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According to this argument , made by scientists such as Carl Sagan and Stephen Hawking , as well as notable personalities such as Winston Churchill , it would be improbable for life " not " to exist somewhere other than Earth .
 Carl Sagan, Stephen Hawking, Winston Churchill
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Carl Sagan, Stephen Hawking, Winston Churchill