The Force: a new candidate for dark matter

Christian Vogt

Independent researcher. Hannover, Germany.

Email: christian (at) jcvogt (dot) de

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Only about 5% of the total mass of the universe consists of ordinary matter (mostly protons, neutrons and electrons, which form atoms). The missing 95% divide into dark matter (ca. 25%) and dark energy (ca. 70%) (Planck Collaboration, 2013) – see Figure 1. In this study, I focus on the former one.

Figure1

Figure 1. Approximated distribution of matter and energy within the universe.

The existence of dark matter is indicated by the effect of gravitational lenses and the orbital velocities in galaxy clusters as well as galaxy rotation curves (for more information see Carroll, 2007). Long story short, to explain some astronomic observations, there is mass missing, which is not visible to us. This missing mass is a result from the presence of dark matter. One candidate for dark matter are Weakly Interaction Massive Particles (so called WIMPs), which may be supersymmetric particles (Freund, 1988). However, experiments such as those of the Large Hadron Collider have not proven the existence of supersymmetry yet. I propose a different candidate for dark matter here.

Galaxies with rotation curves influenced by dark matter are usually far, far away. Due to the limited speed of light, the events in these galaxies we observe now on earth happened a long time ago.

Therefore, to find a new candidate for dark matter, let’s have a look at a place a long time ago, in a galaxy far, far away!

DARK MATTER MIDI-CHLORIANS

This far, far away galaxy, where the plot of Star Wars takes place, is characterized by slightly different physics compared to our own galaxy. The differences in physics may be a result of the presence of dark matter.

What are those differences? As long as they are not jumping into hyperspace and flying faster than light, space ships in Star Wars travel very slowly through space, similar to ships at sea (capital ships such as Star Destroyers) or planes (X-Wings or TIE-Fighters). They seem to be restricted by some medium, limiting their maximum speed. In addition, their engines emit sound waves, which propagate through the apparent vacuum, making, for instance, the characteristic noises of turbolasers and TIEs flying by (Lucasfilm, 1977). The corresponding sound waves have to travel through some medium filling the vacuum. This medium is our candidate for dark matter!  In order to reveal its nature, let’s look at an additional characteristic of the Star Wars galaxy: the Force. The Force is an overall present force field in the galaxy, but it interacts only strongly with other atoms when used by a Jedi.

According to Lucasfilm (1999), the carriers of the Force field are particles called Midi-chlorians [1]. Obi-Wan Kenobi states: “The Force is what gives a Jedi his power. It’s an energy field created by all living things. It surrounds us and penetrates us.” Therefore, the Force seems to interact weakly enough to “penetrate us”, but interacts strongly with certain live beings (Jedi). Further, he says that “[it] binds the galaxy together”. The Force field has to interact gravitationally to achieve this, and, hence, its carrier particles [2] need to have mass. Like other force carriers (electrons, W- and Z-Bosons, Gluons for electromagnetic, weak and strong nuclear interactions, respectively), Midi-chlorians should be particles with integer spin (Bosons). A Feynam diagram of a Force interaction is illustrated in Figure 2.

Figure2

Figure 2. Jedi master Yoda levitating an X-Wing starfigher by the Force as seen in a Feynman diagram. Yoda exchanges Midi-chlorian particles with the X-Wing to lift it.

With the overall present, massive, but mostly weak interacting Midi-chlorians, we have our candidate for a dark matter particle. Figure 3 shows the particles of an extended Standard Model including the Force and its Midi-chlorian carrier particle.

Figure3 [NEW]

Figure 3. Extended Standard Model including the Force. The yin-yang symbol represents two “flavors” of the Midi-chlorian particle: light side and dark side.

MIDI-CHLORIAN MASS AND PARTICLE DENSITY

Assuming the Star Wars galaxy is quite similar to our own Milky Way, I can estimate the mass density of dark matter in this far, far away place. The ordinary mass of the Milky Way is mmw = 4×1011 times the mass of our sun. Dark matter should be approximately five times this mass (25% compared to 5%).

The galaxy is approximate by a disk with a radius of rmw = 105 ly, its thickness is dmw = 3×103 ly (neglecting the bulge at the center). As a consequence, the mass density ρdm of dark matter in the Star Wars galaxy is:

ρdm ≈ 5mmw x (∏ rmw2 dmw)-1 ≈ 5×10-20 kg m-3

As TIEs and X-Wings sound very similar in space and in a planet’s atmosphere (Lucasfilm, 1977; Lucasfilm Animation, 2014), I assume a similar particle density of dark matter Midi-chlorians in space and air in the lower planet’s atmosphere of ρMidi = 2.5×1013 m-3.

Comparing particle density and mass density allows me to calculate the mass of one single Midi-chlorian: mMidi = 2×10-33 kg, which corresponds to about 1 keV.

That is about factor 500 below the mass of an electron. Midi-chlorians seems to be very, very light weighted – which we would expect for a particle of the overall present invisible field of the Force.

DARTH VADER’S MIGHT

What does the parameters calculated above further tells us?

Let’s take into account the fact that Anakin Skywalker (when found by Qui-Gon Jinn), who became later the mighty and evil Darth Vader, has a concentration of 20,000 Midi-chlorians per cell of his body (Lucasfilm, 1999) – the highest measured value so far. Unfortunately, we have no information on the measurement’s method, which would allow to verify the theory of dark matter Midi-chlorians on Earth.

With 1014 cells in a human body, Anakin’s body contains 2×1018 Midi-chlorians. Anakin, or at least Darth Vader, is a big guy. I assume his value to be equal 0.1 m-3 (neglecting in this approximation, however, his loss of limbs after his fight with Obi-Wan Kenobi). This yields a density of 2×1019 Midi-chlorians per m3 for this user of the Force. That means Anakin’s Midi-chlorian density is larger than the galactic background by six orders of magnitude. This seems to be a reasonable value for the mightiest Sith Lord in history.

CONCLUSION

I proposed Midi-chlorians from the Star Wars galaxy as reasonable candidates for a dark matter particle, giving their mass as 2×10-33 kg (about 1 keV), and showing that Darth Vader has about one million times Force in him than the galactic background. To the best of our knowledge, no Jedi inhabits our Earth and our satellites and probes make no sound in space. As an unfortunate turn of events, we seem to live in a very Force-poor part of the universe – making it very hard to solve the riddle of dark matter on this planet.

Future studies will focus on dark energy and its relation to the dark side. In addition, it will be studied whether there is a yet unknown quantum number defining light side and dark side Midi-chlorians and their spontaneous symmetry breaking near Jedi and Sith.

ACKNOWLEDGMENTS

Judith Vogt provided advice and a figure. Thanks also to Klaus Erkens und Marc Wolter for useful comments.

REFERENCES

Ade, P.A.R. & Aghanim, N. & Armitage-Caplan, C. (Planck Collaboration) et al. (2013) Planck 2013 results I Overview of products and scientific results – Table 9. Astronomy and Astrophysic 1303: 5062.

Corroll, S. (2007) Dark Matter, Dark Energy: The Dark Side of the Universe. Guidebook, Part 2. The Teaching Company, Chantilly.

Freund, P. (1988) Introduction to Super-symmetry. University Press, Cambridge.

Lucasfilm. (1977) Star Wars Episode IV: A New Hope. 20th Century Fox, United States.

Lucasfilm. (1999) Star Wars Episode I: The Phantom Menace. 20th Century Fox, United States.

Lucasfilm Animation. (2014) Star Wars Rebels. Disney–ABC Domestic Television, United States.


[1] As a fan of the old movies, it is quite hard for me to mention this topic. However, I will sacrifice true fandom for the sake of science.

[2] The Midi-chlorians are also referred to as lifeforms, living in creatures. However, Jedi use the force also on non-living objects. Therefore, the Force is not limited to interactions between microscopic lifeforms and has to be a fundamental nuclear interaction. Even if there actually is a microscopic lifeform with strong connection to the Force field or generation behavior for Force, I use the term “Midi-chlorian” here for the force carrier particle of the Force.


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Geeky nature

Rodrigo B. Salvador

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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Everybody knows that each species on the planet eventually receives a so-called “scientific name”, a two-piece Latin-like name that serves the purpose of scaring people away from science – even more than they already naturally are. So what good do scientific names do?

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Cyanocitta cristata, the blue jay. Image taken from: Wikimedia Commons.

Well, for starters, having an official name assures that every single scientist in the world will refer to a species by its scientific name. This makes it a lot easier to find information about a given species in the vast scientific literature. Just imagine how easier it is to simply search the literature for information on Cyanocitta cristata instead of looking for citations of its popular names: blue jay (in English), arrendajo azul or urraca azul (in Spanish), Blauhäher (in German), geai bleu (in French), ghiandaia azzurra americana (in Italian), gaio azul (in Portuguese) etc.

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Species in the genus Panthera are all closely related to each other and, thus, all have similar characteristics. Top row, from left to right: tiger (P. tigris), leopard (P. pardus) and a reconstruction of the fossil Longdan tiger (P. zdanskyi). Bottom row, from left to right: jaguar (P. onca), lion (P. leo) and snow leopard (P. uncia). Image taken from: Wikimedia Commons.

Moreover, by stating that a tiger (Panthera tigris) belongs in the genus Panthera, we are saying that it is more closely related to the other species in the same genus (such as the lion, Panthera leo, and the jaguar, Panthera onca) than to any other member of the cat family (called Felidae), such as the Canadian lynx (Lynx canadensis) or the saber-toothed cat (Smilodon fatalis). These statements are the basis for organizing the tree of life.

Now, let us take a moment to review how scientific names work. They have two parts. The first one is the name of the genus, like Panthera in the example above. The second part is called the “specific epithet”, like tigris for the tiger. Now mind you that the species name is not simply tigris. The word tigris means nothing by itself, unless accompanied by the genus name. As such, the complete name of the tiger species is Panthera tigris.

The specific epithet (the cristata of the blue jay example) is usually not a random word. It may help describing a species, giving an idea of what it is like or where it comes from. Let’s take a look now at some useful specific epithets:

  • Take the snail species called Eoborus rotundus, for instance. The specific epithet implies that this particular snail is rotund or round and this is something that makes it different from other species in the same genus. For instance, the species Eoborus fusiformis is, like the name implies, spindle-shaped. As such, the specific epithet serves to point out a feature that makes the species easy to distinguish (diagnose, in the jargon) from other closely related species.

  • The specific epithet can also reflect the place where the species lives or, at least, where it was first found. For instance, we expect to find a bird named Tangara brasiliensis in Brazil and a slug called Arion lusitanicus in Portugal. Sometimes this fails though: the bird Tangara mexicana is not found in Mexico – perhaps a lack of geographical knowledge of the person who named it.

  • An epithet may also reflect the kind of habitat where the species lives in or its mode of life. The snail Cepaea hortensis received this epithet because it is commonly found in groves and orchards.

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The round Eoborus rotundus (left) and the spindle-shaped Eoborus fusiformis (right) are fossil land snails species from the Paleocene/Eocene of Brazil.

Also, there are the not-so-useful names, the ones that are given in honor of someone, commonly a great scientist who usually worked with that group of animals before. For instance, there are loads of species, such as the snail Bulimulus darwini, named after Charles Darwin. Of course, Darwin deserves all the honors possible, but sometimes this habit of naming can become more a matter of ass-kissing than anything else. It is thus common (and useless) to name species after the person who funded the research or even after people who are completely irrelevant to science, such as the zoologist’s wife or children. Therefore, we have lots of women’s proper names, especially in the butterflies. Even worse, almost all birds of paradise are named after European nobility or royalty. It might be cute, be it is useless.

Sometimes, a species is named after a mythological being. This is often also useless, despite being way more awesome, like the owl genus named Athene. Yet, it might also be useful sometimes. For instance, the snail Brasilennea arethusae was named after the nymph Arethusa. This snail was the first fossil land snail found in Brazil and naming it after a forest-dwelling nymph made this very clear (at least to people who know their mythology), in a manner similar to the example of Cepaea hortensis above. Another example is Pseudotorinia phorcysi, a snail that lives in the deep sea, named (by myself and two colleagues) after the Greek deity Phorcys, the god of the hidden dangers of the deep sea.

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Halystina umberlee. The photo on the left was taken on a light stereomicroscope. The one on the right was taken using a scanning electron microscope, which reveals much more details about the structures of tiny creatures.

And now, finally, I arrived where I wanted: the geek names. Some species have received names coming from geek culture. As the first example, there is Halystina umberlee. This is also a deep-sea snail named by myself and the same two colleagues, but this time, instead of the Greek god Phorcys of the example above, we used the goddess Umberlee. She is also a goddess of the dangers of the deep sea, but she is a fictitious deity, coming from the so-called Faerûnian pantheon of the Dungeons & Dragons RPG. To my knowledge, I was the first geek to name a species after something D&D-ish. But I’m far from being the first geek in the history of zoological nomenclature.

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The goddess Umberlee rising from the waves (taken from the book Faiths & Pantheons by Eric L. Boyd & Erik Mona, 2002, published by Wizards of the Coast).

Back in the 19th century, geek zoologists did not have Tolkien or Star Trek yet, so they named their species after the geeky literature of their time. For instance, the jumping spider Bagheera kiplingi – the genus named after the character and the specific epithet after the writer.

From the middle of the 20th century onwards, geekness became much more pervasive. Just to exemplify, we have the spiders Pimoa cthulhu and Aname aragog, the fossil plant Phoenicopsis rincewindii, the mussel Ladella spocki, the fish Bidenichthys beeblebroxi, the dinosaur Dracorex hogwartsia and a whole lot from the Tolkienverse: the weevil Macrostyphlus gandalf, the fossil mammals Protoselene bombadili and Mimatuta morgoth, the leafhopper Macropsis sauroni etc.

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The dinosaur Dracorex hogwartsia, from the late Cretaceous of North America. Its skull really looks like that of a “typical” dragon, but the animal was disappointingly an herbivore. Image taken from: Wikimedia Commons.

Genera (this is the plural of genus!) have also been named after geek culture: the worm Yoda, the slug Smeagol (which has its own precious family, Smeagolidae), the crustacean Godzillius, the snail Cortana (this one is also my fault), the lizard Smaug, the fish Batman (why not an outright bat is something that also baffles me) and the tardigrade (microscopic creatures also known as sea-bears) Beorn, among many others.

One species that deserves a full paragraph here is Han solo. Yes, exactly, I’m talking about the Chinese trilobite. In the official description (from 2005), the author Samuel T. Turvey says that the name comes from to the Han Chinese (by far the most numerous ethnic group in China today) and that the specific epithet solo is because the species is the youngest fossil in the family (meaning the last or sole survivor). Still, Turvey later said that it was all a bet; some friends dared him to name a species after a Star Wars character. But Turvey was rather cowardly in this. He could have stated up front (and proudly) where the name came from. There is no rule in the International Code of Zoological Nomenclature (the code that regulates the names) against this. I have done it myself and lots of geeks before me have been doing it for a long time. The official description of the fossil turtle genus Ninjemys reads: “Ninja, in allusion to that totally rad, fearsome foursome epitomizing shelled success; emys, turtle.” And no editor or reviewer can prevent the name being given. Well, perhaps they could back in 1900-something, where everybody was worried with proper-this and proper-that, but, come on, not in 2005! Dr. Turvey, you have made geekdom both proud and disappointed at the same time. Please get things right from the start next time.

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Skull of the fossil teenager ninja turtle Ninjemys oweni, from the Pleistocene of Australia. Those are some pretty badass spikes and it actually looks a little bit like Slasher. Image taken from: Wikimedia Commons.

OK, I grant you that geek names are not very useful, but they sure give a little color to zoological (and sometimes also botanical) nomenclature. Taxonomy (the science of naming and classifying living creatures) is very nice and all, but the scientific papers in the area can be very arid and lifeless. Therefore, I think that it is a very valid endeavor to try to have some fun while doing taxonomy, especially if you are a geek and have a whole pantheon of heroes, gods and monsters to get your inspiration from.


ACKNOWLEDGEMENTS

I am very grateful to Ed Greenwood, creator of the Forgotten Realms (and, thus, of Umberlee) for his very kind comments on the new species named in honor of the goddess. Also, many thanks to my co-authors of scientific papers for allowing my geekness to run free when naming species.


REFERENCES & FUTHER READING

If you want to know exactly how species are formally described and get their official names, this is the best guide out there: Winston, J.E. (1999) Describing Species: Practical Taxonomic Procedure for Biologists. Columbia University Press, New York.

A less academic approach to the whole naming process can be found in: Wright, J. (2014) The Naming of the Shrew: A Curious History of Latin Names. Bloomsbury Publishing, London.

For a more philosophical view and musings about the importance of naming species for scientists and non-scientists alike, try this one (you might want to skip chapter 9 though, which is far too exaggerated on its glorification of molecular taxonomy): Yoon, C.K. (2010) Naming Nature: The Clash Between Instinct and Science. W.W. Norton & Company, New York.

If you want a taste of what a real taxonomic paper looks like, try this one (where Halystina umberlee came from): Salvador, R.B.; Cavallari, D.C.; Simone, L.R.L. (2014) Seguenziidae (Gastropoda: Vetigastropoda) from SE Brazil collected by the Marion Dufresne (MD55) expedition. Zootaxa 3878(6): 536–550.

For the ones who like rules and want to take a look at the “laws” presiding over animal names, the International Code of Zoological Nomenclature (ICZN, for the intimate) is the one and only guide: http://iczn.org/iczn/index.jsp.

Last but not least, Mark Isaak has compiled a lot of geeky scientific names on his website: www.curioustaxonomy.net/etym/fiction.html. I must confess that I did not know most of them, since they are insect names (rather removed from my area of study). In any case, it is always good to know that I am not alone – there are many other geek zoologists and paleontologists out there. Just take a look at the sheer amount of Lord of the Rings and Silmarillion names; it’s amazing!


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