Okay so just to be straight up with you guys, the ghosts/black holes comparison was a mite disingenuous. You can't recreate a black hole in a lab - that much is for sure - but that doesn't necessarily make their existence as dubious as ghosts, since if a scientist told you to look at the place they saw a black hole, it would probably still be there.
Ghosts don't hold up to the same repeatable conditions, but let's not totally side with those skeptical boffins. They're still not perfect by any stretch. After all, whilst many are convinced that ghosts aren't real, none of them can agree on why exactly so many people are convinced otherwise.
In 1813 physician John Ferriar wrote An Essay Towards A Theory Of Apparitions, where he put forward his idea of ghost sightings as simply optical illusions. Okay, sure, we can buy that. Plus it's a physician telling us this, he's all qualified and stuff, so he must know what he's on about. Except since Ferriar there have been many, many more researchers interested in explaining the paranormal, and almost all of them have disagreed with each other.
Alexandre Jacques François Brière de Boismont (owner of the Frenchest name in existence) claimed so-called spirits were hallucinations, chemist David Turner suggested they may be examples of ball lightning, Joe Nickell reckons they've something to do with the limits of human perception, and IT lecturer Vic Tandy puts poltergeist activity down to humans not being able to process the low-frequency hum of air conditioners properly.
So what does all that tell you? That the scientific community is more divided when it comes to what causes people to experience hauntings than it is about...well, anything, really. Nobody can make up their mind as to a scientific explanation of ghosts, because proving the non-existence of something is hella difficult. And douchey, as we said before. We may not have concrete evidence for the existence of the supernatural, but they have no evidence to the contrary, either. Ha!