摘要
This paper introduces three cosmic expansion models with constant, decelerating and accelerating speed of expansion respectively. Then characters of these cosmic expansion models are compared. Based on these cosmic expansion models, the thresholds of observable universe are calculated via simulations, where the earliest observable cosmic radius <i>R</i>(<i>t<sub>earliest</sub></i>) is always 0.368<i>R</i> (<i>R</i> is cosmic radius at current universe time) for any cosmic expansion models.
This paper introduces three cosmic expansion models with constant, decelerating and accelerating speed of expansion respectively. Then characters of these cosmic expansion models are compared. Based on these cosmic expansion models, the thresholds of observable universe are calculated via simulations, where the earliest observable cosmic radius <i>R</i>(<i>t<sub>earliest</sub></i>) is always 0.368<i>R</i> (<i>R</i> is cosmic radius at current universe time) for any cosmic expansion models.
