Good in Theory

Is the universe infinite? Was there a beginning of time? Einstein himself preferred to think of the universe as unchanging, having neither beginning nor end. Experiments showed the expansion of the universe, proving Einstein wrong. Given this new evidence scientists had two choices: either the universe started in an incredibly dense state and expanded, diluting to the density we observe today (the...

How do rocks form? Neptunism is a theory that suggests all rocks formed in a primeval ocean through sedimentation. Proponents claimed this could explain why we find different types of rock in different layers of the earth. Volcanic phenomena were dismissed as being newer in earth's history and not relevant for understanding most rocks we can observe. While intriguing, this theory did not stand...

At an early stage of development human embryos have gill-like features. Observations like this prompted scientists to suggest that embryo development copies the evolutionary development of the species. Their theory became known as recapitulation theory and had the slogan “ontogeny recapitulates phylogeny”. Many scientists, such as Charles Darwin, disagreed with recapitulation theory even though th...

What is the difference between hydrogen and helium? Before the internal structure of atoms was known atoms were thought to be like tiny pool balls. This can explain different sizes and masses, but fails to explain the difference in chemical properties. That’s when the vortex theory of atoms emerged. Atoms were believed to be vortexes in an aether that permeated everything. This theory went beyond...

After the great success of thermodynamics some scientists started to doubt that mechanics, the theory describing the movement of matter, was fit to describe the underlying nature of reality. They believed that thermodynamics teaches us that energy is more fundamental than matter, leading them to the theory of energeticism. Not only was this theory met with scepticism, its proponents were pretty mu...

Where did humanity as a species come from? By the end of the 19th century scientists had accepted Darwin’s theory of evolution. So what does this mean for humanity? Nowadays humans live (almost) all over the world, but where did the first humans live? Given that we all belong to one species scientists thought that we can’t have evolved independently everywhere, but that there was an original cradl...

How come predators never hunt their prey to extinction? Is this balance of species in an ecosystem a natural law or more of a superstition? Already the ancient Greeks seemed to have believed in a balance of nature and nowadays this terminology is still sometimes used. But what exactly is this balance and can it be defined in a scientific way? This question was raised in the 18th century when the d...

Why does your tea get cold if you leave it standing around for too long? Because the temperature of the tea adjusts to the temperature of the room, but why? The process of transferring heat puzzled many scientists. In the late 18th century caloric theory emerged in which the temperature of a body depends on the amount of “caloric” it possesses. Caloric was thought to be a weightless fluid which fl...

How are living things created? Was there some major event of creation where all generations to come were nested inside their ancestors? Or is the creation of life a process starting when paternal and maternal fluids come together? Before the discovery of cells and atoms, some scientists believed things were infinitely divisible. This led them to the theory that even before a pregnancy there is a s...

To explain why some continents that are now oceans apart seem to have once fit together, scientists hypothesized that the Earth itself must be dynamic. More precisely they thought it was expanding over time, slowly inflating like a balloon, pushing continents apart and creating oceans in between. This theory was momentarily popular but cracks soon started showing. Why was it expanding? Was it gett...

The bridge between alchemy and chemistry was crossed when scientists tried to answer the question: “Why do things burn?”. Starting from the perspective of four elements and arriving at the discovery of oxygen, this 100 year journey is a brilliant showcase of the difference between pseudoscience and science. Why do some materials burn and others don’t? How can we explain why things cease burning? T...

Four seasons, four elements, four directions... four humours. In ancient Greece it seemed clear that just as our world was built from four elements, our bodies must be regulated by four vital fluids. When these humours fell out of balance, disease and bad moods followed. For centuries doctors practiced medicine based on this idea: identify which fluid is winning and remove some of it until the pat...

How do animals adjust to changing environments? Why are some living things much more complex than others? Before Darwin came up with his theory of evolution, Jean-Baptiste Lamarck had a theory of evolution of his own. Instead of using language such as “mutation” and “natural selection”, his theory is one of gradual and intentional change. “Extinction” was also not in his vocabulary, instead he tal...

Clear skies, fresh air, that must mean there are no diseases here? For millennia people believed that the spread of diseases was connected to the quality of the air. If the air was cold, polluted and smelt rotten you were sure to get infected with cholera or the black plague if you were out too long. Miasma theory had an enormous impact on people's habits and even the economy of southern China...

Water waves are movements in water, so light waves are movements in… aether. At least that was the leading theory in the 18th century. Sounds simple enough but nailing down what this aether is leads to curious properties. In truth light waves are quite different from water waves in many respects including that their speed is constant no matter how fast you yourself are going. The history of aether...

Naming the planet closest to the sun after the roman god of fire seems appropriate. The problem: it doesn’t exist. When confronted with data of planetary movements that do not fit your calculations you have two options: your theory is wrong or there is some big object influencing the planetary motion that you did not take into account. Since the latter turned out to be the case once before - and l...