Do Astronauts Age Slower in Space?

The notion that time is a constant in life and passes day after day at the same pace has been challenged by Albert Einstein's Theory of Relativity, which introduced the concept that "time is relative." This idea is difficult to grasp, as it implies that the experience of time can vary depending on our position and speed in space-time, which is not flat but curved and can be distorted by matter and energy. As a result, time can appear to move faster or slower to us in comparison to others in a different part of space-time. Astronauts on the International Space Station, for instance, experience time dilation effects and age slightly slower than those on Earth, as the gravitational force of massive objects bends space-time and slows down the passage of time.

"Gravitational time dilation" is the phenomenon where time moves slower as gravity increases. This effect is why time passes slower for objects closer to the center of the Earth, where gravity is stronger. However, this effect is not noticeable on a small scale, such as spending a lifetime in a basement. The second factor is "relative velocity time dilation," where time moves slower as you move faster. An example of this is the twin scenario where one twin travels close to the speed of light and ages slower than the other twin who stayed on Earth. Gravitational time dilation and relative velocity time dilation can happen simultaneously, as experienced by astronauts on the International Space Station who age slower than people on Earth due to their velocity being greater than the gravitational force. Although the difference is not noticeable, astronauts who spend six months on the ISS age about 0.005 seconds less than those on Earth. Therefore, time is relative, and even the tiniest change in velocity or gravity can affect the passage of time.