THE SCIENCE OF LIGHT AND REFLECTION
The behaviour of light as it is reflected, refracted and diffused through the world has been a source of fascination and mystery for humankind since the dawn of time. Light rays, those luminous and ethereal emanations of the ancient Greeks, touch every part of our earth, and yet have a particular grace when they meet with water. This is where their vibrant radiance is most evident, shining with a life that goes beyond mere sight, to illuminate the imagination.
Early ideas about the nature of light and seeing tended to be more philosophical than scientific, and were always imbued with the mystery of the unknown. For Empedocles, considering the question around 500 BCE, the act of seeing relied on light rays coming both from the eyes and the objects seen. Pythagoras also conceived of light rays as being sent forth from the eyes, encountering and so illuminating the object seen. A few centuries later, Epicurus hit upon the first great truth in the field – that light emitted from a source is then reflected off objects, enabling our eyes to perceive them. At the same time, Euclid, in his famous treatise, Optics, refined this concept into an early theory of reflection. Light, he posited, travels in straight lines, and is reflected off a surface at the same angle it strikes it. This idea would prove itself true over time, although Euclid only seized upon a partial truth – he still imagined the light rays shooting from the eyes themselves.
Centuries later, in 1040, Arab scholars took up the work of elucidating the mysteries of light and reflection begun by the ancient Greeks. It was Ibn al-Hytham, or Alhazen in Latin, who finally arrived at a modern conception of visual perception: that vision is the act of eyes receiving reflected light, rather than light being emitted from them. His comprehensive theory of vision, and some of its component concepts – that light and colour are inseparable, for example – would prove hugely influential in the field of optics up until the 17th century.
The Enlightenment era saw a plethora of discoveries regarding the nature of light. Two models of light – as a wave or as moving particles – competed for primacy, the first championed by Dutch mathematician Christiaan Huygens, the second by Isaac Newton. While his particle theory was disproved in the 19th century, Newton is widely credited with discovering that light is not pure white, but is in fact composed of a spectrum of colour.
Water both reflects, refracts and diffuses light, and in so doing, creates a lively luminosity that is endlessly fascinating. To watch light reflected, sparkling and flashing on the surface of water, is to watch the dance of life itself. And when water refracts the light, the rays pierce the surface, creating that particular underwater effect, that ethereal shimmer that transports us to an otherworldly realm.
The Law of Reflection states that the angle of incoming light, or angle of incidence, is equal to the angle of reflection. So, when they encounter a perfectly smooth surface, light rays are reflected off it in the exact same arrangement. This organized reflection of light rays creates a mirror-like image on the reflective surface. If the incident light is bent, or refracted, the reflected light will bounce off in all directions – what is known as diffuse light. This light enables us to see objects around us as light rays are bounced off every part of their surface. The diffuse light allows us to see these objects, but they are not reflected back at us. In the simplest terms, the smoother the surface, the more it reflects light. One only has to imagine the mirror-like surface of a perfectly still lake, reflecting the snow-capped mountains with crystalline clarity – the ultimate illustration of the Law of Reflection.
Refraction, on the other hand, describes the phenomenon of bending light. When light travels through a transparent medium, like air, to another transparent medium, like water, some of it is reflected, and some pierces the second medium. When it does, it changes direction: this is refraction. The Law of Refraction, or Snell’s Law, is the mathematical formula that predicts the angle of the of light rays as they move through a transparent surface like water. Whether the transparent medium is a glacier-fed lake, a glass prism or a diamond, refraction redirects light.
The wavelengths, or colours, of a light beam arrive at different times, and this is what causes prisms to separate white light into all the colours in the spectrum. This is known as chromatic dispersion – and is what we observe when sunlight is scattered by droplets of water, forming a rainbow of coloured light.
The unique illumination inherent to La Prairie’s place of origin in Montreux, Switzerland, is a ballad of light upon water: it begins as pristine ice and snow that melts into the purest water, filtering through the highest Swiss peaks, infusing itself with rich minerals as it trickles down and diffuses into the lake below. In this slow, fluid journey, light and water meet in a way that is unique to Switzerland. The captivating reflection of light and water is a Swiss enchantment: it dances and glimmers on the surface of the lake; it radiates intricately through the lake’s dynamic waters; it refracts off the lake’s mineral depths. This enchantment is a magical encounter of light and water.
Inspired by the pure light unique to Montreux in Switzerland, La Prairie seeks to harness its power with the White Caviar Collection – the power to enliven, to enhance, to beautify – the very power that artists strive to capture in their works to highlight their subjects.
In 2019, La Prairie scientists established the Equation of Light, which shows that light – or skin luminosity – is a function of colour and reflection. In seeking to uncover new paths to luminosity, they queried how water might impact the reflection of light from the skin – they sought to seize this glimmering luminosity, to re-create its magic.
In 2022, the formula of the new White Caviar Essence Extraordinaire addresses the reflection element of the Equation of Light in three ways. First, by increasing skin hydration, and thus the amount of water in the skin. It also contains collagen-supporting ingredients to help plump the look of the skin and create a firmer appearance. Finally, it gently exfoliates to provide a smooth, light-reflecting finish. Together, these actions enhance reflection of light from the skin.