Researchers say they now know how reactive phosphorus, an important element that helped start life on Earth, got here.  The team’s leader on the project was University of South Florida’s Matthew Pasek. He joins us to talk about his team’s research and findings. Other stories we cover include: After a US sponsored clinical trial in Thailand, scientists have found that a medication used to treat HIV patients can also be effectively used as a preventative.   Students at the University of Virginia have developed a device that could bring improved water quality for millions in the developing world. Plus we have another edition of the Science World Quick Quiz!