According to Science it won't.
Mr. Camping, who seems a perfectly pleasant but perhaps rather confused figure, is probably no different from many other people who begin to believe impossible things- and by no means all of them are senile.
What IS different is the media attention- after all from the media perspective, the end of the world is a pretty big story, although Mr. Camping is probably receiving rather less attention than the sale of Princess Beatrice of York's wedding hat. So I guess that means that Mr. Camping is not widely believed.
What I feel a sad about is that the large amount of money being spent promoting this fairy story is not only essentially wasted money, it is also going to discredit still further organised religion in general. Yet there are some great moral truths which can be found amongst the Hebrew myths and the general smiting of the Bible. The Sermon on the Mount is one of the great moral manifestos ever conceived, the Decalogue of Moses is as clear a set of rules to live by as may be found anywhere.
However this most profound morality is being held up to ridicule by an old man with something of a screw loose. Instead of a sophisticated morality, religion is turned into a laughing stock because Mr. Camping, like so many, sees only the sensationalist myths of the Book of Revelation, which in any event is a highly symbolic chapter, and one that has been subject to wildly different interpretation and dispute over the centuries.
Science, provable and exact in boundary if not in all details, has increasingly addressed issues that the Bible purports to explain, and in many issues it is giving us a far greater insight into our Universe and ourselves. Yet Science and Religion are not equivalent protagonists, as many divines and media commentators might have you think. Religion seeks for a core of truth, but at its heart it makes a leap of faith- that there are things we must take on trust, but if we do so, then we arrive a profound truth and a great certainty. Science does not do this- it proceeds with scepticism and thus seeks to improve knowledge by understanding uncertainty. Religion therefore is certain but Science is uncertain.
This certainty has been the cause of much human suffering- but it is not my place here to condemn such crimes as the Inquisition or the Crusades. It is simply to note that Mr. Camping comes from a long line of millenarian nonsense. I suppose we should just be grateful that he is only wasting money in promoting his certainty- after all many times in the past it has been a price of lives that has been paid.
Of course Science may admit the theoretical possibility that they could be wrong and Mr. Camping, in defiance of all we currently understand about the Universe, is right. However, I do not think that Mr. Camping will return the compliment, at least not until after Sunday. So in the overwhelmingly likely event that we awake on just another normal Sunday the day after Mr. Camping's non-apocalypse, I guess it will be another victory for Science.
Though Mr. Camping may then deserve much ridicule, Science will be able to explain the breakdown in his faculties that enabled him to spout such silliness in the first place. Indeed perhaps we should then probably simply show sympathy for a baffled and confused old man.