One of the great things about my job is Wednesdays. I don’t have any lectures, just a clear day apart from our weekly maths/physics seminar in the afternoons. I often take a walk into my village on Wednesday mornings, and use the opportunity to think about Important Things over breakfast. This morning I was thinking about a lecture I gave yesterday to our students on the Horizon Problem.
The Horizon Problem is a problem with the Big Bang model of the evolution of the universe. It concerns the observation that the furthest flung regions of the universe are further apart than light could have travelled in the age of the universe; yet these regions have the same temperature and identical other physical properties (from measurements of the cosmic background radiation). This is an amazing coincidence, given that the regions could never have been in contact or communicated with one another.
The Horizon Problem is a bit like another conumdrum in Big Bang theory: the Flatness Problem. According to the modern theory of gravity (Einstein’s general theory of relativity), the space-time curvature of our universe could be closed, open, or exactly balanced between the two (flat). Recent evidence from the cosmic microwave background suggests that our universe is exactly flat – worse, mathematics predicts that should it deviate even slightly from flatness, it would quickly become a runaway closed or open universe. Since gravity depends on mass, what this really means is that the density of matter in the universe is at the exact critcal value required for flatness. Why such a precise balancing act? Another amazing coincidence.
Is this God at work or is there a rational explanation? Proposed solutions tomorrow