Build Your Own Time Machine

Special relativity provides a double opportunity for time travel. If you travel at a sizable fraction of the speed of light, time for you slows with respect to the outside world. In effect, you move forward in time. And if you can travel faster than light, you will have a means to move backward in time.

And because there is no special frame of reference, the view of the observer on the moving train is as valid as the view of the observer who isn’t moving. Either two events can be simultaneous, or one can come after the other, depending on how you are moving.

When the speed of light was fixed, measurements that had previously been constant—an object’s mass, its size, and even the passage of time it experienced—became variable.

Anything moving at near the speed of light, Einstein realized, would experience phenomena totally different from the everyday.

Since 1895, when Wells published his book, science has moved on with frightening speed. And that progress has included the theories that makes time travel possible in principle.

However, we can’t dismiss that “glittering metal framework,” as the time machine is first described in the 1895 novel—it is hugely significant. Although traveling in time was not a new idea even then, fictional time travel before that book had relied on dreams or magic

This different way of looking at light not only explained the photoelectric effect, but also provided the foundations of quantum theory.

It all comes down to the relativity of simultaneity.

But Wells transformed it into science fiction (even though that term was yet to be invented), a fictional concept of practical, solid achievement, opening up speculation about how time travel might be achieved and what the implications of traveling back to the Crucifixion, or visiting the far distant future of humanity, might be.