“Negative energy” sounds like something that Captain Kirk and Mr. Spock would have used to get out of a jam in the original Star Trek series. And appropriately enough, as Science Alert reports, using negative energy to draw energy from black holes was first proposed by physicist Roger Penrose in 1969, back when classic Trek was still airing new episodes.
Penrose’s work earned him a belated Nobel Prize just last year. And in an interesting bit of synchronicity, new studies suggest that negative energy could not only be the ultimate power supply but also a way to look for alien life and seek out new civilizations.
Kirk and Spock would surely have approved.
Tapping Into the Ergosphere
Black holes, in spite of their name, can be some of the brightest objects in the universe. The reason is that a black hole’s intense gravity field pulls down any matter it captures. The captured material is accelerated to nearly the speed of light, releasing enormous energy when infalling streams collide.
But this process is only a starting point for drawing energy from black holes. New research published in the scientific journal Physical Review D indicates that rotational energy already captured by the black hole can be extracted by tapping into a region called the ergosphere.
As Universe Today reports, the ergosphere is located just barely above the event horizon that cuts the black hole off from the outside universe. The black hole’s rotating magnetic field produces a breaking and reconnection of magnetic lines of force, and the extreme conditions within the ergosphere ramp up the resulting magnetic particle collisions to maximum intensity.
Delivering 150%
Under the right conditions, such collisions can cause one particle — or an entire particle stream — to fall through the event horizon, acquiring negative energy. The other particle (or stream) picks up a corresponding amount of positive energy and shoots out the ergosphere, carrying more energy than it started with.
This doesn’t quite count as magical free energy from black holes, because the particles that fall through the event horizon cause the black hole’s rotation to slow down. But in the meantime, there’s plenty of stored-up energy from black holes that a sufficiently advanced civilization could draw on. And because of this stored energy, a black hole power extraction system could potentially run at 150% efficiency, according to Universe Today — an efficiency rating we associate with athletes, perhaps, but not actual power generators.
The Sound of Magic
What’s more, in yet another bit of intriguing synchronicity that so often pops up in science, Science Alert reports that a separate research project gave experimenters a foretaste — or at least a fore-listen — of what more than 100% efficiency sounds like.
We do not yet have anything close to the technology needed to tap energy from a black hole. We don’t even have the tech to simulate the black hole with a fast-spinning metal cylinder, as one physicist proposed in 1971.
But a research team in Scotland realized that the Penrose Effect could be demonstrated using sound waves, which are easier to work with because they travel a million times slower than light waves. By spinning a disk faster than sound, speakers mounted on the disk could be made to put out sound at negative frequencies — not quite as weird as negative energy, but still pretty weird.
And when the experiment was run, the sound that came out of the speakers was 30% louder than the power that fed into them could have produced, according to Science Alert. Sound energy was being drawn from the rotating disk by a process analogous to drawing energy from black holes.
To Seek Out New Civilizations
Energy from black holes is pretty awesome, but where does alien life fit in? According to Live Science, while we don’t yet have the ability to plug our power cables into a black hole, advanced civilizations out there may be able to do exactly that. And if someone is doing it, we do have the technology needed to detect it.
“Since fast magnetic reconnection in the ergosphere should occur intermittently in the scenario proposed here, the associated emission within a few gravitational radii from the black hole is expected to display a bursty nature,” the report abstract in Physical Review D states.
This doesn’t necessarily mean that any “bursty” emission from a spinning black hole must be a sign of alien life. But it does give us a guide as to where and how to look for potential signs of power production by advanced alien civilizations. So, stay tuned!
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