Why Do We Assume That Black Holes Are Spherical In Shape?

A black hole is a 3D object whose event horizon is a sphere, because gravity pulls equally in every direction. That spherical shape is mandatory in our familiar three spatial dimensions (plus time). But if extra dimensions exist, Einstein’s equations also allow black holes shaped like rings and even multi-ringed “black Saturns”.

This question has taken scientists on an incredible journey through theoretical physics and mathematical exploration. Currently, the most common belief is that black holes are spherical due to gravity and the laws of physics. However, it does make one wonder about the possibility of black holes with different shapes that have not been explored yet.

So first, the basics: is a black hole 2D or 3D? It’s 3D. A black hole occupies a region of three-dimensional space, and its event horizon (the famous “point of no return”) is the 2D spherical surface that bounds that region. So when astronomers picture a black hole as a perfect sphere, they really mean its event horizon is a 2-sphere wrapped around a 3D volume.

The conventional idea in astrophysics is that this event horizon is spherical. Gravity pulls everything towards the center of mass, forming a sphere. This idea applies to black holes at least in a universe with three dimensions of space and one of time, and in fact Stephen Hawking proved in the 1970s that in 3+1 dimensions a stationary black hole’s horizon must have spherical topology. This is what we similarly observe in planets and stars, as molecular clouds of gas and dust accumulate towards the center, forming a core.

However, in the world of theoretical physics, things have evolved. The possibility of dimensions beyond the known three dimensions of space and one of time has been introduced. In these extra dimensions, physicists are now considering whether black holes could have different shapes.

Exploring Higher Dimensions

Scientists, especially theoretical physicists, are curious about the universe’s basic nature. They have come up with the idea that there might be more than just the three spatial dimensions we know (up-down, left-right, forward-backward), along with the dimension of time. These extra dimensions, even though we can’t see or touch them, could have serious effects on how things work in space.

In these extra dimensions, the usual rule that black holes are spherical might not be entirely true. Scientists have been using math to figure out what shapes black holes might have in these extra dimensions, and guess what? They’ve found some interesting possibilities. Maybe black holes can have different shapes than we have always thought.

Black holes not being round in shape is a new way of thinking about the universe, even though it doesn’t have any direct real-world effects right now. It’s like opening a door to new possibilities in our understanding of space.

Particle Physics And The Theories It Includes 

This field isn’t just theoretical science; it also presents the exciting possibility of real-world discovery. Particle physicists have considered the idea that microscopic black holes could be produced by generating high-energy collisions within particle accelerators. If we could detect these tiny black holes during their brief existence (they would evaporate almost instantly through Hawking radiation), it might offer evidence for the existence of higher dimensions in our universe. To be clear, though, the ATLAS and CMS experiments at the Large Hadron Collider have run multiple searches for these signatures and so far found nothing, ruling them out up to roughly 4.5 TeV. The hunt continues, but no microscopic black hole has been spotted yet.

This intersection of theoretical physics and experimental science is fascinating. Our understanding of non-spherical black holes, while still theoretical, might someday become a reality. In this ongoing search to understand black holes, we are not merely expanding our knowledge of black holes, but also pushing the boundaries of our understanding of the universe itself.

For a long time, experts have assumed that black holes are spherically shaped. However, our exploration of higher dimensions and the mathematical revelations regarding non-spherical black holes encourage us to rethink our cosmic beliefs. Although these theoretical findings may not have direct implications for the real world (yet), they open up a world of possibilities that could change our understanding of the cosmos.

Mathematics For Non-spherical Black Holes

For more than two decades (ever since Roberto Emparan and Harvey Reall published their famous “black ring” solution in 2001), scientists have known that not all black holes are spherical, especially in higher dimensions. Recent work in theoretical physics has shown (through math) that black holes existing in dimensions beyond the usual three can have various shapes, including rings with the topology of a doughnut (S²×S¹) and even multi-horizon “black Saturns”. This is quite different from what we’ve always thought about these mysterious, star-eating objects.

This discovery is based on the math created by Albert Einstein. He developed equations that help us understand how space and time curve around supermassive objects like black holes. In simpler terms, these equations tell us what the shape of a black hole looks like. In normal dimensions, there are round black holes, but in higher dimensions, things get more interesting and complicated.

As we continue our scientific exploration of the cosmos, the perspective people have on black holes, gravity, and the structure of the universe keeps evolving. The search for non-spherical black holes is evidence of the curiosity we humans hold for the most mysterious objects in the Universe. Whether or not these unique shapes exist in the universe, the journey to understand and unravel the mysteries of black holes will undoubtedly lead to more astonishing discoveries in the future.

Summary

The question of why we assume black holes are spherical in shape has taken us through theoretical physics and mathematical exploration. While our current belief in spherical black holes is based on gravity and the laws of physics, we’re now considering the possibility of non-spherical black holes in dimensions beyond our perception. This exciting idea challenges our preconceptions and encourages us to keep pushing the boundaries of our knowledge. Black holes may yet reveal more of their intricate and mysterious designs in the grand tapestry of the universe, reminding us that the cosmos is a stage for endless discovery and exploration.