Negotiating Real and Unreal Experiences of Light

Because of the charming, interesting and colorful effects that can be generated by light, there has been a long history of developing research on light, trying to find ways to first define it and explore it further. Reflection, refraction, and diffraction are all light behaviors of the light (Khan, 2000). In the scientific definition, light refers to all the electromagnetic waves. Edensor (2015) states that light is an electromagnetic wave that can be accepted by the naked eye. Light consists of basic particles called photons, with the attributes of particles and volatility. Light can be spread in a vacuum, air, water and other transparent media.

Figure1. Thomas Young’s sketch of two-slit diffraction of waves, 1803

The understanding of the nature of light was basically centered on two kinds of models: the particle model and, the wave model (Rossing and Chiaverina, 1999). The particle model considers light as ‘a stream of corpuscles or particles carrying energy’ (ibid.), this model was advocated by Isaac Newton during the eighteenth century. Newton claims that after light gets reflected, it moves in perfectly straight lines which can demonstrate the particle nature of light since it is only particles that could travel in such straight lines (Buchwald, 1989). The other, alternative wave model was championed by Christiaan Huygens, from the same generation of scientists like Newton. Huygens suggested that light is an electromagnetic wave, transported through an invisible substance called ether. In the nineteenth century, ‘The Double Slit Experiment’ led by Thomas Young established the validity of the wave model, putting the particle model aside. However, Albert Einstein used the particle model to demonstrate the photoelectric effect in the twentieth century and nowadays, the light is viewed as a phenomenon of a dual nature (ibid.).

The wave-particle duality means that all elementary particles or quantum can be described not only in terms of particles but also, partially, in terms of waves. This means that the classic concepts of the particle and the wave lose the ability to fully describe the physical behavior within the quantum range (Meads, 2015). Einstein describes this phenomenon in this way, ‘It seems that sometimes we have to use a set of theories, and sometimes we must use another set of theories to describe the behavior of these particles, and sometimes both must be used. New difficulties that force us to describe reality with two contradictory perspectives, both of which cannot completely explain the phenomenon of light alone, but together with it’ (Bazavov et al., 2013). In 1924, de Broglie proposed the material wave hypothesis and believed that light and all things are characterized by a wave-particle duality.

Because of its wave-particle duality, light can present various colorful effects such as reflection, chromatic dispersion, and refraction. This nature made light and material interaction a key factor in this discussion. Visible light is an electromagnetic wave with a wave length from 400nm to 700nm,and a corresponding photon energy somewhere between 3.1eV~1.8eV (Panero, 2001). The materials have three possible behaviors for the visible light that are manifested on their surface: transmission, absorption, and reflection (Birnbaum, 2013). Therefore, the material can be divided into different categories according to its light penetrating ability: full transparency, which means there is almost no reflection or absorption of the light (Belmonte, 2013), no transparency, which means completely absorbed or reflected light, and is semi-transparency (Nilforoushan, 2011). The electronic energy gap of the material will absorb the corresponding light in the visible energy range. Of course, there are two extreme situations, if the material’s surface is white, it will completely reflect the light, but if the material’s surface is black it will completely absorb the light. Therefore, it is profound how the difference in the material can totally transform the light effect.

1.2 Thesis project overview

Light and the deployment of different media can create a variety of interactive moments, by producing different visual effects, and offer people diverse special experiences. The influence of the light environment itself is further affected by the personality of each person that is susceptible to light. Therefore, the light will impact on the psychology and physiology of people (Whatley, 1999). In addition, a light environment not only affects the visual nerves, but it also affects the heart, endocrine function, and activity of the central nervous system.

The main purpose of this project is to create an art installation in space that can bring together the feelings of reality and unreality through the deployment light and different media. The installation will interact with people according to their behavior. This report focuses on the study of the light effect and the experience of the installation. The effect of light is related to what kind of media is being used,therefore, the main question of this report can be attributed to what combination of light and material is suitable for the development of a range of light experiences?

This can be divided into three more specific questions:

1. How can light construct the experience of the ‘real’ and the ‘unreal’ and, what sort of light sources and selection of materials are required for these experiences?

2. What is the difference among the light effects generated by different materials and what are the advantages and disadvantages of them towards creating different experiences?

3. What are the parameters that can control and adjust light effects that are led by light and material combinations?

By exploring the combination of different materials and light sources, this thesis explores the light effects that these produce and studies the relationship between the light effect and people’s experience. A design project is developed alongside these studies that determine the final use of materials and the form of installation.

2. Light experience, the ‘real’ and the ‘unreal’

2.1 What is the ‘real’ and what is the ‘unreal’?

The ‘Real’ and ‘unreal’ in this report are related to people’s perception and feelings. People first imagine, guess, believe and then they understand the world. The ’real’ and ‘unreal’ can be distinguished by people according to their own perception and cognition (Stephen, 1997).

According to the ‘Allegory of the cave’, people’s understanding of the environment has an inseparable relationship to what they consider is ‘real’ and ‘unreal’ (Ferguson, 1922). Prisoners in the cave, due to their limited scope of activities, they can only see the moving shadows on the wall. Therefore, based on their understanding, these moving shadows on the wall are for them the ‘real’. After a prisoner is liberated, he develops an understanding of the overall environment, realizing that what he saw as moving shadows were created due to a fire at the other side of the wall that illuminates several moving objects and projects their shadow son the wall. As such, he learns and understands that the shadow he used to recognize as the ‘real’ which is a light projection (Plato, 2008). Therefore, people’s criteria of ‘real’ and ‘unreal’ are based on their understanding of the overall environment, object or a scene.

The experience of the ‘real’ and the ‘unreal’ can be demonstrated by the difference between the human states of dreaming and being awake. The experience in a dream seems to be real. However, when one wakes up, it can be discovered that the reality in the dream is an illusion since the scene in the dream has disappeared. Then how can people tell that objects in a dream are not real? After people seeing these objects, they try to get closer or find these objects, and they are not there. The disappearing of the objects is what makes people judge the substance as ‘unreal’. Changes in the state of the object will make people feel that the object is unreal (Spira, 2017). Relatively, people know when they are awake because, in the waking state, they can touch an object they see. Objects in a ‘real’ experience are in a changeless state.

In this report, the word ‘real’ refers to the state when people see a changeless object or scene and judge the scene they see as true. To be more specific, ‘real’ not only means the objective and real substance, but it also means that people judge what they see is true according to their feelings, such as the prisoners in the cave.Likewise, the word ‘unreal’refersto the state of experience when people see an object or scene they are uncertain about its authenticity and judge the scene as illusory. For example, when people see the reflection of the moon in the water, they have the experience of the ‘unreal’. It is because despite from the fact that the reflection in the water is ‘real’ and can be seen, common sense tells people it’s not the real moon at that position, so people will judge what they see is not true, or ‘unreal’.

2.2 How can different light effects create different experiences?

Light is an important part of our environment and has a certain impact on people’s feelings. Gander (2016) states that ‘Light certainly has a physiological impact on people.’ In our daily life, recreational activities, military activities, and other fields have a variety of light conditions that affect people’s psychology and emotions. Light is a strong driver for visual performance (Grangaard, 1995), regulating various physical processes such as sleep and alertness (Knez, 1995; Wright et al., 2004; Takasu et al., 2002), critical to cognition and emotion (Veitch & McColl, 2001). A recent study suggests that either the positive or the negative emotions of a human are experienced more intensely under bright lights (Ellis, 2014). An example of this can be seen in the criminal review. The examiner often positions the criminals under bright light and ‘to get’the truth out of them. Compare to a normal light environment, a strong light environment makes criminals more likely, to tell the truth. Thus, the light and the experience of people in the environment are closely linked, since different light effects directly influence this experience.

Many projects have studied the light effect and its experience. One of them is the ‘Light in Movement’ of Julio Le Parc. Julio Le Parc is an artist who focuses on optical art and kinetic art, by using light as his main material in his late career. The ‘Light in Movement’ is a piece of sensory artwork. It does not aim to be narratively as same as other works of Julio Le Parc, but it focuses on the ‘visual experience and omits the anecdotal‘(Leyva, 2011).

Figure2. Light in movement of Julio Le Parc.

This work is consisting of stainless steel, mirror, nylon thread and two spotlights and it is inside a dark semi-circular corridor through which both reflection and refraction can be experienced. Viewers will stand below this artwork and observe twinkling light above them which is created by mirror and steel and see the light projection on the wall. The moving, changing point and linear light effect in the space created by this installation can keep the light environment changing, and make viewers feel like they are in an illusory space. Due to the kinetic and colorless light effect of this installation, it can make viewers have an experience of being in an unreal space, and encourage the interaction between the viewer and the installation (Preciado, 2011).

According to the people’s experience of ‘real’ and ‘unreal’,people distinguish‘real’ and ‘unreal’ is distinguished by observing if the existing state changes, so light effect can deliver this experience by changing the state of the light effect itself. If the light can reflect the object truly and objectively, it may offer people a ‘real’ experience of light, such as the daily light environment. If the light effect and environment is uncertain and keeps changing when people explore it, it can offer people an ‘unreal’ experience. Thus, in order to create this experience, light effect needs to be shifting between these two contradictory states.

3. Different materials and ‘real’ and ‘unreal’ light effect

3.1 What light effect can be generated by liquid, film and solid materials?

The experiment is used to explore the relationship between light effect and different materials. By testing the combination of different materials and different light sources, we can see what kind of light effects can be created,and experiment trying to find an appropriate material as a transport media for light to create a light effect for the ‘real’ and ‘unreal’ experiences. Three kinds of materials have been tested, from hard to soft, solid, film, and liquid materials.


Figure3. Refraction of light at the interface between two media of different refractive indices, with n2 > n1

Figure4. refraction and reflection of light in different prisms.

For solid materials, different shapes of prisms and convex lenses have been tested. Prisms and lenses can produce refraction of light. When the wave propagates from one medium to another from any angle other than normal 0°, the refraction is most often observed. The refraction of light means that light interacts with two different materials. Snell’s law states that ‘the ratio of the sines of the angles of incidence and refraction is equivalent to the ratio of phase velocities in the two media, or equivalent to the reciprocal of the ratio of the indices of refraction:

θ as the angle measured from the normal of the boundary, v as the velocity of light in the respective medium, λ as the wavelength of light in the respective medium and n as the refractive index of the respective medium(Wolf,1995).

Differently shaped prisms will make the light produce a different refraction effect. Dispersion is also a kind of light refraction phenomenon. With reflection and refraction, light through a triangular prism will transmit at least two rays of light.

After changing the incident angle of light, the position and number of light transmitted will also change. When using point light as a light source, it is difficult to cause dispersion. It needs to use the mirror to change point light source into the parallel light source. For the prism to cause the dispersion, a dark light environment is also needed, and the dispersion effect in this condition is very weak, as Figure 5 shows. Dispersion is more likely to occur when sunlight or parallel light is used as a light source as shown in Figure 6. Experiments show that the dispersion phenomenon needs a certain incident angle of light.

Figure 5. Dispersion and refraction effect of triangular prism with point light source.

Figure 6. Dispersion and refraction effect of triangular prism with sunlight.

The second prism tested is a dichroic prism. A dichroic prism is a prism that changes one beam of light into two different wavelengths or colors of light. It is usually made up of one or more prisms depending on the wavelength selectivity of the light or the reflection and refraction of the optical coating to choose the needed wavelength.

Figure 7. Dichroic prism experiment. Perpendicular incident angle

Figure 8. Dichroic prism experiment. Incident angle in 45 degrees. 

The dichroic prism used in our experiments is a cube- dichroic prism consisting of four right- angled triangular prisms. When the incident angle of light is perpendicular to the edge of the colored prism, the other three sides of the prism will emit three different colors of light separately as shown in Figure 7. When the angle between the incident angle of light and the color prism is 45 degrees, the dichroic prism will emit two different colors of light from the direction perpendicular to the light source as shown in Figure 8. When the light source is incident from other angles, the dichroic prism will disperse the light into four different colors of light.

Figure 8. Dichroic prism experiment. Incident angle in 45 degrees

Figure 8. Dichroic prism experiment. Incident angle in 45 degrees

Flora Domenis