The heart of John Pendry’s kitchen is dominated by a striking, kaleidoscopic photograph. It presents a dizzying array of purple, green, yellow, and white shards. Given Pendry’s fame for inventing an invisibility cloak – a device that can bend light around objects – one might assume a connection to this groundbreaking work. However, Pendry clarifies that the image simply depicts magnified crystals of vitamin C. He dismisses the invisibility cloak as a past endeavor, stating he has moved on to “more exciting things.”
This seemingly casual remark offers insight into Pendry’s enduring fascination as a physicist based at Imperial College London. He developed a device twenty years ago that sounds like magic, yet its true legacy remains largely underappreciated. If engineers have their way, Pendry’s concepts will soon influence fields ranging from earthquake protection to autonomous vehicles. Despite the far-reaching applications of his famous breakthrough, he appears to give them little personal thought. Instead, his focus shifts to more complex questions, such as whether he can bend light through time, much like he bends it through space, to construct materials that simulate the exotic physics of black holes. These are the ideas that have drawn me to his home for conversation.
Early Explorations and the Dawn of Metamaterials
Pendry’s academic journey began in the 1970s. Initially trained as a theoretical physicist, he later described himself as a “jobbing scientist,” tackling often unfashionable problems. His early interests included the intricate details of how electrons interact with solid matter.
A pivotal moment occurred in the mid-1990s when a collaborator presented him with a novel stealth technology designed to conceal British ships from radar. This technology involved a polymer infused with carbon fibers, arranged chaotically across multiple layers. Pendry’s realization was not about the carbon atoms themselves, but rather the disordered structure of the filaments. This insight led him into the nascent field of metamaterials.
In essence, a metamaterial is a substance possessing properties not found in nature. A mechanical metamaterial, for illustration, might thicken upon stretching. While scientists had conceptualized optical metamaterials capable of manipulating light in ways beyond natural lenses, a practical method for their creation remained elusive. Pendry’s significant contribution was the formulation of a comprehensive theoretical framework explaining how metamaterials function. Crucially, he demonstrated that they could be manufactured by etching microscopic grooves, rings, or pillars into ordinary materials.
The Emergence of the Invisibility Cloak
Pendry recognized this approach as a means to revive a radical proposal from Soviet physicist Victor Veselago. Decades earlier, in the 1960s, Veselago had theorized materials that would refract light in reverse, enabling a simple slab to focus light rather than disperse it. Long considered impossible, Pendry devised a method to make light adhere to the peculiar mathematical rules Veselago had outlined.
The invisibility cloak, unveiled in 2006, brought this abstract physics into public consciousness amidst significant media attention. However, Pendry had first presented the concept a year prior at a conference in San Antonio, Texas, attended predominantly by defense researchers. He humorously recounts being tasked with “gingering things up” by delivering a deadpan presentation on the mathematical intricacies of transformation optics. Just as the audience might have begun to question its practical use, he presented a simple formula and a sketch of a potential invisibility cloak design, prompting an enthusiastic reaction.
This was an uncharacteristic display of showmanship from the typically understated Pendry, but it resonated with his audience. He later collaborated with researchers at Duke University in North Carolina to develop the first functional prototype of an invisibility cloak. This initial version could render a device and an object invisible to microwaves, a relatively simple form of electromagnetic radiation to control. Its appearance, however, was less dramatic than the name suggests, resembling a circuit board rather than a wearable garment.
Lunch with a Visionary and the Myhrvold Connection
Later, Pendry prepared lunch, donning an apron to microwave mushroom soup and set the table. This domestic scene provided a stark contrast to the man whose equations had briefly suggested the possibility of real-world Harry Potter physics. I was informed that the soup was a last-minute choice and not representative of his usual culinary standards, a claim I found entirely believable.
His sitting room features numerous coffee-table books on molecular gastronomy, many authored by Nathan Myhrvold. Myhrvold, a San Francisco-based venture capitalist, also pursues interests in photography and food science. He emerges as a significant figure in Pendry’s narrative, having maintained a long professional relationship with him. The large photograph of vitamin C gracing Pendry’s kitchen wall is, in fact, Myhrvold’s work.
Myhrvold holds approximately 60 of Pendry’s metamaterial patents and has established several companies based on his innovations. He foresees metamaterials being integrated into a wide array of technologies within the next decade, including autonomous vehicles, humanoid robots, and 6G communication satellites. Market projections estimate the sector Myhrvold is targeting could reach around £6 billion by 2033.
Metamaterials Moving into the Mainstream
Metamaterials are now demonstrably advancing toward widespread adoption. Many have achieved commercial viability, with notable progress in the area of “metalenses.” Unlike traditional lenses that rely on curved glass, metalenses manipulate light directly through surfaces patterned with dense arrangements of nanoscale structures. Each of these structures functions as a miniature antenna. The result is an exceptionally thin, sometimes only micrometers thick, lens capable of surpassing the performance of conventional optics. This allows a single flat layer to replace the need for multiple heavy glass elements, a significant advantage for devices like cameras.
“One application is to put them in these drones,” Pendry notes. “You can have tiny, tiny drones that still have very, very good optics, because they have these extremely light lenses.” Smartphones and virtual reality headsets also stand to benefit, enabling high-performance optical systems without the associated weight penalty.
Myhrvold is also leveraging Pendry’s work to revolutionize autonomous vehicles. Many self-driving cars currently depend on lidar, a light-based radar system that scans the environment using sweeping laser beams to construct detailed 3D maps. Traditional lidar systems typically achieve this through mechanically rotating mirrors or entire sensor assemblies, making them bulky, fragile, and costly. Myhrvold’s vision involves developing lidar systems that steer laser beams electronically, eliminating moving parts entirely.
Furthermore, metamaterials are being engineered to control seismic waves traveling through the Earth. Mathematically, these waves share similarities with light, allowing the principles governing optical metamaterials to be applied to divert earthquake vibrations away from a building’s foundations.
Pendry’s Focus: The Science, Not the Business
Despite these commercial prospects, Pendry himself is not driven by commercialization. “I know what I’m good at, and I know what I’m not very good at,” he states. “And developing products was not something I ever got excited about.” In the early stages, he was uncertain if his ideas would ever yield financial returns.
Given Pendry’s evident joy in dissecting minutiae, both in science and daily life, his disinterest in the invisibility cloak is perhaps understandable. The technology has evolved beyond a size and scope that aligns with his preferences. While entire industries are still grappling with its implications, Pendry feels his intellectual contribution is complete. “There comes a point when your research starts running away from you,” he explains. “It’s all very interesting, but I can’t add very much any more. So, let’s do something really new and exciting.”
Temporal Metamaterials: Manipulating Light Through Time
What constitutes this “new and exciting” pursuit? Traditionally, metamaterials have been utilized to control the spatial propagation of light. However, since Albert Einstein’s general theory of relativity, it has been understood that space and time are inextricably linked as space-time. Years ago, Pendry began to investigate the possibility of temporal metamaterials, which would control the movement of light not just through space, but also through time.
Gesturing towards my phone recording our conversation, Pendry explains that smartphone screens utilize a material called indium tin oxide. When struck by a laser, it transitions rapidly from opaque to transparent on ultrafast timescales. To a light wave traversing this material, this change appears almost instantaneous, violating a fundamental principle of optics: the conservation of energy as light interacts with matter. The implication is that a temporal metamaterial can either inject energy into a wave or draw it away, thereby shifting its frequency. Red light could become blue light; microwaves could transform into infrared. These materials, he suggests, function akin to a philosopher’s stone, capable of transmuting one form of electromagnetic wave into another.
These novel metamaterials hold the potential for profound revelations, particularly in exploring physics that typically emerges only under extreme conditions. Consider black holes. In 2023, Pendry calculated the behavior of a material whose internal structure shifts over time at speeds approaching that of light. Under such conditions, the resulting mathematics describes points from which light cannot escape – essentially, an analogue of a black hole’s event horizon. He posits that an experimental realization of these ideas could offer a new avenue for studying black holes in a laboratory setting.
An even more peculiar example relates to the Casimir effect. When two metal plates are placed a few nanometers apart in a vacuum, they are counterintuitively attracted to each other. This phenomenon stems from quantum field fluctuations in a vacuum. Pendry has proposed that dynamically altering a material’s electromagnetic properties over time could generate a dynamic version of this effect. This subtle pressure could be amplified to create a quantum analogue of friction, previously unobserved.
Several independent research groups are currently exploring experimental verification of these concepts using real temporal metamaterials. The development is not without its challenges. Classical optics is predicated on stationary materials, and the mathematical models begin to falter when materials alter on femtosecond timescales. Furthermore, many of the effects Pendry predicts exist at the very edge of detectability. It is precisely within this interstice – where theory, experiment, and intuition momentarily diverge – that Pendry appears most at ease.
Nature’s Metamaterials and a Continuing Quest
Before my departure, Pendry brings a small framed object from beside the fireplace. He shares that, like Myhrvold, he enjoys photography. This particular piece is a photograph he took, repurposed by his wife into a firescreen. It features butterflies he encountered on a walk, most notably an Adonis blue, its wings displaying a vivid, iridescent azure. Pendry explains that this striking color is not a pigment, but rather a result of the butterfly’s wing acting as a natural metamaterial, with its nanoscale architecture scattering light.
“I always like using butterflies when I’m explaining metamaterials to new people,” Pendry remarks. For a moment, I am surprised he does not utilize his world-renowned invisibility cloak as the primary illustration of metamaterials’ potential. However, I soon realize this reflects Pendry’s characteristic disposition: a scientist who prefers not to linger on past achievements but rather to retreat to the laboratory and forge new discoveries.