Mission of the Month: December 2009
Journey to the Outer Limits

It has been an exciting year — exploring the planets, constellations and galaxies in 2009, the Year of Astronomy. And now it is drawing to a close. You and your fellow explorers are taking one last lazy orbit before returning to Earth…

and then you are not!!

The Voyager 1 spacecraft is the most distant man-made object in the universe. Voyager is at the edge of our solar system and passing into interstellar space. As you imagine your travels through space think of Voyager that is over 10 billion miles from earth. Voyager 1 began the trip in 1977 as did Voyager 2. Think of traveling across space for over 32 years and are now just at the edge of the solar system. This travel gives a sense of the vastness of space. As you travel the universe, watch out for NASA's 2 Voyagers. If you got on your bike and started to ride at 10 miles per hour how long would it take for you to ride 10 billion miles? You would pedal for over a million years. Better pack a lunch. So let's jump into a spacecraft that has NASA's latest in engines that can travel at very fast speeds. And here we go…

Black Hole: According to Einstein's general theory of relativity, a black hole (http://imagine.gsfc.nasa.gov/docs/science/know_l2/black_holes.html) is a region of space from which nothing, including light, can escape. It is the result of the deformation of space-time caused by a very compact mass. Around a black hole there is an undetectable surface which marks the point of no return, called an event horizon. It is called "black" because it absorbs all the light that comes towards it, reflecting nothing, just like a perfect black body in thermodynamics. Under the theory of quantum mechanics, black holes possess a temperature and emit Hawking radiation.

Your spaceship is hurtling through space, pulled forward by a force you cannot escape. You are surrounded by darkness. You’re being sucked into a black hole. Ack!! You are a goner — nothing escapes from a black hole, not even light! Which makes them almost impossible to see.

But wait. Stellar black holes are small (only a few to a few tens of kilometers in size). So your spaceship wouldn’t fit into the black hole.

And is that light? Pinpricks of light are in front of you. They are getting larger! Perhaps it wasn’t a black hole. Perhaps it was a worm hole!!

Wormhole: In physics, a wormhole is a hypothetical topological feature of spacetime that is, fundamentally, a 'shortcut' through space and time. Simply, space-time is a two-dimensional (2-D) surface that, when 'folded' over, allows the formation of a wormhole bridge. A wormhole has at least two mouths that are connected via a throat or tube. If the wormhole is traversable, then matter can 'travel' from one mouth to the other via the throat. There is no observed evidence for wormholes, and, although wormholes are valid solutions in general relativity, this is only true if exotic matter can be used to stabilize them. Even if the wormhole is stabilized, even a slight fluctuation in space would collapse it. If such exotic matter (matter with negative mass) does not exist, all wormhole-containing solutions to Einstein’s field equations are vacuum solutions, which require an impossible vacuum, free of all matter and energy.

So what exactly is spacetime? In physics, space-time (or spacetime; or space/time) is a mathematical model that combines space and time into a single continuum. Space-time is usually interpreted with space being three-dimensional and time playing the role of a fourth dimension. Time is a different sort of dimension than spatial dimensions. According to certain Euclidean space perceptions, the universe has three dimensions of space and one dimension of time. By combining space and time into a single manifold, physicists have significantly simplified a large number of physical theories, as well as described in a more uniform way the workings of the universe at both the supergalactic and subatomic levels.

Sound complicated? Well these ideas are complex but think in terms you understand. Spend some time at the library and look up black holes, wormholes, and other object you may encounter. When you find out new things about them, imagine what they would be like. Many things in the universe were written about in fiction before they were found to be real. Maybe your imagination holds the next new discovery!

As you journey through space you would encounter these real and proposed phenomena and possibly even more. Take a virtual ride in the universe with the program Celestia. Celestia can be downloaded at no cost and can have add-ons that include black holes. When installed you can travel to the outer edge of the solar system and look back at the sun, a tiny star in the sky and get a sense of the vastness of space.

Use images from NASA, Hubble, and your travels through the universe with Celestia and let your imagination run wild. Tell us your story of journey on the blog writing your own science fiction story. Check out some science fiction books and read them. Select stories from 100 years ago and stories from today that are written for your age.