Is There a “Mirror Universe” Where Time Goes Backwards? Does time only move forward? Or is that just an illusion? It’s a question that has puzzled physicists for well over a century, and there have been many theories and explanations. The latest, though, suggests that while time moves forward in our universe, it may run backwards in another, mirror universe that was created on the “other side” of the Big Bang. But doesn’t it abide by time-symmetric law or as Julian Barbour and Tim Koslowski suggest “An Arrow” of time?
Nova Next reports that scientists have added an interesting twist to this theory: the expansion after the simulated Big Bang didn’t just happen in one direction, but two. They believe that the Big Bang produced two universes, one a mirror of the other. In one universe, time appears to run forwards. In the other, time runs backward, at least from our perspective.
Here are Billings again, interviewing lead author Julian Barbour from the University of Oxford:
“If they were complicated enough, both sides could sustain observers who would perceive time going in opposite directions. Any intelligent beings there would define their arrow of time as moving away from this central state. They would think we now live in their deepest past.”
They suggest that from that perspective, that perhaps George Lucas’s Star Wars didn’t take place a long time ago in a galaxy far, far away, but in the far future—our deepest past—of our mirror universe.
This abstract is from an “Identification of a Gravitational Arrow of Time” by Julian Barbour, Tim Koslowski, and Flavio Mercati:
It is widely believed that special initial conditions must be imposed on any time-symmetric law if its solutions are to exhibit the behavior of any kind that defines an “arrow of time.” We show that this is not so. The simplest nontrivial time-symmetric law that can be used to model a dynamically closed universe is the Newtonian N-body problem with vanishing total energy and angular momentum. Because of special properties of this system (likely to be shared by any law of the Universe), its typical solutions all divide at a uniquely defined point into two halves. In each, a well-defined measure of shape complexity fluctuates but grows irreversibly between rising bounds from that point. Structures that store dynamical information are created as the complexity grows and act as “records.” Each solution can be viewed as having a single past and two distinct futures emerging from it. Any internal observer must be in one-half of the solution and will only be aware of the records of one branch and deduce a unique past and future direction from inspection of the available records.
Via: Nova Next, © 2014 American Physical Society