Dr Chris Smith and the Naked Scientist team present the latest science news, analysis and breakthroughs. This week: New muscles on a chip technology goes into orbit to find new drugs to block the ravages of weightlessness and ageing, how artificial intelligence looks set to revolutionise how we forecast the weather, and scientists track down the brain pathway that controls the placebo effect. Plus an in-depth look at how athletes compete at the highest level as the Olympic Games get underway.