Does special relativity affect biological processes, such as aging?

Since you were in the rocket, fifty years passed by according to your friends who stayed behind; if any of them survived, they will see you aged only five years in their past fifty years, but according to your own body, you aged five years in five years. Let's say that you are twenty years old and you climb into a rocket, traveling at 99.5% of the speed of light for five years (round trip) of the time you measure. You land back on Earth with the body of a twenty-five-year-old, exactly as if you had spent your five years on Earth.

This phenomenon also applies to particles of a smaller size. For example, a set of identical particles may have a half-life of 10 microseconds according to their own time, which a scientist would accurately measure if the particles were simply positioned in front of him. However, if the particles are accelerated to 99.5% of the speed of light, the scientist will observe that the half-life increases to 100 microseconds on his watch, even though the particles still claim that it is only 10 microseconds.

The timing of a process is altered by special relativistic effects, not the particles' or your body's internal processes.

Yes, time dilation—a phenomenon predicted by special relativity—means that time passes differently for objects moving at different speeds relative to each other. This effect has been observed in high-speed particle experiments and is taken into account in GPS systems. Although time dilation has little effect on human biology at typical speeds, it may become significant for objects traveling close to the speed of light. In everyday life on Earth, however, special relativity has no effect on biological processes, including aging.