art and physics

Year 2 Skills Essay – Physics in Artworks and Visual Art in Physics Dana May Ortmann Gilbert 22/02/2016 Tutor: Chris Hawkes

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Physics in Artworks and Visual Art in Physics by Dana May Ortmann Gilbert Ask anyone what they think are the most opposite fields of study and some will respond with sports exercise and fashion or history and geology, but the most frequent answer will be art and science or more specifically visual arts and physics. Although this is the case, I found myself at an exhibition by Yayoi Kusama admiring her infinity mirror room (see Figure 1) when my friend turned to me and asked why the mirror tunnel resulted in the further reflections looking green – and of course, I could only answer this using my knowledge of physics. So perhaps visual arts and physics is more related than we think. This is why I have chosen to write an essay exploring the connection between the two fields of study. More specifically how artists use physics to create extraordinary art and similarly how physicists use artwork to promote physics. To explore these connections between art and physics I will look further into Yayoi Kusama’s infinity room, Fabian Oefner’s work with ferrofluids named Millefoiri and the light sculpture on the Niels Bohr Institute’s façade illustrating the work at the LHC. To answer my friend’s question about the green mirrors we must first explore what colours are. There are many opposing theories to what colour is and how we see it[1], but for this discussion, I will dismiss the psychological considerations and use a simple definition depending on the reflection of light by objects. When white light (all wavelengths) is shone on an object, some of the light will be absorbed (and re-emitted) and some will be reflected immediately depending on the electron configuration of the atoms on the object’s surface. If for an example all the light is absorbed the object will appear black, if it is all reflected the object will appear white, if only the photons with wavelengths around 510nm get reflected the object will appear green and so on. Objects have colour determined by which photons are reflected off them, so what colour is a mirror? Some theories say that a mirror is a type of white, as it reflects everything. If, for an example, you put a tomato in front of a mirror, then the mirror is exposed to red light and we therefore perceive the mirror as red. If you instead place a pile of crayons in front of the mirror, then the mirror will be exposed to a range of colours and we will therefore perceive the mirror as all the colours of the crayons. Referring back to the above explanation of colour, we know that an object reflecting all colours is white and we can therefore conclude that the mirror’s colour is “smart white”[2].

Figure 1: Yayoi Kusama’s Infinity Room. (Picture by Daniela Uribe.)

22/02/2016 Chris Hawkes


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The idea of mirrors being a smart white colour only applies to ideal mirrors; in reality, they are found to reflect more green light than any other colour. This phenomenon has been examined by R. Lee and J. Hernández-Andrés [3]. They first examined the reflectance of silver used for the backing of common mirrors and the transmission of soda-lime silica substrate (the glass used for mirrors) in the range of 380nm < λ < 780nm (resulting in the graph seen in Figure 2a). Here they found that the glass transmits the most around 510nm and that the silver reflects relatively uniformly for λ > 460nm, but transmits much less at λ < 460nm. By testing the reflectance of several common mirrors, the combined effect of the above measurements became clear as they found the maximum reflectance to occur at 560nm. However it should be noted that the reflectance only varied by approximately 10% in the visible spectrum. The study continued to examine a mirror tunnel proving the increased green reflectance. The reflectance measured after one reflection and after 50 reflections are shown in Figure 2b (please note that the curve representing the 50 reflections has been normalised, as it is much dimmer than the first reflection). Here it is clearly seen how light of wavelength 550nm is reflected much more than any other colour (and the general brightness of the reflected light decreases resulting in a fade from the “correct colour” to a greenish colour and ultimately to black). We now understand that the mirror tunnel in Yayoi Kusama’s Infinity Room had a green shine due to the mirrors’ materials reflecting and transmit more green light than any other colour. Consequences of Kusama’s art can be explained with physical concepts, but Austrian Fabian Oefner intentionally seeks out ways of transforming theoretical physics to art. He made the beautiful photo series named millefoiri including photographs such as that seen in Figure 3. He created the art by placing ferrofluids (black) in

Figure 2a: Reflectance and Transmission of materials for common mirrors.

Figure 2b: Reflectance after 1 and 50 reflections. (Figures 2a and 2b from [3])

Figure 3: Millefoiri by Fabian Oefner (from [15])


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magnetic fields and then placing a variety of watercolours onto the fluid (using a syringe for precision) resulting in all the different colours around the ferrofluid[4]. To explain the patterns created by Oefner I will first explain what a ferrofluid consists of and then proceed to explain its behaviour in magnetic fields, which in turn may explain the pattern in Oefner’s artwork. A simple explanation of ferrofluids are carrier fluids with suspended nanosized magnetic particles. Although metals are technically ferrofluids they are rarely referred to as ferrofluids, as they would only be influenced by very strong magnetic fields at extremely high temperatures [5]. Usual ferrofluids consist of magnetic particles (or littles clusters of molecules) suspended in a liquid, usually these particles consist of approximately 6 x 103 magnetite (Fe3O4) molecules[6]. To avoid these particles attracting each other, sticking together and thusly falling to the bottom of the fluid, surfactants are added to the mixture. Surfactants used in ferrofluids are molecules similar to a long chain of atoms with different properties at each end. One end may be polar and the other non-polar. The non-polar end (or polar end depending on the elements used) will stick to the magnetic particles and thusly the polar (or non-polar) ends will form a sphere around each particle repelling the other particles with a similar charged sphere around them. A simple ferrofluid consists of a carrier fluid with suspended magnetic particles and surfactants preventing the particles from agglomerating, but why does it create the weird shapes in magnetic fields (see Figure 4)? All things in our physical world strive to achieve stability and to minimize their potential energies, for a ball that results in it rolling down hills, for falling water it results in the reduction of the water’s surface tension by minimizing its surface area and for a compass needle it results in its alignment with the magnetic field lines. For ferrofluids, all of the three above examples apply. The fluid’s shape can be predicted by the simplified ferro-hydro-dynamic Bernoulli equation[8],

U = Ug + Us + Um, where Ug is the energy due to the gravitational potential, Us is the energy stored in the surface tension and Um is the magnetic field potential. The ferrofluid tries to minimize the above U. When there is no magnetic field the ferrofluid acts as all other liquids, it is drawn by gravity and has a flat surface (if in a steady container, not in free fall), but when a magnetic field is introduced (above a critical value) the ferrofluid minimises its potential energy by aligning with the magnetic field lines. Of course the gravitational field still affects the fluid and the surface tension still has an effect on the energy resulting in the characteristic peaks of ferrofluids in magnetic fields seen in Figure 4. The spikes are however not just formed due to the energy, but also due to the material. As it is subjected to a magnetic field all the particles in the fluid align in the same way as tiny bar magnets would, which causes all the spikes to repel each other (and because of this the peaks do not have a circular base, but a hexagonal base).

Figure 4: Ferrofluids affected by several magnets. (From [7].)


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After subjecting the ferrofluid to a magnetic field, creating the characteristic peaks Oefner added the paint[4]. The ferrofluid used in his artwork is hydrophobic resulting in the fluid and paint remaining separate. The ferrofluid tried to maintain its stabile position with minimum U according to the magnetic field, but it is obstructed by the paint resulting in the peaks collapsing into small walls. Oefner used physical phenomena to create patterns for his photographs, similarly in Denmark the Niels Bohr Institute (the physics department at the University of Copenhagen) used data from CERN to create a pattern used for their light sculpture on the facade[9]. The staff wished to mediate the work done at the LHC so a team of two physicists, two artists and a programmer was established to create the light sculpture seen in Figure 5 called the NBI Colliderscope. The sculpture consists of 96 LEDs attached to the wall in a hexagonal pattern. The LEDs turn on according to signals directly from the Transition Radiation Tracker (TRT) in ATLAS as a visual representation of the data. To understand the patterns created for the NBI Colliderscope, we must first investigate the physics of the TRT. As the proton beams collide, various particles are emitted from the collision site. The main function of the TRT is to detect transition radiation and use the data to extrapolate a trajectory and determine whether it was caused by an electron or a pion (or other particles). When a charged particle crosses a boundary between materials with different dielectric properties, transition radiation occurs as the particle conserves the continuous electric field by emitting photons[10]. The amount of photons emitted depends on the Lorenz factor, γ, and the boundary crossed[11]. This means that an electron in the ATLAS detector will result in more transition radiation than a pion when passing through the TRT (since electrons have higher γ than pions). The TRT detector establishes transition radiation and detects it via the following setup. Almost 300,000 tubes (or straws) are packed around the collision site[12]. Each straw’s walls is manufactured by combining kapton film, aluminium and carbon-polyimide. The various materials used for the walls were chosen to optimise both stability of the straws and to provide the dielectric boundaries causing the required transition radiation. Each straw is filled with a gas mainly consisting of Xenon (70%). The gas absorbs the radiation causing an ionised path and thusly allows the trajectory of the charged particle to be detected[13]. The straws contain a thin, central, gold wire, which has a voltage across it causing it to attract the negative ions created by the passing of the charged particle. This causes a current in the wire, which is measured and stored as data. If an electron passed through the straw more ions will be created in the gas causing a higher current to be detected than if a pion crossed the barrier.

Charged particles cross the barrier of the straws in the TRT allowing the detector to predict certain variables concerning the particle, and these variables are used to create the pattern used for the NBI light sculpture. The LEDs are designed to be analogous with the

Figure 5: The NBI Colliderscope. (From [9])


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straws in the TRT, in such a way that if the straw is ionised the respective LED lights up. If the current measured corresponds to an electron the LEDs will light for 2 seconds and slowly fade away[14], thusly being more predominant in the pattern than other particles. More generally, the pattern formed by the light re-creates the trajectory of the particle; hence, curves of light are seen on the Niels Bohr Institutes’ façade in a similar way as the charged particles’ paths are curved due to the magnetic field in the detector.

In conclusion, Yayoi Kusama may strive for her audience to question their spiritual lives when observing her infinity room, but it may also result in questions that can only be answered by the use of physics. On the contrary, Fabian Oefner and the Niels Bohr Institute create art to motivate their audience to ask question about the physics used and to create an admiration towards the artistic beautiful side of physics. Even though it may not be clear on a daily basis: physics can be beautiful. The beauty of physics may be displayed as a side effect of the art as with Kusama’s mirror tunnel. It may very intentionally be used (as with Oefner’s Millefiori) to create artwork. Or perhaps it can be interpreted to draw attention to the ground-breaking physics done by physicists all over the world (as with the NBI Colliderscope). Word count: 2133 words


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References [1] Berry, M. (2012). Color. Retrieved from Stanford Encyclopedia of Philosophy: http://plato.stanford.edu/entries/color/ [2] Stevens, M. (2012, Aug 3). What Color Is A Mirror? Retrieved from Youtube:

https://www.youtube.com/watch?v=-yrZpTHBEss [3] J. Hernández-Andrés & R. L. Lee (2003). Virtual tunnels and green glass: The colors of common

mirrors. [4] Oefner, F. (2013, October 3). Psychedelic Science | Fabian Oefner | TED Talks. Retrieved from

Youtube: https://www.youtube.com/watch?v=Mh3_wYHdeVs [5] Odenbach, S. (2001). Magnetoviscous Effects in Ferrofluids. Bremen: Springer. P. 7. [6] Odenbach, S. (2001). Magnetoviscous Effects in Ferrofluids. Bremen: Springer. P. 13 – 14. [7] Ferrofluids. (2016). Retrieved from http://mesa.ac.nz/mesa-

resources/demonstrations/ferrofluids/ [8] M. Erickstad & P. Broberg (2007). Pattern formation of driven Magnetorheological Fluid systems.

University of Minnesota. [9] NBI Colliderscope. (2016). Retrieved from University of Copenhagen:

http://colliderscope.nbi.ku.dk/english/ [10] ATLAS Collaboration. (1998). Electron identification with a prototype of the Transition

Radiation Tracker for the ATLAS experiment. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 200-215.

[11] A. Andronic & J. P. Wessels. (2011). Transition Radiation Detectors [12] ATLAS Collaboration. (2008). The ATLAS Transition Radiation Tracker (TRT) proportional drift

tube: design and. Journal of Instrumentation. [13] DVD, T. A. (Director). (n.d.). The Particles Strike Back [Motion Picture]. Retrieved from Atlas:

http://www.atlas.ch/multimedia/transition-radiation-tracker.html#episode-2 [14] E-mail correspondence with T. C. Petersen. [15] Oefner, F. (2012). Millefiori. Retrieved from Fabian Oefner's Portfolio: http://fabianoefner.com/?portfolio=millefiori

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