# Time travel: Only possible in Hollywood?

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Above:Wormhole travel as envisioned by Les Bossinas for NASA

Fast Fact: Time travel first appeared in the movies in a 1921 adaptation of Mark Twain’s novel A Connecticut Yankee in King Arthur's Court.The idea of time travel is fascinating. Countless TV shows, movies, and books—including Looper, Back to the Future, and Dr. Who—have explored the wonderful idea of moving back and forth through time. This raises a series of interesting questions, including whether such a thing is even possible, and how it might work.

Works of science fiction rarely provide details on exactly how time travel works. However, there are some scientific theories—in particular, Einstein's theory of special relativity and subsequent work by astrophysicist J.R. Gott—that point to certain possibilities.

Fast Fact: Among other concepts, Albert Einstein’s theory of special relativity explores the scientific possibility of time travel.Time Travel Basics

With his theory of special relativity, Einstein introduced the idea that time is relative. This means that time can pass more quickly or more slowly, depending on where you are and how fast you’re moving. Einstein proposed that if you travel faster than another object, your clock ticks more slowly than the object’s clock. However, this effect is only noticeable if you’re traveling at extremely high speeds, approaching the speed of light. For example, if you left Earth on a rocket travelling at almost the speed of light, time on earth would pass more quickly that time in the rocket. When you returned a few years later, many more years would have passed on Earth than you would have experienced. You might meet your great-grandchildren, who could be older than you!

According to same theory, if an object is travelling at the speed of light, time stands still for that object. That’s because, relative to light, it’s not moving. This means that, theoretically, if an object were to travel faster than the speed of light, time would flow backwards for that object (relative to an object that is not moving at all).

Fast Fact: The first popular works of fiction to explore time travel were novels by H.G. Wells: The Chronic Argonauts (1888) and The Time Machine (1895).“Mom, may I borrow the TARDIS tonight?”

Time machines, devices that move people through the fourth dimension (time), appear in many movies and books. While no one has been able to construct a time-traveling DeLorean (yet), the possibility has been explored. In the 1990s, astrophysicist J.R. Gott built upon Einstein’s theories by proposing that space-time could be warped into "closed timelike curves." Theoretically, traveling through these curves in a particular way would allow objects to move backward or forward in time.

However, the power required for this theoretical time machine is about half of the available energy in the entire universe. Perhaps one day this could be accomplished by following the example of Dr. Who, whose TARDIS is powered by the energy from an exploding star.

It’s impossible to predict what amazing technology will be developed in the future. High school field trips to the past? That would be pretty cool! In the meantime, science fiction and theoretical physics keep us wondering.

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#### Melody Montgomery

I completed my Bachelor of Science in Integrated Science at Carleton University. After working in research labs, I entered the Clinical Genetics program at the British Columbia Institute of Technology. I now work in a genetics lab.I volunteered for the Carleton Chapter of Let’s Talk Science's Partnership Program. My activities included leading a forensic science workshop for high school students, judging science fairs, and making slime with kids at a local library.