Another Two Dark Energy Models Motivated from Karolyhazy Uncertainty   Relation
  The K$\acute{\text{a}}$rolyh$\acute{\text{a}}$zy uncertainty relation indicates that there exists the minimal detectable cell $\delta t^{3}$ over the region $t^3$ in Minkowski spacetime. Due to the energy-time uncertainty relation, the energy of the cell $\delta t^3$ can not be less $\delta t^{-1}$. Then we get a new energy density of metric fluctuations of Minkowski spacetime as $\delta t^{-4}$. Motivated by the energy density, we propose two new dark energy models. One model is characterized by the age of the universe and the other is characterized by the conformal age of the universe. We find that in the two models, the dark energy mimics a cosmological constant in the late time. 
Cheng-Yi Sun, Wen-Li Yang, Rui-Hong Yue and Yu Song
hep-th