Octavius, you only �believe� that humans can�t see them. You don�t �know� that, and yet you don�t consider it possible. Your little attempt at ridicule (or was it a joke?) just about sums it up. Because this is something that you, personally, have no experience of, it is beyond your comprehension. Bearing in mind that millions of people claim to have seen ghosts, coming to such a definite, and unsubstantiated, conclusion, is not only offensive - it�s illogical. What you are saying, in effect, is that you know the truth - ghosts and spirits exist - but each and every person who claims to have seen them is either delusional, or they�re idiots, or they�re telling lies. Those who claim that the reason science hasn�t provided us with �visualisation� yet is because they simply aren�t there, assumes they know the truth also, but they don�t. Like you, they have no personal experience to call upon, and so it is a naive and ignorant assumption. No doubt science will provide us with many answers in the future - and it will provide us with answers to such complex questions that we, at this present time, cannot even begin to imagine will surface.
Keyplus, as I�ve said many times, I don�t believe spirits or ghosts or whatever you want to call them have any connection to religion, but have everything to do with nature. It�s true, science does have a long way to go - but it has progressed up until now, and it will continue to do so in the future.