I just finished my second time reading Harry Potter, all seven books in a row.  Just like the first time, it was … magic.  The images of the novel were invoked so vividly, so truly, that afterwards it feels as if I’ve been there and witnessed it all, either under a cover of the invisibility cloak or from a dive into Dumbledore’s Pensieve.  I only wish it all was real, I wish it lasted longer, but the last book is finished and closed, while I remain where I am – a poor Muggle, locked in Muggle’s Azkaban. 

 
 
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We have discussed introduction, optics and acoustics of ghostly manifestations, smells and touch/punch. Here are a few subjects which I haven't touched yet about ghosts.

Sometimes ghosts interact with the living, but sometimes they appear unaware of present day observers. They may come in groups wearing old-fashioned outfits. They also can appear with antiquated technical means, like a man riding a penny-farthing bicycle.

Extreme case one: someone gets a witness of a large event (baseball match) in a place where the stadium used to be seventy years ago. The crowds of oddly dressed people are cheering from the bleachers; they do not pay any attention to the intruders from the future: who cares when it’s a perfect home run!?


 
 
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We have discussed optic, acoustic and, to some extent olfactory manifestations of ghosts, but, as we all know, ghosts also can do things. They can touch you, they can flick a light switch in your room, they can cut you with a razor blade, they can toss a VCR into your head. There are numerous witnesses of such interactions, from a light breeze to a murder by a poltergeist. How can that be possible?We started with the notion that upon their manifestations ghosts absorb energy. I daresay that this absorption of energy can be substantial for a quite brutal demonstration of force, when air gets down more than just a few digits of centigrade and this might be just a side effect. Ghosts also are capable to absorb electrical energy