My photo of Issac Newton’s statue lit up for Grantham’s
#gravityfields. “For the Society of Friends might be thought of as a prism through which the Divine Light passes, to become visible in a spectrum of many colours; many more, in their richest, than words alone can express.”
Newton passed a beam of white light through two prisms, which were held at such an angle that it split into a spectrum when passing through the first prism and was recomposed, back into white light, by the second prism (as shown in Figure 3.1). This showed that the colour spectrum is not caused by glass corrupting the light. Newton claimed this was a ‘crucial experiment’.
A crucial experiment is any experiment devised to decide between two contradictory theories, where the failure of one determines the certainty of the other. Since almost everyone agreed that light must be composed of either particles or waves, Newton used the failure of the wave theory to prove that light is made of particles. Newton concluded that light is composed of coloured particles that combine to appear white.
Newton introduced the term ‘colour spectrum’ and although the spectrum appears continuous, with no distinct boundaries between the colours, he chose to divide it into seven: red, orange, yellow, green, blue, indigo, and violet. Newton chose the number seven because of the Ancient Greek belief that seven is a mystical number.
Newton showed that every colour has a unique angle of refraction that can be calculated using a suitable prism. He saw that all objects appear to be the same colour as the beam of coloured light that illuminates them, and that a beam of coloured light will stay the same colour no matter how many times it is reflected or refracted. This led him to conclude that colour is a property of the light that reflects from objects, not a property of the objects themselves
The Quaker Tapestry consists of 77 panels illustrating the history of Quakerism from the 17th century to the present day.