Douglas Adams wrote "The Hitchhikers Guide to the Galaxy" and included in it that the answer to Life, the Universe and Everything is "42." It turns out that like most artists, he created something he didn't understand fully. He thought he picked "42" on a whim. Head over to Wikipedia's entry about 42 for more information about the history of it.
I like the notion that the answer and the question cannot be known simultaneously, because then the "normal" Universe will be replaced by something even more strange. Indeed, as we learn more, we find how much we don't know, and the Universe does become more and more strange. The clockwork "Music of the Spheres" has been replaced by uncertainty.
Why is "42" the answer? It is quite literally because 6x7=42. 6 carries the meaning of imperfection or tearing down and 7 carries the meaning of perfection or completion. Yin and Yang. Irresistible force meets immovable object. The Universe is full of stuff crashing together and getting more complex. In many processes, some sort of exchange occurs and a little bit of "new" stuff is left over. In the earliest stars, hydrogen got "burned" into helium, but as the star aged and died, some of this stuff got converted into heavier elements. Not much; just a tiny percent. The "frothy" bit: matter that got trapped between the irresistible force of the supernova and the immovable object of the bulk of the star. But this little bit of stellar "ash" is enough to make all the non-star stuff we see around us: planets, water, dirt, air, plants, animals, even to the last bit of "ash" we perceive: our own consciousness.
The first proto-cells formed along the frothy margin of water and clay beds. Our own intelligence likely evolved because we had a very frothy battle for survival; recent research indicates that at one time as few as 2000 people had survived various climate, habitat and competition pressures. We ourselves mature when we abide in the place of our immovable preconceptions getting hammered by our irresistible desire to understand. You see some of the most chaotic (frothy) behavior in people who don't understand yet they are causing their own effects. Their desire to grow is just going to keep putting them in situations of opportunity until they discover their lesson.
So that's the product of 6 and 7: a shower of sparks and ash, resulting in everything we see, everything we know, and everything we wish to become.
Douglas Admas might have picked it because "42 will do," but the truth is he really did stumble upon the Ultimate Answer.