The History of Refrigeration

Salt is one of the cheapest, most commonplace items: It sells for less than a loaf of bread, and during winter, we scatter it liberally on roads and sidewalks. However, there was once a time when salt was considered rare and valuable. In Salt, Mark Kurlansky argues that throughout much of human history, salt was a precious commodity—one that significantly shaped civilizations.

In this guide, we’ll present Kurlansky’s history of salt, describing the role it played in nourishing our ancestors, driving innovation, building empires—and even provoking rebellions. You’ll learn why salting food isn’t just about improving its flavor, why salt harvesting causes sinkholes, and how salt played an important role in several independence movements. Throughout this guide, we’ll supplement Kurlansky’s history of salt with relevant concepts in chemistry, food science, and geology. We’ll also update the book’s ideas with recent research on how we harvest and use salt today.

As the planet heats up, traditional air conditioning has become a necessity for millions. But it’s also a major contributor—through energy consumption and refrigerant emissions—to the problem it’s trying to solve: climate change. New cooling technologies are being developed to address environmental concerns, including more efficient systems and alternative cooling methods. Without such sustainable solutions, global cooling energy demand could triple by 2050.

As the planet heats up, traditional air conditioning has become a necessity for millions. But it’s also a major contributor—through energy consumption and refrigerant emissions—to the problem it’s trying to solve: climate change. New cooling technologies are being developed to address environmental concerns, including more efficient systems and alternative cooling methods. Without such sustainable solutions, global cooling energy demand could triple by 2050.

A scientist whose discoveries could have revolutionized the field of electrical engineering is now suspected of manipulating the results of his studies. This incident highlights the problem with the scientific community’s “publish or perish” culture.

Merchants of doubt are people or organizations who discredit science that threatens their agenda or ideology. The first merchants of doubt were members of the tobacco industry—when scientists discovered that smoking caused cancer, that was bad for businesses. It was also bad for capitalism in general because it suggested that the market wasn’t self-regulating, and lack of regulation was killing people. Other defenders of the free market started using the tobacco industry’s techniques, such as funding new (and hopefully more favorable) studies or calling for balanced media coverage.

In Merchants of Doubt, science historians Naomi Oreskes and Erik M. Conway study the doubt-mongering techniques used in several other important “debates”—nuclear disarmament, acid rain, the ozone layer, climate change, and the pesticide DDT. These techniques are still in use today.

Fast Food Nation: The Dark Side of the All-American Meal shows how the fast food industry has reshaped the American economic system and imprinted itself on the nation’s culture since the 1950s. The industry has profoundly reshaped how American food is produced, marketed, and consumed. The book explores fast food’s exploitative marketing and labor practices, destruction of the nation’s independent farmers, responsibility for the spread of deadly foodborne pathogens like E. coli, and creation of a national obesity epidemic. Fast Food Nation shows us how fast food has exerted a decidedly negative influence on American life.

In The Rational Optimist, science writer and journalist Matt Ridley writes that innovation has been the primary impetus for humanity’s progress and prosperity—driving the advances in technology, culture, and political organization that have made today’s society healthier, wealthier, and safer than any in human history.

Ridley writes that such a cross-pollination of ideas would have been impossible without free trade and the exchange of goods. This is because when we trade goods, we create networks of knowledge that reach beyond local communities and nations—allowing innovators to build upon each other's work.

In this guide, we’ll explore:

• How the exchange of ideas and knowledge has fostered human prosperity
• How trade promotes stable societies
• How our capacity for innovation provides a case for optimism on climate change
• Why free trade is the best way to promote growth and prosperity

We’ll supplement and compare Ridley’s ideas with insights from other writers and thinkers who’ve explored the benefits of trade and free markets, the relationship between capitalism and democracy, and more.

The human race has left a mark on our planet, sometimes through carelessness and sometimes by design, but how permanent are the changes we’ve made? In The World Without Us, science journalist Alan Weisman asks what would happen if the human race vanished overnight. What effects, positive or negative, would our disappearance have on the world? Weisman’s goal is to address humanity’s environmental impact by imagining a world in which nature is allowed to flourish. In many ways, the world that follows us would be significantly different than what came before.

In this guide, we’ll examine Weisman’s portrayal of humanity’s footprint and what Weisman claims would happen if we suddenly disappeared. Also, we’ll look at other views on climate change, nature’s resilience, and the human race’s impact. We’ll list suggestions for how our species might adapt to a greener world, as well as scenarios that might cause our extinction.

American society is inundated with food. There are thousands of options of what to eat and a myriad of ways to eat it. So why does food need defending? In In Defense of Food, Michael Pollan distinguishes between real food and processed food and how the reliance on the latter leads to a society plagued by Western diseases.

From our reliance on industry and science to dictate what we should and shouldn’t eat to the loss of traditional food cultures, the Western diet has wreaked havoc on Americans and created one of the unhealthiest societies in the world. But we can reverse the damage if we repair our relationship with food and support the health of the food chain.

In Sapiens, Yuval Noah Harari uses concepts from biology, history, and economics to tell the story of us, Homo sapiens. We start 2.5 million years ago, when Sapiens make their historical entrance, and end in the future, when the creation of an artificially created superhuman race may mark the end of the Sapiens species. Along the way, we learn how our ability to create imagined realities led to our dominance over other species. We watch as the Agricultural Revolution, the Scientific Revolution, imperialism, capitalism, and the Industrial Revolution change our species in lasting, and not always positive, ways.

Ultimately, we’re left with one question: As we design our future, who do we want to become? Asking the right questions may be more important than finding the right answers. Read this summary to explore our history as a species—in doing so, you’ll see today’s world in an entirely new way.

Fast Food Nation: The Dark Side of the All-American Meal shows how the fast food industry has reshaped the American economic system and imprinted itself on the nation’s culture since the 1950s. The industry has profoundly reshaped how American food is produced, marketed, and consumed. The book explores fast food’s exploitative marketing and labor practices, destruction of the nation’s independent farmers, responsibility for the spread of deadly foodborne pathogens like E. coli, and creation of a national obesity epidemic. Fast Food Nation shows us how fast food has exerted a decidedly negative influence on American life.