After reading that lamp ghosts really exist, I of course had to try for myself. Not having an old lamp, I just tried to rub some electric lamp at home, and to my great surprise, indeed immediately a ghost appeared.
Before I could recover from my surprise, the ghost started to talk with a quite angry voice:
"Can't you humans just stop rubbing lamps? Here I thought if I live in an electric lamp, I'm safe, but no way, only five years, and you rub it. Okay, the rules say I now have to fulfil your wishes, well at least those I can fulfil, but I warn you: I'm completely free to fulfil your wishes however I want, and I can assure you, I will do so in a way that you will wish you had never wished it. So don't bother me with your wishes, or you will regret it."
After a moment I recovered from my surprise, and my mind focused on the words: "at least those I can fulfil" — so he could not fulfil just any wish. Thus I asked: "So what type of wishes can't you fulfil?"
"Why do you think I will tell you that?" the ghost replied.
In a momentary inspiration, I answered: "Because I wish that you do!"
Indeed, the ghost now started to tell me which wishes he can't grant. However, as he had predicted, I indeed soon regretted that wish, because he explained it in such detail and in such an long-winded and complicated way that his explanations lasted a full day, including the night (well, I naturally cannot tell for sure whether the ghost also continued speaking while I was sleeping; he might have waited in order to have more to say when I'm waking up again, but he might also have told some crucial information while I was sleeping, so that I would not know it). For example, he required several hours just to explain, in excruciating detail, that he can't change the past.
OK, here are the rules, as far as I understood them:
- The ghost can only change the future, and only give information about the past (in other words, no causality violation). Future and past are defined relativistically, therefore wishes requiring faster-than-light are also not allowed.
- The only law of nature that can be broken by fulfilling the wish is the second law of thermodynamics.
- In case of wishes having contradicting effects, earlier wishes take precedence over later wishes. So for example, if I wish to live forever, and then later wish to die, then the second wish cannot be fulfilled because it would contradict the first one. However if the wish only undoes the effects of a previous wish without contradicting it, then the wish can and will be granted. For example, if I wish to have a gold bar, and then later wish to no longer have a gold bar, that's no contradiction, and I'll get rid of the gold bar.
- Everything I explicitly specify in a wish will happen as I specified, however if there's any ambiguity in my formulation, the ghost will be free to choose the interpretation it likes most (which of course will be the interpretation I'll like least).
- Everything I didn't explicitly specify in my wish is up to the ghost to decide. However he cannot do anything unrelated to my wish. So for example, if I wish for a gold bar, he may arrange that the gold bar falls on my head and kills me, but he can't arrange that the gold bar is covered with contact poison.
- Wishes about wishes are forbidden (so I can't simply wish that all my wishes are fulfilled the way I mean them).
So surely the safest thing would be to not wish anything. However there are a few things I'd really like to have (just the usual, guaranteed health for the rest of my life, always having enough money, that type of stuff).
So I'd like to know: How can I wish in a way that I'm sure there will be no negative consequences?