{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "0fe8c54c-bf90-43ae-b74c-dacc1629265f",
   "metadata": {},
   "outputs": [],
   "source": [
    "from math import pi"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "3470c0a9-cc70-4e62-a50f-8e959ce4a7db",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "c = 299792458 # speed of light in metres / second"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "44e5cc18-0530-449f-8871-d3e2ccfd9284",
   "metadata": {},
   "source": [
    "Wikipedia gives the following values for the size of the observable universe.\n",
    "https://en.wikipedia.org/wiki/Observable_universe"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "id": "f6f5d59a",
   "metadata": {},
   "outputs": [],
   "source": [
    "# Newton's gravitational constant\n",
    "G=6.674e-11"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "id": "5033a94e",
   "metadata": {},
   "outputs": [],
   "source": [
    "# Volume of observable universe\n",
    "wikivol = 3.566e80"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "id": "a2f682fa",
   "metadata": {},
   "outputs": [],
   "source": [
    "# mass of observable universe\n",
    "wikimass = 1.5e53\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "id": "d5074365",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4.206393718452047e-28"
      ]
     },
     "execution_count": 25,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Density of observable universe\n",
    "wikimass/wikivol\n",
    "# wiki states that as 9.9e-27"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "id": "4817e7e1",
   "metadata": {},
   "outputs": [],
   "source": [
    "wikidens = 9.9e-27"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "id": "5362e106",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "2.227747942230555e+26"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Compute Swarzchild radius of observable universe\n",
    "swarz = 2*G*wikimass/c**2\n",
    "swarz"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "194538aa-8015-4200-a92c-1f81e69769f6",
   "metadata": {},
   "source": [
    "Reed's value for size of the observable universe.  Not sure if this is radius or diameter"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "id": "d01081f9-a095-43f1-90dd-5d8ffc8f8daa",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "2.2572554680727403e+26"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "reeddiameter = 8*pi*c**3/3\n",
    "reeddiameter"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "id": "466c885b",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "1.0011e+43"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "G*wikimass"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a28b0355",
   "metadata": {},
   "source": [
    "How much mass is outside the swarzchild radius?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "id": "ab151e61",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.8701310216615278"
      ]
     },
     "execution_count": 35,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# compute the ratio of both volumes and multiply by the density to get that mass figure\n",
    "(1-(4*pi*swarz**3/3)/wikivol)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "d71a5e37",
   "metadata": {},
   "source": [
    "87% of your required mass is outside your swarzchild radius."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "7d664f45",
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3 (ipykernel)",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.9.5"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 5
}