The following is an excerpt of The Science of Superheroes and Space Warriors published by HowStuffWorks.

When the writers of Star Trek sat down to plan the series, they found themselves confronted with a few problems. They were essentially creating a space opera, a subgenre of science fiction that takes place in space and covers the span of several galaxies and millions of light-years. As the “opera” part of the name suggests, a show like Star Trek isn’t meant to be slow or ordinary. When people think of the series, they probably think of melodramatic plots involving aliens, space travel, and action-packed laser fights.

So the creator of the series, Gene Roddenberry, and the other writers had to find a way to move the show’s characters around the universe in a timely, dramatic fashion. At the same time, they wanted to do their best to stick to the laws of physics. The biggest problem was that even if a starship could travel at the speed of light, the time to go from one galaxy to another could still take hundreds, maybe thousands of years. A journey from Earth to the center of our galaxy, for example, would take about twenty-five thousand years if you were to travel just under the speed of light. This, of course, wouldn’t make very exciting television.

The invention of warp speed solved the opera part of the problem, since it allowed the Enterprise to go much faster than the speed of light. But what was the explanation? How could they explain an object traveling faster than the speed of light, something Einstein proved impossible in his special theory of relativity?

The USS Enterprise
The USS Enterprise

The first obstacle the writers had to confront is much simpler than you’d think. It comes down to Newton’s third law of motion: how for every action, there is an equal and opposite reaction.

What does this have to do with Star Trek and the Enterprise? Even if it were possible to accelerate to something like half the speed of light, such intense acceleration would kill a person by smashing him against his seat. Even though he’d be pushing back with an equal and opposite force, his mass compared to the starship is just too small. The same kind of thing happens when a mosquito hits your windshield and splatters. So how can the Enterprise possibly go faster than the speed of light without killing the members on board?

To sidestep the issue of Newton’s third law of motion and the impossibility of matter traveling faster than the speed of light, we can look to Einstein and the relationship between space and time. Taken together, space (consisting of three dimensions: up-down, left-right, and forward-backward) and time are part of what’s called the space-time continuum.

In his special theory of relativity, Einstein states two postulates:

  1. The speed of light (about 300 million meters per second) is the same for all observers, whether or not they’re moving.
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  1. Anyone moving at a constant speed should observe the same physical laws.

Putting these two ideas together, Einstein realized that space and time are relative—an object in motion actually experiences time at a slower rate than one at rest. Although this may seem absurd to us, we travel incredibly slowly when compared to the speed of light, so we don’t notice the hands on our watches ticking slower when we’re running or traveling on an airplane.

USS Enterprise at warp speed in Into The Darkness.
USS Enterprise at warp speed in Into The Darkness.

What does this mean for the Captain Kirk and his team? As an object gets closer and closer to the speed of light, that object actually experiences time at a significantly slower rate. If the Enterprise were traveling safely at close to the speed of light to the center of our galaxy from Earth, it would take twenty-five thousand years of Earth time. For the crew, however, the trip would probably only take ten years.

Although that time frame might be possible for the individuals on board, we’re presented with yet another problem—a Federation attempting to run an intergalactic civilization would run into some problems if it took fifty thousand years for a starship to hit the center of our galaxy and come back.

So the Enterprise has to avoid the speed of light to keep the passengers onboard in sync with Federation time. At the same time, the Enterprise must reach speeds faster than that of light to move around the universe in an efficient manner. Unfortunately, as Einstein states in his special theory of relativity, nothing is faster than the speed of light. Space travel therefore would be impossible if we’re looking at the special relativity.

That’s why we need to look at Einstein’s later theory, the general theory of relativity, which describes how gravity affects the shape of space and flow of time. Imagine a stretched-out sheet. If you place a bowling ball in the middle of the sheet, the sheet will warp as the weight of the ball pushes down on it. If you place a baseball on the same sheet, it will roll toward the bowling ball. This is a simple design, and space doesn’t act like a two-dimensional bed sheet, but it can be applied to something like our solar system. More massive objects like our sun can warp space and affect the orbits of the surrounding planets. The planets don’t fall into the sun, of course, because of the high speeds at which they travel.

The ability to manipulate space is the most important concept in regard to warp speed. If the Enterprise could warp the space-time continuum by expanding the area behind it and contracting the area in front, the crew could avoid going the speed of light. As long as it creates its own gravitational field, the starship could travel locally at very slow velocities, therefore avoiding the pitfalls of Newton’s third law of motion and keeping clocks in sync with its launch site and destination. The ship isn’t really traveling at a “speed,” per se—it’s more like it’s pulling its destination toward it while pushing its starting point back.

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