Are We Living In A Black Hole?

In Cosmology by Brian Koberlein7 Comments

Here’s an idea, what if the universe and everything we see around us is actually inside a black hole?

Whenever I’m asked this question, what folks typically have in mind is that the universe began as an infinitely dense point, just like the singularity of a black hole, and because of cosmic expansion there’s a limit to how far we can observe, so maybe that’s like the event horizon. While it’s an interesting idea, things aren’t quite so simple.

To begin with, the universe did not begin with an explosion from a single point. It was definitely very hot and dense in its early period, but it didn’t begin as a singularity. In fact there is debate whether black holes themselves have singularities. So while there are similarities between the two, we can’t simply equate them.

The limit of what we observe (the size of the observable universe) also doesn’t match up with the hypothetical event horizon of a “cosmic” black hole. For any mass you can calculate what is known as the Schwarzschild radius, which is the radius of a simple black hole of that mass. The mass of the observable universe is on the order of 1054 kg, which gives a Schwarzschild radius about 5 times larger than that of the observable universe.

So maybe we’re just in a really big black hole, and we just see a part of it. Not really. Just because you can calculate a Schwarzschild radius that doesn’t mean an object is a black hole. Even if the Schwarzschild radius encloses all of your mass, it still isn’t necessarily a black hole. On a basic level the density of the observable universe is pretty uniform. If you don’t worry about cosmic expansion, then the radius of the observable universe increases at the speed of light with age, so the total mass of the observable increases with time. This is true in an expanding universe as well, but that’s a different story. The thing is, the Schwarzschild radius increases linearly with mass, but the enclosed mass of the observable universe increases with the radius cubed. As the observable universe increases over time, then the Schwarzschild radius eventually grows faster than the radius of the observable universe.

Some models propose "baby universes" forming from black holes in our universe.

Some models propose “baby universes” forming from black holes in our universe.

For a true black hole you can’t just calculate its size. You have to look at the overall structure. Our universe isn’t collapsing in on itself, it’s expanding at an ever increasing rate. So it doesn’t have the necessary structure to be the interior of a black hole. But there are some models that do propose that our universe was formed by the black hole of another universe. These models are very speculative, but generally propose that the super-dense interior of a black hole could create a “baby universe” that expands to become its own universe. Technically you could say this new universe is “in” the black hole that spawned it, but because of the bendable nature of space and time that’s not particularly meaningful. The new universe would in no way be limited by the size of the black hole, and would exist on its own once it formed.

So it’s an interesting idea to speculate about, but there is no evidence to support the idea that our universe is in a black hole.



  1. Let me analyze that as a well informed amateur.

    In a black hole time slows to a crawl. The outside universe dies in mere seconds for any observer on the inside. The outside universe blueshifts and for all practical purposes becomes an explosion of pure light. This explosion occurs from everywhere inside the black hole. since everything is falling in from all directions. All matter inside the black hole is in a state very similar to being very close to the speed of light, in all directons. When objects come very close to the speed of light they functionally shrink in the direction of motion, but without an outside universe there is no telling what the direction of motion is.

    From the perspective of an observer inside the black hole all matter races away from the observer, in all directions. Even the source universe may become a remote eternity away and redshifts in to a faint cosmic background buzz. That’s the same in what would happen in a black hole, right?

    1. (1) Scientists pointedly state that they do not know what the inside of a black hole looks like, so you cannot expect any scientist to comment on your guess.

      (2) The CMB is not just a random “explosion of pure light” that is mysterious and used to justify any guess on its origin. It has actually been studied in detail and fitted neatly into functional scientific models. “It’s the light from a blueshifted other-universe” is not one of those models.

  2. If the universe were stretching out faster than the speed of light, it could be explained by being in a black hole without having to turn to the enigmatic dark matter explanation. Additionally, if the universe ends in a Big Crunch, that would be nothing less than a universe-wide black hole. No escape.

  3. So here is my theory. Just wanted to make clear I am just an average person with no specific background in physics or math or any sort of scientific field. I am just an avid reader and mind wanderer who is interested in a variety of subjects pertaining to life, universe and humanity.

    With that said and from my basic understandings of some of the various theories evolving today, it is my belief that out Universe is one smaller universe inside a system of other universes one each larger than the next and it goes does from ours as well.

    I believe we are inside a blackhole and the reason our Universe is constantly expanding is due to the amount of matter that the main blackhole we are in is constantly pulling new “information” and energy from a larger source leading to the expansion of our universe and the “dark matter” that is abundant in space. It makes sense that there is a central part of our universe due to the different rotation of stars and matter in different hemisphere in the Universe caused by torsion from different gravity fields in the Universe. The outter being the stronger field much like center of a planet internal gravity opposed to the shell. If this makes sense im trying to explain it the only way I know how.

    With that said I believe the “Big Bang” itself was caused from the initial blackhole being formed and consuming matter from another Universe causing what we know today as our world we live in. Im sure there is a way to eventually prove this case and I believe it will eventually come to light that new universes are constantly forming and developing much like our system it is merely a process of continual life and death. Like all things we see on our planet that evolve and become other things i believe the universe acts in the same manner and continuously performs these processes over the course of billions of years opposed to evolution we have occurring over hundreds of thousands/millions. Its just a constant rebirth and recycling of matter and energy creating new systems and new life one off spring of another.

  4. The idea of our universe being inside a black hole doesn’t seem that far out. Mathematically, the prediction is that inside a black hole’ s event horizon, every possible direction would point towards the singularity. I believe that it has been observed that no matter in which direction we look, galaxies are accelerating towards the singularity.

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