In this engaging episode of Cosmic Queries, astrophysicist Neil deGrasse Tyson is joined by guest Matt O'Dowd, an expert in black holes, quasars, and gravitational lensing. They discuss topics ranging from energy density surrounding black holes and Hawking radiation to the potential effects of the Big Rip on the universe and the fascinating potential of solar gravitational lens missions.
Stephen Hawking's discovery that black holes radiate, known as Hawking radiation, is a central topic in the episode. This radiation causes the mass of black holes to leak away over time, leading to discussions on whether information can eventually escape black holes. Many physicists now believe that the energy and information falling into a black hole can eventually leak away as radiation. This relates to the notion of entropy, a measurement of hidden information in a system, which increases as a black hole grows and consumes objects.
The episode also delves into time dilation, the expanding universe, and relativistic effects. Stellar mass black holes can create accretion discs and become "mini-quasars" in specific situations, such as when orbiting another star. Quasars, usually found in distant galaxies, are closely connected to the so-called "Quasar Epoch" in the universe, which occurred a few billion years ago before the formation of lower mass galaxies like the Milky Way.
Shifting gears, the expert panel discusses the Big Rip, the uncertain idea that if dark energy's strength increases over time, the accelerating expansion of the universe could eventually tear everything apart. It remains unclear how black holes would be affected by such an event. Another topic of conversation is gravitational lensing and its potential role in understanding dark energy. Lensed quasars often provide valuable information about the infrastructure of quasars themselves and can help researchers study their behavior.
Lastly, the potential for a solar gravitational lens mission is examined. This ambitious idea would involve using the sun as an additional lens for a telescope in the outer solar system, potentially allowing for observation of individual planets orbiting distant stars. While the concept is exciting, it faces numerous challenges, including the obstruction of light by the sun and the need to reconstruct images captured by the telescope.
The Cosmic Queries episode with Neil deGrasse Tyson and Matt O'Dowd offers a fascinating and accessible discussion on various topics related to black holes and the universe, providing insights on both current knowledge and future possibilities for exploration and discovery.