Scientific Theories
[size=3][color=#29384e][font=Times New Roman]In science[/font][font=宋体]，[/font][font=Times New Roman] a theory is a reasonable explanation of observed events that are related. A theory often involves an imaginary model that helps scientists picture the way an observed event could be produced. A good example of this is found in the kinetic molecular theory[/font][font=宋体]，[/font][font=Times New Roman] in which gases are pictured as being made up of many small particles that are in constant motion.[/font][/color][/size][size=3][color=#29384e][font=Times New Roman] [/font][/color][/size]
[size=3][color=#29384e][font=宋体] [/font][font=Times New Roman]A useful theory[/font][font=宋体]，[/font][font=Times New Roman] in addition to explaining past observations[/font][font=宋体]，[/font][font=Times New Roman] helps to predict events that have not as yet been observed. After a theory has been publicized[/font][font=宋体]，[/font][font=Times New Roman] scientists design experiments to test the theory. If observations confirm the scientist[/font][font=宋体]‘[/font][font=Times New Roman]s predictions[/font][font=宋体]，[/font][font=Times New Roman] the theory is supported. If observations do not confirm the predictions[/font][font=宋体]，[/font][font=Times New Roman] the scientists must search further. There may be a fault in the experiment[/font][font=宋体]，[/font][font=Times New Roman] or the theory may have to be revised or rejected.[/font][/color][/size]
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[size=3][color=#29384e][font=宋体] [/font][font=Times New Roman]Science involves imagination and creative thinking as well as collecting information and performing experiments. Facts by themselves are not science. As the mathematician Jules Henri Poincare said[/font][font=宋体]，“[/font][font=Times New Roman]Science is built with facts just as a house is built with bricks[/font][font=宋体]，[/font][font=Times New Roman] but a collection of facts cannot be called science any more than a pile of bricks can be called a house.[/font][font=宋体]”[/font][/color][/size]
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[size=3][color=#29384e][font=宋体] [/font][font=Times New Roman]Most scientists start an investigation by finding out what other scientists have learned about a particular problem. After known facts have been gathered[/font][font=宋体]，[/font][font=Times New Roman] the scientist comes to the part of the investigation that requires considerable imagination. Possible solutions to the problem are formulated. These possible solutions are called hypotheses.[/font][/color][/size]
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[color=#29384e][font=宋体][size=10.5pt] [/size][/font][size=10.5pt]In a way[/size][font=宋体][size=10.5pt]，[/size][/font][size=10.5pt] any hypothesis is a leap into the unknown. It extends the scientist[/size][font=宋体][size=10.5pt]‘[/size][/font][size=10.5pt]s thinking beyond the known facts. The scientist plans experiments[/size][font=宋体][size=10.5pt]，[/size][/font][size=10.5pt] performs calculations[/size][font=宋体][size=10.5pt]，[/size][/font][size=10.5pt] and makes observations to test hypotheses. Without hypothesis[/size][font=宋体][size=10.5pt]，[/size][/font][size=10.5pt] further investigation lacks purpose and direction. When hypotheses are confirmed[/size][font=宋体][size=10.5pt]，[/size][/font][size=10.5pt] they are incorporated into theories[/size][/color]
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