How Sergei Krikalev Became the World’s Greatest Time Traveler

Russian cosmonaut Oleg Kononenko is currently the world’s most experienced space traveler in terms of time-dilation, having spent over 1,110 days in orbit. Due to the effects of special and general relativity, Kononenko has aged approximately 0.025 seconds less than his peers on Earth. While this phenomenon is often described in popular media as “time travel into the future,” it is a scientifically verified, cumulative result of orbital velocity and reduced gravitational pull, as documented by official spaceflight records.

How does spaceflight cause time dilation?

According to the Institute of Physics, time dilation occurs because time does not pass at a uniform rate for observers moving at different velocities. Einstein’s 1905 special theory of relativity dictates that a clock moving at high velocity appears to run slower than a stationary clock. For an astronaut aboard the International Space Station (ISS), which travels at approximately 27,600 kilometers per hour, this effect accumulates over time. While the effect is negligible during a single flight, it becomes measurable over years of service. As of 2026, records indicate that long-duration spacefarers like Oleg Kononenko have effectively “gained” milliseconds by moving faster than the Earth’s surface.

Why do gravity and velocity compete?

The total time-dilation effect is a combination of two distinct relativistic phenomena. While special relativity suggests that velocity slows down time, Einstein’s 1915 general theory of relativity posits that gravity also influences the rate at which time passes. Clocks closer to a massive body, such as Earth, run more slowly than those further away. Because the ISS orbits 400 kilometers above the surface, astronauts experience a weaker gravitational field, which causes their clocks to run slightly faster—the opposite of the effect caused by their high orbital speed. According to calculations by Universe Today, the velocity-based slowing effect is five to six times stronger than the gravity-based acceleration, resulting in a net gain of “future time” for the astronaut.

How do cumulative records change over time?

The status of “most time-dilated human” is constantly shifting as new missions extend the total time spent in orbit. Sergei Krikalev, who held the record for years, accumulated approximately 0.02 seconds of dilation over his 17-year career. By 2015, Gennady Padalka surpassed Krikalev’s cumulative record. Current data confirms that Oleg Kononenko now leads this metric. The following table illustrates how these figures compare based on historical flight records:

Frequently Asked Questions

Is time travel into the future actually possible?

Yes, but not in the way science fiction depicts it. Relativistic time dilation is a proven physical reality. Astronauts who spend significant time at high velocities age slightly slower than people on Earth, effectively arriving in the “future” by a few milliseconds.

Could humans ever travel years into the future?

To achieve significant time dilation—such as years instead of milliseconds—a traveler would need to move at a substantial fraction of the speed of light. At 99 percent of the speed of light, time would pass seven times slower for the traveler than for a stationary observer, according to Einstein’s special relativity.

Does this affect the health of astronauts?

No. The amount of time dilation experienced by current space station crews is far too small to have any detectable impact on biological processes or the human experience of time.

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