# How fast would an observer have to travel in order to be able to study an entire star's life in one human lifetime?

Humans live for about 80 years. A star, however, lives from 1 million to trillions of years, depending on its mass. If humans want to have a detailed study of the life of a $$1 M_\odot$$ star, how fast would they have to travel, and would it be viable?

We want it so that $$1 \text{ year at the speed of x% of c} = \dfrac{10^{10}}{80} \text{ stationary years}$$. The Lorentz factor (in terms of c) is $$\gamma=\dfrac{1}{\sqrt{1-v^2}}$$. Solving for $$v$$ with $$\gamma = \dfrac{10^{10}}{80},$$ we get $$v=0.999999999999999968c = 299792457.999... \text{m}\cdot\text{s}^{-1}$$. This is definitely impossible, as the energy requirements are astronomically large: $$5572282108577709241 \text{J}\cdot c^{-2} \cdot 125000000 =696535263572213655125000000 \text{J} = 7.75 \cdot 10^9 \text{ kg of mass converted to energy}$$