3 days ago
What could go wrong? Scientists create the world's first black hole BOMB in the lab
It might sound like the culmination of a Bond villain's latest evil scheme.
But the world's first 'black hole bomb' has officially become a reality.
This theoretical doomsday device uses a series of spinning mirrors to reflect and amplify the waves of energy escaping from a black hole.
In real black holes, this energy grows exponentially until it is either vented or the whole system explodes with the power of a supernova.
Thankfully, the version created in the lab is just a safe demonstration model.
Instead of drawing its power from a black hole, the bomb amplifies magnetic fields through a complex series of mirrors.
During testing, the black hole bomb did explode - although the scientists reassure that this was 'nothing serious'.
Professor Danielle Faccio, co-author of the study from the University of Glasgow, said: '[It was] more of a "pop" than an actual explosive "bang".
However, she added: 'If one scaled this up in size, the "bang" would become more serious.'
The key to the black hole bomb is an effect known as 'superradiance'.
Professor Vito Cardoso, an expert on superradiance from the Instituto Superior Técnico, Portugal who was not involved in the study, told MailOnline: 'Superradiance is the phenomenon whereby radiation is amplified when it interacts with a rotating object.
'In simple terms: if you send sound or electromagnetic waves of very low frequency to a spinning cylinder then certain "modes" will come back with more energy! In other words, energy is transferred from spinning objects to radiation.'
There isn't anything mysterious about taking energy from a spinning object - just think about how you gain energy by stepping onto a spinning carousel.
The black hole bomb simply applies this idea to a strange quirk of black hole physics - with explosive results.
Due to 'weird and counterintuitive' rules of general relativity, when objects spin very close to a black hole they appear to gain energy from nothing.
Professor Faccio explained: 'Seen from the outside, you will see an object or wave reflect away from the black hole and gain energy in the process.
'If you now create a surrounding cavity or mirror of some kind so that the wave gets reflected back and forth between the mirror and black hole, you will have a continuous and runaway amplification effect.'
How does a black hole bomb work?
A black hole bomb works by exploiting an effect called superradiance.
When radiation approaches a spinning black hole it gains energy before escaping.
This slightly slows down the spin of the black hole like someone stepping onto a carousel.
But if the energy is reflected back inwards, this speeds up the spin of the black hole and amplifies the energy again.
The radiation bounces back and forth from the black hole and the mirror becomes stronger each time.
Eventually, there is so much high-energy radiation that the heat and pressure overwhelm the system and it explodes.
Eventually, this high amplitude energy builds up between the mirror and the black hole and heats up so much that the pressure causes the entire system to explode.
Since the nearest black hole is around 1,500 light-years from Earth, testing this theory in practice has been essentially impossible.
However, in their pre-print paper, the researchers demonstrated that the basic physics behind the theory really does work.
Instead of using a black hole, the experimental version rotates a 4-centimetre-diameter aluminium cylinder inside three layers of metal coils which are spun around the cylinder.
The rotating coils can be used to both produce a magnetic field and reflect some of the field back into the system.
In this model, the coils take the place of the mirrors while the magnetic fields play the role of light spinning around a black hole.
During their testing, the researchers discovered that the small, low-frequency magnetic fields were quickly amplified into much larger signals.
Even without the coils producing a magnetic field, the spinning device would still generate a runaway signal just like a black hole would.
While the lab-based black hole bomb isn't nearly as powerful as a real black hole bomb, it was still capable of producing shocking amounts of power.
Professor Faccio said: 'The electrical components in our setup were literally exploding!'
While you might worry that the technology could be used to make an actual bomb, Professor Faccio insists it is 'hard to see' how this could happen.
In fact, the researchers point out that this process could be beneficial in energy collection processes like what is already happening inside wind turbines.
Instead, the more terrifying possibility is creating a real black hole bomb out in space.
Theoretically, this could allow you to create a limitless source of energy.
Although our own civilisation isn't yet up to the task, there is nothing to prevent another society from creating a scaled-up version of Professor Faccio's device.
Professor Cardoso says: 'We can easily imagine a slightly more advanced civilization than us using something like this with a black hole!
'It's amazing, extracting energy from the vacuum to power a society.'
But, just like nuclear power, a vast source of energy can quickly become a bomb if it isn't managed correctly.
'Any piece of technology with an immense power can always be dangerous,' concludes Professor Cardoso.
'In this particular case, a bad regulation - like nuclear plants - could lead to overproduction of radiation and therefore to explosion.'
BLACK HOLES HAVE A GRAVITATIONAL PULL SO STRONG 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 as intense sources of gravity which hoover up dust and gas around them. Their intense gravitational pull is thought to be what stars in galaxies orbit around.
How they are formed is still poorly understood. Astronomers believe they may form when a large cloud of gas up to 100,000 times bigger than the sun, collapses into a black hole.
Many of these black hole seeds then merge to form much larger supermassive black holes, which are found at the centre of every known massive galaxy.
Alternatively, a supermassive black hole seed could come from a giant star, about 100 times the sun's mass, that ultimately forms into a black hole after it runs out of fuel and collapses.
When these giant stars die, they also go 'supernova', a huge explosion that expels the matter from the outer layers of the star into deep space.
