ABSTRACT
It had been known since ancient times that a moist atmosphere would split light
from the sun into a rainbow of colors. In 1672, Newton used an apparatus similar
to that shown in Figure 1 to demonstrate that the same type of splitting could be
effected using a glass prism as the active element. In this work, he showed
that the refractability of the light increased on passing from red to violet
and postulated a corpuscular theory for the nature of light. Unfortunately,
Newton’s great reputation discouraged others from challenging his theory, and
this situation persisted until a new wave theory was presented to the Royal
Society by Young in 1801. Needless to say, a fierce scientific and philosophical
debate ensued. In 1815, Fresnel developed a mathematical theory to interpret the
phenomenon of interference and also explained the polarization of light by
assuming that the light vibrations, which pass through a medium, are contained
in a plane transverse to the direction of propagation. The great controversy
over the wave versus corpuscular nature of light was resolved in 1850 by
Foucault, who designed a revolving-mirror apparatus that could measure the
velocity of light through different media. He conclusively demonstrated that
light travels more slowly in water than it does in air, a finding that was required
by the wave theory but incompatible with the corpuscular theory of Newton.
