Science, Art, Litt, Science based Art & Science Communication

Physicist Todd Johnson has been working at Fermilab for 30 years, but he also dabbles in art. He’s all about capturing lightning-like fractal patterns in plastic cubes with the help of a linear accelerator. He doesn’t do this at Fermilab, but at a commercial polymer cross-linking facility in Ohio . Per Symmetry Breaking:
Johnson arrives at the facility with stencils laser-cut from steel or handmade from sheet lead; clear acrylic hunks of varying sizes; and a lot of ideas. He sends his pieces of acrylic through the accelerator’s electron beam, which is designed to break chemical bonds in plastics. Because acrylic is an insulating material, the beam scatters through the material, losing momentum as it goes. Only areas of the acrylic not covered by a stencil are exposed to the beam, allowing Johnson to create shapes.

Eventually the beam coalesces into a pool of electrons that desperately want to escape but can’t—an invisible puddle of potential energy. Releasing that energy is a simple but arresting process. To do it, Johnson uses a hand-made tool reminiscent of a crude, oversized syringe. It works like a click pen—press on one end and the tip comes out the other with enough force to puncture the acrylic. The instant the tool punctures the surface, there’s a burst of white light as the pool of excited electrons escapes from the material, leaving trails of vaporized acrylic in its place.

On their way out of the acrylic, the electrons follow the same natural laws that govern all systems that flow—electricity snaking its way from a storm cloud to Earth, rivers branching into ever smaller creeks and streams, or the spidery web of veins that distributes blood throughout your body.

The fern-like patterns created through this method often form on the skin of people struck by lighting, caused by the capillaries under the skin rupturing from the shock wave generated by the electrical discharge. When lightning strikes sand, it can create fulgurites, as the sand is fused into glass by the intense heat.

The colloquial name for these sorts of branching patterns is “lightning flowers,” but they are also called “Lichtenberg figures” in honor of 18th century physicist Georg Christoph Lichtenberg.


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