In Arthur C. Clarke's Space Odyssey series, Monoliths are machines in black cuboids whose sides extend in the precise ratio of 1 : 4 : 9 (12 : 22 : 32) built by an unseen extraterrestrial species whom Clarke dubbed the Firstborn and who he suggests are the earliest highly intelligent species to evolve in the Milky Way. In the series of novels (and the films based on these), three Monoliths are discovered in the Solar System by australopithecines and their human descendants. The characters' responses to their discoveries drive the plot of the series and influence its fictional history, particularly by encouraging humanity to progress with technological development.
The first monolith appears at the beginning of the story, four million years before the present era. It is discovered by a group of australopithecines and triggers a shift in evolution, starting with the ability to use tools and weaponry. It is later revealed that thousands of other Monoliths exist elsewhere in the galaxy.
Origins
The species that built the Monoliths is never described in detail, but some knowledge of its existence is given to Dave Bowman after he is transported by the star-gate to the "cosmic zoo", as detailed in the 1968 novel 2001: A Space Odyssey and its 1982 sequel, 2010: Odyssey Two. The existence of this species is only hypothesized by the rest of humanity, but it is obvious because the Monolith was immediately identified as an artefact of non-human origin.
The species that built the Monoliths developed interstellar travel millions or billions of years before the present time. In the novels, Clarke refers to them as the "Firstborn", since they were quite possibly the first sapient species to possess a significant capability of interstellar travel. Members of this species explored the universe in the search of knowledge, especially about other intelligent species.
While these early explorers discovered that life was quite common, they observed that intelligent life was often stunted in its development, or else died out prematurely. Hence, they set about fostering it. Though not at all morphologically similar to humans, the Firstborn were nonetheless creatures of "flesh and blood", and like humans, were originally mortal.
However, the evolutionary development projects they began would by their nature require very long time spans to complete, far longer than the lives of their creators. Therefore, the aliens created increasingly complex automated machines to oversee and carry out their projects over the eons. When they encountered a living world that had features in favour of the evolution of intelligent life, they left behind the Monoliths as remote observers that were also capable of taking a variety of actions according to their creators' wishes. One such planet, encountered when it was still quite young, was Earth. They also observed Jupiter and its watery moon, Europa. The decaying ecology of Mars was also visited, but passed over in favour of more fruitful locations like Earth. The Firstborn left behind three Monoliths to observe and enact their plan to encourage hominids to pursue technology and space travel.
As described in Clarke's novel, the Firstborn discovered later how to transfer their consciousness into computers, and thus they became thinking machines. In the end, they surpassed even this achievement, and were able to transfer entirely from physical to noncorporeal forms—the "Lords of the Galaxy"—immortal and capable of travelling at great speeds. The Firstborn had abandoned physical form, but their creations, the Monoliths, remained, and continued to carry out their original assignments.
Tycho Magnetic Anomalies
The term "Tycho Magnetic Anomaly" is something of a misnomer when referring to "TMA-0" and "TMA-2", since neither of these is found on the Moon (let alone in Tycho Crater) and neither one of them emits any significant magnetic field, as described in the novel 2010: Odyssey Two. (The characters in some of the novels do refer to this anomalous nomenclature quizzically.) In the novel, the Russian crewmen of the spaceship Alexei Leonov refer to TMA-2 as "Zagadka" (from the Russian word for "enigma", "mystery", or "riddle").
Tycho Magnetic Anomaly-1 The name Tycho Magnetic Anomaly-1 (also known as TMA-1) refers to the strong magnetic field found somewhere in the lunar Crater Tycho by an American scientific satellite. Astronauts find that this magnetic anomaly is caused by an alien Monolith buried about 15 meters below the surface. In the novel, when the Monolith is excavated and examined, it is found to be a black cuboid whose sides extend in the precise ratio of 1 : 4 : 9 (12 : 22 : 32). Its measurements are given in the novel as , actually a ratio of 1:4:8.8. The monolith is sitting on a platform of the same material above undisturbed rock. Clarke suggests that the sequence or ratio extends past the three known spatial dimensions into much higher dimensions.
TMA-1 was dug up during the lunar night but, after sunrise and its exposure to direct sunlight, TMA-1 emits a single powerful burst of energy, interpreted as radio waves – aimed at Iapetus (a moon of Saturn) in the novel or Jupiter in the motion picture. (The subsequent novels follow the continuity of the film, placing all of the activity around Jupiter.) Its powerful magnetic field disappears immediately. In the novel, some scientists speculate that its magnetic field came from large electric currents, circulating in a system of superconductors for millions of years as an energy-storage mechanism. All of that electric power was expended in the one signal aimed at what would be discovered to be TMA-2.
Tycho Magnetic Anomaly-2 An identical object (except in size) was found later, orbiting Jupiter (or on a moon of Saturn in the first novel, although this was changed to Jupiter in the sequel, 2010: Odyssey Two). This object was dubbed "TMA-2", a term that the book calls "doubly inappropriate": it had no magnetic field, and was millions of miles from Tycho. (TMA-2 was often referred to as "Big Brother" due to David Bowman's comments on its larger size.) TMA-2 acted as a Star Gate and transported Dave Bowman across the galaxy in 2001 and brought his consciousness back again in 2010, at which time it duplicated itself over a million times to transform Jupiter into a star. Afterwards, TMA-2 became the home for the digitized minds of Bowman and HAL and supposedly moved to Europa to watch over the evolution of life there. In 2061: Odyssey Three, it is implied that TMA-2 is the monolith found resting on its side on Europa because it has the same size (2 kilometers long) and contains the digitized minds of Dave Bowman and HAL; however, no character refers to it as TMA-2 or Big Brother, instead christening it "The Great Wall". In 3001: The Final Odyssey, the author changes the description of the Europan monolith to be 20 kilometers long, so it is unclear whether TMA-2 changed size or it is actually a different monolith. In any case, HAL and Bowman infect that monolith with a computer virus after it is learned that its superiors are sending an order to destroy humanity. As a result of the virus, TMA-0, TMA-1, and TMA-2/The Great Wall disappear from the Solar System.
Tycho Magnetic Anomaly-0 In the year 2513, the first Monolith to be encountered by humankind's prehistoric evolutionary predecessors (the ones featured in the first novel) was found in Olduvai Gorge, buried in ancient rock, and retroactively dubbed "TMA-0".
Other Monoliths
Other than the Monoliths bearing TMA labels, there are many other Monoliths that are seen in the series. In two instances, millions of Monoliths are generated for a limited time. In the first, in 2010: Odyssey Two, millions of Monoliths are generated to transform Jupiter into a star, subsequently named Lucifer. In the second, in 3001: The Final Odyssey, millions of monoliths are generated to block both the Earth and human-settled Ganymede from their primary star in an attempt to destroy the humans. Other specific monoliths are described below.
The Great Wall A large Monolith is found resting on its side on Europa in the 2061 novel. It is nicknamed the Great Wall after the Great Wall of China due to its horizontal orientation. It is believed to be watching over the Europans in a manner similar to what TMA-0 did on Earth in the first book. The 2061 novel implies that this Monolith is TMA-2 from the previous novel, but the characters never refer to it as TMA-2 or "Big Brother." It is described as being the same size as TMA-2 and is the home to the digitized minds of Bowman and HAL just as TMA-2 was at the end of the last novel. However, the 3001 novel changes the description of the Great Wall to be 20 kilometers long, so it is unclear whether this monolith is the same as TMA-2 or not. In 2061, Bowman and HAL describe how it was knocked on its side and possibly damaged by the impact of Mount Zeus, a vast diamond shard from Jupiter's core that struck Europa's surface some time following Jupiter's transformation. But in 3001, the monolith on its side is described as having a purpose to protect the evolving Europans. (Arthur C. Clarke admitted to changing some concepts each time he wrote another sequel novel so it is not possible to fully reconcile TMA-2 and The Great Wall.)
Minilith A small Monolith appears before Heywood Floyd in 2061 on board the Galaxy spacecraft. He nicknames it "Minilith" for its small size compared to other observed Monoliths. At the end of the book it is explained that Halman used the Minilith to replicate Heywood Floyd's consciousness to help him uncover the Monolith's operations.
Superior Monolith In the 3001 novel, it is realized that back in the early 22nd century, TMA-2 broadcast a status report message to a point 450 light years away and is just now receiving instructions in return. Although unseen, this is assumed to be another monolith which is in charge of the monoliths in the Solar System. In other words, TMA-2 was reporting to its Superior.
Appearance and capabilities
In both films, all the Monoliths are black, extremely flat, non-reflective rectangular solids. In the first novel, the monolith on the African savannah was transparent and "it was not easy to see except when the morning sun glinted on its edges", but became less transparent when active and was described as a crystal.
In the novels and in the films, the dimensions of the monoliths are in the precise ratio of 1 : 4 : 9 (the squares of the first three positive integers). These dimensions are the main source of debate about the simple external design of the Monoliths. It is suggested in the 2001 novel that this number series does not stop at three dimensions.Clarke A (1968). 2001: A Space Odyssey, Signet. "How obvious—how necessary—was that mathematical ratio of its sides, the quadratic sequence 1:4:9! And how naive to have imagined that the series ended at this point, in only three dimensions!"
The Monoliths come in several different sizes: TMA-0 and TMA-1 are both about 11 feet long, TMA-2 is two kilometers long, and the "minilith" is smaller than TMA-1. The Great Wall Monolith is described as being two kilometers long in the 2061 novel but 20 kilometers long in the 3001 novel. Monoliths may be able to assume any size, because in 2010: Odyssey Two, the Star Child, created from the astronaut Dave Bowman, cryptically notes that the Monolith is actually one size – "as large as necessary".