A conversation with one of my students got me to thinking about how science is done and the distinction of the ‘Theory’. Time and again this idea comes into question because the layman’s definition of a theory is very different from the one used in science.
There are a large number of deifinitions of ‘Theory’, but I think that the one that most people have in their heads is this: “an unproved assumption.” I tend to favor one more like this: “a working hypothesis that is considered probable based on experimental evidence or factual or conceptual analysis and is accepted as a basis for experimentation,” however, even this suggests much less conviction than a scientist would mean when they used the word. Personally, I think the inclusion of the word ‘hypothesis’ reveals this because this is something altogether different in the vocabulary of a scientist.
Webster again: Hypothesis – “a proposition tentatively assumed in order to draw out its logical or empirical consequences and test its consistency with facts that are known or may be determined.”
A working example of how these two terms relate…
The Germ Theory states that some micro-organisms cause some diseases. Someone working on Germ Theory may have a hypothesis that some microorganism ‘X’ causes disease ‘Y’. Germ theory is the overarching idea of organisms causing disease (fairly well established), the hypothesis is that ‘X’ causes ‘Y’.
This is a nice example, because there is a well-known series of experiments that outline what steps to take to test if this hypothesis is supported. Robert Koch (http://en.wikipedia.org/wiki/Robert_Koch) outlines these in the 19th century and they keep his name, Koch’s postulates.
These postulates state that to establish that an organism is the cause of a disease, it must be:
- found in all cases of the disease examined, while absent in healthy organisms
- prepared and maintained in a pure culture
- capable of producing the original infection, even after several generations in culture
- retrievable from an inoculated animal and cultured again.
If all of these hold, then we say that this hypothesis has support.
Another hypothesis that has been under investigation lately is how the existence of the Higgs Boson could provide more support for the Standard Model (part of The Atomic Theory). Recent News of this has been reported on BBC at : http://www.bbc.co.uk/news/science-environment-21785205. The AAAS provides this chart (you can think of it as the Periodic Table for elementary particles):
How does this ‘test’ anything? Basically, the Higgs Boson is required in order for the standard model to be correct, i.e. it predicts the existence of this particle.
The hypothesis is that this particle exists as predicted, the Theory is the larger structure that encapsulates this hypothesis.
Altogether, the workings of the Higgs Boson/ Higgs Field underlies our conception of why atoms have mass. Although there is more to it, this also leads to a somewhat better idea of why there is gravity (another Theory).
Oh, and ‘Fact’. That doesn’t really exist. Maybe mathematics…?