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from a booklet by Professor Moshe Kaveh

President of Bar Ilan University

When a child enters primary school, and finally begins to learn Rashi, he encounters Rashi's commentary on the verse "And G-d said: Let there be luminaries in the heavens"(Genesis 1:14). The Talmud (Hullin 60b) quotes Rabbi Shimon ben Pazi: "It is first written ' the two great luminaries', and then it is written 'the great luminary.' How is this explained? The Moon said to the Almighty: 'Master of the World, is it possible for two kings to rule under one crown?' The Almighty replied: 'Go and diminish yourself'."

Although this parable has an important moral lesson for all generations, it is also interesting to ask whether there is any relation between the Genesis text and science, or at least the science of the ancient world. The idea that the Earth was destined to revolve around the "two luminaries" generates great curiosity. Is such a thing possible?

Before providing answers for legions of kindergarten teachers and their pupils to the questions listed above, it is useful to survey briefly the history of the universe and the scientific theory of the formation of the Sun and the Moon. The universe originated about 15 billion years ago in a violent explosion, popularly known as the "big bang". Immediately after the big bang, the entire universe was filled with radiation. Part of the radiant energy was immediately and spontaneously transformed into the elementary particles of matter, and after only one second (!), protons and neutrons were formed.

Three minutes after the "big bang", the first atomic nuclei were formed, primarily helium. At that time, the temperature of the universe was one billion degrees! Great drama! The physics of electromagnetic waves, elementary particles, and nuclear physics, which constitute about 75% of the physics curriculum for the B.Sc degree in every university, all originated within three minutes!

The rate of the subsequent development of the universe was greatly slowed. About 300,000 uneventful years were to pass after the "big bang" as the universe gradually cooled down. However, when the universe finally reached a temperature of about 6000 degrees, dramatic events again began to happen. The first signs appeared of the the present-day structure of the universe, which consists of different materials.

These scientific findings aroused great excitement seven years ago, when the results of the COBE satellite reached the Earth. This satellite, launched into space in 1989 with the most sophisticated equipment on board, succeeded in measuring the radiation that reaches our planet from a distance of over 500 million light years. (One light year is the distance travelled by light in one year, nearly 10 trillion kilometres). The photographs taken by COBE showed the development of the universe starting from 300,000 years after its origin. How much time had to pass until the formation of atoms, the study of which constitutes the remaining 25% of the university physics curriculum? The first atoms were formed about 10 million years after the "big bang".

When were the Earth, Sun, and Moon formed? Physicists have learned that the solar system came into being about 10 billion years after the "big bang", that is, about five billion years ago. The Sun and planets appeared first, but the Moon was not formed until about 50 million years after the planet Earth.



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