'I am NOT an alcoholic': Gerard Butler reveals the real reason behind his stretch in rehab. Actor Gerard Butler has revealed his rehab agony and set the record straight over rumours of his alcoholism. The 42-year-old Scot checked into the Betty Ford Centre in February for three weeks after being injured in a surfing accident. He said: 'Maybe a stronger person wouldn't have needed to go. But I'm glad I did it.
Gravity is one major force that creates tides. In 1687, Sir Isaac Newton explained that ocean tides result from the gravitational attraction of the sun and moon on the oceans of the earth (Sumich, J.L., 1996).
In most places, there are two tides a day. They each have a high point (the high tide) and a low point (the low tide). We speak of a flood tide coming in towards high tide, and an ebb tide going out towards low tide. The period of the tide is about 12 hours and 25.2 minutes, exactly half a tidal lunar day.