What exactly causes the high tides?
The ocean tides were observed by the shore dwellers and by the daring seafarers of early history. They soon saw that one of the regular daily high tides tallies with the passing of the moon overhead and they concluded that all the rising and falling tides are controlled by the moon. Our knowledge of the tides has progressed a long way since our early ancestors discovered their relationship to the moon. They assumed that the purpose of this heavenly body was to cause high and low tides to wash up and down upon the beaches of the Earth. In most places, two high and two low tides occur in a 24-hour day and during a lunar month their heights vary somewhat with the changing phases of the moon. The explanation of all this had to wait for the thoughts of a brilliant young man named Isaac Newton. As a student in his early 20s, Newton figured out the laws of gravitation and in some 300 years no one has corrected his figures. We had to grasp his Explanation of the gravitational attraction betwee
