In relativity when an object approaches the speed of light, $c$,its volume decreases due to length contraction. As a thought experiment, consider a rectangular metal box travelling at a relativistic speed. The inside of the box is filled with a gas, such that if the pressure of this gas is beyond a certain limit then the box will explode. According to Boyle's law, as volume decreases the pressure increases. So in this case would an outside observer see the box explode?
Now consider a new case where the same box filled with gas is kept at rest.This time an observer is moving at a relativistic speed close to $c$. According to frame of this moving observer he will see the box moving close to speed $c$, so would he see the box exploding due to the increase in pressure?