46458
Neither Newton nor Huygens satisfactorily explained " diffraction " - the blurring and fringing of shadows where , according to rectilinear propagation , they ought to be sharp .
 Newton, Huygens
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Newton, Huygens