September 22nd brings cosmologist Lee Smolin to Virtually Speaking. His current work involves questioning the widely held view among cosmologists that our universe is one of many, many universes–that it is part of a mulitverse.
Three decades ago, talk of other universes was not seen by most physicists to be part of science. Most research in theoretical physics and cosmology concerned observable features in our universe and most papers and seminars referred to experimental results. However, since then there has been a gradual shift, during which it first became acceptable to work on theories that described not only our universe, but other possible universes, universes with less or more dimensions, or universes with different kinds of particles and forces. In the last few years, we have moved further away from theories of our one universe, as these other worlds went from being logically possible to hypothetically actual. It is now common to hear about the multiverse – a quantum cosmology that takes for granted that the visible universe at we see around us is just one of a vast or infinitenumber of universes.
Lee has come to believe that this view (that he shared) is mistaken, and the linked article explains why. One of the more interesting problems with the multiverse point of view is that it implies (in the formal, logical sense of the word) that the multiverse is time-less, that time is an emergent property of a particular universe, and is not a fundamental property. In Lee’s view, this is a serious problem, nearly as serious as the difficulties the multiverse paradigm has in generating testable hypotheses.
We get better results, he says, if we operate with a model of one universe that includes real time as a fundamental property. The difficulty with this paradigm is it violates a fundamental assumption of experimental physics, that the universe’s laws are uniform everywhere, and throughout time.
You can read a summary at the link above, or watch a video of Lee and his co-author presenting their position.