Barbara M. Tomotani1 & Rodrigo B. Salvador2

1 Netherlands Institute of Ecology; Wageningen, The Netherlands. Rijksuniversiteit Groningen; Groningen, The Netherlands. Email: babi.mt (at) gmail (dot) com

2 Staatliches Museum für Naturkunde Stuttgart; Stuttgart, Germany. Eberhard Karls Universität Tübingen; Tübingen, Germany. Email: salvador.rodrigo.b (at) gmail (dot) com

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The video game Overwatch is Blizzard Entertainment’s new hit, released on May 2016 for Microsoft Windows, PlayStation 4 and Xbox One. In the game, the so-called “heroes” spend most of their time trying to kill each other to secure a payload. While the morals of these self-proclaimed heroes are rather open to debate, one of them at least has some redeeming personality traits. The hero Bastion is a nature-loving animal-friend robot. Actually, the single animal to appear in the whole game (besides the hominids, of course) is Bastion’s pet bird, called Ganymede (Fig. 1).


Figure 1. Left: Bastion with Ganymede (official artwork from the game). Image extracted from Overwatch Wiki. Right: Ganymede (official artwork from the game). Image extracted from “Bastion Reference Kit” (official Overwatch website).

Ganymede’s design is an original creation of Blizzard’s artists, although it resembles in shape and size a northern cardinal, Cardinalis cardinalis (Linnaeus, 1758), a common species in Canada and the USA. Cardinals usually have a red plumage (Fig. 2A), but there are rare naturally occurring yellow mutants, called xanthochroic cardinals (Fig. 2B). Ganymede also has a white area around its eyes, a trait not seen in cardinals, but well-known from species of the genus Zosterops (commonly known as “white-eyes”; Fig. 2C), which live in tropical Africa, Southeast Asia and Australasia.

bastion-fig-2Figure 2. Left: A male northern cardinal, Cardinalis cardinalis. Photo by Stephen Wolfe (2011); image extracted and modified from Wikimedia Commons. Center: A xanthochroic northern cardinal. Photo by Jim McCormac (2013), extracted from “Ohio Birds and Biodiversity”. Right: A Japanese white-eye, Zosterops japonicas (Temminck & Schlegel, 1847). Photo by Laitche (2016); image extracted and modified from Wikimedia Commons.

Despite being based in an American species, Ganymede seems to be native to European forests. The bird appears on its home forest in the animated short The Last Bastion (from August 2016), which takes place in the outskirts of Stuttgart, Germany. There is no bird here in Stuttgart that looks like Ganymede (one of us lives here, by the way). Actually, in the whole European bird fauna, only the golden oriole, Oriolus oriolus (Linnaeus, 1758), comes close to it, with its yellow color and dark horizontal stripe across the eyes (Fig. 3). However, its slenderer body shape, thinner beak and lack of crest are all very different from Ganymede.


Figure 3. A male golden oriole (Oriolus oriolus). Photo by Pawel Ryszawa (2008); image extracted from Wikimedia Commons.

Moreover, in the Eichenwalde stage (which, in the game’s lore, is located nearby Stuttgart), there is a painting resting above the hunting lodge’s fireplace (Fig. 4). This painting shows four local bird species; one of them is the “Ganymede species”, while the others seem to be actual species: the Eurasian blue tit (Cyanistes caeruleus (Linnaeus, 1758)) and two titmice. The latter are American species and seem to represent the tufted titmouse (Baeolophus bicolor (Linnaeus, 1766)), even though one of them is more bluish in color.


Figure 4. Fireplace of the hunting lodge in the Eichenwalde stage, with close-up of the painting. Screenshots from the game.

As we pointed out before, Ganymede’s design is an original creation and does not represent an actual species, although some of its features might be traced to the cardinal. Despite the problems with Ganymede’s identification, Bastion’s bird friend can also appear in the guise of actual real-life bird species. To do so, the player must simply equip a “skin” for Bastion (”skin” is basically the gaming jargon for “outfit”). By changing Bastion’s “skin”, Ganymede’s appearance may also change.

The common and rare skins (alongside the legendary Overgrown skin) do not change Ganymede’s appearance, but the epic and legendary skins do. Here we identify all the bird species that most resembles Ganymede’s look and tell a little bit about their biology.


Let’s start with the “proper” red northern cardinal, Cardinalis cardinalis (Fig. 5A). This species belongs to the family Cardinalidae and is also commonly known as redbird, being easy to identify due to its color, black “mask” and crest. Ganymede appears as a male cardinal (females are light brown). These birds eat mainly seeds, grains and fruits, but feed their young with insects. They are found from Belize and Guatemala, through Mexico and eastern USA, all the way to Canada. The species was introduced by humans in other American states, like California and Hawaii. Cardinals are common in residential areas and visit bird feeders. They were prized as pets due to their bright plumage and song, but thankfully now have full legal protection.

Next, we have Ganymede appearing as a blue jay, Cyanocitta cristata (Linnaeus, 1758) (Fig. 5B). This species belongs to the family Corvidae (ravens, crows, jays and magpies) and has a distinct color pattern. As a matter of fact, the color pattern of Ganymede’s wings is a little bit simplified when compared to the actual bird’s complicated gradation of colors. Blue jays can be found in central and eastern USA and Canada; they eat nuts, grains and small invertebrates. These birds are typically monogamous, pairing for life; genders are similar in plumage and size. Blue jays are very intelligent, with complex social systems.


Figure 5. Bastion’s skins, accompanied by a close-up of Ganymede and a photo of the actual bird species in which he was based. Bastion’s skins are screenshots from the game; the images were extracted from Overwatch Wiki. A. Bastion’s Omnic Crisis skin. Northern cardinal, Cardinalis cardinalis (photo by Stephen Wolfe, 2011; image extracted and modified from Wikimedia Commons). B. Bastion’s Defense Matrix skin. Blue jay, Cyanocitta cristata (photo by Mdf, 2005; image extracted and modified from Wikimedia Commons).

Bastion’s two “wooden” skins are fittingly accompanied by a Ganymede looking like two species of woodpeckers (family Picidae): the red-naped sapsucker, Sphyrapicus nuchalis Baird, 1858 (Fig. 6A; although it is also reminiscent of the pileated woodpecker, Dryocopus pileatus (Linnaeus, 1758), and the downy woodpecker, Dryobates pubescens (Linnaeus, 1766)) and the Arizona woodpecker, Leuconotopicus arizonae (Hargitt, 1886) (Fig. 6B). The sapsucker, as its name implies, drills hole in trees to feed on the plant’s sap, also eating insects that are attracted to the sap. These birds can be found throughout the Great Basin region and the Rocky Mountains, in North America. The Arizona woodpecker has a more restricted range, occurring in the southern parts of Arizona (obviously) and New Mexico, USA, and in western Mexico. This species feed mainly on insects (especially beetle larvae), but may also eat fruits and acorns. Similar to the case of the blue jay above, the color pattern on Ganymede’s head, chest and wings are very simplified in relation to the real animals. Also, there is some divergence in color: while the male Arizona woodpecker has a red crest, Ganymede has a yellow one, which makes him more similar to female woodpeckers.


Figure 6. Bastion’s skins, accompanied by a close-up of Ganymede and a photo of the actual bird species in which he was based. Bastion’s skins are screenshots from the game; the images were extracted from Overwatch Wiki. A. Bastion’s Antique skin. Red-naped sapsucker, Sphyrapicus nuchalis (photo by Glenn Bartley, 2011; extracted from Glenn Bartley Nature Photography, used with permission). B. Bastion’s Woodbot skin. Female (left) and male (right) Arizona woodpecker, Leuconotopicus arizonae (photos respectively by Alan Wilson, 2007, and Nature’s Pics Online, 2007; images extracted and modified from Wikimedia Commons).

The last two of Bastion’s skins are based on steampunk designs. Therefore, they needed a more city-dwelling bird to accompany him. Ganymede thus appears as a rock pigeon, Columba livia Gmelin, 1789 (family Columbidae), the common pigeon we have in large cities. The Gearbot skin has a common rock pigeon (Fig. 7A), while the Steambot skin is accompanied by an albinistic pigeon (Fig. 7B). We judge it is an albinistic (instead of a leucistic; see Box 1 below) bird, because the beak also does not have the usual black pigmentation (it is pinkish yellow). We could not check if the same is true for Ganymede’s legs, though, as we have yet to unlock this very expensive skin in the game.


Figure 7. Bastion’s skins, accompanied by a close-up of Ganymede and a photo of the actual bird species in which he was based. Bastion’s skins are screenshots from the game; the images were extracted from Overwatch Wiki. A. Bastion’s Gearbot skin. Rock pigeon, Columba livia (photo by Diego Delso, 2012; image extracted and modified from Wikimedia Commons). B. Bastion’s Steambot skin. Albinistic rock pigeon, Columba livia (photo by Maria Corcacas; image extracted from Project FeederWatch, a partner organization of the Cornell Lab of Ornithology and Bird Studies Canada, used with permission).

Unsurprisingly, all the birds above are American (Blizzard’s headquarters is in California). As explained above, the depictions are not completely true-to-life, but simplified in some instances. This is to be expected, we guess, since the game’s developers would not need focusing too much on a scientifically accurate depiction of a bird. They would rather be more worried about making all the shooting fun. Nevertheless, it seems the team at Blizzard clearly put a lot of effort in making Ganymede, as not only his appearance but also his movements in the game are all very realistic (the model for Ganymede in the animated short The Last Bastion was done based on the pet parrot of a Blizzard employee). The two pigeon “skins” for Ganymede even change his body shape to make him look like a pigeon.

Box 1. Albinism and leucism

Both albinism and leucism are genetic variations, meaning they are conditions defined by the genes the animal inherits from its parents. Albino animals show a complete (or partial) absence of the pigment called melanin in their skin, hair, feathers, scales, cuticles and irises. Melanin is responsible for brown and black colors. Thus, albinos are very light-skinned, with white hairs and red eyes (the lack of pigment in the eyes means that the light is reflected by the blood vessels). This failure to produce melanin is usually caused by the absence or malformation of an enzyme involved in its production. Common albino animals include white lab rats and mice and rabbits. People with albinism are also rather common.

In leucism, however, there is only partial loss of pigmentation. This means paler hairs (or feathers, etc.), often “creamy” in color, but with no changes to the eyes. It is also different from albinism in another regard: leucism is a reduction in several types of pigment, not only melanin. Leucistic peacocks are very commonly bred in captivity and leucistic lions are a fan-favorite in zoos.

On the opposite side of albinism, there is a condition called melanism. The over-deposition of the black pigment melanin in hairs (or feathers, etc.) results in very dark animals, like the black jaguar.


Nevertheless, despite all the care in making Ganymede, there are some major inconsistencies (besides the whole “American-bird-in-German-forest” issue discussed above). Until Gamescom (in August 2016, when the animated short The Last Bastion was premiered), we supposed that Ganymede was a male. This was based on: (1) the name, which is a male one (originally from Greek mythology); (2) it is crested and colorful, which is common of male birds, while females often have a plainer look; and (3) it sings a lot, which is also a typical male activity in birds (usually used for defending territory or courtship).However, in the aforementioned animated short, Ganymede is building a nest, which is typical female behavior. It is very rare for male birds to do the nest building (this is only seen, for instance, in species of weavers and megapodes). Moreover, Bastion’s Overgrown skin, which relates to the short, has a nest with eggs place on the robot’s shoulder (Fig. 8). Needless to say, only females can lay eggs. Moreover, the incubation and hatching is usually also done by females; male birds only rarely incubate eggs. Of course, the eggs from the Overgrown skin are way too large (Fig. 8) to belong to Ganymede anyway.


Figure 8. Bastion’s Overgrown skin (screenshot from the game). Image extracted from Overwatch Wiki.

Ganymede’s sex is never directly alluded to in the game or official material, although sometimes we could find the pronouns “he” and “his” referring to it on Blizzard’s websites. Curiously, the same is true for Bastion, who is almost always referred to by the pronoun “it”, but sometimes by “he”.


The player can also customize Bastion’s victory pose, which is shown after the match if he/she was part of the winning team. One of Bastion’s poses is called Birdwatching, because, well, he is watching his bird (Fig. 9).

It might sound surprising to some that birdwatching is not only an actual pastime but a very popular one at that. But what exactly is it?


Figure 9. Bastion’s Birdwatching victory pose (screenshot from the game). Image extracted from Overwatch Wiki.

Birdwatching, also called birding, is basically an activity of wildlife observation, where you go out to observe, of course, birds. You can do this, of course, with the naked eye, but it is better done with a good pair of binoculars (or sometimes a telescope). It’s a hobby that actually attracts a huge lot of people (Fig. 10), especially when a rare bird is involved. There are, of course, guides for beginners explaining everything about how to start birding, like Birding for Beginners: A Comprehensive Introduction to the Art of Birdwatching (by S. Buff, 2010), and websites like All About Birds (by the Cornell Lab of Ornithology).


Figure 10. Birdwatchers (often called simply “birders”) at Caerlaverock, UK, watching a rare (in Europe) White-tailed Lapwing, Vanellus leucurus (Lichtenstein, 1823). Photo by MPF (2007); Image extracted and modified from Wikimedia Commons.

After you’ve started your birding campaigns, you will want to know the names of the birds you’re seeing. To identify the bird species, you can use one of the several field guides and handbooks in existence. These books have drawings and/or photos of the birds, with guidelines to identify them. These guides are usually restricted to a single country (or sometimes just part of it, if the country is too large, like Brazil or the USA) or continent (like Europe). It’s very easy to find one at your bookstore or online store, since they are often called “Birds of Somewhere” (Fig. 11). Of course, there are now also websites that act as these guides, such as the RSPB’s Bird Identifier (see References below).


Figure 11. Examples of “bird books”, with the covers of Birds of Australia (by K. Simpson & N. Day, 2010, 8th ed.), Birds of Venezuela (by S.L. Hilty, 2003, 2nd ed.) and Collins Bird Guide (by L. Svensson et al., 2010, 2nd ed.).

Moreover, birdwatching actually involves a lot of hearing, because you will most often hear the bird before seeing it (if you see it at all). Thus, it is also good to know what each species’ vocalization sounds likes. There are several websites to identify birds’ calls, such as the Smithsonian’s Guide (see References below). Of course, both for image and song identification, there are now lots of apps, such as eBird Mobile, BirdsEye, Collins Field Guide and Bird Song Id, among several others. Unfortunately, these websites and apps are still largely restricted to the USA and Europe, while the greatest (and some would say most splendorous) bird diversity is found in Australasia and tropical America.

Birdwatching is all about enjoying nature and having fun, but birders worldwide abide by a “code of conduct” of sorts (see, for example, the code of the American Birding Association). Nowadays, our more ecological-prone society is concerned about the impact that our activities have on the animals and their environment. Thus, birdwatching etiquette usually includes promoting the welfare of birds and their habitats, limiting the birders’ impact (photographing, using playback devices, keeping your distance from nests etc.) and thus mitigating the stress caused to the animals. Basically, have fun, but let the birds live their life – that’s what Bastion does anyway.


American Birding Association. (2016) ABA Code of Ethics. Principles of Birding Ethics. Available from: http://www.aba.org/about/ethics.html (Date of access: 23/Jul/2016).

BirdLife International. (2012) The IUCN Red List of Threatened Species. Available from: http:// www.iucnredlist.org/ (Date of access: 30/Jun/2016).

Cornell Lab of Ornithology, The. (2016a) All About Birds. Available from: https://www.allabout birds.org/ (Date of access: 30/Jun/2016).

Cornell Lab of Ornithology, The. (2016b) Project FeederWatch. Available from: http://feeder watch.org/ (Date of access: 30/Jun/2016).

Gamepedia. (2016) Overwatch. Available from: http://overwatch.gamepedia.com/Overwatch_Wiki (Date of access: 30/Aug/2016).

Glenn Bartley Nature Photography. (2016) Bird Photography from Canada and around the World. Available from: www.glennbartley.com (Date of access: 30/Jun/2016).

McCormac, J. (2016) Ohio Birds and Biodiversity. Available from: http://jimmccormac.blogspot. nl/ (Date of access: 30/Jun/2016).

Mcgraw, K.J.; Hill, G.E.; Parker, R.S. (2003) Carotenoid pigments in a mutant cardinal:  implications for the genetic and enzymatic control mechanisms of carotenoid metabolism in birds. The Condor 105: 587–592.

Overwatch. (2016) Bastion Reference Kit. Available from: https://playoverwatch.com (Date of access: 30/Jun/2016).

Overwatch Wiki. (2016) Overwatch Wiki. Available from: https://blzgdapipro-a.akamaihd.net/med ia/reference/bastion_reference.pdf (Date of access: 26/Jun/2016).

RSBP. (2016) Bird Identifier. Available from: http://www.rspb.org.uk/discoverandenjoynature/discoverandlearn/birdidentifier/ (Date of access: 23/Jul/2016).

Smithsonian’s National Zoo. (2016) Guide to North American Bird Songs and Sounds. Available from: http://nationalzoo.si.edu/scbi/migratory birds/education/nasongkey.pl (Date of access: 23/Jul/2016).


We are very grateful to Anne Marie Johnson (Project FeederWatch) and Glenn Bartley for granting us permission to use their photos here.


Barbara Tomotani is a birdwatcher bird-scientist and was a marked presence at Blizzard’s store booth during Gamescom, hoping to find a Ganymede plush.

Rodrigo Salvador is a biologist, but now is found mostly escorting payloads as either D.Va or Lúcio. He has his fair share of Plays of the Game as Bastion, though.

Check other articles from this volume

Is the Great Attractor a Tengen Toppa Gurren Lagann?     

João V. Tomotani

Universidade de São Paulo; São Paulo, Brazil.

Email: t.jvitor (at) gmail (dot) com

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Space is a big place. Quite big, actually. Huge may be a more appropriate adjective. So huge that it received the title of “final frontier” by a famous television series, since you are not really supposed to traverse it. (The question remains, though: for it to be a frontier, isn’t it supposed to have something on both sides?) The vastness of space is both mysterious and fascinating. Man, in his ceaseless curiosity and desire for knowledge (and also the need to understand the universe around him to avoid the discomfort of death by starvation or cold), developed the science known today as Astronomy, as an attempt to unveil the mysteries of the universe. Since space is such a humongous place, one can expect it is full of mysteries. Enters the Great Attractor.


The Great Attractor is a gravitational anomaly, a massive (and controversial) one. It is indirectly “observable” by its effect on the motion of galaxies, and its presence, mass and position were estimated based on the peculiar velocity of the Local Group, the galaxy group that includes the Milky Way (Kocevski & Ebeling, 2006). A nice video explaining it was made by the SciShow Space (www.youtube .com/watch?v=N9qeOhJ9dbg). It is also a quite funny name with the potential for several jokes (Fig. 1 is not one of them, but it could be).

Great Attractor Figure 01

Figure 1. “Dark Flow” (XKCD, 2008; available from https://xkcd.com/502/). Note that the (rather controversial) Dark Flow phenomenon is not the same as the Great Attractor. I included this strip, though, because it is funny.

The observation of the Great Attractor is difficult when restricted to the length of optical waves, due to the presence of the Milky Way. The plane of the Milky Way outshines (due to its stars) and obscures (due to the dust) many of the objects behind it (NASA, 2013). This unobservable space is called the Zone of Avoidance (ZOA; a very neat name by the way), or “Zone of few Nebulae” as initially proposed by Proctor in 1878 (Kraan-Korteweg, 2000). Not to be confused with the Phantom Zone, the prison dimension to where the people of Krypton sent their prisoners.

The ZOA was “avoided” by astronomers because of the difficulties in analyzing the obscured galaxies known there (Kraan-Korteweg, 2000). Figure 2 shows a picture from the NASA/ESA Hubble Space Telescope taken in 2013 focusing on the Great Attractor. The region behind the center of the Milky Way, where the dust is thickest, is very difficult to observe at optical wavelengths.

Figure 2. “Hubble Focuses on ‘the Great Attractor’”. This field covers part of the Norma Cluster as well as a dense area of the Milky Way. The Norma Cluster is the closest massive galaxy cluster to the Milky Way. The huge mass concentrated in this area and the consequent gravitational attraction makes this region of space known to the astronomers as the Great Attractor. Picture retrieved from http://www.nasa.gov/mission_pages/hubble/science/great-attractor.html (NASA, 2013).

In this study, I shall propose a slightly unusual hypothesis to what could be the Great Attractor. Could this gravity anomaly be an outcome of the presence of a very big robot?

Box 1. The Local Group, Clusters, Superclusters and other ginormous things

The Great Attractor’s location is estimated to be at a distance of somewhere between 150 and 250 million light-years from the Milky Way (something between 1.4 x 1024 and 2.4 x 1024 meters and quite far indeed). But both the Great Attractor and our own Milky Way belong to the same structure, known as the Laniakea Supercluster (“Laniakea” means “immense heaven” in Hawaiian). The Milky Way resides in the outskirts of this supercluster, whose diameter is 500 million light-years, while the Great Attractor resides closer to its center. A supercluster is a (very) large group of smaller galaxy clusters or galaxy groups (like our own Local Group) and is among the largest known structures of the cosmos. The Laniakea Supercluster was discovered in 2014, encompasses 100,000 galaxies, contains the mass of one hundred million billion Suns, and consists of four subparts, previously known as separate superclusters (The Daily Galaxy, 2015).


Japan has a peculiar relationship with robots, which have an important and established position in the country’s pop culture. The word mecha (abbreviation of “mechanical”) now refers to a whole genre of movies, manga, anime and live-action series (the tokusatsu) involving mechanical objects (vehicles, robots etc.), autonomous or manned, which quickly became popular in Japan and abroad.

While the first robot appearance in sci-fi culture is usually attributed to the tripods of H.G. Wells in 1897, the first appearance of a giant humanoid robot is attributed to Tetsujin 28-Go, a manga from 1956 by Mitsuteru Yokoyama. However, perhaps the greatest symbol of the mecha genre, and Japanese culture in general, is from a 1952 manga by Osamu Tezuka: the boy-robot Tetsuwan Atom (Astro Boy in the West). This manga was released in post-war Japan, a moment of drastic changes in culture, industry and society, where science and technology promised economic growth and transformation of social structures (Hikawa, 2013). Astro Boy was adapted into anime in the 1960s and quickly made its way to the West. Other works of the mecha genre, particularly those with giant robots (e.g., Gundam, Mazinger Z, Macross, Neon Genesis Evangelion) influenced many western works like the Transformers cartoon, the Power Rangers TV series and the movie Pacific Rim.

Giant fighting robots are already a reality, by the way. Groups of American and Japanese engineers, in their desire to hasten Judgment Day, built giant robots of a few tons, capable of firing missiles and engaging in heavy fighting (Fig. 3).

Great Attractor Figure 03

Figure 3. The American (Megabots Inc.) and Japanese, named Kurata, giant robots (Suidobashi Heavy Industries). Source: http://www.popularairsoft.com/megabot-challenges-japanese-kuratas-giant-robot-duel.

What does this entire story about Japanese robots have to do with the massive gravity anomaly from the introduction, you ask? Well, a 2007 Japanese animation called Tengen Toppa Gurren Lagann decided to explore how “giant” a giant robot could be.

The Tengen Toppa Gurren Lagann (henceforth TTGL; Fig. 4) is the largest mecha shown in the anime. According to the official series guide, the TTGL is about 10 million light-years tall (Gurren Lagann Wiki, 2016). This is somewhere around 9.46 x 1022 meters, or about 100 times the diameter of the Milky Way. It is a fairly giant robot.

Great Attractor Figure 04

Figure 4. The Tengen Toppa Gurren Lagann, a quite big mecha. Official artwork from the series, available from Gurren Lagann Wiki.

The existence of a robot 10 million light-years tall is very questionable for some practical reasons. The usefulness of a robot of this size is also doubtful. How could a robot of this size engage in combat (or do anything, actually)? Since nothing restricted by the physics of our universe can move faster than light, the act of throwing a single punch would take a few million years. It would take a few million years more for the pilot of this robot to find whether the punch hit the target or not. It would be a long fight. These practical questions will henceforth be disregarded here. The question posed is only one: could the Great Attractor be a consequence of the existence of the TTGL?

Box 2. The Super TTGL

In the follow-up movie, a version of the robot entitled Super Tengen Toppa Gurren Lagann was introduced because, why not? The Super TTGL is 52.8 billion light-years tall according to the official guide book, making it about 58% the size of the universe. We shall not consider this robot. 


Well, not exactly.

The first thing I need to do is estimating what is the mass of a robot of this size. This is not that simple, since humanity has not yet been able to build something so gargantuan. A rather crude way to do this is by applying the square-cube law (see Box 3) based on smaller robots with known mass. Since we have the height and mass of the Kurata Japanese robot (4 meters, 4.5 tons; Wikipedia, 2016a), we can use it for our estimate.

Box 3. The square-cube law

The square-cube law was proposed by Galileo Galilei (1564–1642), who was apparently the first to notice that the volume of a particular object or being increased in cubic proportion to an increase in their linear dimensions, while the strength increases in square proportion (cross section of the muscles). A review of this concept was conducted by Froese (2006).

The square-cube law has a number of practical applications, including studies in Biology and civil engineering, besides being a very interesting concept to be assessed in pop culture. It is not uncommon that, for super heroes, strength and size are treated almost synonymously. Heroes and villains (e.g., the Hulk, Giganta, and Apache Chief), grow in size constantly for fighting or performing feats of strength. In practice, achieving an absurd size is not practical, since the square-cube law suggests that the weight of the heroes grow much faster than their strength (that would mean they would be unable to even stand up). This law is unfortunately a significant impediment to building colossal robots.

Interestingly, the spell enlarge person from the tabletop RPG Dungeons & Dragons agrees with half of the law (Cook et al., 2003). To double in size, the target of the spell has its weight multiplied by eight, in accordance with the “cube law”. However, the target receives a fixed Strength modifier of +2, instead of having an increase proportional to his/her base Strength value, which would make more sense.

Applying the square-cube law to estimate the mass of the TTGL, we get the results shown on Table 1. In addition to the mass of the TTGL, I estimated the mass of other fictitious robots. This comparison was made to assess whether this estimate would be appropriate, given that several of these giant robots have established weights in official guides and other “literature”.

The robots chosen for comparison were: the ATM-09-ST VOTOM (Vertical One-man Tank for Offense and Maneuvers) from the anime Armored Trooper Votoms (1983); the Gundam RX-78-2 from the anime Mobile Suit Gundam (1979); the T800 from the movie Terminator (1984; the height was defined as that of the actor Arnold Schwarzenegger; the weight of a T800 is unknown but it is thought to not exceed 1 ton, since the robot take actions such as riding a motorcycle); the autobot Optimus Prime from the movie Transformers (2007); the jaeger Gipsy Danger from the movie Pacific Rim (2013); and the real robot from Megabots Inc. mentioned above (the weight of the Megabot is known; the estimate is only for comparison purposes). Moreover, Table 1 has also the Sun and the Milky Way for comparison. We can see that, for larger robots (Optimus Prime and bigger), the estimated weight by the square-cube law becomes much greater than that given by the official guides. This lighter weights can be partially “explained” for some robots by using unknown material: Optimus Prime is made of Cybertron materials and Gundams from Luna Titanium or Gundarium. In the case of a Jaeger, I can only assume that the futuristic technology of Pacific Rim was able to develop lightweight robots to that extent (or that the movie producers just did not care).

Table 1. Height and weight of giant robots and other things. The “Estimate” column is the weight estimated using the square-cube law (having Kurata’s weight and height as basis). The “Official” column is the official (or actual) weight.

Great Attractor Table 01

The mass of the Great Attractor is estimated to be about 1.000 trillion times the mass of the Sun (Koberlein, 2014). This is equivalent to circa 2 x 1042 tons, well below the estimated mass of a TTGL of 6 x 1067 tons. Just from this difference, it appears that the Great Attractor could not be a TTGL, or the gravitational attraction would be many times stronger than the one perceived (even considering that the estimated weight is wrong by a few orders of magnitude). Moreover, this is not the only problem. Such a monstrous mass distributed in such a small space would probably collapse and become a black hole.

The Schwarzschild radius (or gravitational radius) is a concept that expresses what should be the radius of a sphere such that, if the mass of the entire object was within this sphere, the escape velocity of the surface of this sphere would be equal to the speed of light (i.e., you would not be able to escape its gravitational field). When the remains of a star, for example, collapse so that its size is below this radius, the light cannot escape its gravitational field and the object is no longer visible, becoming a black hole (Beiser, 2003). The Schwarzschild radius can be calculated by:

Great Attractor Equation 01

where: rs is the Schwarzschild radius; G is the gravitational constant; M is the mass of the object; and c is the speed of light in vacuum.

An object whose real radius is smaller than its Schwarzschild radius is called a black hole. Calculating the Schwarzschild radius for the Milky Way, the Sun, and the TTGL gives us Table 2.

Table 2. Comparison of the Schwarzschild radii of Sun, Milky Way and TTGL, with their real radii. The real radius of the TTGL is considered half its height.

Great Attractor Table 02

From Table 2, we can see that in the case of the TTGL, the Schwarzschild radius is many times larger than its actual size (even considering that the square-cube law has overestimated the mass of the robot by some orders of magnitude). This means that the robot, if existed, would become a giant supermassive black hole.

Incidentally, the estimated mass of the TTGL is also several times greater than the estimated mass of the observable universe (considering only ordinary matter), that is 1050 tons. Thus, it is unlikely that a robot this big exists.


Well, not necessarily.

As shown by Table 1, many other robots in fiction do not follow the square-cube law to the letter. Some reasons may be proposed: they are made of fictional materials (supposedly not yet discovered by man), such as Gundarium or some Cybertron material; they were built by advanced and/or alien technology; or for any magical/supernatural reasons.

The same can be valid for the TTGL, in a way. The robot is made of “a mass of continuously materialized Spiral Power”, according to the anime lore (Gurren Lagann Wiki, 2016). This Spiral Power (Fig. 5) is presented in the anime as a physical model, the connection between living beings and the universe (besides being a religion of sorts). Such definition could make us treat the structure of the TTGL as strictly “magical”, discarding any physical interpretation of its existence. Nevertheless, the robot is composed of “mass”, so it has a gravitational field.

Great Attractor Figure 05

Figure 5. The protagonist of the Tengen Toppa Gurren Lagann anime overflowing with Spiral Power. Screenshot from the anime; image taken from Gurren Lagann Wiki.

As such, I propose a second analysis for the TTGL. Knowing the estimated mass of the Great Attractor as 2 x 1042 tons, I assume that to be the mass of the TTGL. Calculating the Schwarzschild radius for that mass, we have Table 3.

Table 3. Comparison of the Schwarzschild radius of the TTGL with its real radius, considering that the TTGL has the same mass as the Great Attractor.

Great Attractor Table 03

Thus, a mecha of this size and weight might not collapse into a black hole, also having a “Schwartschild radius / real radius” ratio not so different from those of the Sun and Milky Way.


Well, not really.

You see, early this year, scientists managed to identify a whole bunch of galaxies hidden in the Zone of Avoidance (Staveley-Smith et al., 2016). These researchers used a multibeam receiver on a 64-m Parkes radio telescope and uncovered 883 galaxies, many of which were never seen before.

Therefore, it is more likely that the gravity anomaly detected is because of this concentration of galaxies rather than due to the existence of a giant robot 10 million light-years tall. But you never know…

Great Attractor Figure 06

Figure 6. You never know… Image adapted from the video “Laniakea: our home supercluster”, by Nature Video; available from: https://www.youtube.com/watch?v=rENyyRwxpHo.

Box 4. The Ring (1994)

In his 1994 novel “The Ring”, fourth book of the “Xeelee Sequence”, British hard science fiction writer Stephen Baxter proposed yet another interesting hypothesis for the origin of the Great Attractor. In his novel, the alien race Xeelee was losing a war against beings of dark matter, and retreated through an escape hatch. This escape hatch (the Ring from the title) was made of something too small to be seen by the naked eye, a cosmic string, a flaw in space time. A single inch of this “material” would weight ten million billion tons on the surface of the Earth. The ring had a mass of several galactic clusters and measured 300 light-years across, 10 million light-years in diameter. In Baxter’s book, it is discovered that this immense construction is the reason behind the Great Attractor (Orbital Vector, 2007).


I am grateful to Henrique M. Soares for helping to formulate this study’s question and developing the analysis; and to Gabriel K. Kiyohara for comments that helped putting some things in perspective (pun intended).


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