So-called white dwarf stars are very old stars that have collapsed in upon themselves, thus becoming much smaller than they were at an earlier age while retaining the same mass. As a result of their evolution, they are almost unbelievably dense. From the law that every active force produces more than one change, it is an inevitable corollary that through all time there has been an evergrowing complication of things. Every solid, regardless of its shape or size, has a point at which it is in perfect balance. This point is the central point at which its mass and weight are concentrated.
Any explanatory theory is grounded on classification.
Classification is impossible without ignoring some characteristics of each of the items to be classified. At first, the production of reinforced plastic required a great deal of work that had to be done by hand. This was a drawback in modern mechanized industry, in which emphasis is on speed and efficiency. Engineers have designed dams that can be built across the mouth of a river to use by the flow of the river and the rise and fall of the tides to produce electricity. As the tide rises, water flows from the ocean across turbines in the dam to produce power until the dam is closed at high tide.