Like part of a cosmic Russian doll, our universe may be nested inside a black hole that is itself part of a larger universe. In turn, all the black holes found so far in our universe—from the microscopic to the supermassive—may be doorways into alternate realities.
Beyond the event horizon lies a truly minuscule point called a singularity, where gravity is so intense that it infinitely curves space-time itself. This is where the laws of physics, as we know them, break down, meaning all theories about what lies beyond are just speculation.
Unlikely. Recent developments that show our universe is expanding at an ever-increasing rate. The cause of the expansion, called dark energy, is not understood, but it appears that the universe is destined to undergo a slow and cold death.
No human has ever been inside of a black hole. Humans are not yet capable of interstellar travel. Even if a human was able to travel to a black hole, he or she would not be able to survive entering it. Black holes condense all the matter that falls into it into one point called a quantum singularity.
New research motivated by string theory suggests possible, and equally strange, fates for evaporating black holes. We still don't know exactly what happens when black holes die. Ever since Stephen Hawking discovered that black holes evaporate, we've known that they can potentially disappear from our universe.
By their calculations, quantum mechanics could feasibly turn the event horizon into a giant wall of fire and anything coming into contact would burn in an instant. In that sense, black holes lead nowhere because nothing could ever get inside.
When an unlucky victim falls into the event horizon of a black hole, they will survive for a finite amount of time. If you fall straight down into a stellar black hole, you'll last a fraction of a second. For a supermassive black hole, you might last a few hours.
Some theorists have even argued for more, up to an indefinite number of possible dimensions. Other physicists suggest that experimental results have thrown cold water on the case for higher dimensions, leaving us only with the familiar three dimensions of length, width and height, plus the dimension of time.
So far, the evidence supporting the idea of a multiverse is purely theoretical, and in some cases, philosophical. Some experts argue that it may be a grand cosmic coincidence that the big bang forged a perfectly balanced universe that is just right for our existence.
Cosmologists aren't sure if the universe is infinitely big or just extremely large. To measure the universe, astronomers instead look at its curvature. The geometric curve on large scales of the universe tells us about its overall shape. If the universe is perfectly geometrically flat, then it can be infinite.
Black hole news: Standing on edge of black hole would cause 700 years to pass in 1 minute.
The nearest known black hole is Gaia BH1, which was discovered in September 2022 by a team led by Kareem El-Badry. Gaia BH1 is 1,560 light-years away from Earth in the direction of the constellation Ophiuchus.
Black holes are dark, dense regions in space where the pull of gravity is so strong that nothing can escape. Not even light can get out of these regions. That is why we cannot see black holes—they are invisible to our eyes. Because nothing can get out of black holes, physicists struggle understanding these objects.
While researchers have never found a wormhole in our universe, scientists often see wormholes described in the solutions to important physics equations. Most prominently, the solutions to the equations behind Einstein's theory of space-time and general relativity include wormholes.
When matter falls into or comes closer than the event horizon of a black hole, it becomes isolated from the rest of space-time. It can never leave that region. For all practical purposes the matter has disappeared from the universe.
There is no way a black hole would eat an entire galaxy. The gravitational reach of supermassive black holes contained in the middle of galaxies is large, but not nearly large enough for eating the whole galaxy.
It is possible for two black holes to collide. Once they come so close that they cannot escape each other's gravity, they will merge to become one bigger black hole. Such an event would be extremely violent. Even when simulating this event on powerful computers, we cannot fully understand it.
It would take 10100 years, or a googol, for a supermassive black hole to fully disappear. “The entire age of the universe [is] a fraction of [the time] it would take,” says Priyamvada Natarajan, a researcher at Yale University who probes the nature of black holes. “As far as we're concerned, it is eternity.”
Not really. According to NASA, no black hole is close enough to be a danger to us. Plus, the sun is not massive enough to explode to form a black hole.
Black holes are absolutely silent, as they are creatures of pure gravity. But while black holes produce no sound of their own, they can generate sound waves in their environment.
Black holes have two parts. There is the event horizon, which you can think of as the surface, though it's simply the point where the gravity gets too strong for anything to escape. And then, at the center, is the singularity. That's the word we use to describe a point that is infinitely small and infinitely dense.
Time Can Change
In addition to gravity stretching and squashing objects, another strange phenomenon that a traveler would observe close to a black hole is something called time dilation, in which time passes slower closer to the black hole than further away.
After just a few minutes more — 21 to 22 minutes total — the entire mass of the Earth would have collapsed into a black hole just 1.75 centimeters (0.69”) in diameter: the inevitable result of an Earth's mass worth of material collapsing into a black hole.