A theory is an explanation, or a testable model, capable of predicting occurrences and can be tested or otherwise falsified through observation.
There are some things in this world that are classed as a theory. Evolution is not a proven fact and is therefore classed as theory, as is the Big Bang, gravity and whatever Einstein was talking about with his E=MC2 thing.
Also just a theory is the idea that the citizens of Russia are today going to vote for a new President as Vldaimir Putin steps down to cool his heels as Prime Minister.
What we all know is that there is only one ticket in town and he goes by the name of Putins bestest buddy, Dmitry Medvedev.
The 42-year-old Prime Minister is up against the leader of the Communist party, Gennady Zyuganov, and the leader of Liberal Democrats, Vladimir Zhirinovsky. Making up the ballot paper is ultra nationalist, Vladimir Zhirinovsky who recently suggested that Condoleezza Rice should be taken to an army barracks and given a "good pleasuring". Each has as much chance of succeeding as i have of looking out my window and seeing a flying pig silhouetted against a blue moon.
So what can we expect from the new Russian leader as he slips behind the desk marked 'President' in the Kremlin?
Not much change from what Putin got up to actually judging by the Election posters that have portrayed the pair side-by-side with the slogan "Together we will win".
With Putin the 2nd most powerful official in Russia, we can expect Medvedev to be having his strings pulled with all the frequency of a second hand thunderbird puppet.
The UK Prime Minister, Gordon Brown who was handpicked by his successor and rose to take power without an election, will be keeping his head down on this one then.