Sunday, December 07, 2008

God or multiverse?

I do not want to predict the future. I once predicted my own future. I had a very firm prediction. I knew that I was going to die in the hospital at the Academy of Sciences in Moscow near where I worked. I would go there for all my physical examinations. Once, when I had an ulcer, I was lying there in bed, thinking I knew this was the place where I was going to die. Why? Because I knew I would always be living in Russia. Moscow was the only place in Russia where I could do physics. This was the only hospital for the Academy of Sciences, and so on. It was quite completely predictable.

Then I ended up in the United States. On one of my returns to Moscow, I looked at this hospital at the Academy of Sciences, and it was in ruins. There was a tree growing from the roof. And I looked at it and I thought, What can you predict? What can you know about the future?
(Andrei Linde).

Discover magazine has an interesting article by Tim Folger on the anthropic principle and the multiverse hypothesis. The article raises two important questions, the first of which concerns the power of scientific methodology to confirm the existence of other universes:

1) If you have a theory which explains the nature of our universe, and which entails, as a by-product, the existence of other universes, and if such a theory makes a prediction about our universe which is subsequently confirmed by observation or experiment, and if there is no other theory available with the same explanatory and predictive power, then does this constitute indirect evidence for the existence of those other universes? In other words, even if one cannot directly confirm the existence of other universes, does the confirmation of a theory which predicts other universes constitute indirect confirmation of the multiverse hypothesis?

The second question concerns the purported choice between God or a multiverse:

2) If there is no theory with explanatory and predictive power which entails that our life-permitting universe is the only logically possible universe, then is there a rational choice between the existence of a multiverse, in which all types of universe exist, or the selection and creation of our universe by a supernatural deity? What rational method could be employed to make such a choice?

The second question here presents something of a false dichotomy. One could, alternatively, accept the provisional inadequacy of our theoretical capability, but not abandon the notion that our universe is the only logically possible universe. One could also alternatively suggest that our universe was selected and created, not by a supernatural deity in the sense described within religious scripture, but by a non-supernatural intelligent being within another universe. One could suggest that our universe is a program running on a computer in another universe, or that our universe was created in a laboratory within another universe. These latter options are special types of multiverse hypothesis because they require the existence of other universes in which the creating agency exists, but they do have the novelty of combining the multiverse hypothesis with the notion that our universe was created by conscious choice, (although that itself is a special type of physical process).


Anonymous said...

The simulation and experiment theories strike me as silly, because you've just swished the dirt around, replacing "why does our Universe exist and have self-aware life" with "why does that other Universe exist and have self-aware life". I fail to see the improvement.

Gordon McCabe said...

Theories which are true are generally considered to be better than theories which are false, hence if our universe actually was created by an intelligent agency in another universe, then a theory which incorporates that fact would be better than one which suggests otherwise.

However, it's certainly true that such an explanation begs for a further explanation of how the other universe exists. Ultimately, you either have an infinite regress, or at some point you reach something whose existence is logically necessary.

For example, one could adopt Max Tegmark's proposal that all mathematical structures physically exist. There is, one can propose, only one type of existence: absence of contradiction. What we deem the physical universe is simply one particular mathematical structure, which exists by virtue of being free from contradiction. All other mathematical structures exist, but only those containing cognitive self-aware substructures possess observers capable of asking what the mathematical structure of their universe is.

passer by said...

goodness me, this is a hard blog to follow...ill have another glass of Sunday lunch wine and give it a go!

.........Teg person fella, sounds right to me, from what I know about set theory (very little) we don't just have infinite's, but infinite's, infinite's, therefore Math is giving us a good guide to probability, regardless of what the physics says or believes.

I suspect that out of absolute chaos comes certain order, by which I mean if I had a million dice, and had infinite throws and time, i can guarantee that at some point i will throw a straight million, million sixes, straight off the bat, its certain, it has to be.

Given that, in a years ahead, when I close my eyes and my wife kisses me goodbye, i can think with some certainty that we will indeed be together again. This seems to me to be gods gift to us, certainty realised through uncertainty? so the answer is both.

Well it makes sense to me anyway :0)

Doug Hudson said...

The answer to the first question is clearly No. If A implies B, it does not follow that B implies A.

We do know however, that if B is shown to be false, then it follows that so is A.

Gordon McCabe said...

Ah, but think Bayesian, Doug. The question is not whether confirmation of such a theory entails the existence of other universes, but whether the confirmation of such a theory is evidence of other universes.

In Bayesian probability, if a theoretical hypothesis, with some prior probability, entails some eventuality, and if that eventuality is observed, then the probability of the hypothesis being true increases.