﻿THE 
  PHYSICS 
  OF 
  THE 
  UNIVERSE 
  

  

  By 
  Sir 
  James 
  Jeans, 
  Sec. 
  R. 
  S. 
  

  

  The 
  ancients 
  were 
  for 
  the 
  most 
  part 
  content 
  to 
  regard 
  the 
  universe 
  

   as 
  a 
  theatre 
  which 
  had 
  been 
  specially 
  constructed 
  for 
  the 
  drama 
  of 
  

   human 
  life. 
  Men, 
  and 
  even 
  the 
  gods 
  that 
  man 
  had 
  created 
  in 
  his 
  

   own 
  image, 
  came, 
  lived, 
  and 
  disappeared 
  after 
  strutting 
  their 
  tiny- 
  

   hour 
  upon 
  a 
  stage 
  to 
  which 
  the 
  eternal 
  hills 
  and 
  the 
  unchanging 
  

   heavens 
  formed 
  a 
  permanent 
  background. 
  While 
  some 
  thought 
  

   was 
  given 
  to 
  the 
  birth 
  of 
  the 
  universe, 
  and 
  its 
  creation 
  or 
  emergence 
  

   from 
  chaos, 
  very 
  few 
  thought 
  of 
  it 
  as 
  living 
  its 
  life 
  and 
  passing 
  from 
  

   birth 
  to 
  death 
  in 
  the 
  same 
  way 
  as 
  a 
  man 
  or 
  a 
  tree 
  passes 
  from 
  birth 
  to 
  

   death. 
  

  

  In 
  modern 
  times 
  the 
  idea 
  of 
  secular 
  change 
  crept 
  into 
  the 
  picture. 
  

   Geologists 
  began 
  to 
  study 
  the 
  earth 
  as 
  a 
  changing 
  structure, 
  and 
  

   astronomers 
  to 
  give 
  thought 
  to 
  the 
  evolution 
  of 
  the 
  stars, 
  recognizing 
  

   them 
  as 
  bodies 
  which 
  are 
  born, 
  live 
  their 
  lives 
  of 
  gradual 
  change, 
  and 
  

   finally 
  die. 
  But 
  the 
  ultimate 
  constituents 
  of 
  the 
  universe, 
  the 
  atoms, 
  

   were 
  still 
  supposed 
  to 
  be 
  immune 
  from 
  change. 
  The 
  hypothesis 
  

   that 
  all 
  matter 
  consisted 
  of 
  permanent, 
  indivisible, 
  and 
  unchangeable 
  

   atoms, 
  which 
  had 
  been 
  advanced 
  so 
  far 
  back 
  as 
  the 
  fifth 
  century 
  

   B. 
  C. 
  by 
  Leucippus 
  and 
  Democritus, 
  remained 
  practically 
  unshaken 
  

   until 
  the 
  end 
  of 
  the 
  nineteenth 
  century. 
  The 
  ageing 
  of 
  the 
  universe 
  

   was 
  supposed 
  to 
  amount 
  to 
  nothing 
  more 
  than 
  a 
  rearrangement 
  of 
  

   indestructible 
  units 
  which 
  were 
  themselves 
  incapable 
  of 
  any 
  sort 
  of 
  

   change 
  or 
  decay. 
  Like 
  a 
  child's 
  box 
  of 
  wooden 
  bricks, 
  the 
  atoms 
  

   made 
  many 
  buildings 
  in 
  turn. 
  

  

  ATOMIC 
  CHANGES 
  

  

  Then 
  Crookes, 
  Lenard, 
  and, 
  above 
  all, 
  Sir 
  J. 
  J. 
  Thomson, 
  began 
  

   to 
  break 
  up 
  the 
  atom. 
  The 
  bricks 
  of 
  the 
  universe 
  which 
  had 
  been 
  

   deemed 
  unbreakable 
  for 
  more 
  than 
  2,000 
  years 
  were 
  suddenly 
  shown 
  

   to 
  be 
  very 
  susceptible 
  to 
  having 
  fragments 
  chipped 
  off; 
  a 
  milestone 
  

   was 
  reached 
  in 
  1895, 
  when 
  Sir. 
  J. 
  J. 
  Thomson 
  showed 
  that 
  these 
  

  

  1 
  The 
  first 
  Henry 
  Herbert 
  wyis 
  Memorial 
  Lecture 
  of 
  the 
  University 
  of 
  Bristol, 
  delivered 
  at 
  the 
  University 
  

   on 
  Oct. 
  30. 
  Reprinted 
  by 
  permission 
  from 
  Supplement 
  to 
  Nature, 
  Nov. 
  3, 
  1928. 
  

  

  161 
  

  

  