Thursday, February 28, 2008

Free Will in the Multiverse

Consider undergoing brain surgery. During the operation you are awoken so that the brain surgeon can do tests on you to see if certain brain areas can be cut away safely. During these tests you may be able to see parts of your own brain. What a strange sight that must be! But however closely you look at your own brain, you can never see it in full detail. The reason is that everything you see must be stored in your own brain, so storing the entire state of the brain will necessarily exhaust all the available brain capacity. Note that this argument you can take "full detail" to be only the relevant information about the brain that defines you.

This means that we cannot know, even in principle, who we really are. In a multiverse setting, this in turn implies that we must always associate ourselves with ensembles of near exact copies. Assuming that each of our copies evolves deterministically, their evolution will diverge after a while. So, our future is not deterministic. And this will, of course, happen whenever we feel that we have a choice over our actions and we haven't made up our minds on what action to take.

Because the argument above shows that our consciousness should be associated with some ensemble of near exact copies and not with any particular copy, it seems that from the perspective of the conscious entity, there does exist a real free will and not just an illusion of it as is the case in single universe settings.