LIGHT AND DARK
Praise belongs to Allah Who created the heavens
and the earth and appointed darkness and light... (Qur'an, 6:1)
We all know that without light a person cannot see his surroundings
with the naked eye. However, the light that we can see is only a
very small part of all light-emitting energy. There are other kinds
of light-emitting energy that human beings cannot perceive, such
as infra-red, ultra-violet, x-rays and radio waves. Human beings
are effectively blind to such light waves.
It is interesting, therefore, that the word for "darkness" in the
Qur'an is always in the plural. The Arabic word, "ththulumat,"
is used in the plural in 23 verses of the Qur'an, and never used
in the singular. The use of the word "darkness" in the Qur'an indicates
that in addition to those light waves we can see, there may also
be other kinds.
Only recently did scientists discover why the plural may have been
used here. Wave lengths vary in a form of energy known as electromagnetic
radiation. All the different forms of electromagnetic radiation
behave as energy waves in space. This can be compared to the waves
which form when a stone is thrown into a pond. As the waves on a
pond can be of different sizes, so electromagnetic radiation has
Stars and other sources of light do not all give off the same kind
of emissions. These different rays are classified according to their
wavelengths. The spectrum of wavelengths is quite wide. There is
a 1025 (a billion times a billion times a billion) difference
between gamma rays, with the smallest size wavelength, and radio
waves, which are the largest. Nearly all the rays emitted by the
Sun are squeezed into just one part of this 1025 spectrum.
In order to better understand the colossal dimensions of this figure,
it will be useful to make a comparison. If we wanted to count to
1025, and if we counted day and night without pause,
it would take us 100 million times the age of the Earth to finish.
The different wavelengths in the universe are distributed within
a spectrum of just such a size. 70% of the different wavelengths
emitted by the Sun are limited to a very narrow spectrum between
0.3 microns and 1.5 microns. There are three kinds of light within
that band: visible light, infra-red light and ultraviolet light.
Despite occupying a band less than 1 in 1025, the rays
known as visible light represent 41% of all the Sun's rays.
As has been discussed, electromagnetic waves perceivable
to the human eye are responsible for only a very small part of the
light spectrum. The other regions represent only darkness for human
beings, who are blind to wavelengths outside that band.52
52. Husaini, Qur'an for Astronomy
and Earth Exploration from Space, 175-182.