reaction. - Ecosystems : A community of organisms that have complex relationships to each other. The Great Mental Models series demystifies once elusive concepts and illuminates rich knowledge that traditional education overlooks. This series is the most comprehensive and accessible guide on using mental models to better understand our world, solve problems, and gain an advantage. “I’m really glad this exists in the world and I can see that I will be recommending it often.” — Matt Mullenweg, co-founder of WordPress, founder and CEO of Automattic “If you’ve read Charlie Munger’s Almanack this is the book you deeply crave in its wake. … Learn the big ideas from the big disciplines and you’ll be able to twist and turn problems in interesting ways at unprecedented speeds. … You owe yourself this book.” — Simon Eskildsen “This is what non-fiction books should aspire to be like. Informative, concise, universal, practical, visual, sharing stories and examples for context. Definitely, a must-read if you’re into universal multi-disciplinary thinking.” — Carl Rannaberg “I can truly say it is one of the best books I’ve ever had the pleasure of getting lost in. I loved the book and the challenges to conventional wisdom and thinking it presents.” — Rod Berryman “Want to learn? Read This! This should be a standard text for high school and university students.” — Code Cubitt Shane Parrish is the author of the New York Times bestseller Clear Thinking . He is an entrepreneur and wisdom seeker behind the popular website Farnam Street, where he focuses on turning timeless insights into action. His work has been featured in nearly every major publication, including The New York Times , The Wall Street Journal , and The Economist . His weekly newsletter, Brain Food , has captivated the minds of over half a million subscribers worldwide and his podcast, The Knowledge Project , is one of the most popular in the world. Relativity Put it into perspective. The theory of relativity is founded on empathy. Not empathy in the ordinary emotional sense; empathy in a rigorous scientific sense. The crucial idea is to imagine how things would appear to someone who's moving in a different way than you are. -Steven Strogatz We often think someone is wrong because they see things from a different perspective than we do. Relativity helps us to understand that there is more than one way to see everything. That doesn't mean everyone's perspective is equally valid, only that we might not have the most complete view into a problem or situation. Thought Experiments That Changed the World The science of relativity is best explained through two famous thought experiments-one conducted by Galileo and the other by Albert Einstein. Each describes a situation that demonstrates the reality of differing perspectives. Thought Experiments In volume 1, we dedicated a chapter to thought experiments because they are such valuable mental models. Frequently used as tools by scientists, thought experiments let us take on the impossible, evaluate the potential consequences of our actions, and reexamine history to make better decisions. They are rigorous applications of the scientific method to determine what we can infer from what we can imagine. In the 1630s, Galileo discovered that any two observers moving at constant speed and direction will obtain the same results for all mechanical experiments they perform. Galileo's original thought experiment describes a scientist on a ship moving at constant velocity. The scientist is belowdecks with no portholes to give him a frame of reference for the movement of the ship. When this scientist drops a ball from waist level, he will notice only the vertical movement caused by gravity. He will observe that th