StarTalk Podcast: Cosmic Queries – Edge of the Universe with Neil deGrasse Tyson and Janna Levin

Neil deGrasse Tyson introduces the Startalk episode focusing on cosmic queries about the edge of the universe. He discusses the topic with Chuck, mentioning his book 'Black Hole Blues' about the discovery of gravitational waves. They explore the concept of the universe being finite yet having an infinite structure, like a fractal that infinitely divides. The idea of traveling in a straight line and potentially returning to the starting point is compared to circumnavigating the Earth.

The conversation delves into the possibility of the universe being infinite in its structure, with dimensions that could be small and wrapped up. Tyson uses the analogy of a straw to explain how dimensions can be large in one direction and small in another, leading to the concept of space-time origami. They discuss the implications of extra spatial dimensions and how they might be perceived through high-energy experiments like those at the Large Hadron Collider.

Paul Love's question about the universe's shape is addressed, with Tyson explaining that the universe's expansion does not imply a spherical shape. He clarifies that space itself was created in the Big Bang, and every point in the universe was once at the center of the explosion. The analogy of a balloon being stretched is used to illustrate how the universe's expansion is not like an explosion into pre-existing space.

Brendan's question about a new study suggesting the universe is in the shape of a loop is discussed. Tyson explains that the universe's shape is still unknown, and while it could loop back on itself, this would not necessarily be indicative of its actual shape. The observable universe is described as being about 92 billion light years across, and the possibility of the universe folding back on itself is explored.

Tim Braid's question about a study suggesting galaxies may be rotating in sync is addressed. Tyson expresses skepticism about the study's conclusions, noting that interactions over such vast distances are unlikely due to the expansion of the universe. The discussion turns to the Andromeda galaxy and the future collision with the Milky Way, highlighting how the night sky will change as a result.

The conversation continues with a focus on the visibility of the Andromeda galaxy and the Milky Way. Tyson explains that even if Andromeda were closer, it would not appear brighter due to the way surface brightness works. The discussion also touches on the limitations of human vision in observing celestial objects and the importance of understanding the universe's structure through mathematical models.

David Eduardo Morales Martinez's question about the difficulty in proving the existence of other dimensions is discussed. Tyson explains that if additional dimensions were large, they would manifest in observable ways. The analogy of a hollow sphere passing through two dimensions is used to illustrate how higher dimensions might appear to us. The conversation also touches on the possibility of dark matter and dark energy being related to extra dimensions.

The discussion turns to the idea that matter consumed by black holes could be recycled as dark energy. Tyson explores the concept of black holes potentially being as large as entire universes inside and the implications of this for understanding dark matter and dark energy. The conversation also delves into the theoretical possibility of black holes being a form of dark matter.

The concept of information preservation in black holes is explored, with Tyson explaining that information about particles is preserved even when they fall into a black hole. The idea that the information becomes encoded on the event horizon, suggesting a holographic nature of the universe, is discussed. The conversation also touches on the Voyager 2 spacecraft and its discovery of new details about interstellar space.

The final segment addresses the concept of dark energy, with Tyson suggesting it could be thought of as an 'invisible ocean' surrounding us. The discussion includes the idea of dark energy being a quantum phenomenon trapped in extra dimensions. The conversation concludes with a reflection on the importance of understanding the universe on both the largest and smallest scales, highlighting the intersection of quantum physics and general relativity.