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  ANNUAL 
  EEPORT 
  SMITHSONIAN 
  INSTITUTION, 
  192'7 
  

  

  the 
  number 
  of 
  electrons 
  and 
  protons 
  in 
  a 
  star 
  must 
  continually 
  

   decrease. 
  

  

  With 
  this 
  figure 
  before 
  us, 
  it 
  is 
  clear 
  that 
  the 
  comparatively 
  feeble 
  

   stellar 
  temperatures 
  of 
  less 
  than 
  1,000,000,000 
  degrees 
  must 
  be 
  

   quite 
  inoperative 
  in 
  regard 
  to 
  the 
  main 
  generation 
  of 
  stellar 
  energy 
  ; 
  

   indeed, 
  the 
  heat 
  of 
  the 
  hottest 
  of 
  stellar 
  interiors 
  can 
  have 
  no 
  more 
  in- 
  

   fluence 
  on 
  the 
  rate 
  of 
  annihilation 
  of 
  matter 
  than 
  a 
  warm 
  summer's 
  

   day 
  has 
  on 
  the 
  rate 
  of 
  disintegration 
  of 
  uranium. 
  Thus 
  it 
  seems 
  

   abundantly 
  clear 
  that 
  what 
  is 
  annihilating 
  the 
  matter 
  of 
  the 
  stars 
  

   is 
  neither 
  heat 
  nor 
  cold, 
  neither 
  high 
  density 
  nor 
  low, 
  but 
  merely 
  the 
  

   passage 
  of 
  time. 
  

  

  These 
  considerations 
  notwithstanding, 
  it 
  has 
  been 
  suggested 
  by 
  

   Russell 
  (Nature, 
  August 
  8, 
  1925) 
  , 
  whose 
  ideas 
  were 
  afterwards 
  adopted 
  

   by 
  Eddington 
  (Nature, 
  May 
  1, 
  1926), 
  that 
  the 
  annihilation 
  of 
  matter 
  

   (which 
  they 
  agree 
  to 
  be 
  the 
  ultimate 
  source 
  of 
  stellar 
  radiation) 
  may 
  

   be 
  produced 
  by 
  the 
  raising 
  of 
  ordinary 
  matter 
  to 
  a 
  critical 
  tempera- 
  

   ture 
  of 
  some 
  thirty 
  or 
  forty 
  million 
  degrees. 
  Russell 
  suggests 
  that 
  

   matter 
  is, 
  broadly 
  speaking, 
  inert 
  until 
  it 
  reaches 
  this 
  critical 
  tem- 
  

   perature, 
  when 
  an 
  unlimited 
  transformation 
  of 
  matter 
  into 
  radiation 
  

   suddenly 
  takes 
  places. 
  

  

  In 
  addition 
  to 
  running 
  foul 
  of 
  the 
  physical 
  principles 
  just 
  ex- 
  

   plained, 
  this 
  suggestion 
  encounters 
  the 
  difficulty 
  that 
  the 
  generation 
  

   of 
  energy 
  it 
  provides 
  would 
  not 
  only 
  be 
  unlimited 
  but 
  also 
  illimit- 
  

   able; 
  when 
  once 
  it 
  began 
  there 
  would 
  be 
  no 
  stopping 
  it. 
  The 
  pro- 
  

   posal 
  of 
  Russell 
  and 
  Eddington 
  would, 
  in 
  effect, 
  make 
  matter 
  ther- 
  

   modynamically 
  unstable 
  at 
  stellar 
  temperatures 
  by 
  endowing 
  it 
  with 
  

   the 
  properties 
  of 
  an 
  explosive 
  at 
  its 
  flash 
  point. 
  When 
  once 
  stellar 
  

   matter 
  reached 
  its 
  flash 
  point, 
  its 
  resulting 
  annihilation 
  would 
  gener- 
  

   ate 
  so 
  much 
  heat 
  that 
  the 
  adjacent 
  matter 
  would 
  also 
  in 
  turn 
  be 
  

   raised 
  to 
  the 
  flash 
  point, 
  and 
  the 
  whole 
  star 
  would 
  almost 
  instantane- 
  

   ously 
  explode 
  into 
  radiation. 
  The 
  sliy 
  would 
  show 
  no 
  steady 
  star- 
  

   light, 
  but 
  merely 
  a 
  succession 
  of 
  apparitions 
  of 
  novae 
  of 
  the 
  most 
  

   terrifying 
  kind, 
  as 
  the 
  various 
  stars 
  reached 
  their 
  flash 
  points 
  and 
  

   " 
  popped 
  off 
  " 
  in 
  turn. 
  In 
  spite 
  of 
  the 
  astronomical 
  eminence 
  of 
  its 
  

   father 
  and 
  stepfather, 
  I, 
  for 
  one, 
  find 
  it 
  impossible 
  to 
  accept 
  a 
  

   hypothesis 
  which 
  is 
  not 
  only 
  contrary 
  to 
  the 
  general 
  principles 
  of 
  

   physics 
  but 
  also 
  against 
  which 
  the 
  very 
  stars 
  fight 
  in 
  their 
  courses. 
  

  

  A 
  general 
  mathematical 
  discussion 
  of 
  the 
  stability 
  problem 
  shows 
  

   that 
  a 
  star 
  built 
  of 
  matter 
  the 
  rate 
  of 
  generation 
  of 
  energy 
  of 
  which 
  

   is 
  absolutely 
  unaffected 
  by 
  changes 
  of 
  temperature 
  and 
  density 
  will 
  

   be 
  dynamically 
  stable. 
  But 
  such 
  a 
  star, 
  although 
  stable, 
  has 
  not 
  

   much 
  stability 
  to 
  spare. 
  If 
  we 
  change 
  the 
  properties 
  of 
  our 
  stellar 
  

   matter 
  in 
  the 
  sense 
  of 
  making 
  an 
  increase 
  of 
  temperature 
  increase 
  

   the 
  rate 
  of 
  generation 
  of 
  energy, 
  we 
  lessen 
  the 
  already 
  small 
  margin 
  

  

  