According to Einstein's theory of special relativity, it is possible to be years older than your identical twin because time can tick at different speeds depending on how you are moving.
In this theory, one of two twins travels at near the speed of light to a distant star, then he returns to Earth. Relativity dictates that when he comes back, he is younger than his identical twin.
Special relativity is an idea that was first proposed by Albert Einstein and explains how space and time are connected for objects that are moving at a consistent speed in a straight line. One of its most famous aspects concerns objects moving close to or at the speed of light.
“One example of relativity is to imagine two people on a train playing ping-pong. The train is traveling at around 30 mph north. When the ball is hit back and forth between the two players, the ball appears to the players to move north at a speed of around 2 mph, and then south at the speed of 2 mph. Now imagine someone standing beside the railroad tracks watching the ping-pong game. When the ball is traveling north it will appear to travel at 32 mph (30 mph plus 2 mph). When the ball is hit in the other direction, it still appears to travel north, but at a speed of 28 mph (30 mph minus the 2 mph). To the observer by the side of the train, the ball always appears to be traveling north. The result is that the speed of the ball depends on the "relative" position of the observer. It will be different for the people on the train than for the person on the side of the railroad tracks, “ says Physics for Kids.
Special relativity tells us that a clock traveling at a high speed past an observer appears to be ticking slower. Since relativity says that there is no absolute motion, the twin traveling to the star would see his brother’s clock moving more slowly, and the twin on Earth would also see the other brother’s clock moving slow. So, if this were the case, wouldn’t both brothers be the same age?
This paradox is addressed in many books but is rarely solved. When the paradox is discussed, it is done so very briefly usually saying that the twin feeling the acceleration is the one who is younger by the end of the trip. Hence, the brother who travels to the star is younger. While the result is correct, the explanation is confusing. So, what is the twin paradox?
Consider two twins, named Kevin and Bob. On their twentieth birthday, Kevin decides to get in a rocket and take off into outer space, traveling at near the speed of light. He journeys around the universe at this speed for about 30 years, returning to Earth when he is 50 years old. Bob on the other hand, has just turned 95 years.
In this example, there are two frames of reference that move differently from each other, so they experience time differently. This is known as Time Dilation. Because Kevin was traveling so rapidly, time dilation was in effect, therefore making him age slower than his twin, Bob, on Earth.
Story by Ava Macie
Gushanas, Timothy. “NASA Twins Study Confirms Preliminary Findings.” NASA, NASA, 31 Jan. 2018, www.nasa.gov/feature/nasa-twins-study-confirms-preliminary-findings.
“Physics for Kids.” Ducksters Educational Site, www.ducksters.com/science/physics/theory_of_relativity.php.