Coming Full Circle

We've come a long way since we considered our astronomical ancestors, looking up at the sky and wondering. We have come to the end of our story, a story that—as is obvious from the daily paper—is still being written. We live in an incredible age, when the discovery of accretion disks around black holes and distant Type Ia supernovae at the edge of the visible universe are reported on the evening news, along with doings of movie stars and musicians.

As we've seen in this chapter, it is possible to contemplate the universe on scales much larger than may be directly relevant to us—scales on which its curvature (positive or negative) becomes significant, and our comfortable Euclidean-Newtonian reality gets deliciously bent out of shape. And your imagination needs no telescope, nor even the night sky, to take this trip.

As exciting as these findings are, and as stunning as the NASA and other images are that you will find on the Internet, remember to go outside as often as you can and look at the night sky. With or without a telescope, the planets, stars, and galaxies that you see are indeed out there, real, and immeasurable in their beauty. Open, closed, or flat, the universe isn't going away any time soon.

The Least You Need to Know

V The future of the universe is limited to two basic possibilities: Either it will expand forever or eventually collapse.

V The density of matter in the universe determines whether gravity will be able to halt the expansion of the universe that started with the Big Bang.

V Depending on the observed density of the universe, we say that it is open, closed, or flat. An open universe will expand forever, a closed universe will collapse on itself, and a flat universe will expand at a slower and slower rate.

V Inflation, a sudden expansion in the scale of the universe that occurred early on, might explain why the universe looks flat and homogeneous.

V Recent observations suggest strongly that we live in a flat universe, and that there is not enough mass in the universe to pull it all back together in the endgame counterpart of the Big Bang—the Big Crunch.

Telescopes Mastery

Telescopes Mastery

Through this ebook, you are going to learn what you will need to know all about the telescopes that can provide a fun and rewarding hobby for you and your family!

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