5288
In the 1990 s , Joseph Polchinski discovered that the theory requires higher-dimensional objects , called D-branes and identified these with the black-hole solutions of supergravity .
 person: Joseph Polchinski
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 person: Joseph Polchinski