Radiant

Excerpts stitched from “Media Hot and Cold” (Starosielski, 2021)
 
In 2010, the United States military deployed a new technology to Afghanistan: the Active Denial System. Nicknamed the “heat ray,” the system directs a millimeter wave beam at human subjects up to a half mile away. Electromagnetic radiation penetrates the human body only 1/64 inch, but it produces an extraordinary sensation of being burned—of being scalded by hot water or set on fire. The military fired thousands of test shots on volunteers’ bodies and reported that while the system left no mark or burns, “the instinctive repel response [was] universal.”[1] In the military’s attempt to demonstrate the system’s immaterial nature, the heat ray became one of the most-studied nonlethal weapons in the history of the Department of Defense; its precise effects documented by independent review boards, human-effects researchers, and technology specialists. These groups concluded that it was one of the least physically intrusive crowd control and security technologies and that, within established limits, it enacted no physiological harm on its targets—merely a sensation of harm, a sensation of heat. It was, some argued, the “Holy Grail of crowd control.”[2] The military staged events to garner support for the heat ray, zapping reporters and demonstrating the absence of burns, scars, or debilitation. After it was recalled from Afghanistan, the system was redubbed the Assault Intervention Device and installed in Los Angeles’s Pitchess Detention Center in order to weaponize heat domestically against incarcerated people.[3] There was public opposition, the American Civil Liberties Union contested its use, and the heat ray was ultimately decommissioned.
 
The Active Denial System encountered resistance in part because it evoked a deeply ingrained imagination of the heat ray—a thermal weapon of bodily disintegration. “It is still a matter of wonder how the Martians are able to slay men so swiftly and silently,” H. G. Wells writes in *The War of the Worlds* in 1898. “However it is done, it is certain that a beam of heat is the essence of the matter. Heat, and invisible, instead of visible, light.”[4] While Wells’s fictional heat ray gun causes its target to burst into flames, the Active Denial System leaves no perceptible trace. As an instrument of thermal violence, the Active Denial System modulates behavior in a way that makes a victim’s action look intentional, deferring accountability away from its operators. Even when transmitted directly from military installations, heat effects remain indeterminate, prompting speculation and interpretation.
 
The Active Denial System is a radiant thermal medium. Radiant thermal media generate, intensify, or channel electromagnetic waves to produce thermal effects. They can also directly leverage the infrared part of the spectrum for communication. While convective and conductive media transform the environment into a conduit for thermal communication (altering temperature through air circulation, water, interfaces, screens, minerals, architectures, and social practices), radiant thermal media organize materials to reflect, refract, or block spectral transmissions. Radiant thermal media also have a distinct physical correlate: all bodies that have a temperature of greater than zero degrees Kelvin (−273.15°C/−459.67°F) emit thermal radiation in the form of waves. These wavelengths generally correspond to the body’s temperature. Most entities in the universe emit radiation in the visible light or the infrared part of the spectrum. The sun emits radiation in the infrared range of the spectrum (with wavelengths above 700 nm), as visible light (400 nm to 700 nm), and as ultraviolet light (below 400 nm). Human bodies tend to emit radiation at around 10 μm (micrometers). The plume of a jet’s engine emits radiation at around 3 μm to 8 μm (enabling heat-seeking missiles to locate it).
 
What is distinct about infrared thermal radiation, compared with visible or ultraviolet radiation, is that it’s the form of electromagnetic radiation emitted by most objects, bodies, and phenomena that people have contact with in everyday life. It is a form of wave communication in which bodies are immersed and to which they are often responsive. These emissions are not “heat” as we normally know it—they are not a transfer of energy but rather an electromagnetic effect of heat. In a seminal study of radiance, Rahul Mukherjee describes critical aspects of radiant infrastructures: even as they manage imperceptible energy, they are inevitably leaky, and they pull together the public and the private, the spark of development and the threat of contamination.[5] Notably for media theory, radiation moves even in a vacuum—the dissemination of radiant heat thus requires no medium. Radiant thermal media often manage rather than simply relay: they organize the multitude of thermal emissions being sent at all times in all directions, most of which are sent in wavelengths undetectable by human vision.
 
Because radiant thermal media involve spectral negotiations, they are intimately connected to other forms of spectrum management: the manipulation of light waves, radio waves, and television signals. As a result, radiant-heat management and transmission systems are closely linked to existing wave-transformation systems: how we engage, imagine, and organize heat fundamentally reflects the landscape of other communications media. In turn, the politics and potential of the media spectrum inflect the possibilities for thermal organization.
 
In the early twentieth century, experiments with three parts of the electromagnetic spectrum—light, radio, and infrared—were intertwined and imagined as part of the development of new communications systems. Although infrared radiation had been sensed long before it was “discovered” in 1800, following the development of the light-based photophone in the late nineteenth century, infrared was imagined as a means of communication. Infrared circuits were later adopted as a means of television transmission, including in the early television systems designed by John Logie Baird. However, while radio waves became a substrate of mass media in the 1920s and 1930s, infrared waves were not broadly adopted as a means of media transmission. The early media history of channeling infrared is largely a story of failure, of attempts that were ultimately superseded by wave communications in other parts of the electromagnetic spectrum. As the infrared spectrum was populated with the promiscuous emissions of so many human and nonhuman heat producers, it was much more widely engaged during this period as a medium of sensing rather than a means of signal exchange.
 
At the same time that scientists and engineers were experimenting with infrared, radio manufacturers were experimenting with radiant heat. With the expansion of shortwave radio in the early twentieth century, people discovered that shortwave transmitters didn’t simply send voices and signals—they also sent heat. Alongside experiments with infrared telegraphy and telephony, this catalyzed experiments with “radio fever”: the use of shortwaves to heat bodies in medical practices, to cook food, and to transmit power. The experiments also generated new ideas about radiant heating in which subjects were targeted by heat rays from afar, rather than warmed or cooled by their immediate environment. These systems formed the foundation for the Active Denial System today, even if they used a different part of the electromagnetic spectrum.
 
In the early decades of the twentieth century—especially the years following World War I, a new sensibility emerged of what heat was and what it could become: a communications circuit. Like the Active Denial System, in this moment thermal communication was imagined as a direct channel by which waveforms and, as a result, bodily activity could be modulated. Contrary to the operation of stoves, air conditioners, fans, and sweatboxes, all of which work largely via environmental modification and through the amplification of existing temperatures, in these experiments heat was imagined as a vector, a directional force that moved in time and space and was itself intended to produce directional movement. These systems channeled radiance into thermal circuits, transmitting heat signals and heat effects in a classic mode of communication, often to send messages directly and point to point.
 
These early twentieth-century experiments illuminated the affective and visceral potential of the infrared spectrum and composed a foundation for many subsequent infrared media technologies. But it was not until the mid-twentieth century, with the development of silicon media, plastic insulation, and lasers, that infrared signals were finally used in circuits of mass mediation. In the 1970s and 1980s, infrared waves came to constitute the beams of remote controls. Heat rays began to be used as “ink” to inscribe ubiquitous thermal paper receipts. And in the 1990s, consumer infrared linked computer laptops and personal digital assistants before being replaced by Wi-Fi and Bluetooth (two technologies that don’t require line-of-sight connections). During this period, however, infrared still remained marginal as a mass transmissions medium.
 
In the twenty-first century, infrared signals became the substance of global digital media. The final sections of this chapter focus on the latest iteration of infrared communications: the radiant signals channeled down fiber optic cables. Inspired by the “optics” of these systems, those who write about and represent the cable network that carries most digital media traffic have often focused on “light” as the medium of transmission. But digital content—from social media posts to streaming video—is not encoded in visible light but in infrared waves. Massive amounts of data are transduced into heat rays and channeled across oceans and continents on hair-thin pieces of glass. Today’s digital network is an infrared network.
 
As the infrared spectrum expands as a medium for signal exchange, the capacity to control infrared radiation shapes conditions for the global distribution of media. This in turn dramatically expands capacities for sensing and manipulating temperatures. As one example of this, today infrared-based digital communications networks are being transformed into the most expansive thermal-sensing network on earth. New technologies enable infrared waves on fiber-optic cables to register temperature, with the potential to turn the global internet’s infrastructure into a massive thermometer. While infrared radiation has long been entangled with telegraphy, radio, and television, climate change is now thermally entangled with the base substrate of the global internet. How people send infrared signals through the internet—and their dependence on digital platforms—materially expands the possibilities for sensing the warming of the planet as a whole.