Friday, November 27, 2009

Quantum Objects

[I have a piece in Nature on an art exhibition in the US by Julian Voss-Andreae, who has been working for some time now on representations of ideas, concepts and objects in physics and chemistry. This latest show is called ‘Quantum Objects’, and there are images of it here. I have written previously about Julian’s chemistry-related sculptures. I think Julian’s work is some of the best there is on the sci-art interface, creating a genuine point of confluence rather than, as all too often happens, a kind of awkward shotgun marriage.

In the course of preparing the piece, I had an exchange with Julian about the thinking behind his work, during which he said far more than I could accommodate in the article. This was all good stuff, so I’ve appended his comments below.]

When once asked what his Third ('Eroica') Symphony meant, Beethoven is said to have sat down at the piano and started to play it. Physicists might seek analogous recourse when asked to explain quantum theory – by writing down Schrödinger’s wave equation. And even this was Schrödinger’s attempt to provide a concrete embodiment of the still more abstract ‘description’ in Heisenberg’s austere matrix mechanics. Some of the field’s pioneers concluded that perhaps all we can ever meaningfully hope for by way of representation are the equations.

This implies that any attempt to show quantum concepts using images, whether for experts or non-specialists, is doomed to be misleadingly reductive. But maybe another alternative is to subvert our preconceptions through art. That is the view of Oregon-based sculptor Julian Voss-Andreae. Art, he says, ‘freed nowadays from the presupposition that it needs to visually accurately represent reality, has a unique potential for indicating aspects of reality that science cannot.’

Voss-Andreae is better placed to judge than most artists, for he was previously a physicist working at the forefront of experimental quantum physics at the University of Vienna, where he came face to face with the counter-intuitive aspects of the theory. In 1999 he participated in a ground-breaking experiment showing that even objects as ‘big’ as C60 molecules may display the wavelike property of interference (M. Arndt et al., Nature 401, 680-682; 1999). Voss-Andreae’s portrayals of ‘quantum objects’ are now on display in an exhibition called Worlds Within Worlds, running until April at the American Center for Physics in College Park, Maryland.

‘There simply are no consistent mental images we can create to understand the world as it is portrayed in quantum physics, because our brains are exquisitely adapted to making sense of the world on our scale’, says Voss-Andreae.  ‘I want to increase the audience’s capacity to intuit the unfathomable deeper nature of reality by sensually experiencing the works.’

This attempt to leap beyond the logical is an impulse with an obvious appeal to artists, but Voss-Andreae is not the first to find inspiration in the way that modern physics requires it of us. In the early twentieth century, Surrealist artists such as André Breton and Salvador Dalí were excited by what they saw as the challenge posed by quantum theory and relativity to conventional notions of causality, time, geometry and objectivity (see Gavin Parkinson’s Surrealism, Art and Modern Science; Yale University Press, 2008). Yet their enthusiasm was due as much to the new physics’ perceived radicalism and assault on convention as it was to any genuine interest in the theories, and they didn’t understand the science terribly well.

But who does? Perhaps the biggest problem for any artist seeking to mine quantum theory is that some of the fundamental issues are still not agreed by its practitioners. The disputes about interpretation among the early pioneers such as Einstein, Bohr, Heisenberg and Schrödinger are now legendary (see Manjit Kumar’s Quantum; Icon, 2008), but this by no means implies that they are behind us. The Copenhagen interpretation favoured by Bohr and Heisenberg, with its wave-particle duality, probabilistic picture and observer-induced collapse of the wavefunction is still not universally accepted, and the nature of the transition from quantum to classical behaviour continues to be debated. Meanwhile, the failure to unify quantum theory with gravitation remains one of the most well advertised lacunae in physics, seeming to leave open the possibility that quantum theory is a stop-gap, a mere mathematical convenience.

It’s therefore arguably either brave or foolhardy to try to represent quantum phenomena visually. Perhaps Voss-Andreae’s greatest asset as a former physicist is that he knows how much we don’t know, and how much is contingent. In some of his works, the inverted commas of analogy are explicit to the knowing eye. Quantum Corral materializes something that could hardly be less material: the wavelike properties of electrons (first reported in Nature in 1927). Here they are represented in a block of wood milled to the contours of electron density seen in 1993 around a ring of iron atoms on the surface of copper using a scanning tunnelling microscope. The gilded surface reminds physicists that it is the mobility of surface electrons in the metal which accounts for its reflectivity (and the coloration of gold is itself a relativistic effect of the metal’s massive nuclei). But for art historians, this gilding not only invokes the crown-like haloes of medieval altarpieces but could also allude to the way gold was reserved in the Renaissance for the intangible: the other-worldly light of heaven.

Night Path and Spin Family (Bosons and Fermions), with their webs of metal wire or silk thread in solid steel frames, hark back to the sculptures of Naum Gabo, themselves inspired by the appearance of new mathematical geometries and models. Yet Night Path shows a quantum idea: the path-integral approach to the trajectories of light, in which the passage of a photon is considered to be the integral over all possible paths, calculated by slicing up time. Here, however, Voss-Andreae is not trying to produce a ‘textbook’ representation. ‘I do not show a fixed end point as Feynman’s method demands’, he says. ‘Instead in my piece the paths emerge from one point and then keep opening up. The artwork is not meant to accurately illustrate the technique of path integration; I made it to illustrate the ‘feel’ of it.’ In the Spin Family series, inspired by the quantized spin states of the two classes of fundamental particles, the diaphanous thread allows us to visualize superpositions of states while cautioning against too literal a picture of what ‘spin’ itself represents.

A feeling of intangibility and the subjectivity of points of view pervades Quantum Man, a walking figure created from parallel slices of steel in which the particle-like concreteness seen from the front shifts to wave-like near-invisibility viewed from the side. This sense of an object on the point of disintegrating is a common trope of recent artistic efforts to capture ideas in physics, from Antony Gormley’s Quantum Cloud series to Cornelia Parker’s Cold Dark Matter. Put the pieces together yourself, they seem to say – because that’s how the world works anyway.

Q&A with Julian Voss-Andreae

PB: Do you actually want to give viewers a flavour of the ideas behind the quantum works, or are you simply using the science as a launching point for something more abstract?

J V-A: I do want to give a flavor of the underlying ideas, at least while the sculptures are on display at the American Center for Physics. I am displaying them with explanatory text to alert the audience to the fact that there is a real concept behind each piece. For this show I wanted to make works that physicists can relate to. But I didn’t want to stop there. I am always seeing the physics (or other sciences) as a starting point for creating something that develops its own life as an art object. I want people who don’t have a background in science to enjoy the work as well. I want to increase the audience’s capacity to intuit the unfathomable deeper nature of reality by sensually experiencing the works.
PB: Do you feel that quantum theory is really something that can be, or ought to be, visualized at all? - I guess the answer to that must clearly be 'yes'

J V-A: Well, the way my own mind functions I cannot really grasp anything without images. I have to make images for myself, real ones or in my mind, if they don’t exist. And I believe that this is so for many if not most people. So if you look at any quantum mechanics textbook there are lots of images - especially in books from your culture. In Germany people have often tried to get rid of images [even though they have the word ‘anschaulich’]; there was for example a movement in mathematics, I believe in the 1960s, which banned images altogether from their books because the authors felt it is a flawed practice since every image can always portray only one special case. That is of course true, but most of us still need images. Many of the more complicated things visualized in quantum physics textbooks are clearly illustrations of a single facet of something more complex and more abstract, something that the mathematical description might be able to express in one coherent concept but that we sometimes cannot grasp within one coherent (mental) picture. You are probably familiar with Bernd Thaller’s work: He creates movies of quantum systems, typically of the time evolution of wave functions. Using color value and hue to encode different variables he is able to portray complete wave functions including their phase. It looks beautiful how they move and it is very instructive. So, I definitely think quantum theory can and should be visualized.
PB: But what would you say to the view that any such representation is bound to create an artificially concrete representation of something that is beyond our capacity to intuit?

It has been recognized that quantum theory does not admit of a realistic interpretation. For example, we have no accurate space-time representation of a particle, say an electron:  it is neither a wave nor a particle nor any other “thing”. So there is certainly a danger in presenting artificially concrete representations without making sure they are correctly understood as only a facet of something more complex or altogether different. A well-known example of such a misunderstanding is the ubiquitous hydrogen atom model. There are the earlier models that show electrons as particles orbiting the nucleus in discrete orbits. Then there are the representations of electrons as wave-functions: countless textbooks show the images of s, p, d,… orbitals. [These models often contain an additional imprecision in that they illustrate only the angular dependence of the wave function, and not also the radial one. I am sure there are quite a few scientists who would draw those spherical harmonics if asked ‘what a hydrogen atom looks like’.] But even if the observable electron density is pictured, there still remains a problem, namely the very notion that a hydrogen atom (or any quantum “object”, for that matter), is an object, and has a particular appearance independent of the means used to observe it, or for that matter any objective existence at all. So in the case of the H atom, even if the correct three dimensional shape of the probability density is pictured it is still a potentially misleading abstraction because you need to keep in mind that this shape merely represents tendencies for results of possible electron position measurements, whereas the phenomenal reality it refers to are the discrete and apparently random positions at which the electron is actually measured when an experiment is carried out in which that wave-form represents the prepared state. In fact, there is always a danger of taking any image or model too literally (Whitehead’s “fallacy of misplaced concreteness”). Using images in science or philosophy to illustrate states of affair is therefore quite generally a two-edged sword, and one needs to know the limits of a picture, and use it with discrimination and intelligence.  So with that caution, I would say that art, freed as it is nowadays from the presupposition that it needs to visually accurately represent reality, has a rather unique potential for indicating aspects of reality that science cannot.

In a related vein, I don’t think that a specific piece of art has a single correct “interpretation” (as is true for a textbook image). To me, good art is something that has (by virtue of its sensual and conceptual properties) the potential to give rise to a web of meaningfully interlocking interpretations. So my experimentation ultimately aims at finding (in that sense) ‘good’ art objects. [Btw, it is interesting to relate this to the quantum mechanical measurement process: Art is like an unmeasured wave function with tendencies, a superposition of possibilities (the different interpretations). Then comes the individual’s interpretation of the art work in a specific instance, analogous to the physical measurement that reduces it to one classical answer and forces the system into that state.] 

To further comment on the relationship between my art and the science it relates to:  a piece like “Night Path” (the Feynman paths one) if shown in a textbook, might lead to the misunderstanding that there are a finite number of actual paths to be added. Of course, the number really needs to be infinite to yield the correct result. Moreover, I do not show a fixed end point as Feynman’s method demands; but instead in my piece the paths emerge from one point and then keep opening up. But the art work here is not meant to accurately illustrate the technique of path integration. I made it to illustrate the ‘feel’ of it. I like the idea of having these myriad paths that wiggle around in a completely ‘non-physical’ fashion (i.e. being everywhere at every time) and that they get more and more important in the classical trajectory’s vicinity because there the phase oscillates slower. So I took a Gaussian distribution around a parabola and used the pseudo random generator in the computer to calculate where to make holes into the slices. I followed the output of the algorithm quite strictly because I didn’t want to bias the result with ‘human pseudo randomness’. Before I built the piece I visualized it in the computer to fine-tune the parameters involved (the shape of the trajectory, the sigma of the Gaussian etc.) and that gave me the idea of evoking an image of a meteor falling through the night, which then informed the choice of colors. That is where I allow myself the ‘poetic departure’ from physics. For a textbook, I would not have used a parabola and I would have collected the paths back into a single endpoint. So my hope is to convey this bizarre feeling of the path integral approach (even if it is not recognized as such) by merging it with an image (the meteor) that is known to everyone. I always feel I am experimenting here. Not only with the materials and algorithms etc. but also with having an idea and turning it into a real object to see what it does to me and others. This is where my experimental art work departs from experimental physics: I am ultimately interested in creating an art object, something that strikes a chord in the viewer.

[I think it is key to display the works in an art setting. Even though it is the American Center for Physics in this case, the place where the sculptures are displayed is designated to displaying art and the audience knows that. The same is true for the display on my website.]

[Concerning the wording in your question: Do you mean capacity to intuit or capacity to understand? There are obviously things that are beyond our capacity to understand in the sense that we cannot find a single coherent mental image that provides a complete description of that thing. But maybe we can intuit a solution to a paradox even though we cannot understand it.][PB: I agree, and that’s indeed what I meant: intuition does not necessary imply rigorous understanding, but is perhaps all we can hope for here, especially if one isn’t a specialist.]
PB: I'm also interested in whether there are any artists who provide particular inspiration for you, either from a purely visual point of view or because they have similarly tried to articulate and present rather abstract ideas and phenomena.
J V-A: I am influenced visually by a lot of things in art and architecture. I frequently get ideas from other artists about how to solve problems technically or they give me an idea what could work visually. I don’t have a particular artist that I draw inspiration from when it comes to taking images from science to create art. But on a more abstract level there are artists I greatly admire for the intensity of their work and because they lead the way with their visions and their ability to realize them. There is one artist in particular I feel I have an odd connection with and that is Antony Gormley. It happened several times already that I had an idea and found out later that he had gone in that direction. We are interested in very similar things and he is very systematic and efficient in exploring them. I would love to meet him one day.

PB: Can you also tell me a little about how the exhibition came about?

J V-A: The curator, Sarah Tanguy, had asked me a few years ago if I was interested in showing my work at the American Center for Physics because she thought my work would fit well there. Last year, after she was able to secure the funding, I was supposed to have the show. But after I had thought about it and decided to make all works which had to do with quantum physics, I realized that I needed another year to finish them.

Statement on the website, also displayed at the exhibition (J V-A)
The term “Quantum Object”, although regularly used in physics, is really an oxymoron. An ‘object’ is something that lives completely in the paradigm of classical physics: It has an independent reality in itself, it behaves deterministically, and it has definite physical properties, such as occupying a well-defined spot in time and space. For the ‘quantum’ all those seemingly self-evident truths become false: Its reality is one that is relative to the observer, the principle of causality is violated, and other features of materiality such as clear boundaries in space and time, objective locatedness or even identity, do not pertain.
After struggling with quantum physics for the last hundred years we cannot escape the fact that there simply are no consistent mental images we can create to understand the world as it is portrayed in quantum physics, because our brains are exquisitely adapted to making sense of the world on our scale, as perceived through our unaided senses. My hope is that the unique ability of art to transcend the confines of logic and literal representation and to offer glimpses of something beyond can help us open up to a deeper understanding of the world and to wean ourselves from the powerful grip classical physics has had over the last centuries on our every perception of reality.
General Artist Statement (J V-A)

My diverse interests, investigations and works as both scientist and artist are ultimately derived from my lifelong fascination with Nature. As an observational painter in my youth I was so intrigued by the natural sciences and its philosophical implications, that I subsequently spent the next eight years studying physics at European universities. I earned my degree in physics participating in a seminal experiment at the boundary between quantum physics and philosophy. I then moved to the United States to study art and began developing a body of sculptural work often inspired by scientific themes, such as quantum physics or the structure of protein molecules, the building blocks of life.

I create art by taking something I see or know and translating it into an object. This translation starts out being guided by clearly expressible ideas and tends to develop into something successively complex and less accessible through logic and words. The act of creation contains an extraordinary and most fulfilling aspect I find impossible to understand intellectually: The creative moments are not governed by my conscious thought. On the contrary, it is typically the unconsciously contributed aspects, executed in a certain meditative state of mind that brings the work to life, adding new and often surprising layers of meaning.

It is important for me to create works in a spectrum ranging from mostly intellectual to mostly intuitive in order to generate a cross-inspiration between both approaches. Achieving the right balance of intellect and intuition, of science and art, is central to both my work and my life. In fact, I feel unable to clearly distinguish between the concepts of intellect and intuition, which are commonly perceived as polar opposites, and I strive to unify these opposites into a single more fundamental idea. I am motivated by the desire to create a broader understanding of Nature than the one provided by science alone: My work allows intuiting our world by offering a sensual experience of what is usually accessible only through our intellect.