You're welcome to analyze this dream, but not allowed to use the words “string” and “loop.”
If you read science blogs frequently you'll probably have come across one or the other posting of a science related tattoo. (See eg here for a nice compilation.) It always leaves me wondering what drives people to do that. It's one of these emerging social and cultural trends that are so complex even the people doing it don't know why they're doing it. It is, from an evolutionary perspective, very interesting what weird behaviors intelligent creatures can develop in large groups. My attempt to understand humans recently brought me across the paper “Modifying the body: Motivations for getting tattooed and pierced” (Wohlrab, Stahl and Kappeler, Body Image 4 (1007) 87). They start with an interesting historical summary (please see paper for references):
“[Tattooing and body piercing] have a long history and are well known from various cultures in Asia, Africa, America, and Oceania. There is also evidence for the prevalence of tattoos in Europe, dating back over 5000 years. Although the appearance of tattoos and body piercings varied geographically, they always possessed a very specific meaning for the particular culture. Piercings were often used in initiation rites, assigning their bearer to a certain social or age group, whereas tattoos were utilized to signal religious affiliations, strength or social status. In Europe, the practice of tattooing was predominant among sailors and other working class members from the beginning of the 20th century onwards. Later on, tattoos assigned affiliations to certain groups, such as bikers or inmates. In the 1980s the punk and the gay movement picked up invasive body modification, mainly as a protest against the conservative middle class norms of society.
Until the 1990s, body modifications remained a provocative part of various subcultures. In the last decade tattoos and piercings have increased tremendously in popularity, rising not only in numbers but also involving a broader range of social classes.”
Thus, historically tattoos seem to predominantly have been used to signal affiliation to or sympathy with a group. The paper is basically a literature survey, and the authors then identify ten motivations for getting tattooed that have been studied. These are: 1) Beauty, art and fashion 2) Individuality 3) Personal narrative 4) Physical endurance 5) Group affiliation and commitment 6) Resistance 7) Spirituality and cultural tradition 8) Addiction (to obtaining the tattoo) 9) Sexual motivation (in the case of tattoos: expressing affectation or emphasizing the own sexuality) 10) No specific reason (eg under the influence of drugs).
For what science tattoos are concerned, I think we can forget about the last category. It seems quite unlikely to me the average guy on the street will get drunk and wake up the next morning with the Wheeler-DeWitt equation on his shoulder. For what point 4) is concerned, I think we can leave this aside as well. I don't think the physical endurance is higher for scientific motives. Unless maybe there's a mistake in the equation.
For what sexual motivations are concerned, it is in this context interesting to draw upon a recent survey, conducted in Germany (sample size approximately 2500, as reported in “Machen Tattoos sexy?” forschung SPEZIAL. Das Magazin der Deutschen Forschungsgemeinschaft, 2/07, 22-25). More than 10% of men and more than 8% of women were tattooed. The age range that currently dominates the wedding market (18-36 years) has the largest fraction of tattooed people. Men are more likely to be tattooed on arms and legs, whereas women prefer places that can easily be covered by cloths: back, belly, bottom. Not so surprisingly, men prefer designs with skulls, weapons and such, whereas women prefer flowers and animals. Maybe the most interesting fact though is that while only 8% of women had a tattoo, 56% of the participants with a tattoo had a partner who was also tattooed. So there's clearly some matching going on there. Another study in which participants were shown images of tattooed people revealed that both women and men judged people with tattoos to be more “aggressive” and “dominant.” Maybe for some, that is a desired effect?
Needless to say, all that reading didn't really explain why people want to have an equation on their arm. I can relate to the beauty/fashion motivation to some extend, but I suspect that if your fashion statement are Maxwell's equations you'll get more confused than admiring looks. I suppose the most likely motives are thus personal narrative and showing group affiliation and commitment. Or maybe we're seeing an attempt of resistance to anti-intellectualism? Not to mention that you can upload the photo to your blog and collect cheers. As for myself, I've fleetingly considered getting tattooed once or twice, but my tastes are at the best metastable and whatever the design, I'd probably get fed up with it after a few months, so tattoos are not for me.
Anyway, it is sometimes very refreshing to read an article in a journal I had never heard of before like Body Image. The most amusing part was this sentence from the abstract, right out of the ivory tower:
“[A] profound understanding of the underlying motivations behind obtaining tattoos and body piercings nowadays is required.”
Sure, I mean, unstable financial systems are ruining the lives of millions of people, climate change is about to erode the basis of many economies posing a threat for global political and social stability, each year about 5 million people still die because they don't have enough to eat, but what's really required is a profound understanding of why people punch needles through their nipples. If you replace “motivations behind” with “structure of” and “obtaining tattoos and body piercings” with your favourite physics term, I'm sure you'll find the same sentence in a significant fraction of arxiv papers...