Time travel for explorers? It’s precarious.

Learn how Einstein’s theory of relativity works and how there’s no scientific reason to believe time travel is impossible.

Is it conceivable to go through time? Indeed, and you’re doing it at this moment, speeding into the future at an amazing pace of one second of the second. Regardless of whether you’re watching paint dry or wishing you had more hours to visit with an amigo from away, you’re basically continually going through time at a similar speed. In any case, this isn’t the sort of time travel that has excited endless sci-fi journalists and produced a class so huge that Wikipedia includes more than 400 movies in the “Films no time like the present Travel” classification. Characters in movies, for example, “Specialist Who,” “Star Trek,” and “Back to the Future” jump into an insane vehicle to go back on schedule or twist into what’s to come.

After traveling through time, the players must decide what happens if you alter the past or present with information from the future (which is where time travel stories intersect with the idea of parallel universes or alternate timelines).Although many people are attracted by the prospect of altering history or seeing the future before it happens, no one has ever proved back-and-forth time travel or developed a mechanism of moving a human over considerable periods of time without destroying them in the process. In his book “Black Holes and Baby Universes” (Bantam, 1994), physicist Stephen Hawking noted, “The best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future.”

However, science does allow for some time travel. The theory of special relativity proposed by scientist Albert Einstein, for example, suggests that time is an illusion that shifts relative to an observer. Time, with all its aftereffects (boredom, aging, etc.) will be experienced considerably more slowly by an observer traveling near the speed of light than by an observer at rest. That’s why, after a year in space, astronaut Scott Kelly aged slightly slower than his identical brother who remained on Earth.Other scientific hypotheses concerning time travel exist, such as some strange physics involving wormholes, black holes, and string theory.

Time travel, for the most part, is the subject of an ever-growing number of science fiction literature, movies, television episodes, comic books, video games, and other media.In 1905, Einstein proposed his theory of special relativity. It has become one of the core tenets of contemporary physics, along with his later development, the theory of general relativity. For objects moving at constant speeds in a straight line, special relativity addresses the link between space and time.

The theory’s brief version is deceptively straightforward. To begin with, everything is measured in relation to something else; there is no “absolute” frame of reference. Second, light travels at a constant pace. It remains constant regardless of what is measured or where it is measured from. Third, nothing has the ability to travel faster than the speed of light.Actual, real-life time travel emerges from those fundamental tenets. An observer traveling at a high rate will experience time at a slower rate than someone who isn’t.While we don’t accelerate humans to near-light speed, we do transport them around the world at 17,500 miles per hour (28,160 kilometers per hour) aboard the International Space Station. Scott Kelly, an astronaut, was born after his twin brother, Mark Kelly, who was also an astronaut. Scott Kelly was in orbit for 520 days, while Mark was in space for 54 days.

The age gap between the two guys has expanded due to the difference in the speed at which they experienced time over the course of their lives.”Whereas before I was only 6 minutes older, today I am 6 minutes and 5 milliseconds older,” Mark Kelly said in a panel discussion on July 12, 2020, as previously reported by Space.com. “Now I’ve gotten that out of his system.”

The difference in an astronaut’s life span that low earth orbit creates may be insignificant — better suited for family jokes than true life extension or reaching the distant future — but the time dilation between people on Earth and GPS satellites travelling through space does make a difference. The Global Positioning System, or GPS, communicates with a network of a few dozen satellites in high Earth orbit to assist us know exactly where we are. The satellites circle the planet at a speed of 8,700 mph (14,000 km/h) at a distance of 12,500 miles (20,100 kilometers).

The slower an object moves relative to another object, the slower that first object sees time, according to special relativity. According to the American Physical Society publication Physics Central, this effect removes 7 microseconds, or 7 millionths of a second, off each day for GPS satellites with atomic clocks. Then, according to general relativity, clocks that are closer to the center of a huge gravitational mass like Earth tick slower than clocks that are farther away. Because GPS satellites are far farther from the center of the Earth than clocks on the ground, each day adds 45 microseconds to the GPS satellite clocks, according to Physics Central.

The net result is an additional 38 microseconds when combined with the negative 7 microseconds from the special relativity estimate. Engineers must account for an extra 38 microseconds in each satellite’s day to maintain the accuracy needed to target your car or phone — or, because the system is operated by the US Department of Defense, a military drone — in order to maintain the accuracy needed to pinpoint your car or phone. The onboard atomic clocks do not advance to the next day until they have been running for 38 microseconds longer than comparable clocks on Earth.Given those figures, it would take more than seven years for a GPS satellite’s atomic clock to desynchronize from an Earth clock by more than a fraction of a second.

This type of time travel may appear as insignificant as the age difference between the Kelly brothers, but given the hyper-accuracy of modern GPS technology, it does matter. Your phone can pinpoint your exact location in space and time if it can communicate with the satellites flying overhead.


Yes, time travel is a viable possibility. But it’s not exactly like you’ve seen in the movies. It is possible to experience time passing at a rate other than 1 second per second under certain circumstances. And there are important reasons why we need to comprehend this type of time travel that occurs in the real world.