The Great Mental Models, Volume 2

From the 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 Some of the mental models covered in this book include: <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.

Auteur

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.

Texte du rabat

"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"--

Échantillon de lecture
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 the ball drops to the floor of the ship. However, there is also a horizontal movement that the scientist doesn't perceive. Both the scientist and the ball are also moving the distance covered by the ship as the ball is falling to the ground.

An outside observer, someone standing on a nearby beach or a fish in the water, can detect the complete movement of the ball because their perspective is different. By being outside the ship, they see a more complete version of reality. The scientist on the boat would have to make a conscious effort to remember that both he and the ball are moving with the ship. Before you conclude that the motion of the ship should be obvious to the scientist, consider how often you reflect on your movement through space every day. Right now, you probably feel as though you're stationary. However, if you're on Earth, you're moving around the sun at sixty-seven thousand miles per hour. Galileo developed this thought experiment partly thanks to his belief that Copernicus was right and that the Earth itself is in motion that we do not feel.

Perspective influences what we perceive as reality and how we understand the world. Galileo's thought experiment is one you can use all the time. Imagine the scientist performing experiments on the boat and ask yourself: Now what does a fish see? And how does that relate to what the scientist experiences? Imagine being either one, or a bird in the sky, and you start to get an idea of how multiple eyewitness accounts of the same robbery can be so different.

To use this yourself, imagine seeing a situation through the eyes of all the participants. Changing your perspective and looking at things through the eyes of others not only reveals blind spots but also creates empathy.

In the early 1900s, Einstein used another famous thought experiment when developing his theory of special relativity, which linked mass and energy using the formula E = mc. This formula demonstrates that energy is equivalent to mass times the speed of light squared. With this theory, Einstein stated that the speed of light is fixed within any frame of reference moving at a constant velocity, and therefore there is no fixed frame of reference from which one can measure the physical laws. This is what Galileo had argued, but his ideas were put aside in the 1700s in favor of a view that said there was an absolute frame of reference. Einstein's theory of special relativity revived Galileo's ideas.

Einstein's thought experiment to describe special relativity illustrated the concept that observers in relative motion experience time differently. This means that two events can happen simultaneously from one observer's perspective and at different times from another observer's perspective. Both are right. Here is the experiment:

Imagine you are watching a train go by. Lightning strikes each end just as the train's midpoint is passing you. The lightning strikes are each the same distance from you, so you correctly conclude that the two bolts of lightning hit the train at exactly the same time.

Later on, you catch up with your friend, who was on the train. "Crazy that two bolts of lightning struck your train at exactly the same time," you say.

"What are you talking about?" she responds. "The front of the train got hit by lightning first."

You dismiss her interpretation. After all, you witnessed the whole thing. But here is what was happening for her:

She was sitting at the midpoint of the train. If the train had been stationary, she would have observed the two lightning strikes being simultaneous like you did. However, because the train was moving, the light from the rear strike had farther to travel to reach her. She perceived the light from the strike at the front first. So, she correctly concluded that the lightning strikes were not simultaneous; the one in front happened first.

These are two valid interpretations of the same event. …