I recently read a book by Martin Rees, "On the future". I found it an agile small book packed full with wisdom and interesting considerations on what's in the plate for humanity in the coming decades, centuries, millennia, billions of years. And I agree with much of what he wrote in it, finding also coincidental views on topics I had built my own judgement independently in the past.

One of the things Rees notices is that life in the cosmos is probably overwhelmingly "electronic", as he writes - or as I would put it, artificial, although I understand his wording is more descriptive than mine in a sense. This realization came to me quite naturally, by pondering on the logical necessity for advanced civilizations to produce general artificial intelligence, and on the intrinsic robustness of artificial life to withstand interplanetary travel, extinction-level events, and eternal boredom (Rees himself can't help quoting Woody Allen on eternity, "it is quite long, especially toward the end".)

The other thing I can't help mentioning here, among many others which find me looking eye to eye with the astronomer (perhaps we need binoculars then?) is the fact that the big bang is quite likely not unique in the history of the Universe (where by capital U I mean to point at "everything anywhere anytime"). 

Why, I have built my understanding of Physics in the certainty of the validity of the totalitarian principle, the one which states that in nature "everything that is not forbidden is compulsory". That principle is a great way to describe the necessity of physical phenomena in the absence of conservation laws forbidding them to take place. I do believe that principle has no exception, so the blatant evidence of the big bang which created the universe we live in (lowercase u) is enough evidence for me to prove that universes must be commonplace - and commontime - in the Universe.

If you think that the above is not good science you may be right. We lack falsifiability, and we are speculating without a chance of finding one nice day a speck of evidence. Still, I find this realization of great significance. Rees in his book mentions a question posed to astronomers - at what level do you place your belief in the multiverse: would you bet your goldfish on it, or would you be willing to bet your dog, or would you go all in and bet your life on it? 

Rees report that when the question was posed he declared he was willing to bet his dog, and Andrei Linde was almost going to bet his own life on the existence of the multiverse. And Steven Hawking said he was glad to bet both Rees' dog and Linde's life on the matter. As for me, I think I would not bet my dog on it, I love him too much, but I find the betting game a bit silly, as odds should not be measured with the amount one is ready to put on the plate: besides the different value we subjectively give to goldfish and dogs, it is rather a matter of conviction, regardless of one's betting prudency.

I believe the multiverse exists, and although its existence is probably irrelevant to our lives, and even more likely untestable by physical experiment, I find it a fascinating realization, perhaps even deeper than the other grand question, the one on the existence of free will. Which leads me to ask myself another poignant question: if I were given the chance of knowing the truth on one single question that can be answered by a simple yes or no, what would that question be?

I am torn. I think I would love to have a definite answer on the free will issue, but perhaps its answer would affect me too much. So I think I would go with the following: "Does the same universe, defined as all that there is which is observable, exist in more than one copy in spacetime?". As ill-defined as this question may be, I trust that it would be met with sufficient benevolence to produce a meaningful answer, whatever happened to be the all-knowing entity it is posed to. I would also count that entity to accept that by "copy" we could agree to mean "indistinguishable by experimental means". 

Now let us consider what Yes and No to the above question would mean, along with similar answers to the "do humans possess free will?" question. If there is, there has ever been, and there will ever be only one universe like this one, and if there is free will, then the burden on us humans is the biggest - we can't find consolation in the chance of living again our lives, somewhere, sometime; and our future depends on our actions, which is also an unforgiving thought. On the other extreme, if there are multiple copies of our universe, and if we have no free will, we can completely relax. In-between are situations we could also feel good about: no free will but a guarantee of living an infinite number of times the same existence would be quite acceptable. And a single universe to live in, ever, but without free will, means we can sit back and enjoy this one ride, knowing there is no way we can screw it up.

In the comments thread I will be happy to read your own formulation of a grand question. Remember, it must be one with a yes or no answer.