Friday, May 11, 2007

Meditations on a speck of sky

When I first saw this Hubble Space Telescope picture I was impressed by its beauty and the claim in the associated article that at least 1500 galaxies were contained in the image--which only covers about 0.00000025% of the sky. However, what really surprised me was the assertion that the picture would look very similar regardless of where the telescope was pointed, as long as there wasn't something "close" in the way (e.g. the Milky Way or its neighbors). To me this implied that either our galaxy is at the center of the universe (unlikely and rejected by astronomers), or I didn't know what the hell was going on.

A couple of years later I can report that this “every direction looks the same” assertion does make sense to me--although some aspects still make my head hurt. The reasons for this apparent "center of the universe" view relate to the physics of the Big Bang. A couple of key points:

  • The Big Bang was not an explosion in space. There was no space before the Big Bang and no time. The Big Bang not only created all the matter in the universe, it also created the framework (space) to hold it, and the time to run it.
  • In the Big Bang's very early phases the universe expanded much faster than the speed of light. It was space, not matter or light that was expanding so the Einsteinian speed limit was not violated. This early hyper expansion, called the inflationary phase, ended when the universe was about a meter across. One of the resulting effects was that matter, which was caught up in the expansion, became very evenly distributed throughout the universe. By the way, the spot where you are now sitting was inside that meter wide universe.
  • Because it started out so evenly distributed, even when matter eventually got around to clumping together into galaxies the large scale uniformity of the universe was preserved. The result is that our view of the far away universe looks the same in all directions.

As I learned about the beginnings of the universe as defined by the current, general relativity based theories, there was an unexpected harmonizing with Biblical accounts of creation. As Dr Hugh Ross points out , the most common description used in the Bible for the creation of the heavens (11 times) was that they were “stretched out”. For example: "This is what God the Lord says--he, who created the heavens and stretched them out" Isaiah 42:4 It is inspiring to me that these 2000+ year old words can be re-interpreted from formerly puzzling passages into respectable descriptions of the formation of the universe as astrophysics now describes it.