Mini black holes could supply world with power or destroy us says Hawking
Mini black holes could supply the world with all the electric power it needs, but also have the potential to destroy every one of us if we did not learn how to control them properly, says the eminent British theoretical physicist, cosmologist, author and Director of Research at Cambridge University’s Centre for Theoretical Cosmology, Prof. Stephen Hawking.
Mini black holes could become the Holy Grail of our energy needs and the solution to global warming, as well as our ultimate nightmare, he explained.
In his second Reith Lecture on BBC Radio 4, Prof. Hawking said that a black hole the size of a mountain would give off enough power to provide all our global electrical energy requirements – it would emit gamma rays and X-rays at a rate of approximately 10 million megawatts.
If we wanted to use a mini black hole to provide our electrical energy, it would have to be in orbit, otherwise it would sink to the Earth’s centre and would probably start consuming our planet.
He then explained that in the presence of a black hole, one member of a pair of virtual particles could fall back into the black hole, leaving the other particle with no partner “with which to annihilate”.
While the forsaken particle (or anti-particle) might follow its partner back into the black hole, it could also escape to infinity “where it appears to be radiation emitted by the black hole,” he explained.
Getting energy from black hole not easy
Prof. Hawking emphasized that harnessing a mini black hole would be no easy feat. There is no way it could be housed in a power station, because it would go straight through the floor plus the Earth’s crust, etc. and end up in the centre of our planet.
If we do ever manage to have such a black hole, it would have to be orbiting the Earth if we wanted to keep hold of it, he added.
Prof. Hawking suggests mini black holes could be created in extra dimensions of space time. He explained that the ‘extra dimension’ refers to something else – different from the three dimensions plus time (the 4th) we are all familiar with.
Prof. Hawking said:
“According to some theories, the universe we experience is just a four dimensional surface in a ten or eleven dimensional space. We wouldn’t see these extra dimensions because light wouldn’t propagate through them, but only through the four dimensions of our universe.”
“Gravity, however, would affect the extra dimensions and would be much stronger than in our universe. This would make it much easier to form a little black hole in the extra dimensions.”
So, if we used a mini black hole to provide us with energy, and got the science slightly wrong, is there a risk it could destroy us? What if black holes just get more and more powerful, would one eventually consume the Earth?
The Large Hadron Collider (LHC) at CERN in Switzerland might make it possible for us to observe this phenomenon, Prof. Hawking said. It has been recently revamped – it was already a mighty beast before, now it is a super-mega beast.
Prof. Hawking said:
“Two beams of particles travel round this tunnel in opposite directions, and are made to collide. Some of the collisions might create micro black holes. These would radiate particles in a pattern that would be easy to recognize.”
What is a black hole?
Black holes are enigmatic places that exist in our Universe, in galaxies, and behave a bit like giant-superpowerful vacuum cleaners that suck stuff in using gravity.
Anything that comes within the grip of a black hole’s incredibly powerful gravitational pull has no escape, it will eventually end up in its centre.
In order to escape from a black hole’s pull (once you are in it), you would need an infinite amount of energy to get away.
We know about them but don’t see them
Scientists are sure black holes exist. They say the laws of physics predict their existence, and they do things in space which proves to us they are there. However, nobody has ever ‘seen’ one and observed what happens to matter when it falls inside. Physicists have some theories, but really, they cannot be sure of anything they say.
The moment somebody manages to detect a black hole and can look inside it, science will have taken one of the greatest leaps in its history, it will be as big a milestone in scientific progress for humans as the invention of the wheel, physicists say.
Some say Prof. Hawking’s most famous discovery was when he demonstrated that black holes emit some radiation. Previously, scientists had thought that black holes could not get smaller because nothing could escape their massive gravity. The radiation from black holes has become known as Hawking Radiation. (Image: Adapted from minerva.union.edu)
By looking into a black hole and seeing what goes on, we would have moved beyond Albert Einstein’s work, and would have a considerably deeper understanding of the Universe.
The Event Horizon
The Event Horizon, in the world of black holes, is an invisible line (a threshold), beyond which matter cannot escape its gravitational pull – the point beyond which ‘resistance is futile’, as the Borg would say.
Albert Einstein published his General Theory of Relativity in 1915, one-hundred and one years ago. In it he stated that the strength of an object’s gravitational field is directly proportional to how dense the matter within it is – the higher the density, the stronger the gravity is.
That’s great, you might say, but is there a point at which this process stops? In a black hole, there is nothing that can resist its overwhelming gravity. According to most scientists, when matter enters a black hole it is crushed into nothing, i.e. it is squashed out of existence.
You can download the MP3 of Prof. Hawking’s second Reith Lecture. (Image: BBC Radio 4)
Infinitely dense with no volume is impossible, isn’t it?
If there is no end to the process, it means that a *singularity is infinitely dense with no volume. That sounds impossible, right? Many scientists doubt it is possible and wonder whether anything like it could really exist.
* In this context a ‘singularity’ is the centre of a black hole, where matter is infinitely dense.
Quantum gravity theories, which look at gravitational matters in the smallest scales possible, try to explain what goes on. String theory is one of them, but there is not one theory that is strong enough to be deemed compelling.
According to Stuart Clark, who wrote the book The Unknown Universe (Head of Zeus) and co-hosts the podcast The Stuniverse, a successful quantum gravity theory would allow us to do two things:
– Look into a black hole and see what goes on inside it.
– Learn an awful lot more about the Big Bang, i.e. the origin of our Universe. Relativity predicts that a singularity could also appear during the Big Bang.
Prof. Hawking and the Nobel Prize for Physics?
At the age of seventy-four, Prof. Hawking has been awarded dozens of prizes, including the keys to several cities and institutions, plus he is a fellow of many prestigious centres of excellence.
However, the Nobel Prize for Physics – the biggest prize of them all – has eluded him.
There is growing talk this year in the media and scientific community that he is close to being awarded the big prize, because evidence is emerging that may prove his work into black hole radiation.
Prof. Hawking believes that black holes emit radiation – this is known as Hawking Radiation. If his theory is right, smaller black holes would eventually evaporate and disappear.
If Hawking Radiation can be proved, as far as he is concerned, the Nobel Prize will be his for the taking.
During the Reith Lecture, Prof. Hawking talked about his theory and the evidence that might be emerging. He displayed a picture of the prizewinner’s medal. Does this mean he knows he is very close?
What is Hawking Radiation?
Black holes are not really completely black, Prof. Hawking explained. They emit radiation because of the quantum effected close to the Event Horizon. Consequently, matter escapes from them and eventually they disappear completely.
He predicted that energy fluctuations from the vacuum caused the generation of pairs of particle-antiparticles of virtual particles close to the Event Horizon. One of the two particles falls back into the black hole, while the other one perhaps escapes before they have a chance to cancel each other out (annihilate each other).
The particle that gets away has positive energy while the one that falls into the black hole has negative energy relative to the Universe outside. So, the black hole loses energy, and consequently mass (because E = mc2).
Hawking Radiation cannot be verified … yet
He made this discovery and proudly announced it in the 1970s. There is just one major problem – nobody has been able to prove (verify) his predictions.
Before his Hawking Radiation theory was announced, scientists had assumed that black holes would never get smaller because nothing escaped them and anything that entered the Event Horizon got sucked in.
All bets among scientists are on that with the revamped Large Hadron Collider, tiny black holes will be found in the remains of smashed particles. We would then be able to study them and perhaps prove Hawking’s theory.
Video – Black Holes and Hawking Radiation
In this video actor Morgan Freeman talks about black holes and Hawking Radiation.