If I have to send a beta particle in space and if the space is completely empty (from matter and energy just imagine!!!!) What would happen to the particle? If I put a very good GM in 1 Km from the source should I detect the beta particle if the beta particle has the power of 0.5 Mev? Dose the beta particle decomposition in the emptiness of the space and why (there is nothing in that space to absorb the beta particle.) should the beta particle just continue moving until it hits something that absorb it or not!!!! Sorry about my Q maybe it look like a naive Question but really believe me I never get an answer that make me rest. and i post it in other places so i hop to get more than one opinions thank you all !!!!!!!