Scientific knowledge is based on observations of nature. From observations of many different events and situations, scientists try to find patterns and create generalizations as to the underlying fundamental processes involved. Then they experiment again to see if the right guess was made of what the rule is that nature follows under a given situation. Experiments determine scientific truth. The scientist usually learns about nature by using controlled experiments in which only one thing at a time is varied to determine whether or not a particular situation, feature, or circumstance can be determined to be the cause of an observed effect. The experiments can be repeated by anyone as many times as they want to verify that the effect is reproducible. The astronomer cannot do controlled experiments. They cannot even examine things from a variety of angles. What astronomers do is collect light and other radiation from celestial objects and use all of their information and creativity to interpret the signals from afar. They look for the experiments nature has set up for us and hone on a few basic characteristics at a time.
Often the evidence for a particular hypothesis is indirect and will actually support other hypotheses as well. The goal is to make an observation that conclusively disproves one or more of the competing theories. Currently unresolvable questions may be resolved later with improved observations using more sophisticated/accurate equipment. Sometimes new equipment shows that previously accepted theories/hypotheses are wrong!
Scientific models and theories must make testable predictions. If an explanation is offered that has no concrete test that could disprove the explanation in principle, it is not a scientific one. This characteristic of scientific explanations is often the distinguishing one between scientific and other types of theories or beliefs (religious, astrological, conventional wisdom, etc.). Do understand that a scientific theory can be incorrect but still be considered a good scientific theory because it makes a testable prediction of what will happen under a given set of observing or analysis circumstances.
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last updated: January 5, 2015