Not too long after writing my posts about different possible parallel universes, I read an article about a paper challenging the very premises of both level I parallel universes and the many-worlds interpretation of quantum theory. I wanted to bring this article up to show just how speculative this particular subject is and to illustrate that the idea of parallel universes is still debated in the scientific community.
The paper was written by two Spanish researchers, Francisco José Soler Gil and Manuel Alfonseca. Their argument boils down to this: while we cannot disprove these parallel universes, they are so unlikely that they are more appropriate for the realms of philosophy and science fiction than actual science. Their biggest bone of contention lies with an assumption that both level 1 parallel universes and the many-worlds interpretation share: that the universe is infinite. They argue that this assumption is questionable at best. They say we just don’t have enough data to know for sure (though measurements from WMAP hint that the universe might be infinite) and, throughout the history of science, we have to turned out to be wrong when scientists have assumed infinities.
With respect to level 1 parallel universes, they take issue with a couple items. First, there is infinity and there is INFINITY, i.e. some infinities are larger than others. In this case, while there may be copies of you out there, the number of possible histories is much much larger than the number of copies of you. Thus, they argue, the likelihood that there is an exact copy of you out there living this same history is so small as to be virtually nothing.
With respect to the many-worlds interpretation, the authors find pretty much every assumption made in applying the many-worlds interpretation to be very doubtful. The biggest problem they have with this type of parallel universe is that the proponents of the many-worlds idea present it as probable instead of highly speculative, or at least just theoretical: “This is . . . a theoretical conclusion. In practice, authors and popular writers usually present these speculations as though they were very probable, practically proved by science.”
And so, within months of the start of this blog, you can already some theoretical science in action. One theoretician writes a paper proposing something, and another challenges the weak points of that theory. Experimental science is a bit different since then you are starting to work with actual recorded data, but the idea is the same.