Exploring the Universe

An essential element of exciting science fiction is voyaging to the far reaches of the universe. But with current technology, a trip to the closest star, Alpha Centauri, would take more than 80,000 years!

Much faster ships, traveling at a significant percentage of the speed of light, would shorten the journey. Space travelers could also take full advantage of the slowing down of time at high speeds. For example, a spaceship traveling at 75 percent the speed of light would reach Alpha Centauri in 5.7 "Earth years." But for the astronauts on the ship, the trip would take only 3.8 years.

Of course, the technology required for such high speeds is not available--and may not be for many, many years, if ever. The fastest spaceships of today travel at only 0.00004 percent the speed of light.

The stars in the Big Dipper constellation are many light years away--and inaccessible by modern spacecraft. The most cutting-edge proposals for new engine technology would enable humans to travel at 0.1 percent the speed of light--thousands of times faster than current technology. Even so, a trip to any of the stars of the Big Dipper would take tens of thousands of years.

Mizar & Alcor: 80 light years away
 Length of trip (proposed technology): 84,000 years

Alioth: 360 light years away
 Length of trip (proposed technology): 370,000 years

Dubhe: 86 light years away
 Length of trip (proposed technology): 93,000 years

Time warp!

Although often the subject of science fiction films, time travel--at least to the future--is theoretically possible, according to Einstein's Theory of Relativity. (Time travel to the past remains impossible.) But these bizarre contraptions that spin and flash wildly as they send people hurtling though time will always remain in the realm of fantasy.

Time traveler

Cosmonaut Sergei Avdeyev spent a total of 748 days on the Russian space station Mir during three separate missions. Because Mir was moving relative to Earth, it was also a time machine. Avdeyev is 0.02 seconds younger than he would have been had he never traveled in space.