After years of training, double-amputee Oscar Pistorious achieved his dream this week, when South Africa’s athletics federation selected him for the country’s team in the track and field world championships. Pistorious – who was born without fibulae, or calf bone – achieved an Olympic qualifying time of 45.07 seconds for the 400-meter dash last month. But not everybody is rooting for him to succeed. Some critics are saying that Pistorious’s prosthetic legs have unfairly boosted his performance in time trials. Hugh Herr, associate professor and director of the Biomechatronics Group at MIT’s Media Lab, set the record straight.