Multiple Universes and Anthropic Principle It is now widely accepted that the universe began with a ‘big bang’, in which an enormous explosion released a vast amount of matter and energy that expanded and eventually created what we observe today. If you accept this to be true then the next response is usually to ask what caused the big bang. That’s a more contentious issue that most scientists disagree about, but there are popular theories to help us make sense of this incredibly complicated and often confusing idea. The latest theories are based on multiple universes, where there are an infinite number of different dimensions, most of which are believed to be connected in some way. Black holes are a means of removing matter from the universe through a point of infinite density where matter contracts into an infinitesimally small area, presumably ending up elsewhere. The theory says that there should be corresponding “white holes” that eject matter into another universe in the reverse process to their dark cousins. So it’s possible that a black hole in an earlier universe gave rise to ours while black holes in ours are creating yet more universes. At the moment, four ‘fundamental’ forces are believed to govern the universe: gravity, electromagnetism and two nuclear forces responsible for radioactivity and holding the nuclei within atoms together. If these forces, which came into existence after the big bang, were even slightly different to now then galaxies, stars, and hence black holes, might not have formed and we would not exist to observe and measure them thus making the universe a lifeless and chaotic mess. This ‘weak’ anthropic principle doesn’t tell us much about the origin of our universe though. On a grander scale, we would like to know the chances of finding life in other universes and whether their fundamental physical laws are similar to ours. Creating a ‘useful’ universe with nicely balanced fundamental forces seems extremely unlikely. You might therefore be tempted to suggest that only a God could have ‘designed’ such a thing, but strong anthropic principle suggests otherwise. Universes with balanced fundamental forces are more likely to create black holes. Any that don’t are less likely and so produce fewer lifeless universes. The cycle follows a sort of Darwinian evolution where a lack of black holes limits the spread of ‘bad’ universes and we predominantly get ones similar to our own and hence it is almost inevitable that we should find ourselves in such a balanced universe and that there should be life in others. Unfortunately, we may never confirm these theories as there is currently no way of testing them, which is why experimental physicists view the idea with considerable scepticism. The fact is that the mathematical equations necessary to neatly deal with the impracticalities will not convince most people. To paraphrase the mathematician, Martin Gardner, “Isn’t it much simpler to believe in one universe and its creator than there being countless billions upon billions of other worlds?” Well, yes, but that’s not nearly as interesting is it? .