Fifty years ago, Roger Penrose sketched an idea so audacious it sounded like a trick. Drop an object into the swirling region just outside a spinning black hole, let it split in two at the right moment, and one piece can fly back out carrying more energy than the whole thing had going in. The extra energy is not free. It is skimmed off the black hole's rotation, which slows down by a hair. Penrose had, on paper, found a way to mine a black hole.
The physicist Yakov Zel'dovich soon pushed the idea further. He argued that you would not even need a black hole. Any object spinning fast enough should be able to amplify a wave that hits it the right way, handing the wave some of its rotational energy. It was a beautiful prediction with one crippling problem. To do it with light, you would have to spin a physical object faster than light itself. For half a century, that was that. The physics was real, the demonstration was impossible, and the whole thing lived on chalkboards.
A team at the City University of New York has now moved it off the chalkboard and onto a bench.
The 50-year-old idea behind the experiment
Writing in Nature on 8 July, researchers at CUNY's Advanced Science Research Center reported building a device that reproduces the essential physics of the Penrose-Zel'dovich process, no black hole and no cosmic distances required. The work was led by Andrea Alù, a distinguished professor and founding director of the center's Photonics Initiative, with postdoctoral researcher Hadiseh Nasari as lead author and former PhD student Hady Moussa as co-lead.
What makes the result striking is not that they confirmed the theory. It is that they sidestepped the one obstacle everyone assumed was fatal. You cannot spin matter faster than light. So they did not spin anything at all.
Rotation without anything that spins
The device is a ring of electronic resonators, small circuit elements arranged in a loop. Nothing in it physically rotates. Instead, the team rapidly changed the properties of each element in a carefully timed sequence around the ring, so that a pattern travels around the loop like a wave of activity passing from one segment to the next. To an incoming electromagnetic wave, that traveling pattern looks and behaves exactly like ultrafast rotation.
The team calls this synthetic rotation, or as Alù describes it, "synthetic time-engineered rotation." Because the spin is an illusion built out of timing rather than motion, it can imitate rotational speeds that no motor, turbine, or physical object could ever reach. The wall that stopped everyone for fifty years, the fact that real objects have a speed limit, simply does not apply to a pattern you paint in time.
What the waves actually did
When electromagnetic waves with the right rotational character entered the ring, they came out stronger. They had extracted energy from the synthetic rotation and been amplified, precisely as Penrose and Zel'dovich predicted a wave would when it steals energy from a spinning object. "Waves with the appropriate rotational characteristics extracted energy from the system and became amplified, reproducing the essential physics of the Penrose-Zel'dovich process," Moussa said.
Importantly, the amplification was selective and broadband. The device boosts only waves with the correct rotational signature, and it does so across a wide range of frequencies. That is not just a pretty confirmation of old theory. It is the behavior you want from a real component.
Where this could lead
The researchers point toward wireless communications, classical and quantum optics, and new ways to manipulate and amplify light and information. A compact amplifier that adds energy to a signal by tapping an engineered "rotation," rather than by the usual noisy electronic means, is an appealing building block, especially for quantum systems where every stray bit of noise is an enemy. The work was funded by the U.S. Department of Defense, the National Science Foundation, and the Simons Foundation, which tells you the practical interest is already there.
None of this powers a city or extracts anything from an actual black hole. What it does is turn a thought experiment about the most extreme objects in the universe into a small device you can characterize, tune, and eventually put to work.
The R&D takeaway
The lesson here is not about black holes. It is about what you do when a great idea hits an impossible constraint.
For fifty years the constraint on the Penrose-Zel'dovich effect was treated as a full stop: light-speed rotation cannot be done, therefore the experiment cannot be done. The CUNY team refused to accept that the constraint applied to the goal. They asked a sharper question. What is rotation actually doing to the wave, and is spinning matter the only way to produce that effect? Once rotation was reframed as a property you could synthesize in time instead of a motion you had to physically achieve, the impossible number stopped mattering.
That is a move worth keeping close. When a project stalls against a hard physical or practical limit, the reflex is to attack the limit head-on or abandon the goal. The third option, and often the best one, is to separate the outcome you need from the mechanism everyone assumes must deliver it. The mechanism is where the wall is. The outcome may have another door.
Sometimes you cannot break the limit. So you build something that never had it.
Sources: "Wave amplification via synthetic time-engineered rotation," H. Nasari, H. Moussa, A. Alù et al., CUNY Advanced Science Research Center, published in Nature, 8 July 2026 (DOI: 10.1038/s41586-026-10725-y); "A black hole theory comes to life in the lab," CUNY ASRC and EurekAlert!, July 2026; reporting via ScienceDaily and Phys.org, July 2026.
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