Time travel is an interesting topic that gets the scientific communities all excited. However, to a layman, it looks something like this – you fire up a futuristic-looking time machine which allows you to travel back and forth in time and have awesome adventures! While you can blame Hollywood for this dramatized idea, time travel is not all science fiction. Thanks to Einstein’s Theory of Relativity and time dilation, time travel does happen. In fact, Russian cosmonaut Sergei Krikalev has already done it. He holds the record for traveling 0.02 seconds into his own future!

In his career, Sergei Krikalev has gone on six expeditions, and he is famous for having spent over 803 days in space.

Russian mechanical engineer and cosmonaut, Sergei Krikalev is one of the most renowned rocket scientists in the world. He has gone on six space flights and spent a total of 803 days, nine hours, and 39 minutes in space. His journey started in 1985 when he was chosen to be a cosmonaut. By early 1988, he started training for his first mission on the Mir space station. On 26th November of 1988, the expedition started with the launch of Soyuz TM-7. Krikalev and crew returned to Earth five months later on 27th April of 1989.

On May 19, 1991, Krikalev’s second Mir mission began with the launch of Soyuz TM-12. Due to delayed crew replacement, Krikalev needed to prolong his stay. He returned to Earth on March 25, 1992. His third expedition, STS-60 Space Shuttle Discovery, took off on February 3, 1994. After logging another eight days, seven hours, and nine minutes in space, Krikalev returned home on 11 February 1994.

STS-88 Space Shuttle Endeavour was a 12-day mission that ran from 4th to 15th December of 1998. Krikalev’s final two expeditions were aboard the International Space Station. ISS Expedition 1 launched on October 31, 2000, and he left the ISS on 18th March of 2001. His final mission, ISS Expedition 11, began on April 14, 2005, and continued until 10 October 2005.

Spending so much time around Earth’s orbit meant that Krikalev has experienced the most time dilation. That means he has technically traveled in time.

Krikalev’s extended stay on the ISS or the International Space Station has added one more achievement to his name – time travel! To understand how it works, you first need to know that to travel in time, one would have to achieve the speed of light while traveling in space. So, if we could build a spaceship that can go fast as the speed of light or 186,000 miles per second, we could possibly travel in time. Albert Einstein was the first to theorize that.

While orbiting around Earth, the ISS travels at the speed of approximately 7.66 km per second, which, though impressive, is nowhere near the speed of light. However, when you combine the speed of the International Space Station and the extended period of time that Krikalev spent in space, you will see that he has actually traveled 0.02 seconds into the future, and it is possible due to the process called time dilation.

Time dilation can be calculated using Einstein’s theory of relativity, which states that time moves differently for two objects that are experiencing different gravity levels or traveling at different speeds.

Differences in relative velocity and gravity can cause time dilation, but each factor affects time differently. For example, while orbiting the planet, satellites and astronauts stay further away from Earth’s center than people on the ground. Therefore, they will experience reduced gravitational time dilation. That means time would move slightly faster for the astronauts, and when they return to Earth, they would technically be coming back into the past. However, velocity affects the time dilation differently. In this case, clocks would tick relatively slower for the astronauts than people on the ground. That means upon returning to Earth, the astronauts will have to adjust their clocks by advancing the time.

Because Earth’s gravity is weaker than many other planet’s, gravitational time dilation has very little effect. Relative velocity is the primary factor that causes astronauts to experience time dilation. However, current technology can only achieve a limited velocity. That means its effects on time travel are minuscule. For example, if an astronaut spends six months on the ISS, he/she will have aged less than people on Earth, but only by a difference of 0.007 seconds. The difference would have been far greater if the ISS traveled at the speed of light.

(Sources: 1, 2, 3, 4)