# The speed of light and unstable matter

Mr.E is on a luxury spaceship travelling about 1/2 the speed of light and finds a cubic lump of unstable matter(attached to a bomb) in his cabin. He of course is an expert with bombs but this device is based on the unstable matter's critical mass. The lump of matter fluctuates a tiny amount constantly but if it is more than 2k.g, (say for the sake of argument) it will cause the bomb to explode. Right now it is at 1.9999k.g., if the ship accelerates making it over 2kg relative to the people anxiously monitering the ship from Earth they would think it should detonate yet relative to Mr.E and the fellow passengers its mass is still under 2kg?? Is this loose reasoning valid?

• No, with the critical mass, you are thinking about something like an atomic bomb. Now, the thing is that while the mass would increase, you'd still have as many atoms in the material. And therefore not enough to get a chain reaction and thus an explosion. – Raskolnikov Apr 15 '14 at 6:14
• If an object is accelerating towards c would any inherent radioactivity of the object increase? – user128932 Apr 15 '14 at 6:22