# size of the Universe

22 May 2013Can you estimate a minimum size of the Universe \(\chi_K\) given current bounds on the curvature parameter \(\Omega_K\) and compare this length scale to the size \(\chi_H=c/H_0\) of the observable Universe?

maths bonus question: What’s the slope of \(x^{\sin(x)^x}\) at \(x=0\) and where’s the first minimum in the positive \(x\)-range?

physics bonus question: Why do neutrons in neutron stars not decay? With neutron decay half-time of about a quarter of an hour, neutron stars should decay rather quickly!