Not that I agree with the Troll AC that began this, but you are confusing 'Hypothesis" and "Fact". According to the Oxford English Dictionary, a "fact" does in fact need to be true and/or correct. A "hypothesis" is a statement that can be tested to determine Fact or Fiction. "Opinion", however, is a statement that cannot be tested since it based upon one's personal view or beliefs.
n. 1. a thing that is known to have occurred, to exist, or to be true. 2. a datum of experience (often foll. by an explanatory clause or phrase : the fact that fire burns; the fact of my having seen them). 3. (usu. in pl.) an item of verified information; a piece of evidence. 4. truth, reality. 5. a thing assumed as the basis for argument or inference.
n. (pl. hypotheses) 1 a proposition made as a basis for reasoning, without the assumption of its truth. 2. a supposition made as a starting-point for further investigation from known facts (cf. THEORY). 3. a groundless assumption.
n. 1. a belief or assessment based on grounds short of proof. 2. a view held as probable. 3. (often foll. by on) what one thinks about a particular topic or question (my opinion on capital punishment). 4. a a formal statement of professional advice (will get a second opinion). b Law a formal statement of reasons for a judgement given. 5. an estimation (had a low opinion of it).