How Science Is Done

Scientific observation does not differ fundamentally from any other kind of observation. One thing we ask is that it be repeatable. Scientists tend to mistrust single observations on unusual phenomena (such as UFO sightings). Also, like detectives reconstructing an accident, they tend to mistrust witnesses untrained in proper observation or emotionally involved in what is being described, or both.

Books have been written about what Science really is. Clearly, it has to do with knowledge, and it also has to do with skills. Scientists use their special knowledge and skills to find out about how things and forces work together to make up the world around us. "The world around us" includes everything we can measure or at least perceive, from invisible and elusive particles such as neutrinos (which weigh practically nothing) to clusters of galaxies so large it takes millions of years for light to go from one end to the other. "The world around us" includes Life and its history, the things that make our planet so special and wonderful. And it includes the flow of goods and money, and the way decisions are made by the various levels of government – that is, economics and political science. The natural sciences differ from the social sciences in that much of natural science deal with phenomena which can be replicated, in principle, while this is practically never the case for the social sciences.

The fields in the natural sciences that are closest to the social sciences are geology, ecology and cosmology, all of which deal with history, that is, with evolving systems. History can never be precisely repeated, and the narrative recounting what happened is always subject to revision and re-interpretation.

Science is what scientists actually do, not what philosophers and sociologists say they do, or should do, or could do. Science is not the same as engineering, which deals with making things for human use or with fixing things - although the most inventive engineers are invariably good scientists and most scientists rely on engineers because they need advanced instruments and computers for their work. Science is not the knowledge codified in an encyclopedia, although scientists know a lot of facts.

Science is a procedure for converting observations into "understanding", or more precisely into general rules about what will be observed given certain conditions. Such conditions can be brought about in an experiment. For example, take a pot of water with a tight lid on it and heat it. The lid will be lifted and vapor will escape to make steam. Or freeze a can of chicken soup: it will burst. Finding out why this is so, and predicting when it will occur, is a matter of physical science. The same principles governing the steam-producing pot are found again when studying clouds and storms. The principles governing bursting-upon-freezing explain why ice floats.

Thus, by extracting rules from some observations, we can "explain" or "predict" seemingly unrelated different observations. Making up sets of rules is called "generating hypotheses." Scientists love to do this because if a hypothesis survives a lot of challenges it becomes accepted theory, and if it is important, the scientist who invented it looks sharp. Scientists spend much of their time testing hypotheses, that is, they try to shoot down sets of rules, preferably rules that have been invented by others. Some theories are fundamental to a whole network of hypotheses. If your team can show that this theory is wrong, you have just won the Super Bowl!

Here are some examples of successful science:

The hypothesis that the seafloor renews itself all the time (Harry Hess, 1962) could readily be falsified if we found rocks older than 200 million years on the deep-sea floor. More than a thousand holes were drilled since Hess suggested this, and no one ever found anything older than about 150 million years. Good guess.
The hypothesis that mammoths and rhinos died out in Eurasia with the advent of the Great Ice Age (Louis Agassiz, 1866) was disproved when it was shown that the extinction occurred at the end rather than at the onset of the ice ages in the northern hemisphere. Tough luck.
The hypothesis that Mars is inhabited (Percival Lowell, 1908) was shown to be highly unlikely when it was discovered that Mars has a very thin atmosphere, and was made untenable by the close-up pictures of the Mariner and Viking spacecraft in the 1960s and 1970s, showing that the structures Lowell had seen were natural features, not artificial ones. Nice try, but no cigar.
The hypothesis that the Moon was once torn from Earth (suggested by George Darwin, son of Charles) was out of favor but received support from the finding, based on direct sampling by the Apollo 11 mission (1969), that rocks from the Moon are much like those in Earth's mantle. Hmmm; could be true after all; perhaps a collision was responsible (proposed by William Hartmann in 1974).

Some theories have proved their worth and have survived all attacks for a long time. No one attempts to disprove them anymore because this would be a waste of time. Examples for such theories are that matter is made of atoms, that color is tied to the wavelength of light, that people and apes have common ancestors, that adding carbon dioxide and methane to the atmosphere produces warming, that continents move at a rate of about an inch a year and that the sun is a nuclear furnace converting hydrogen into helium (as do most other stars). These theories, in sequence, were invented 2000 years ago, 350 years ago, 150 years ago, 100 years ago, 80 years ago and 60 years ago. They have become fundamental to doing science. Saying that any one of these things is not so will not identify you as a skeptic (worth listening to), but as one who has missed class (worth ignoring).

In summary, "science" is about making conjectures to explain what we observe, and demolishing as many conjectures as possible while obtaining ever better explanations. Although scientists have "opinions" in their field of expertise, these are founded on observation and theory rather than on "belief", and they remain open to challenge. Traditional "belief", which is the certain knowledge that something is just so, based on being told when young or based on special individual insight, remains important in human affairs and cannot be replaced by science. Such belief allows us to live together as civilized beings. Ethical behavior, for example, is largely a result of belief rather than of science: Observation tells us that the sun shines equally upon the just and the unjust, so a preference for being just must come from ethical principles rather than from scientific analysis.