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The astronomer Carl Sagan speculated that all of the terms , except for the lifetime of a civilization , are relatively high and the determining factor in whether there are large or small numbers of civilizations in the universe is the civilization lifetime , or in other words , the ability of technological civilizations to avoid self-destruction .
 Carl Sagan
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Carl Sagan