4375
Sean M. Carroll , who specializes in theoretical cosmology and field theory , explains two competing explanations for the origins of the singularity , which is the center of a space in which a characteristic is limitless .
 person: Sean M. Carroll
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 person: Sean M. Carroll