Maybe a science knowledge is a fact ,so it is truth. However science always change ,not only science ,the whole world always change .In the changeable world ,truth is not always the only truth! When scientists believe sun is hot in this time,people will believe it .And it is the truth on this world .
We view perceive things with our minds thanks to our 5 sense. Our brains then create a "reality" based on these representations of the actual "real" world. Im saying that everything is virtual to us, like a virtual reality game, its not real but a representation of real life.
Therefore, truth is what we perceive, despite it being possible and likely being a false image of the "real" world. Hence... A lie is nothing more than the new truth due to the new perception we created due to our every changing perceptions. Number of people don't matter it depends on whose truth it matters to. Lol?
Take as an example someone suddenly saying that the Earth is a cube. Now, lets say that 61% of the world agrees. That 61% cannot change that lie into a truth, because the Earth has been proven to be spherical. Truths are based on facts, and facts are what something definitely is or isn't. In the case of a cube Earth, facts prove that the 39% of people are telling the truth and that the 61% are lying.
(A historical example can be garnered from the Geocentric and Heliocentric Theories.)
A lie is a lie unless confirmed by truth, in which case it becomes fact.
If enough people believe we can shoot lasers from our feet, can we? No, no we can't. Or how about a lie most people believe, like video games make you violent (large amounts and comparable) if you think they make people violent, will they? Lies can be seen as the truth, but will never be the truth
Even if tons of people believe in a lie, like religion or secular humanism, it doesn't make it so. Most people do, however, believe in lies. Most of these lies, like the ones propagated by people who believe in God or those tho are secular humanists are liars, and noone needs to believe their nonsensical lies that they spout.
Of course, the fact that there is no solid evidence does not necessarily guarantee something is not true, but it also works the other way around; the simple fact is that believing something cannot change what actually happened. For example, if someone had committed a crime, but there was no evidence and he was presumed innocent, does that mean the crime will revert itself? No; belief is strong, but not nearly enough so to change what really is.