Since moving to Alberta and having young kids, I've learned so much about dinosaurs. It helps having my lab space down the hall from famous paleontologist, Dr. Philip Currie and paleobotanist, Dr. Eva Koppelhus. Walking around the UAlberta campus, you can't ignore the numerous pieces of scientific evidence collected to build theories that increase our understanding and knowledge of prehistoric life and ecosystems. I guess what's left me dissatisfied with these theories, is that by being related to prehistoric life, there is no way to prove the theories, nor is there any way to disprove them. We can't, for example, time travel back to confirm Philip Currie's famous theory that tyrannosaurs were social creatures. Hey, now. Be careful what you say. In science, there is no such thing as just a theory. A theory isn't just a guess. It is a general explanation of the available scientific evidence. To be considered a scientific theory, they must be based on an accumulation of scientific evidence. Theories are created from multiple pieces of evidence, and can't be based on a single event or observation. For example, Philip Currie's theory of social interactions between tyrannosaurs is supported by a body of evidence, not just a single observation or event. Scientific theories packaged scientific evidence or systematic observations into an easy to understand explanation. A good theory will account for all the evidence available, not just the evidence that supports it. A theory that is just based on confirmatory evidence and that ignores refuting evidence, would be considered biased and would not be considered scientifically useful for generating predictions. So a biased theory is not "Just a theory," it's an opinion because it's not accounting for all of the available evidence. A good theory will create good hypotheses. When we have a cohesive story that explains all of the available evidence, then we can make predictions or hypotheses about future observations or related phenomena. Scientists aim to build theories based off systematically collected evidence. But what guides the collection of evidence is the generation of hypotheses. Because a theory is only as strong as the evidence that supports it, to weaken the theory, we need evidence that disproves it. Strong theories can withstand disproof. In science, hypotheses are predictions that are generated to test a theory, and in effect, disprove a theory. Based on the track ways discovered by other paleontologists, let's look at Currie's theory that tyrannosaurs were social. If I want to disprove Dr. Currie's theory about the social nature of tyrannosaurus, I can't just call it just a theory to weaken it. I need to generate hypotheses to disprove it. The beauty of the process of Science is that theory building is a dialogue of evidence and systematic observations. Because a theory explains multiple pieces of evidence and cannot be based on a single event or observation. So even though the theory, as we have discussed it, rests on this single track way site of three tyrannosaurs walking in the same direction, there are multiple other observations that also support this theory, like tyrannosaur bone beds that contain the remains of many individuals of mixed ages suggesting that they died and possibly lived together in larger groups, and that many social behaviors may have been common in tyrannosaurs, like the famous T-Rex. It is important to note that there is no threshold for evidence to support a theory. No amount of evidence will ever be sufficient to prove a theory. In science, we don't talk about evidence as proof or fact. Evidence may support or refute a theory and based on the evidence available, we can evaluate it to update, reject, or accept a theory. The accumulation of evidence that aligns to tell the same story, and absence of refuting evidence to disprove it, would give us an increased confidence in the accuracy of the theory. Theories are more than just guesses. They are a general explanation of the available evidence. Therefore, a theory can be overturned based off new evidence. Because a theory is built based off a body of evidence. Multiple observations stemming from multiple tests of different hypotheses are needed to form a theory. A theory cannot be based on a single event or observation, it must be based on multiple observations. A strong theory has no evidence against it, but a strong theory will never be proven because there is no threshold of evidence needed to prove a theory. So we accept theories until we see evidence against them. This is why it is so important for scientists to keep an open mind towards new observations as they may be useful to support or refute theories, or general explanations of accumulated knowledge in the field.