# Does the speed of light affect aging?

The phenomenon of time dilation in space for a long timeexcited the minds of science fiction writers from around the world. However, the question of how strongly the astronaut’s movement with the speed of light affects his biological clock was first described in the so-called “twin paradox,” in which the astronaut travels into space on a high-speed rocket, and his twin brother remains on The 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 almost remain the same.

The speed of light can have a strong effect on the aging processes that occur in the body of astronauts.

Why does the speed of light slow down time?

Slowing down time goes back to special theoryEinstein’s relativity, which teaches us that motion 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, in essence, is time. Time in this case is measured differently for the astronaut and his twin, who remained on Earth. A clock in motion will be ticking slower than a clock that we observe 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 the portaltechnologyreview.com, time dilation is not a thought experiment or a hypothetical concept - it is real. The Hafele-Keating experiments conducted back in 1971 proved a unique opportunity to almost completely stop the time at the moment when two atomic clocks were on airplanes flying in opposite directions. The relative movement had a measurable effect, creating some time difference between the two hours. A similar phenomenon was also confirmed in other physical experiments (for example, rapidly moving muon particles are subject to longer decay than all others).

Richard Keating and Joseph Hafele, proving the possibility of time dilation

In modern science, it is believed that on“Relativistic velocities”, which usually start at one tenth of the speed of light, manifest the effects of relativity in one way or another. In this case, the astronaut returning home from space travel, upon return, will look much younger than his friends and family representatives of the same age who remained on Earth. The question of how much younger he will look will directly depend on the speed of the spacecraft.

See also: NASA scientist has shown how slow the speed of light can be

However, there is another point thatworth 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 film, which shows that the proximity of a black hole can literally stretch time on another planet, turning one hour spent on the planet Miller into the equivalent of seven Earth years.

This form of time dilation is also real,which is proved in Einstein's general theory of relativity. Gravity in this case can significantly distort the matter of space-time, forcing the clock located closer to the source of gravity to undergo a much slower flow of time than usual. An astronaut who finds himself in close proximity to a black hole will age much later than his twin brother, who decided to stay at home. This situation, perhaps, can be a great scenario for the new Hollywood blockbuster.