2019年USAAAO决赛第1题
来自astro-init
Jingsong Guo(讨论 | 贡献)2020年3月7日 (六) 17:36的版本
英文题目
1. (7 points) Assuming that the present density of baryonic matter is $$ρ_{b0} = 4.17*10^{-28} kg/m^3$$ , what was the density of baryonic matter at the time of Big Bang nucelosynthesis (when $$T \sim 10^{10} K$$)? Assume the present temperature, $$T_0$$ to be $$2.7 K$$.