What is a theory?
In science, a theory is not the same as a guess or a hunch. A theory is an explanation of how the world works, based on facts – the results of numerous observations, experiments and calculations. A theory can, and should, constantly be tested. If new findings are not compatible with an existing theory, then the theory should be refined. Over time, as scientists all over the world gather more evidence and challenge an existing theory, the theory becomes stronger and provides more accurate explanations. But theories do more than that. They also allow us to make predictions of what we should observe if a theory is true.
A great example of a theory that has grown really solid is the Theory of Evolution. Since Darwin first presented the theory in 1859, it has been tested over and over again, using improved techniques and knowledge from a range of disciplines, and an enormous amount of scientific evidence has been gathered. We now know that Darwin was right in many ways, and wrong in some cases. The improved theory can explain how Life has evolved – and keeps evolving – and it has inspired use in a number of other fields such as medicine development and advanced computer programming.
The scientific method
Science starts with a question. Questions can range from being concrete and well-defined (“Which molecule can block a G protein-coupled receptor in the cell membrane?”) to really big and abstract (“How did Life begin?”). The next step is to form a hypothesis, and idea of what the answer might be. The important thing about a hypothesis is that can be tested. To do this, you come up with experiments to test your hypothesis. The results of these experiments lead to conclusions that can either confirm your hypothesis, or contradict it. You must be prepared to make changes to your hypothesis, based on what you find. Quite often, your results will make you think of new questions, which can lead to new discoveries! Doing science is almost never a straight line from idea to conclusions.
This could for example mean understanding a certain chemical reaction. Which molecules are formed when certain chemicals are mixed? Under which conditions (temperature, pH etc) does the reaction take place? Which properties of these molecules are crucial for the reaction to take place? Building an understanding around these things opens new questions and possibilities. Can we make the reaction take place faster by altering the conditions? Can we make a similar reaction happen, that results in new molecules that are useful in some way?
It is also very important for scientists to interact with other scientists. By discussing each other’s work and trying to repeat each other’s experiments, scientists help make sure that the results are valid and interpreted correctly.