How We’ll Get to Alpha-Centauri | Cosmic Queries #115

In a special "Cosmic Queries Poppuri" edition of StarTalk, Neil deGrasse Tyson and Chuck Nice delve into a diverse array of questions from their audience, exploring everything from the boundaries of our universe to the linguistic quirks of astrophysics.

The Multiverse: Bubbles and Collisions

The concept of a multiverse, a collection of multiple universes, sparks a fascinating discussion. Tyson explains that there are several theoretical variations of the multiverse, often arising from the complex mathematics of the early universe, where quantum physics, general relativity, and string theory intertwine. One popular model envisions our universe as a bubble within an enormous grid of spacetime, with other bubbles representing other universes. These bubbles are theorized to be separated in such a way that inter-universe travel or interaction is impossible. The question of where one universe ends and another begins becomes a philosophical one, akin to asking where the end of a bubble is—it's also its beginning.

While these bubbles are expanding, they are not believed to overlap. Scientists have even conducted experiments, analyzing the cosmic microwave background (CMB) for statistical anomalies that might indicate an impingement from another universe. So far, no such signatures have been found, suggesting our universe remains distinct. Another multiverse theory posits entirely separate bubbles, embedded in higher dimensions, expanding independently and never meeting. A crucial and potentially dangerous aspect of these multiverses is the likelihood that the laws of physics could differ slightly from one to another. Imagine visiting another universe where the charge on an electron is different, potentially causing your atoms to fly apart or collapse.