Experiment proves old theory of how aliens might use black holes for energy

Researchers create a device to test a 50-year-old physics theory from the famed Roger Penrose.

Cygnus X-1 black hole

Cygnus X-1 black hole.

Credit: NASA/CXC/M.Weiss
  • Scientists prove a 50-year-old physics theory by Roger Penrose.
  • The theory explains how energy could be harvested from black holes by advanced aliens.
  • Researchers from the University of Glasgow twisted sound waves to show that the effect Penrose described is real.

A theory proposed 50 years ago to explain how energy might be harvested from a black hole was verified by an experiment. Scientists from the University of Glasgow were able to provide first proof for an idea from 1969 by the famed British physicist Roger Penrose, who predicted that only an advanced alien civilization would be able to get energy in the black hole's ergosphere – the outer layer of its event horizon.

Why would it take aliens to do this? Penrose thought that if you lower an object into the ergosphere, you could produce negative energy. But for this to work, the object would have to be moving faster than the speed of light. Penrose envisioned a mechanism that would split an object dropped into the black hole in two, with one part going into the hole while the other would be recovered. As explains the press release from the University of Glasgow, the recoil generated by this process would result in the saved half gaining energy from the black hole's rotation.

Of course if this sounds complicated, it really is and only a very high-tech futuristic civilization would be up for the challenge, concluded Penrose.

What the scientists were able to do now was to test this idea by an experiment based on the proposal from another physicist, Yakov Zel'dovich. He suggested in 1971 that Penrose's theory could be proven by using "twisted" light waves, which would create energy by hitting a rotating metal cylinder and utilizing the rotational Doppler effect.

While Zel'dovich's approach also proved impractical, the scientists from the Glasgow University's School of Physics and Astronomy devised a setup of a small ring of speakers that twisted sound waves in a way similar to how he wanted to twist light. The advantage is that sound waves need a significantly slower rotating surface compared to light.

Check out how the researchers explain their work

The team sent twisted sound waves towards a rotating sound absorber from a foam disk. Microphones positioned in the back of the disk captured the sound that passed from the speakers through the disc, which spun faster and faster.

What the scientists found was that this process produced clear changes in the frequency and amplitude of the sound waves, courtesy of the unusual behavior of the Doppler effect, which normally describes how for example, the pitch of a siren from an emergency vehicle seems to rise as it heads towards you but drops when it moves away. This happens because sound waves come at you with more frequency when the ambulance closes in, but less so after it goes past.

The paper's lead author, Marion Cromb, a Ph.D. student in the University's School of Physics and Astronomy, explained that rotation transforms this linear effect and pulls in energy. "The rotational doppler effect is similar, but the effect is confined to a circular space," he pointed out. "The twisted sound waves change their pitch when measured from the point of view of the rotating surface. If the surface rotates fast enough then the sound frequency can do something very strange—it can go from a positive frequency to a negative one, and in doing so steal some energy from the rotation of the surface."

The set-up of the experiment.

Credit: University of Glasgow

The researchers were able to show that as they increased the speed of the spinning disc, the pitch of the sound kept dropping until it disappeared, then it came back up to 30 percent louder than before.

Marion called what they heard during the experiment "extraordinary," adding that the "negative-frequency waves are capable of taking some of the energy from the spinning foam disc, becoming louder in the process—just as Zel'dovich proposed in 1971."

Whether aliens are using this approach to get energy from black holes is certainly hard to ascertain, but the researchers are planning to investigate whether this effect extends to other sources like electromagnetic waves.

Check out their new paper "Amplification of waves from a rotating body" in Nature Physics.


A brief history of human dignity

What is human dignity? Here's a primer, told through 200 years of great essays, lectures, and novels.

Credit: Benjavisa Ruangvaree / AdobeStock
Sponsored by the Institute for Humane Studies
  • Human dignity means that each of our lives have an unimpeachable value simply because we are human, and therefore we are deserving of a baseline level of respect.
  • That baseline requires more than the absence of violence, discrimination, and authoritarianism. It means giving individuals the freedom to pursue their own happiness and purpose.
  • We look at incredible writings from the last 200 years that illustrate the push for human dignity in regards to slavery, equality, communism, free speech and education.
Keep reading Show less

Astrophysicists: Gamma-ray jets exceed the speed of light

Scientists find that bursts of gamma rays may exceed the speed of light and cause time-reversibility.

An artist's drawing of a particle jet emanating from a black hole at the center of a blazar.

Credit: DESY, Science Communication Lab (used with permission by Astronomy Picture of the Day, which is co-managed by Robert Nemiroff at Michigan Tech).
Surprising Science
  • Astrophysicists propose that gamma-ray bursts may exceed the speed of light.
  • The superluminal jets may also be responsible for time-reversibility.
  • The finding doesn't go against Einstein's theory because this effect happens in the jet medium not a vacuum.
Keep reading Show less

​'The time is now' for cryptocurrencies, PayPal CEO says

Is Bitcoin akin to 'digital gold'?

Technology & Innovation
  • In October, PayPal announced that it would begin allowing users to buy, sell, and hold cryptocurrencies.
  • Other major fintech companies—Square, Fidelity, SoFi—have also recently begun investing heavily in cryptocurrencies.
  • While prices are volatile, many investors believe cryptocurrencies are a relatively safe bet because blockchain technology will prove itself over the long term.
Keep reading Show less

"Clean meat" approved for sale in Singapore

Singapore has approved the sale of a lab-grown meat product in an effort to secure its food supplies against disease and climate change.

Credit: Adobe Stock / Big Think
Politics & Current Affairs
  • Singapore has become the first country to approve the sale of a lab-grown meat product.
  • Eat Just, the company behind the product, will have a small-scale commercial launch of its chicken bites.
  • So-called "clean meats" may reduce our reliance on livestock farming, which kills billions of animals worldwide every year.
  • Keep reading Show less
    Scroll down to load more…
    Quantcast