VisionRevolution

In 1666 a young Isaac Newton made his first inquiry into the nature of light. Shining a ray of sunlight through a prism, he was able to produce an array of colour. But he was unable to explain why the prism revealed this spectrum, and he was unaware of all the light that our eyes cannot see. In the centuries that followed scientists would slowly discover this invisible light that fills the universe, and this light would reveal the secrets of the universe to them. In seven talks, Anne Cleary and Denis Connolly introduce us to the history of light - 400 years of discovery and experiment, from Newton to Einstein and beyond…

I. Particles or waves? (38’34”)

One of the things that makes science difficult is that it takes a lot of imagination…

Richard Feynman

The quest to understand light stretches from antiquity up to the present day, and even now all its mysteries have not been fully elucidated. The School of Looking consider some of the concepts that scientists, artists and philosophers theorised to explain light, and marvel at the incredible feats of imagination required.

II. Gamma & X rays (27’44”)

The late 19th century was a time of huge innovation, with new scientific advances announced every year. Wilhelm Conrad Röntgen discovered the X-Ray and developed a technique for taking photographs through solid matter, risking his health and that of his wife in the process, and Paul Villard identified another sort of penetrating ray, later called the Gamma ray, while experimenting with a radium sample lent to him by colleagues Marie and Pierre Curie.

III. Utraviolet (24’58”)

UV radiation was discovered by Johann Wilhelm Ritter in 1801, who dubbed it “Chemical Rays”, observing that the radiation made silver chloride turn black. Flowers have pigments that reflect UV, just as they have pigments that reflect visible light, and these pigments are visible to the UV sensitive eyes of navigating bees. But what do these colours look like? Can we even imagine a colour that a bee can see but that we cannot?

IV. Visible light (32’13”)

We call the central band of the electromagnetic spectrum, the part that we and some other primates see, “visible light”, but in fact most animals do not see colours as we do. Mammals (horses, dogs, cats...) are mostly dichromats, and see wavelengths in the blue and yellow areas of the spectrum. The Mantis Shrimp has four times as many colour receptors as we do. But what can a creature with such a relatively tiny brain do with all this colour information?

V. Infrared (24’48”)

When William Herschel discovered invisible light beyond the red end of the visible spectrum in 1800, he referred to it as “heat rays”, because the instrument that detected it was a thermometer. We now have Infrared cameras that show us heat information as visible light. The resulting image may resemble what our eyes see in unfamiliar colours, but in fact it offers us sensory information unlike any that we have: a true sixth sense - heat vision!

VI. Microwave (29’56”)

Microwaves are in fact the only electromagnetic radiation with wavelengths comparable to our human scale: between one millimetre and one meter. We associate the word with our time because of the humble kitchen appliance that goes by the name, but it’s true significance is on an entirely different scale. Microwaves have shown us the horizon of the observable universe: the first light that our universe ever produced which has travelled for 13.7 billion years.

VII. Radio waves (32’22”)

The Italian Minister of Post and Telegraphs scrawled “Alla Lungara” across a letter requesting funds to develop a wireless telegraph machine, received from Guglielmo Marconi in 1896. The hospital for the mentally ill in Rome was on Via della Lungara at the time, so “Alla Lungara” clearly meant “to the mad house”. Marconi’s invention went on to change the world, laying the foundations of a communications revolution that still continues.