I don't see the problem. There seems to be no logical reason that local laws can't change because of arbitrarily complicated nonlocal rules. You can even see nontrivial examples of this in practice in some modern technology. Various of Microsoft's operating systems have reportedly contained substantial amounts of code to recognize particular usage patterns characteristic of particular old applications, and change the rules so the old application continues to work even though it depends on old behavior which has otherwise disappeared from the new operating system. Vaguely-similar principles of global patterns changing local decision rules also appear, in less-nauseating ways, in all sorts of software for solving hard optimization problems (optimizing compilers, finding the optimum move in Chess, finding the optimum schedule for a big logistics operation...). What would go impossibly wrong if you rewrote physics with added rules which recognize patterns characteristic of presence or absence of patterns (like "living organism" and "magical incantation") and which rejigger the local rules as a consequence?

Changing the local rules specifically to stomp out technology without making the rest of the universe's behavior unrecognizable is a tricky job, since you are correct that everything tends to be cross-coupled in weird ways. But I think one could at least make existing technology pretty frustrating. One way to start would be by making a list of a hundred or a thousand technogically useful patterns (things heating up to combustion temperature, things bending around a fulcrum, sizable things rotating or oscillating many many times without changing shape, lots of energy being stored for a long time in an elastic object) and make case by case hacks to damp them out (spontaneously cooling things when they rise above 100 degrees Celsius, letting the lever soften and bend, etc.) whenever they weren't preceded by the suitably magically approved pattern of causality. (So, e.g., you can light a fire with a spell, and perhaps by striking suitably hard objects against each other, but not with a match or a magnifying glass. And you can use hinges as long as they are between bones in a living organism.) The result would be a very weird universe, but if I remember correctly (from long, long ago), the universe in those books was supposed to be very weird anyway.

The problem is this:

There are only two rules: quantum chromodynamics and universal gravitation, and hopefully they can be united into one. "[I]f you rewrote physics with added rules" is a non-starter.

It is actually quite astounding that so much physical behavior is allowed in such a paltry context. The things that do happen are in an extremely select set of events.

Universal Fire

by Eliezer Yudkowsky 3 min read27th Apr 200743 comments

95


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.  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...

No.

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.

95