Naked Scientists: obesity policy, carbon-14 diamond batteries, and dark comets

Overview

The Naked Scientists delivery covers science breakthroughs across health policy, energy storage, and space science with expert guests and host commentary. In this episode the discussion spans obesity policy in the UK, a novel power source using radioactive carbon in diamond, and celestial objects that challenge our ideas about the solar system. The show also features a Question of the Week on nuclear energy and a look at recent space observations.

Key insights

• Obesity policy debate centers on a potential junk food levy and public health implications
• A carbon-14 diamond battery could provide tiny, long lasting power in extreme environments
• Dark comets and new JWST observations expand our understanding of small bodies in the solar system
• A QOTW explores direct energy from nuclear decay versus traditional fission systems

Overview

The podcast presents a curated tour through recent science news and expert interviews, anchored by host Chris Smith. The episode threads together public health policy, innovative energy storage technology, and space science to show how research translates into real world applications and insights. Throughout the show, guests discuss their work and the broader implications for society, technology and exploration.

Obesity policy and public health storytelling

The discussion begins with commentary from the UK chief medical officer about obesity, its social and economic dimensions, and the call for stronger regulation of junk food to address both health and worklessness. The program then turns to Chris Van Tulleken and the Royal Institution Christmas lectures, focusing on how ultra processed foods shape physiology and planetary health. The speakers emphasize communicating complex science to young audiences while avoiding stigma and ensuring that messaging supports empowerment rather than anxiety. They outline the structure of the lectures and the approach to demonstrations that connect energy in food to cellular energy pathways, including oxidative phosphorylation. The conversation highlights the role of independent science and policy solutions, with attention to how kids learn about processing and nutrition without being overwhelmed by messaging about danger.

Power from radioactivity in diamonds

A central feature of the episode is carbon 14 diamond batteries. Tom Scott from the University of Bristol explains how radioactive carbon 14 is embedded inside diamond to generate electricity directly through decay, producing a beta particle that initiates an electron cascade within a diode structure. The device is designed so that radioactivity cannot escape the diamond cage, making it intrinsically safe. The battery delivers microamp currents at a couple of volts and can last for thousands of years given the 5300 year half life of carbon 14. Applications are described as low power and long lasting, suitable for harsh environments, space, or remote monitoring where regular replacement is impractical. The team uses a ham and cheese style analogy to explain the layered structure of the device and how energy is harvested and directed into a circuit. While not intended to replace lithium ion batteries, these diamond based sources could power devices with extremely long life spans in challenging settings, such as pacemakers or deep sea sensors, with a chirp mode approach for periodic data transmission.

Neanderthal admixture timing

The podcast then moves to genetic history, where ancient DNA and recombination provide a clock for when modern humans interbred with Neanderthals. The interview explains how the length of surviving Neanderthal DNA segments helps estimate the number of generations since admixture. Using a generation time of 29 years and long Neanderthal segments in ancient individuals over 45,000 years old, the researchers place the mixing event around 45 to 49 thousand years ago, likely in the Middle East. The conversation discusses what genes carried Neanderthal DNA that may have aided immune responses and disease resilience, and why certain regions show Neanderthal deserts on the X chromosome that may reflect ancient mating incompatibilities. The segment weaves in context about Neanderthal biology, human migration, and the ongoing relevance for understanding human evolution and immune genetics.

Dark comets and JWST observations

The next topic shifts to space science, revisiting Oumuamua and clarifying why it was not an alien spacecraft but rather a small interstellar object. The program then reports on seven new dark comets that show non gravitational accelerations due to outgassing, underscoring how observational astronomy uses indirect evidence to infer activity. In addition, a separate James Webb Space Telescope finding reveals large numbers of decameter sized asteroids in the main belt, offering new data on the distribution and dynamics of small bodies in our solar system. David Rothery from the Open University provides expert interpretation of how these objects move, the cause of observed trajectory changes, and what the findings mean for planetary science and asteroid dynamics.

Question of the Week

The episode closes with a viewer question about alternative methods to extract electricity from nuclear fission beyond steam turbines. The response outlines a theoretical approach that uses kinetic energy of fission fragments to create current in a surrounding electrode, requiring ultra-thin fuel and addressing significant technical challenges. A second question about continental configurations and what lay on the other side of a supercontinent invites reflection on plate tectonics and early Earth geography. The QOTW segment demonstrates how practical questions can lead to deeper explanations of nuclear physics and Earth science.

Takeaways

Across these topics the episode highlights how science communication, policy, and technology intersect. It shows the value of long horizon energy ideas like carbon 14 diamonds alongside immediate policy choices and the evolving understanding of human evolution and solar system small bodies. The Naked Scientists present a mosaic of science that informs public discourse and scientific curiosity alike.