The Universe Is Flat

I meant to mention this remarkable scientific news story before, and it sort of slipped my mind. Which is kind of hard for me to believe, given that it concerns nothing less than the ultimate fate of the entire universe. Indeed, I've always thought that if some omniscient being offered to answer me any one question, "Is the Universe open or closed?" would at the very least be a top-five contender.

The news, in case you're too lazy to click on the above link, is that a spacecraft called the Microwave Anisotropy Probe has finished mapping the distribution of residual energy left over from the Big Bang. The results, apparently, have led scientists to the following remarkable conclusions:

1. The universe is "flat." This means that the universe will not eventually cease expanding and start contracting, collapsing inward under the force of its own gravity until it eventually ends in a Big Crunch (a "closed" universe). Instead, it will keep on expanding forever (an "open" universe). It also means, however, that the amount of mass in the universe is exactly at the critical limit below which it would have eventually suffered a Big Crunch fate. This cannot possibly be a coincidence (and in fact, I believe it's a predicted result from a particular theoretical model called "inflationary cosmology").

2. The universe is exactly 13.7 billion years old. (Well, almost exactly. The error margin is 0.2 billion years in either direction.)

3. The first stars in the universe began to shine only about 200 million years after the Big Bang, much earlier than theorists had predicted. If my astrophysics weren't so incredibly rusty, I might have some sort of comment to make about the implications of that, but, alas, it's been a long time since I've so much as thought about the technical details of star formation.

4. Last, and possibly most interestingly, it seems that 73% of the mass of the universe is made up of a sort of "dark energy," a mysterious something that has the property of causing the universe's rate of expansion to actually increase, despite the pull of gravity. (Go ahead, call it anti-gravity if you like. I don't know what else to call it...)