A boy visits the National Museum of Scotland during the Edinburgh International Science Festival held in Edinburgh, Scotland, Britain, April 1, 2013. The 25th Edinburgh International Science Festival was held from March 23 to April 7. (Xinhua/Guo Chunju)

People visit the National Museum of Scotland during the Edinburgh International Science Festival held in Edinburgh, Scotland, Britain, April 1, 2013. The 25th Edinburgh International Science Festival was held from March 23 to April 7. (Xinhua/Guo Chunju)

People visit the National Museum of Scotland during the Edinburgh International Science Festival held in Edinburgh, Scotland, Britain, April 1, 2013. The 25th Edinburgh International Science Festival was held from March 23 to April 7. (Xinhua/Guo Chunju)

People visit the National Museum of Scotland during the Edinburgh International Science Festival held in Edinburgh, Scotland, Britain, April 1, 2013. The 25th Edinburgh International Science Festival was held from March 23 to April 7. (Xinhua/Guo Chunju)