X-rays are high energy electrons that can cause damage when exposed under extreme conditions. The best technology that can block it is using a lightweight type of metal foam. It can take in high energy collisions which also exhibits high forces. it does not only block x-rays but also, neutron radiation and gamma rays. A gamma ray primarily consists of pure energy and no mass is true. In fact it consists of high energy photons and massless. They have no charge and when exposed to any kind of material, it just passes through as if nothing is blocking it.
Efforts to relate gamma-ray bursts with specific sources has had what results so far?