Imagine what your history class would be like if time travel were possible. You could travel back to 1620 and watch the Pilgrims land at Plymouth Rock, or set your time machine for July 4, 1776, and watch Thomas Jefferson sign the Declaration of Independence, or even see the Wright Brothers on December 17, 1903 make their historic flight over the sands of Kitty Hawk, NC. History would no longer be trapped in our textbooks. We could live through the important moments of the past and see what really happened! You might be amazed that time travel already exists in some ways. One day, we might even be able to travel far into the future!

To understand time travel, you must first know how to define time. Take a few minutes and try to write down a simple definition. It isn’t that easy is it? You may be surprised, but even the best scientists find it hard to put time into words.

We all think we know what time is. Probably the easiest way to see time is to watch the ticking hands of a clock. One clever teacher even put this message above the clock in her English class: "A note to clock watchers: Time passes... will you?" There are lots and lots of clues about time in our daily lives. Have you ever seen a newspaper after it sat a few days in the light and turned yellow? Your body also shows the effects of time. In fact, you've probably even grown a little taller this year.

You'll find many definitions of time in the dictionary. The simplest one is that it is a series of events with a past, present and future. In fact, we are all time travelers of a sort. Even as you read this, you are traveling into the future at a rate of 60 seconds per minute, 60 minutes per hour and 24 hours per day.

Any event that has not happened yet is in the future. Once we reach an event, we've traveled forward through time. When you wake up tomorrow morning, you will have traveled a few hours through time to reach that point. But there's another way that may be possible for us to travel hundreds or thousands of years into the future. Time Rockets!

The key to speeding up time travel and allowing us to jump into the future is to build vehicles that can travel at the speed of light - or at least near light speed. Light speed equals 186,000 miles per second! That is about 11 million times faster than a car traveling at 60 mph! Scientists claim that time actually slows down for you as you near light speed. So, if you had a time machine that allowed you to travel at the speed of light, time would slow down for you - but it would remain the same for those not in the time machine.

But, here's the hitch. Scientists don't believe that matter can actually reach the speed of light. The good news is that we don't need to travel at the speed of light to travel through time. In fact, we already have spaceships that can jump into the future.

The space shuttle travels at about 17,500 miles per hour. That's 40,000 times slower than the speed of light speed. But, even at that speed, scientists calculate that astronauts aboard the space shuttle travel a few nanoseconds into the future. A nanosecond is a tiny speck of time - only a billionth of a second. It is so fast that, by the time you can blink your eye, 400,000 nanoseconds have gone by! If we could build a spaceship that is thousands of times faster than the space shuttle, then we could travel weeks or years into the future.