The Great Mental Models, Volume 2: Physics, Chemistry and Biology

by Shane Parrish

Taking action that works with the world is more effective, less stressful, and ultimately more rewarding. We don’t waste our time fighting to accomplish the impossible.

In the first book, we explained that a mental model is simply a representation of how something works. We use models to retain knowledge and simplify how we understand the world. We can’t relearn everything every day, and so we construct models to help us chunk patterns and navigate our world more efficiently.

Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less. Marie Curie

Relativity helps us to understand that there is more than one way to see everything.

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

Galileo thus demonstrated that perspective influences what we perceive as reality and how we understand the world.

You will always have limitations to your frame of reference that you need to account for in an effort to better understand reality. You must recognize what these limits are and, in situations where the risks are high or the outcomes important, take steps to augment your perception.

There are two broad types of perspectives that we learn: differing physical perspectives, such as that the view out of your neighbor’s window is different than yours; and conceptual perspectives, such as that people have different feelings or beliefs that in turn influence their perspectives.

Our memories of the past are also distorted by what we know now, such as when a witness learns a new piece of information during a case and feels they knew it at the time.2 These and other common memory distortions feed into the subjectivity of eyewitness reports. People rewrite and reshape their memories, often to fit their existing beliefs. We often feel committed to our original perception and unconsciously adjust our memories to support what we think we originally saw.

We have all been in situations where we have a totally different perspective on events than the person standing next to us. It’s important to be aware of and compensate for different perspectives if you want to get the most complete picture possible of the situation you are in. What you see is never all there is.

John, when people thought the earth was flat, they were wrong. When people thought the earth was spherical, they were wrong. But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together.” » Isaac Asimov

When you see someone doing something that doesn’t make sense to you, ask yourself what the world would have to look like to you for those actions to make sense.

While we all see our own version of events, the goal is to enlarge our perspective to be a closer representation of reality by removing some of the factors that cloud our judgment.

It is good to know something of the customs of various peoples, so as to judge our own more soundly and so as not to think that everything that is contrary to our ways is ridiculous and against reason, as those who have seen nothing have a habit of doing. » Descartes

How other people frame something is their vantage point. It’s not an unobstructed description of reality, but rather their individual perspective. Making efforts to understand someone’s view helps you understand their frame, their set of beliefs and biases that guide how they see their world.

The core concepts of relative perspective and framing have a broad application. When someone gives you something, an opinion, a report, an article, a plan, consider how it is framed. Who is involved in this information, and what do you know about their vantage point? Knowing the factors that influence how a person frames issues helps you understand their perspective and how you can use it to augment your own.

Perspective often comes from distance or time. If you’re trying to solve a problem and you’re stuck, try shifting your vantage point.

Examples of this are moving up and contemplating the bigger picture, moving down and seeing more details, or assuming the perspective of other stakeholders—customers, suppliers, partners, government. Many problems become clearer if you extend the timeline. What does this situation look like in the weeks, months, and years ahead? Assuming different perspectives allows you to gain a more complete understanding of what’s really going on.

We all get stuck, frustrated when no one seems to understand us, or angry that we aren’t making progress based on how we understand the world. This is when it is most helpful to remember relativity and refresh our perspective by stepping outside of ourselves for a little bit.

Reciprocity teaches us why win-win relationships are the way to go, why waiters leave candies with the bill, why it’s a good idea to use the least force possible to secure an outcome, and why a lot of companies don’t permit their employees to accept gifts. This model demonstrates why we should view giving as being as valuable as having. It prompts us rewrite the Golden Rule to say, “Do unto others knowing that something will be done unto you.”

So what exactly is reciprocity? In physics, reciprocity is Newton’s third law, which states that for every force exerted by object A on object B, there is an equal but opposite force exerted by object B on object A.

Consider the tackle in American football. The force that the defender puts on the receiver’s body in order to bring him to the ground is equivalent to the force felt by the defenseman’s body during the tackle. You can’t initiate force without having a force put on you. For the tackle, this is very important. If the defenseman felt nothing there would be no incentive for him to be strategic in the application of his force on the receiver. And who would actually want to be a receiver if this were the case? If the guy who initiates the force feels nothing—much better to be him. Since this is not the case, the tackle is more about using the least amount of force required to bring the receiver to the ground. It’s better for the receiver, and it’s also better for the guy doing the tackling, because the more force you apply to others, the more damage you do to yourself. Reciprocity can be summed up like this: when you act on things, they act on you.

For every action, there is an equal and opposite reaction. » Newton’s Third Law

The meaning behind these expressions, which implies an expectation of reciprocity, is perhaps best summed up by another Latin phrase: “do ut des,” translated as, “I give, so that you may give.”

Life is an iterative and compounding game. In the words of Peter Kaufman, it pays to “go positive and go first.” Also, remember that people make mistakes. Assuming there is no maliciousness, it pays to forgive.

When it comes to reciprocity, we need to understand, “We are driven more strongly to avoid losses than to achieve gains.”3 This is why putting ourselves out there, engaging people who might dismiss or reject us, is so scary. Because in the one-off situation, the pain it will cause is perceived as stronger than the positive feelings of acceptance. The trick is to start looking at outcomes in the aggregate instead of focusing on each unique situation.

The rise of the “win-win” In the physical world, the law of reciprocity works 100% of the time. The harder you punch a wall, the more force pushes against your fist, the more damage is caused to both you and the wall. In the biological world, reciprocity doesn’t have the same perfect record. However, it has been discovered to work much more often than not, and thus harnessing it has significant long-term benefits.

Humans engage in two types of reciprocity with each other: direct, which is “I help you and you help me;” and indirect, which is either a pay-it-forward concept, “I help you and then you help someone else,” or more about reputation building—“I help you, building a reputation as one who helps, so that someone else helps me in the future.” Both kinds work.

Schadenfreude is a German word that has the literal translation of “damage-joy” and the more nuanced translation of delight or satisfaction at another person’s misfortune or suffering.

A lot of people seem to expect the world to just hand them things without putting in any effort. This is a poor strategy because it doesn’t align with the human behavior you can observe around you every day. Reciprocation teaches us that if you give people cynicism and curtness or nothing at all, you are likely to receive the same. But if you give people opportunity and the benefit of the doubt, you will, more often than not, be on the receiving end of the same behavior.

Become what you want to see in the world and it will be so. If you want an amazing relationship with your partner, be an amazing partner. If you want people to be thoughtful and kind, be thoughtful and kind. If you want people to listen to you, listen to them. The best way to achieve success is to deserve success. Small changes in your actions change your entire world.

Thermodynamics refers to a set of laws that provide the ultimate foundation in how the world really works. It helps us understand randomness and disorder in systems and explains the conversion of energy from one form to another, the direction in which heat will flow, and the availability of energy to do work. One of the most useful aspects of thermodynamics is that it applies to all systems everywhere in the known universe, giving it a broad applicability. All work requires energy, and all systems are headed toward equilibrium.

The first law of thermodynamics states that energy cannot be created or destroyed; it can only be transferred or changed from one form to another, such as from light to heat. The first law is known as the law of conservation of energy and it deals with the transfer of energy. There are two forms of energy exchange—heat and work. Heat is energy exchange through thermal interaction and work is energy exchange by any process other than heat. Whereas work can be completely converted into heat, heat cannot be completely converted to work.

The second law of thermodynamics states that entropy (a measure of disorder simply understood as energy unable to be used to do work) of an isolated system always increases. Isolated systems are those that spontaneously progress toward the state of maximum entropy of the system, also described as thermal equilibrium—no net heat flow between objects. The entropy of the universe only increases with time. One of the impacts of this law is that we need to expend energy to create order. Without the deployment of energy, all things move away from order.

Entropy reminds us that energy is required to maintain order. You need to anticipate things falling apart and focus on prevention.

The energy state of an economy—that is, its temperature—largely determines what its members can do and how fast they can do it. Temperature—the average kinetic energy of the moving molecules in a gas—affects every chemical process and every physical property associated with life. It influences not only the cost of doing business, but the speed at which tasks can be accomplished, and perhaps most importantly the range of adaptive options available. Temperature is, in other words the crucial link between energy and time; the two components of power.» Geerat Vermeij

Much of thermodynamics is about equilibrium, including the fact that two systems of different temperatures, when exposed to each other, eventually become the same temperature.

Murray Gell-Mann, a Nobel prize winning physicist, clarifies entropy in contexts such as organizing a pile of coins or the mixing of jelly and peanut butter in their containers. Why is it that if someone knocks the table the coins will get mixed up, or that despite their best efforts your children inevitably get jelly into the peanut butter jar and vice versa? “The explanation is that there are more ways for [coins] to be mixed up than sorted. There are more ways for peanut butter and jelly to contaminate each other’s containers than to remain completely pure. To the extent that chance is operating, it is likely that a closed system that has some order will move toward disorder, which offers so many more possibilities.”

The Value of Contrast The problem of equilibrium. Writing in Twilight of the Idols, Friedrich Nietzsche says of politics, “Almost every party grasps that it is in the interest of its own self-preservation that the opposing party should not decay in strength.”1 This is pointing out that there is value in contrast. If all the forces are balanced, a true state of equilibrium, there is no change, no growth, no movement. It is contrast that drives development.

In Into The Woods, John Yorke suggests that the way we tell stories is indicative of our desire to find order in the world. Stories are an attempt to tame the terrifying randomness that surrounds us. As we go through life, we are constantly absorbing chaotic information that we make sense of through narratives. Yorke writes that “every act of perception is an attempt to impose order, to make sense of a chaotic universe. Storytelling, at one level, is a manifestation of this process.”

We are drawn to stories that make things feel a little less random, just as we are drawn to storytellers who seemingly simplify complexity. We are all aware of disorder and the natural uncertainty that follows it and are attracted to stories that reduce it.

Entropy is a law of thermodynamics, arguably the one we struggle with understanding the most.

Nothing escapes the laws of thermodynamics. Everything is moving toward equilibrium, including people, culture, ideas, and information. Of course, total equilibrium means no life, so the place where there is no difference in anything is the place where everything rests. Thus, while pursuing difference is worthwhile and necessary, it’s important to understand that any barrier you try to erect will face a relentless pressure to attain equilibrium. Therefore, it’s important to remember that it takes a lot of work to maintain separation.

Starting something is hard, but so is stopping something.

In physics, inertia refers to the resistance a physical object has to a change in its state of motion. Things at rest don’t start moving on their own, and planets continue to circle the sun without a means of propulsion. The phenomenon of inertia is the subject of Isaac Newton’s first law of motion, which states, “An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.” If a force—for example, friction—is not present, the object will continue as it was, moving in the same velocity or remaining at rest. Left to themselves, systems resist change.

Inertia is a useful model to try to understand some elements of our behavior, including our thinking patterns and habits. Our natural inclination to reject the new is in part normal resistance to the effort required to change. Keeping things as they are requires almost no effort and involves little uncertainty. We need force to effect change, and force requires effort. This model offers a lens to help us understand resistance to change and why we fail ourselves when we get complacent.

Inertia implies that once we stop doing something, getting started again is harder than continuing the whole time would have been.

For, like a mass in Newton’s first law of motion, once our minds are set in a direction, they tend to continue in that direction unless acted on by some outside force. » Leonard Mlodinow

Most of the time, our consumption patterns are based on habit, not new thinking. We buy what we buy and have the preferences that we do because we’ve had them for a long time.

When we go to the grocery store we seldom invest the energy to apply critical thinking to the products we’ve bought dozens of times. The longer we’ve been buying something the more ingrained this product is in our lives. Even if we find out it is unhealthy, we seldom switch immediately, if at all. We can understand why this happens by looking at Newton’s second law,