Christopher Nolan’s hit sci-fi blockbuster Interstellar there’s a moment in which your mind is blown out the back of your head. Cooper and Brand (played by Matthew McConaughey and Anne Hathaway) are exploring Miller’s planet, a celestial body with “punishing” gravity at 130% more than that of Earth’s.
Something called time dilation takes effect, in turn, making every hour on this planet, seven years back on Earth. Every second is an entire day passing by, enough so that Cooper’s kids end up older than him.
It’s a terrifying concept to grapple with — and McConaughey screaming “Murr!” over Hans Zimmer’s stentorian score doesn’t help — but it’s no doubt perplexing to the greatest degree.
Interestingly enough, one man on Earth has encountered this phenomenon directly. Sergei Krikalev, the only man who has ever time traveled.
Who is this time-traveling Jedi?
Sergei Krikalev is a Russian cosmonaut and mechanical engineer. He holds the record for most time spent in orbit around the Earth at 803 days.
Because Krikalev spent so much time in space away from Earth’s center of gravity, time dilation (or the slowing down of clocks) caused him to be 0.02 seconds younger than other people born at the same time as him.
“Without Einstein’s general theory of relativity, our GPS system wouldn’t be working.” — Ron Mallet
Being away from Earth’s gravity causes clocks to run a tiny bit faster than they would here. Therefore, every astronaut experiences time dilation and Krikalev experienced it the most.
Sure speeding up 0.02 seconds isn’t enough to visit Earth 100 years from now and say hello to Skynet and our artificial intelligence overlords, but it's an amazing discovery nonetheless!
Today Krikalev even holds the title for the world’s most prolific time traveler.
A tiny painless explanation of how time travel works
Einstein’s Theory of Relativity is based on two core basic principles.
One is that the laws of physics don’t change, even when objects move at constant speeds to each other. In other words, the speed of light is a fundamental constant.
The other principle is that the speed of light is the same for everyone, no matter how they move in relationship to the light source.
“Without Einstein’s general theory of relativity, our GPS system wouldn’t be working,” said Ron Mallet, an astrophysicist in an interview. “That’s also proof that Einstein’s [theories are] correct.”
In order to time travel, engineers would have to build a space ship that could travel at the speed of light (186,000 miles-per-second). Unfortunately, we do not have technology anywhere close to that at the moment.
I know, bummer.
Anyway, now that you’re an expert physicist let’s get on with the rest of the story.
Why time travel will happen, someday
Einstein once wrote:
“People like us who believe in physics know that the distinction between past, present, and future is only a stubbornly persistent illusion. Time, in other words, is an illusion.”
Like in Interstellar you wouldn’t feel a passage of time; everything would feel normal while the rest of the world speeds up to around you. Hence the “relativity” of Einstein’s theory.
One popular time travel theory involves black holes. Essentially you’d move a rocket ship rapidly around a black hole like the Gravitron ride at a carnival.
“Around and around they’d go, experiencing just half the time of everyone far away from the black hole. The ship and its crew would be traveling through time,” physicist Stephen Hawking wrote in the Daily Mail in 2010.
One of the key reasons Krikalev was able to experience dilation and break records was the Soviet Union forgot him in space for 311 days. The Cold War ended while he was up there, so the country that sent him to space no longer existed.
Krikalev stayed in space twice as long as the mission originally called for. Even so, that wouldn’t be enough to deter him from space travel as he wouldn’t retire from space flight until 2007.
“Space can be fun, depending on who you are with” — Sergei Krikalev
One Reddit user voiced his disappointment with Krikalev’s achievement in a thread about time travel. “That’s not time travel,” they wrote.
Certainly, it’s not as cool as Marty McFly and Doc Brown going 88 mph in a time-traveling Delorean; or Bill and Ted’s phonebooth “Rufus.” But for all us Star Trek fans (i.e. the nerdiest of the nerds) I think it's fascinating!