The phenomenon of time dilation in space has long excited the minds of science fiction writers from all over the world. At the same time, the question of how strongly the movement of an astronaut at the speed of light affects his biological clock was first described in the so-called “paradox of twins”, in which an astronaut travels into space on a high-speed rocket, while his twin brother remains on Earth. It is believed that upon returning to the blue planet, the astronaut will find his twin aged, while the appearance of the space traveler himself will remain almost the same.
The speed of light can have a profound effect on the aging process in astronauts
Why does the speed of light slow down time?
Time dilation dates back to Einstein's special theory of relativity, which teaches us that movement in space actually creates changes in the flow of time. The faster you move through the three dimensions that define physical space, the slower you move through the fourth dimension, which is essentially time. Time is then measured differently for the astronaut and his twin, who stayed on Earth. A clock in motion will tick slower than the clock we see on Earth. However, if the astronaut moves at a speed close to the speed of light, the effect will be much more pronounced.
According to an article published on technologyreview.com, time dilation is not a thought experiment or a hypothetical concept - it is real. The Hafele-Keating experiments carried out back in 1971 proved the unique possibility of almost completely stopping time at the moment when two atomic clocks were on planes flying in opposite directions. Relative movement had a measurable impact, creating some time difference between the two hours. A similar phenomenon has also been confirmed in other physical experiments (for example, fast moving muonic particles are subject to a longer decay time than all others).
Richard Keating and Joseph Hafele, proving the possibility of time dilation
In modern science, it is believed that it is at “relativistic speeds”, which usually start at one tenth of the speed of light, that the effects of relativity are manifested in one way or another. In this case, an astronaut returning home from space travel, upon return, will look significantly younger than his friends and family members of the same age who remained on Earth. The question of exactly how much younger he will look will directly depend on the speed of the spacecraft.
At the same time, there is one more point that is worth mentioning: time can slow down not only due to the influence of the speed of light, but also as a result of the influence of some gravitational effects on it. You may have seen Christopher Nolan's Interstellar, which shows that the proximity of a black hole can literally stretch time on another planet, transforming one hour spent on Miller's planet into the equivalent of seven Earth years.
This form of time dilation is also real, which is proven in Einstein's general theory of relativity. Gravity can then significantly warp the matter of spacetime, causing clocks closer to the source of gravity to undergo a much slower flow of time than usual. An astronaut who finds himself in the immediate vicinity of a black hole will age much later than his twin brother, who decides to stay at home. Such a situation, perhaps, could be an excellent scenario for a new Hollywood blockbuster.
