Cosmos 2: The Friedmann Equation

Don't Panic

Sections

  1. Introduction
  2. Schwarschild Radius
  3. Free-Fall Time
  4. Hubble Quantities

  1. Introduction

    2.

  2. Schwarschild Radius

    3.        print*
       c=2.99792458d8    ! https://en.wikipedia.org/wiki/Speed_of_light
       g=6.67408d-11     ! https://en.wikipedia.org/wiki/Gravitational_constant#Value_and_dimensions
       xmsun=1.98855d30  ! https://en.wikipedia.org/wiki/Solar_mass
       rsch=2.d0*g*xmsun/c**2
       print*,'rsch'
       print*,rsch
! 2953.3608479793502
! 1234 56  significant digits

  3. Free-Fall Time

    4.        print*
       print*,'Free-fall time for a uniform sphere.'
       g=6.67408d-11     ! https://en.wikipedia.org/wiki/Gravitational_constant#Value_and_dimensions
       pi=acos(-1.d0)
       con=sqrt(3.d0*pi/32.d0)
       cona=sqrt(3.d0/(8.d0*pi))
       cong=con/sqrt(g)
       print*,'con,cong,cona'
       print*,con,cong,cona
!  0.54270094091870069        66430.094538655190       0.34549414947133550
!                             12345 6

  4. Hubble Quantities