The “Bright Black” exhibit lets you see how your senses work, and more specifically – how your brain processes information about the brightness of the objects you are observing.
Our eyes are easily deceived! The exhibit, which was built in our workshop, proves this in an irrefutable and extremely simple way!
The brightness of the surface we are observing depends on the amount of light that the surface is able to reflect. This quantity is measured using a unit called albedo (Latin for whiteness). However, our senses work qualitatively (by comparison) rather than quantitatively (numerically). To say whether something is light or dark, quiet or loud, cold or hot, we need to have a point of reference. When it comes to temperature, this is obvious – the point of reference for us is our body temperature. For sound and light, though, we need some external points of reference. Whether an object is perceived as white or black (light or dark) depends on its background. For example, when we look at the Moon reflecting the light of the Sun, it seems much brighter than it really is – in fact, the rocks on its surface are dark. This is because we see it against the background of a completely black space.
The exhibit, designed and constructed by us, makes it possible to observe how the human brain interprets the amount of light reflected by the surface of a given object depending on its surroundings. The visitor illuminates each of four tiles characterised by an increasing albedo one by one while observing their brightness. Towards the end of the experiment, the tile that seemed white at first looks almost black.
We have made the “Bright Black” exhibit according to our own design on the basis of similar exhibits available at the Exploratorium in San Francisco and at the Swiss Technorama. Designing and building a good exhibit (i.e. one that works in an understandable and tangible way to present a particular phenomenon) on your own is a considerable challenge. It requires not only a thorough knowledge of the laws governing the phenomenon but also a skilful translation of theory into practice. Therefore – as always – we checked all of our assumptions and ideas one by one and performed countless prototype and material tests when implementing the “Bright Black” exhibit.
The success depended primarily on the choice of the right tile material. The challenge was to find a material that would enable us to show that what seems white to us at first can be perceived as almost black when put in the vicinity of objects with a higher albedo. In the experimental phase, we considered using various types of materials. Ceramic tiles seemed ideal for our exhibit but we rejected them due to a possible problem with the availability of spare parts in the future – after all tiles in a series are sold, it is usually impossible to buy identical ones. Ultimately, we chose laminates because of the ease of processing and the high availability of this material – even over a long time.
While working on the exhibit, we devoted many hours to selecting the right tiles so that they would differ in the value of albedo just slightly but sufficiently to ensure the desired effect. We used several colour patterns and finally chose tiles in shades coming from two different palettes. Since people – unlike devices – cannot be calibrated and the eyes of individual people differ in sensitivity and resolution in terms of the perception of brightness, our tests measured albedo taking into account feedback from many people. Some of us saw the shade of white as whiter while others considered it beige. However, everyone agreed on one thing: each subsequent tile was brighter than the previous one. We did a lot of tests and finally found what we had been looking for! Bright black… or a whiter shade of white!
The many months of work resulted in an extremely simple but surprising exhibit! Like most of our exhibits, it was made with the utmost reverence and entirely manually by our specialised craftsmen!
You can find the “Bright Black” exhibit in the Experimental Zone.