Question: expansion of a perfect gas into vacuum is related with
[{'answer': 'entropy', 'provenance': [{'wikipedia_id': '1867005', 'title': 'Joule expansion', 'start_paragraph_id': 2, 'start_character': 248, 'end_paragraph_id': 2, 'end_character': 255, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1867005', 'title': 'Joule expansion', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 503, 'bleu_score': 0.9712154609069981, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10475874171808926927}, 'section': 'Section::::Abstract.'}]}]