2. Asking good scientific questions

“When it is not clear under which law of nature an effect or class of effect belongs, we try to fill this gap by means of a guess. Such guesses have been given the name conjectures or hypotheses.” Hans Christian Ørsted.

    The scientific method revolves around the formulation of an initial hypothesis. In some of the labs described in this manual, and to different extents, each group will be free to formulate its own question (which should of course be somewhat related to the topic of the lab). So how can we think up of good hypotheses?

    First of all, what is exactly a hypothesis? The dictionary tells us that it is “a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation”. In the context of the scientific method, a hypothesis is an “educated guess” made to explain a (usually not yet understood) natural phenomenon.

    A good scientific question should be asked in relation to a context, in other words there should be a motivation for asking the question. “Educated guess” means that the hypothesis should be at least partially based on currently available evidence. Therefore the more familiar you are with a topic, the easier it will be to ask pertinent questions and to formulate good hypotheses.

    Another important aspect is that a good scientific hypothesis should be falsifiable, meaning that it is possible to prove or disprove it (compare: “The frequency of a pendulum is independent from its initial velocity” and “God exists”). In practice, a good hypothesis is one that you can prove or disprove using the equipment at your disposal and the time allotted for your experiment.

    The best hypotheses can lead to quantitative predictions, meaning that you will not just be looking for trends in your observations, but for a quantitative agreement between your data and the predictions deriving from your hypothesis. For example, compare: “The frequency of a pendulum increases with the length of the pendulum” and “The period of a pendulum,  , is proportional to the square-root of , with . Both predictions are correct, but the second is much more interesting, because it is a test of Newton’s second law, and can lead to a measurement of the gravitational constant .

     Finally, a good hypothesis should follow the principle of parsimony, meaning that it should be short and to the point.