If the Universe is expanding, what is it expanding into?

Van writes in with, 'A friend is encouraging me to take a cancer screening test that screens for many different cancers. A review of one test says: "While overall it picks up 90% of stage 4 cancers, it only detects an average of 17% of stage 1 cancers. Yet it is being touted as a test that can detect cancer early." Are these tests worthwhile?' James Tytko took on the question with the help of Professor Rebecca Fitzgerald, Founding Director of the Early Detection Institute at the University of Cambridge... Like this podcast? Please help us by supporting the Naked Scientists

If dinosaurs hadn't been wiped out by a mass extinction event, would there have been room for humans to grow into the successful species we are today? That's what Colin wants to know, and James Tytko has promised to find the answer. He spoke with Dr Charlotte Kenchington from the University of Cambridge's Department of Earth Sciences... Like this podcast? Please help us by supporting the Naked Scientists

Pamela wants to know whether the distribution of chemical isotopes is the same on other planets as it is on Earth. Take carbon, for example, 99% of which is carbon-12 on Earth while 1% is carbon-13? To find the answer, James Tytko asked Xander Byrne from the University of Cambridge's Institute of Astronomy... Like this podcast? Please help us by supporting the Naked Scientists

David wants to know whether the intricate and varied spiders' webs seen in nature are a product of arachnid instinct, or something that is cultivated across their life. To get to the truth, James Tytko sought out spider expert Professor Sara Goodacre from the University of Nottingham... Like this podcast? Please help us by supporting the Naked Scientists

Jim writes in to say, 'Sometimes when I pinch near my knee, I will feel a tingling or tickling sensation behind one of my shoulder blades. What's up with that?' James Tytko found him an answer, with help from neuroscientist Dr Mark Hoon from the NIH... Like this podcast? Please help us by supporting the Naked Scientists

Oscar asks whether the snail stuck on the inside of his car wheel while he went for a drive would have felt the effects afterwards. Jon Ablett from the Natural History Museum helped James Tytko with the answer... Like this podcast? Please help us by supporting the Naked Scientists

Akori wants to know whether it is safe to eat vegetables and herbs grown where animals have been buried in the past. James Tytko sought the help of Professor Malcolm Bennett at the University of Nottingham's School of Veterinary Medicine and Science... Like this podcast? Please help us by supporting the Naked Scientists

Thanks to Jim Dale for the answer! Like this podcast? Please help us by supporting the Naked Scientists

This week, Carl writes in to ask whether he can be cured of specific musical anhedonia. This is a condition whereby a person can hear and distinguish between different types of music and the emotion they convey, but doesn't feel moved in the same way most people do. James Tytko took on Carl's conundrum with the help of Malinda McPherson, Assistant Professor at Purdue University's Department of Speech, Language and Hearing Sciences... Like this podcast? Please help us by supporting the Naked Scientists

When listener Suzy is taking pictures of the night sky, she makes use of longer shutter speeds to capture more light to get better images of stars. That got her thinking, do human eyes also have a shutter speed? James Tytko took up the question... Like this podcast? Please help us by supporting the Naked Scientists