From Spiritual Forces to Plasma Physics

How Victorian Curiosity Shaped the Study of Electrical Discharges and Matter

In the nineteenth century, science stood at a crossroads between the visible and the invisible. New discoveries in electricity, magnetism, radiation, and atomic theory were challenging humanity’s understanding of what matter truly was. At the same time, spiritualism—the belief that unseen intelligences or forces could interact with the physical world—was becoming popular among intellectuals and the public alike. It was within this turbulent landscape that early plasma physics emerged, not as a purely technical discipline, but as an extension of humanity’s long-standing fascination with unseen forces.

One of the most intriguing figures in this transitional period was Sir William Crookes, whose work bridged chemistry, electrical science, and spiritual investigation. Crookes is best known in physics for his experiments with electrical discharges in gas-filled and near-vacuum tubes, which led to the discovery of what he called radiant matter—now known to involve electrons and plasma behavior. At the same time, he was a public investigator of spiritualist phenomena, conducting séance experiments and publishing reports on psychic effects.

To modern readers, this may sound contradictory or even unscientific, but in the Victorian era it was not unusual. Electricity itself had once been mysterious—an invisible “fluid” capable of animation, movement, and transformation. Magnetism was equally enigmatic, acting at a distance without physical contact. When cathode rays appeared inside vacuum tubes as glowing streams moving through empty space, bending in magnetic fields, and illuminating glass, they seemed to confirm the existence of invisible forces previously only imagined.

Crookes initially encountered cathode rays through improvements in vacuum technology during the 1870s. As gas pressure inside sealed glass tubes was reduced, electrical discharges no longer behaved like simple sparking gas but instead formed glowing streams traveling from electrode to electrode. Crookes noticed that when the tube was highly evacuated, rays appeared to move in straight lines and could push small objects—clear evidence they possessed momentum.

This experimental environment produced something very close to what modern physics now calls low-pressure plasma. Ionized gas, free electrons, and electromagnetic forces all interacted to produce a glowing state of matter that fit neither classical gas nor solid descriptions. This “fourth state of matter” would later be formally named plasma, but the physical reality had already been revealed in Crookes’ darkened laboratory.

At the same time, Crookes’ involvement in spiritualism shaped the direction and language of his thinking. He believed science had not yet discovered all forces operating in nature and suspected that electricity and matter might someday explain phenomena that spiritualists attributed to spirits. He did not conclude that spirits were electrical effects—but he argued that both might represent pieces of a hidden universe still poorly charted.

Unlike Crookes, most physicists involved in cathode ray research were not drawn into spiritualist movements. Scientists such as J.J. Thomson, who later identified the electron in 1897, approached the phenomenon through measurement, mathematics, and repeatable experimentation. The scientific method gradually pulled cathode rays away from philosophical speculation and into atomic physics. Still, Crookes’ belief in invisible forces did not weaken his scientific ability—it arguably intensified his willingness to explore the unknown when others hesitated.

In the twentieth century, plasma research expanded beyond vacuum tubes into astrophysics, electrical engineering, and fusion science. Lightning, stars, auroras, flames, and neon lights were all recognized as plasma phenomena. Human-made plasma was eventually confined using electromagnetic fields in experimental reactors such as tokamaks—machines designed to replicate energy production inside stars.

This journey—from séance rooms to fusion laboratories—reveals something important: early science was not always cleanly separated from mysticism. Instead, it evolved from it. What mattered most was not whether a scientist entertained mysterious ideas, but whether they tested them with instruments rather than merely symbols.

Crookes represents the complex humanity behind scientific discovery. He was neither fully right nor entirely misguided. He explored invisible forces, but history later revealed that many of those forces were not spiritual at all—they were physical, measurable, and governed by laws not yet known in his time.

Today, when plasma is contained inside magnetic fields in fusion reactors or used in electronics manufacturing, it is easy to forget how strange this state of matter once appeared: glowing, untouchable, responsive to unseen influences. In Crookes’ laboratory, it must have felt alive.

And perhaps that feeling—that sense of standing before something neither solid nor empty—is what truly connects his spiritual curiosity to his scientific brilliance: the recognition that reality is far larger than what the eye can see.