Science

Time Dilation Time dilation stems from Einstein’s theory of special relativity, which says that moving clocks tick more slowly by a factor (called the Lorentz factor). At everyday speeds, the Lorentz factor is approximately one, so the effect is negligible. Near light speed, it becomes dramatic. Here’s the Lorentz factor formula showing how the factor increases with speed: $$ \begin{aligned} &\gamma = 1/\sqrt{1 - v^2/c^2}\\ &\text{where}\\ &\hspace{1em}\gamma = \text{Lorentz factor}\\ &\hspace{1em}v = \text{relative velocity between two objects}\\ &\hspace{1em}c = \text{speed of light} \end{aligned} $$Project Hail Mary The ship in Project Hail Mary (the Book and Movie) travels at about 92% of light speed, so the Lorentz factor is approximately 2.55. In reality, the ship would most likely accelerate for half the trip and decelerate for the rest, but let’s keep it simple using constant velocity. One year on the ship corresponds to about 2.55 years outside it. That’s why a journey that feels like a few years to Grace can become more than a decade for Earth. ...