2019年USAAAO决赛第1题

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 $$2.7 K$$.

中文翻译

1.(7 points) 假设当前重子物质的密度为$$ρ_{b0} = 4.17×10^{-28} kg/m^3$$，那么在大爆炸核合成时（当$$T \sim 10^{10} K$$）时，重子物质的密度是多少？假设当前温度，$$T_0$$，为$$2.7 K$$。