Black holes are among the most fascinating and hotly debated objects in the universe.
They have captured the public imagination for decades, thanks in part to the late Stephen Hawking, who transformed them from a difficult-to-understand scientific theory to a source of mysterious wonder.
They have also filtered popular culture through science fiction magazines, Star Trek, and Hollywood blockbusters.
But what are the five strangest and most captivating theories about black holes that are so unfathomable they are mind blowing?
Here MailOnline take a look.
Mysterious: Black holes are among the most fascinating and hotly debated objects in the universe (file image)
1. They are surrounded by a ‘ring of fire’
In 2019, astronomers took the first image of a black hole located in a distant galaxy.
Described by scientists as ‘a monster’, it is three million times the size of Earth.
The image shows an intensely bright ‘ring of fire’, as the researchers described it, surrounding a perfectly circular dark hole.
“It feels like looking at the gates of hell,” said Heino Falcke of Radboud University in Nijmegen, the Netherlands.
As black holes consume matter that strays too close, they compress it into a superheated disk of glowing gas.
In the image of the gigantic black hole at the heart of the nearby galaxy Messier 87 (M87), the underside of the ring appears bright because gases are being whipped toward Earth.
The black hole also bends light around it, which is what creates the circular shadow.
In a historic first, scientists have captured a remarkable image of a supermassive black hole at the heart of our Milky Way.
2. They have ‘hair’
In 2015, the late physics professor Stephen Hawking suggested that black holes were not the “eternal prisons” many believe them to be, adding that it was possible for data to escape from the abyss.
A year later, he expanded on the theory by stating that the answer lies in the zero-energy particles, or “soft hair,” that sit on the black hole’s horizon.
In 2015, Professor Stephen Hawking suggested that black holes were not the “eternal prisons” many believe them to be, adding that it was possible for data to escape from the abyss. A year later, he expanded on the theory by stating that the answer lies in the zero-energy particles, or “soft hair,” that sit on the black hole’s horizon (archive image)
It suggests that the particles that settle on the event horizon, the black hole’s boundary, would consist of photons and gravitons, which are subatomic packets of light and gravitational energy.
These very low or even zero energy quantum particles deposited at the edge of the black hole can capture and store information gleaned from particles falling into the black hole.
This means that while the particles that fall into the black hole may disappear, their information remains on the brink of oblivion in this “soft hair” of quantum particles.
The theoretical physicist compared the return of information to a burned encyclopedia, where the information would not technically be lost, but would be incredibly difficult to decipher.
The hypothesis hasn’t been proven, but it could help resolve a long-standing paradox about what happens to the gas and dust that falls into a black hole.
3. They emit gas sources
The powerful gravitational grip of a black hole means nothing can escape if it gets too close to the edge of the hole.
But many of these mystery objects are actually surrounded by an accumulation of gas and dust that surrounds black holes a bit like water running down a drain.
According to a 2018 study, this accumulation of material is a three-step process.
The powerful gravitational grip of a black hole means nothing can escape if it gets too close to the edge of the hole. But many of these mystery objects are actually surrounded by a buildup of gas and dust, shooting directly into the air and looking a lot like fountains.
First, the cold gas forms a disk near the plane of rotation, heating up until the molecules break apart.
Some of these molecules are ejected above and below the disk, which then fall back down to create a fountain-like structure.
Alternative observations also suggest that this motion produces arcuate rings surrounding the inner columns of matter, which shoot directly into the air and closely resemble fountains.
4. They are the source of Dark Energy
Last month, scientists at Imperial College London made an exciting announcement about black holes.
They excitedly revealed that the objects could actually be the unknown energy source known as Dark Energy.
Essentially, the Big Bang theory of the creation of our universe originally predicted that its expansion would slow down, or even begin to contract, due to the pull of gravity.
Breakthrough: Scientists have found the first evidence that black holes are the source of dark energy. They studied galaxies and the supermassive black holes at their hearts. Pictured is NGC 1316, a lenticular galaxy about 60 million light-years away in the constellation Fornax.
But in 1998, astronomers were surprised to discover that the universe was not only continuing to expand, but that this expansion was also accelerating.
To explain this discovery, it was proposed that a ‘Dark Energy’ was responsible for pulling things apart with more force than gravity.
This was related to a concept that Einstein had proposed but later discarded: a ‘cosmological constant’ that opposed gravity and prevented the universe from collapsing.
However, black holes posed a problem: Their extremely strong gravity is hard to oppose, especially at their centers, where everything seems to break apart in a phenomenon called a “singularity.”
To delve into the problem, a A team of 17 researchers from nine countries studied nine billion years of black hole evolution.
They looked at old, inactive galaxies and found that black holes gain mass in a way that is consistent with them containing vacuum energy, or dark energy.
In fact, the size of the universe at different times closely matched the mass of supermassive black holes at the heart of galaxies.
In other words, the amount of dark energy in the universe can be explained by the energy of the black hole vacuum, which means that black holes are the source of dark energy.
5. They can be ‘back doors’ to other parts of the universe
Deep inside a black hole lies the gravitational singularity, where space-time bends to infinity, and anything that passes by can survive.
Or so it has always been thought.
However, in a recent study, the researchers suggested that there may actually be an exit via a wormhole at the center of the black hole, acting as a “back door.”
Deep inside a black hole lies the gravitational singularity, where space-time bends towards infinity, and no matter what happens you can survive (stock image)
According to this theory, anything that travels through the black hole would be “spaghettized,” or stretched to the extreme, but would return to its normal size when it emerged in a different region of the universe.
While it is unlikely that a human would survive this process, the researchers say that the matter inside the black hole would not be lost forever as previously thought, but instead would be expelled to another area of the universe.
And, the researchers say, there would be no need for ‘exotic’ energy to generate the wormhole, as Einstein’s theory of gravity suggests.
BLACK HOLES HAVE SO STRONG A GRAVITATIONAL PULL THAT NOT EVEN LIGHT CAN ESCAPE
Black holes are so dense and their gravitational pull is so strong that no form of radiation can escape them, not even light.
They act like strong sources of gravity that suck in dust and gas around them. Its strong gravitational pull is thought to be around what stars in galaxies orbit.
How they are formed is still poorly understood. Astronomers believe they may form when a huge cloud of gas up to 100,000 times larger than the sun collapses into a black hole.
Many of these black hole seeds then merge to form much larger supermassive black holes, which lie at the center of all known massive galaxies.
Alternatively, a supermassive black hole seed could come from a giant star, some 100 times the mass of the sun, which eventually becomes a black hole after it runs out of fuel and collapses.
When these giant stars die, they also go ‘supernova’, a huge explosion that ejects matter from the star’s outer layers into deep space.