505: A Bunch of Rocks

Explain xkcd: It's 'cause you're dumb.
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Explanation

Cueball awakens to find himself trapped for eternity in an endless expanse of sand and rocks. At first, he uses this time to derive all of mathematics and physics, including quantum mechanics and general relativity. Next Cueball creates a computer that can process any possible function, out of rocks and rules for the interaction between rocks. He then simulates a particle followed by the interactions between particles, followed by the entire universe. The amount of time it takes to simulate the change in the universe from one instant to the next takes an extremely long time as the time it takes to update just one row of rocks can be measured in eons.

Cueball then apologizes for any flaws we see in the simulation. This implies that the audience is living in Cueball's simulation, making Cueball essentially God.

The final frame cuts to a classroom where a bored student stares at his hands waiting for class to end. Cueball admonishes the student for thinking that class is lasting forever. The joke being that the boredom felt in a classroom is nothing compared to the boredom that inspires Cueball to spend his time toiling to keep the universe moving. Indeed the minutes of lecture actually took many "billions and billions of millennia" for Cueball to simulate.

The title text suggests that Rule 34 should be called on Wolfram's Rule 34. Rule 34 (see 305: Rule 34) is a humorous rule of the Internet which states "If you can imagine it, there is porn of it. No exceptions." Wolfram's Rule 34 is a cellular automaton. Therefore, the title text says that someone has made pornography featuring the cellular automaton in question.

Graphs

The three diagrams in the "Physics, too. I worked out the kinks..." panel are, from left to right:

  1. The Normal distribution of the Gaussian curve marking the points that represent a standard deviation of σ and 2σ. This is one of the fundamental building blocks of statistics. In quantum mechanics particles are viewed as inherently random, therefore the time at which a particle will decay, the position of a particle and its velocity are all calculated using similar curves. A deviation of at least σ occurs 32% of the time where a deviation of 2σ or more occurs about 5% of the time.
  2. The Epitaph of Stevinus, an explanation of the mechanical advantage of using an inclined plane. The inclined plane is one of the six classical simple machines, one of the fundamental building blocks of mechanical and civil engineering.
  3. The last graph is unknown. It may represent coupled pendulums, length contraction, or a hypothetical solution to something we haven't derived yet.

The graph that represents particle interaction is a Feynman Diagram. This shows the interaction of subatomic particles that collide and exchange some momentum via a photon. The slope of the middle line represents the distance moved and the time lost/gained during the interaction.

Notes

The Swiss patent office line refers to Albert Einstein, who was employed as a Swiss patent clerk while coming up with his theory of special relativity. This joke is also referenced in 1067: Pressures. Also, there is a standing joke that very few important inventions have come from Switzerland, since the country hadn't been involved in the world wars, and thus has not been part of the weapons race, nor was it a driving force in the preceding Industrial Revolution.

In the center of the comic, the binary numbers pointing to the particle are both 42. This is a reference to the comedic answer to the Ultimate Question of Life, the Universe, and Everything from the The Hitchhiker's Guide to the Galaxy series.

Cueball mentions that if we see an artifact flutter in and out of reality he must have made a mistake in the last "billions and billions of millennia." This implies that the small period of time the artifact is present in his time is much longer than our universe has existed. That is a very long time.

Cellular Automaton

Cueball uses the rocks to build a cellular automaton, a computational model based on simple rules to advance from one state to the next. Certain cellular automata are Turing-complete, which means that they can be used to represent any conceivable algorithm if expanded infinitely. He specifically seems to be running Wolfram's Rule 110, which is capable of universal computation. When using Rule 110 for universal computation, one builds a background pattern, which can be seen in the comic as the pattern of smaller triangles, and then performs computation by sending out "rockets" to collide and interact with each other.