Einstein
Temporal Engineer
Well, as long as Einstein had "how old are you" question in mind 101%, and assuming him and The Observer are not playing a game on all of us
Then either The Observer is either a Time Traveler or a Mind Reader (assuming that Einstein is indeed 42)
There is no other explanation and I don't buy the theory that he "guessed it".
@ Einstein, I fail to spot any surprise or WTF expression from you (again apologies, as I did not read all the pages of the thread) on how he came up with 42 (and I'm assuming that is your real age).
Peace
It was a test for time travelers to pass with ease. Since it requires the use of a time machine to pass the test. He answered my question before I posted the question. I did ask him to answer the question I haven't asked him yet. But the number he replied with was what I assumed to be his age. My age is a bit older than that. However I was surprised. Since I fully expected no one to ever pass the test.