﻿194 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1927 
  

  

  great 
  as 
  on 
  the 
  day 
  of 
  its 
  discovery. 
  Whence, 
  for 
  example, 
  does 
  the 
  

   energy 
  come 
  which 
  enables 
  a 
  negative 
  electron 
  to 
  disregard 
  the 
  

   enormous 
  attraction 
  of 
  the 
  positive 
  nucleus 
  for 
  itself 
  and 
  eject 
  

   itself 
  with 
  an 
  energy 
  of 
  several 
  million 
  volts 
  away 
  from 
  that 
  nucleus 
  ? 
  

   It 
  is 
  just 
  as 
  though 
  a 
  liuge 
  stone 
  instead 
  of 
  remaining 
  on 
  the 
  earth 
  

   were 
  sudenly 
  to 
  decide 
  to 
  shoot 
  out 
  into 
  space 
  with 
  enormous 
  velocity 
  

   against 
  the 
  pull 
  of 
  gravity. 
  Having 
  set 
  up 
  the 
  principle 
  of 
  the 
  

   conservation 
  of 
  energy 
  as 
  our 
  universal 
  guide, 
  philosopher, 
  and 
  

   friend, 
  we 
  physicists, 
  of 
  course, 
  said 
  that 
  either 
  the 
  electron 
  which 
  

   had 
  thus 
  ejected 
  itself 
  from 
  the 
  nucleus 
  must 
  have 
  suddenly 
  absorbed 
  

   the 
  requisite 
  energy 
  from 
  some 
  unknown 
  ether 
  waves 
  which 
  are 
  

   shooting 
  through 
  all 
  space, 
  or 
  else 
  it 
  must 
  have 
  been 
  already 
  en- 
  

   dowed 
  with 
  an 
  enormous 
  kinetic 
  energy 
  inside 
  its 
  infinitesimal 
  

   nucleus, 
  and 
  some 
  kind 
  of 
  entirely 
  unknown 
  trigger 
  had 
  acted 
  to 
  

   release 
  this 
  energy. 
  The 
  first 
  hypothesis 
  has 
  already 
  been 
  weighed 
  

   in 
  the 
  balance 
  and 
  found 
  wanting, 
  so 
  that 
  the 
  second 
  is, 
  as 
  we 
  now 
  

   suppose, 
  all 
  that 
  is 
  left. 
  Thus 
  we 
  saved, 
  after 
  a 
  fashion, 
  our 
  nine- 
  

   teenth 
  century 
  faces, 
  though 
  the 
  seeking 
  for 
  any 
  kind 
  of 
  mechanical 
  

   model 
  to 
  carry 
  the 
  enormous 
  subatomic 
  energies 
  released 
  in 
  the 
  

   radioactive 
  process 
  seems 
  so 
  hopeless 
  that 
  it 
  has 
  ceased 
  to 
  be 
  an 
  

   interesting 
  diversion 
  in 
  the 
  kindergarten 
  of 
  the 
  physicist. 
  In 
  a 
  

   word, 
  radioactivity 
  not 
  only 
  revealed 
  for 
  the 
  first 
  time 
  a 
  world 
  

   changing, 
  transforming 
  itself 
  continually 
  even 
  in 
  its 
  chemical 
  ele- 
  

   ments, 
  but 
  it 
  began 
  to 
  show 
  the 
  futility 
  of 
  the 
  mechanical 
  pictures 
  

   upon 
  which 
  we 
  had 
  set 
  such 
  store 
  in 
  the 
  nineteenth 
  century. 
  

  

  Fourth. 
  It 
  may 
  have 
  been 
  something 
  of 
  a 
  blow 
  to 
  the 
  nineteenth 
  

   century 
  to 
  learn 
  of 
  the 
  general 
  transmutability 
  of 
  the 
  elements, 
  

   but 
  how 
  much 
  more 
  of 
  a 
  shock 
  to 
  find 
  that 
  the 
  principle 
  of 
  the 
  

   conservation 
  of 
  matter 
  itself 
  is 
  definitely 
  invalid. 
  Beginning 
  in 
  

   1901 
  the 
  mass 
  of 
  an 
  electron 
  was 
  shown 
  by 
  direct 
  experiment 
  to 
  

   grow 
  measurably 
  larger 
  and 
  larger 
  as 
  its 
  speed 
  is 
  pushed 
  closer 
  

   and 
  closer 
  to 
  the 
  speed 
  of 
  light. 
  But 
  of 
  much 
  greater 
  interest 
  than 
  

   that 
  is 
  the 
  fact 
  that 
  Einstein 
  worked 
  out 
  of 
  the 
  relativity 
  formulae 
  

   a 
  general 
  relation 
  between 
  the 
  two 
  quantities, 
  energy 
  and 
  mass, 
  of 
  

   the 
  form 
  mc^ 
  = 
  E 
  in 
  which 
  tii 
  means 
  mass 
  in 
  grams, 
  c"^ 
  is 
  the 
  velocity 
  

   of 
  light 
  squared, 
  or 
  the 
  enormous 
  number 
  9 
  X 
  10-°, 
  and 
  E 
  is 
  energy 
  

   in 
  ergs. 
  This 
  equation 
  seems 
  now 
  to 
  have 
  the 
  best 
  of 
  experimental 
  

   credentials. 
  If 
  it 
  is 
  a 
  correct 
  one, 
  it 
  means 
  that 
  matter 
  itself 
  in 
  

   the 
  Newtonian 
  sense, 
  the 
  quantitative 
  measure 
  of 
  which 
  is 
  mass 
  or 
  

   inertia, 
  has 
  entirely 
  disappeared 
  as 
  a 
  distinct 
  and 
  separate 
  entity, 
  

   as 
  an 
  invariant 
  property 
  of 
  any 
  system. 
  In 
  other 
  words, 
  matter 
  

   may 
  be 
  annihilated, 
  radiant 
  energy 
  appearing 
  in 
  its 
  place; 
  and 
  in 
  

   view 
  of 
  the 
  enormous 
  value 
  of 
  the 
  factor 
  9X10-'°, 
  a 
  very 
  small 
  

   number 
  of 
  grams 
  of 
  matter 
  may 
  transform 
  themselves 
  into 
  a 
  

   stupendous 
  number 
  of 
  ergs 
  of 
  energy. 
  

  

  