In L. Sprague de Camp’s fantasy story The Incomplete Enchanter (which set the mold for the many imitations that followed), the hero, Harold Shea, is transported from our own universe into the universe of Norse mythology.1 This world is based on magic rather than technology; so naturally, when Our Hero tries to light a fire with a match brought along from Earth, the match fails to strike.
I realize it was only a fantasy story, but… how do I put this…
In the late eighteenth century, Antoine-Laurent de Lavoisier discovered fire. “What?” you say. “Hasn’t the use of fire been dated back for hundreds of thousands of years?” Well, yes, people used fire; it was hot, bright, sort of orangey-colored, and you could use it to cook things. But nobody knew how it worked. Greek and medieval alchemists thought that Fire was a basic thing, one of the Four Elements. In Lavoisier’s time the alchemical paradigm had been gradually amended and greatly complicated, but fire was still held to be basic—in the form of “phlogiston,” a rather mysterious substance which was said to explain fire, and also every other phenomenon in alchemy.
Lavoisier’s great innovation was to weigh all the pieces of the chemical puzzle, both before and after the chemical reaction. It had previously been thought that some chemical transmutations changed the weight of the total material: If you subjected finely ground antimony to the focused sunlight of a burning glass, the antimony would be reduced to ashes after one hour, and the ashes would weigh one-tenth more than the original antimony—even though the burning had been accompanied by the loss of a thick white smoke. Lavoisier weighed all the components of such reactions, including the air in which the reaction took place, and discovered that matter was neither created nor destroyed. If the burnt ashes increased in weight, there was a corresponding decrease in the weight of the air.
Lavoisier also knew how to separate gases, and discovered that a burning candle diminished the amount of one kind of gas, vital air, and produced another gas, fixed air. Today we would call them oxygen and carbon dioxide. When the vital air was exhausted, the fire went out. One might guess, perhaps, that combustion transformed vital air into fixed air and fuel to ash, and that the ability of this transformation to continue was limited by the amount of vital air available.
Lavoisier’s proposal directly contradicted the then-current phlogiston theory. That alone would have been shocking enough, but it also turned out…
To appreciate what comes next, you must put yourself into an eighteenth-century frame of mind. Forget the discovery of DNA, which occurred only in 1953. Unlearn the cell theory of biology, which was formulated in 1839. Imagine looking at your hand, flexing your fingers… and having absolutely no idea how it worked. The anatomy of muscle and bone was known, but no one had any notion of “what makes it go”—why a muscle moves and flexes, while clay molded into a similar shape just sits there. Imagine your own body being composed of mysterious, incomprehensible gloop. And then, imagine discovering…
… that humans, in the course of breathing, consumed vital air and breathed out fixed air. People also ran on combustion! Lavoisier measured the amount of heat that animals (and Lavoisier’s assistant, Seguin) produced when exercising, the amount of vital air consumed, and the fixed air breathed out. When animals produced more heat, they consumed more vital air and exhaled more fixed air. People, like fire, consumed fuel and oxygen; people, like fire, produced heat and carbon dioxide. Deprive people of oxygen, or fuel, and the light goes out.
Matches catch fire because of phosphorus—“safety matches” have phosphorus on the ignition strip; strike-anywhere matches have phosphorus in the match heads. Phosphorus is highly reactive; pure phosphorus glows in the dark and may spontaneously combust. (Henning Brand, who purified phosphorus in 1669, announced that he had discovered Elemental Fire.) Phosphorus is thus also well-suited to its role in adenosine triphosphate, ATP, your body’s chief method of storing chemical energy. ATP is sometimes called the “molecular currency.” It invigorates your muscles and charges up your neurons. Almost every metabolic reaction in biology relies on ATP, and therefore on the chemical properties of phosphorus.
If a match stops working, so do you. You can’t change just one thing.
The surface-level rules, “Matches catch fire when struck,” and “Humans need air to breathe,” are not obviously connected. It took centuries to discover the connection, and even then, it still seems like some distant fact learned in school, relevant only to a few specialists. It is all too easy to imagine a world where one surface rule holds, and the other doesn’t; to suppress our credence in one belief, but not the other. But that is imagination, not reality. If your map breaks into four pieces for easy storage, it doesn’t mean the territory is also broken into disconnected parts. Our minds store different surface-level rules in different compartments, but this does not reflect any division in the laws that govern Nature.
We can take the lesson further. Phosphorus derives its behavior from even deeper laws, electrodynamics and chromodynamics. “Phosphorus” is merely our word for electrons and quarks arranged a certain way. You cannot change the chemical properties of phosphorus without changing the laws governing electrons and quarks.
If you stepped into a world where matches failed to strike, you would cease to exist as organized matter.
Reality is laced together a lot more tightly than humans might like to believe.