Standing in one of the largest neo-natal units in the world at Hamad Hospital in Qatar, you would not immediately be able to draw a link between the pioneering medical research being conducted and the work of physicists from the 9th century.In this episode of Science in the Golden Age, theoretical physicist Jim al-Khalili guides us through a journey of discovery where he highlights the links between medical research in the Golden Age of Science during the 9th and 14th centuries and the modern practice of medicine today.At Hamad Hospital, a new treatment is being trialled for babies born with a neurological disorder called neo-natal encephalopathy. Senior consultant Dr Samawal Lutfi explains how the double blind placebo control method ensures the accuracy of the study. This notion of a control group goes all the way back over a thousand years to a Persian physician by the name of Al-Razi who built the first hospitals in Baghdad. He was an early proponent of applying a rigorous scientific approach to medicine and used a control group when testing methods to treat meningitis in the 9th century.At Harefield Hospital in the UK, we meet Professor Magdi Yacoub, a pioneering transplant surgeon and one of the world's leading heart specialists.Professor Yacoub explains how the 13th century Syrian scholar Ibn al-Nafis redefined the understanding of pulmonary circulation. He challenged the commonly accepted wisdom of the Greek scholar Galen, who had said that blood passes directly between the heart's right and left ventricle through the septum, the dividing wall that separates them. Ibn al-Nafis put forward the idea that blood could not pass directly between the right and left chambers of the heart - and that the lungs had a role to play in this process. Ibn al-Nafis' description was not widely accepted at the time, and it wasn't until his manuscript was re-discovered in the 20th century that his work was universally recognised.From Al-Razi, to Ibn al-Nafis, to the 10th-century