A subatomic particle moves through the laboratory at $0.90 \mathrm{c}$. Laboratory experimenters measure its lifetime, from creation to annihilation, to be 2.3 ps $\left(1 \mathrm{ps}=1\right.$ picosecond $\left.=10^{-12} \mathrm{s}\right)$ According to the particle, how long did it live?