What really exists today and what is definitely fake?

First of all, we know very little. Paradoxically the more we know the more we realize we don’t know. Every new scientific discovery produces far more questions than it answers. Einstein observed that as our sphere of knowledge grows so does the circumference of ignorance. To me it comes down to what is reasonable to believe and what is unreasonable? Vikings and Pirates are reasonable things to believe in; they do not violate any law of physics or logic in order to exist. Ghosts and poltergeists are not reasonable to believe in because their existence is not reasonable. If it turns out that Vikings and Pirates were just stories and that there is some yet undiscovered force that allows for ghosts and poltergeists than I may be mistaken but based on what we know today I’ll go with Vikings and Pirates and discount ghosts and poltergeists. There are things that fall between these extremes. Extraterrestrial visitors may exist. We do not have the technology to visit other star systems but such technology is foreseeable. We also do not know how common life is in our galaxy. If and advanced civilization of intelligent life exists on a nearby star system they may have decided to commit vast resources to visit other living planets but if life is very rare than the odds of visitors being close enough to visit us would also be very unlikely. So this would be possible but rather unlikely. Bigfoots may exist; it seems like we would have compelling evidence if they did like a captured live specimen or at least some remains of a dead bigfoot but there is a slight possibility that a large undiscovered primate may lurk in our woods. There are also things that have an element of truth to them but are mostly false. There are no vampires but there was a rather nasty man called Vlad Dracul or Vlad the Impaler who tortured thousands of people by impaling them on spikes. The Dracula story is fiction but it was based on a real person. Ockham and Hume gave us some very good ways to determine what things we should tentatively accept as real. Ockham’s Razor said that the simplest explanation that explains all observed data is the best one. Is it more likely that ghosts exist or that people who see them have overactive imaginations? The former is impossible by physical and logical laws but the later certainly isn’t. Hume said that no testimony is sufficient to explain a miracle unless the testimony is so compelling that its falsehood would be more miraculous than its truth. In other words, the more extraordinary a claim the more evidence is required to establish it. Hume also observed that when presented with new phenomena that it is more likely to be like something we already observed than something entirely new. When I was a lad scientists believed that tidal forces caused the same side of Mercury to face the sun all the time much like the same side of the Moon always faces the Earth due to tidal forces. Now we know that isn’t true though its day is 2/3’s as long as its year. No doubt there are many things we accept today that will be shown incorrect in the future.