The Twin Paradox
It is possible to be older than your identical twin. Einstein's theory of special relativity says this is possible because time can tick at different speeds depending on how you are moving.
from Physics Girl
Key Facts In This Video
According to Einstein's Theory of Special Relativity, it's possible to be older or younger than your twin because time can take faster or slower depending on how you're moving. (0:06)
The first postulate of Special Relativity states that the laws of physics are the same for everyone's perspective while in uniform motion. (0:21)
The second postulate is that the vacuum speed of light is the same for all observers. (0:55)