The more advanced a medical intervention is, it seems, the less invasive it is to perform. For example, bariatric surgery once entailed opening a patient's abdomen from navel to diaphram; today such operations are done laparoscopically through incisions mere centimeters in size. Now researchers at the Massachusetts Institute of Technology have built a prototype robot that can perform simple procedures inside the stomach without any incisions or external tethers at all—the patient just swallows it.