It seems like such a straightforward idea that it’s surprising no one has attempted it before: mapping everything from subatomic particles to superclusters on a chart based on mass and radius. Now that someone has, the results pose intriguing—and perhaps slightly unsettling—questions.
This groundbreaking chart was created by Dr. Charles Lineweaver and graduate student Vihan Patel. They utilized a log-log graph, the only format capable of encompassing the immense range of sizes and masses between the very small and the very large. Certain areas of the chart are labeled as “forbidden” based on established laws of physics or where, as Patel explains, “quantum mechanics blurs the very nature of what it really means to be a singular object.”
The most striking feature of the chart is a black line dividing the region marked “forbidden by gravity” from the zone occupied by familiar objects. Along this line are black holes. “The larger the mass of a black hole, the lower its density,” Lineweaver told. While the leftward portion of the line remains theoretical, scientists have observed black holes of various sizes, from the remnants of collapsed stars to the colossal supermassive black holes at galactic centers, confirming this established pattern.
Following the black hole line upward on the chart reveals something extraordinary: the entire observable universe—the region within the “Hubble radius”—also lies along this line. Essentially, if a black hole were as large as the universe we can observe, it would have the same density. This raises profound questions: Could the universe itself be a black hole? And if so, what would that mean for our understanding of reality?
Dr. Charles Lineweaver and Vihan Patel are not the first to explore the idea that the universe might be a black hole, though others have arrived at this concept through different methods. While the idea may seem far-fetched, their findings suggest a consistent pattern. The universe has always aligned with the black hole line on the chart, even when accounting for its expansion over billions of years. This alignment includes all known mass and energy within the Hubble radius, including dark matter and dark energy, as energy and mass are interchangeable. The fact that the universe was also on this line billions of years ago, when the Hubble radius was much smaller, makes it unlikely that this is a coincidence.
The observable universe shares certain features with black holes, such as an event horizon—a boundary beyond which no information can escape. However, for the universe to truly qualify as a black hole, one would need to assume that everything outside the Hubble radius exists in a zero-density Minkowski space (essentially a vacuum). This assumption is widely considered unlikely by most cosmologists, including Lineweaver, leaving the implications of the chart open to interpretation. He speculates that the universe might even be an "inside-out black hole," an idea that warrants deeper investigation.
One significant obstacle to determining whether the universe is a black hole—or something similar—is the lack of knowledge about the interiors of black holes themselves. “Nothing can exist to the left of the black hole line,” Lineweaver explains, referring to regions of the chart forbidden by known physics. However, questions remain about whether the center of a black hole could be denser than the black hole as a whole. Theoretical physics, including general relativity and quantum mechanics, provides conflicting answers to these questions. This unresolved tension continues to challenge our understanding of both black holes and the universe at large.
The chart also raises intriguing questions about the origins of the universe. “At the smaller end, where quantum mechanics and general relativity intersect, lies the smallest possible object—a structure known as an instanton,” explained Vihan Patel. “This suggests that the universe may have begun as an instanton, which has a defined size and mass, rather than as a singularity, a theoretical point of infinite density and temperature.”
While the term “singularity” is more commonly associated with the Big Bang in popular discourse, Charles Lineweaver advocates for greater recognition of the instanton model, which he considers a more plausible explanation for the universe’s beginnings.
The research is available as an open-access publication in the American Journal of Physics.
