The Enterprise picks up a distress signal from a nearby planet and upon investigation, they are hit with a beam of spiroid radiation. This radiation causes every living thing on the ship to shrink. Kirk beams down to the planet and materializes at his full size, as the transporter retained his original body pattern. While on the surface, he sees a miniature city. These Terratins are the decedents of Terra-Ten, a lost Earth colony. Their ancestors were originally shrunk after exposure to a supernova’s radiation. They enjoyed a peaceful existence until their planet ramped up its volcanic activity. Shrinking the Enterprise crew was the only way for them to communicate and ask for help.
Shrink rays and mini adventures are common in Sci-Fi, but they often ignore all the biological and physical challenges inherent in tiny living in exchange for cinema friendly giant object perils. The truth is, the human body would struggle with cellular function and gas exchange at that size. Smaller animals tend to have a higher metabolism and energy requirement compared to larger ones, relative to body weight. For example, a mouse needs to eat ~67 times the number of calories that an elephant eats per kilogram of body weight (Mortola, 2023). Shrinking the poor Enterprise crew to the size of a mouse or smaller would increase their metabolism proportionately. It’s amazing that they didn’t stop for snacks the entire time they were fighting to control the ship.
The mechanisms for shrinkage given in the show was that either the crew was being contracted or the ship was expanding. They later confirm that all organic matter on the ship is shrinking due to the “spiro-form fracturing of dilithium molecules”. In other words, the spiroid radiation that everyone was exposed to just tightly winds things. McCoy determines that everyone’s weight remains consistent, and they retain the same number of molecules, but the space between them is shrinking. In reality, smaller organisms would have fewer molecules and cells overall; changing the space between molecules would increase the density of the organism to a point where its cellular processes might break down. At this level, molecules must move freely around the cell to interact with their targets and carry out functions. However, when Spock suggests that the distance between atoms is relatively the same as the distance between stars, he may be referring to a natural length scale set by the cosmological constant.
To crunch this astronomical subject into a tragic oversimplification, the cosmological constant represents the energy density of empty space. It influences the distance between stars and how fast galaxies move away from us, but it has little bearing on the space between and within atoms. Yes, atoms are also mostly empty space, but this tiny emptiness is occupied by negatively charged electrons, which would repel one another if they were squished too close together. Significant pressure or temperature would be required to achieve this, enough that the Enterprise crew would have a hard time surviving it. Also, how densely were they planning to be compacted before collapsing into a black hole?
The computer helps the crew calculate how small they would shrink based on how tightly DNA can wind. In this scenario, the DNA strands wouldn’t break, they would just stop winding. It seems that the writers simply liked the spiral shape of DNA and wanted to relate it with fictional spiroid radiation. In reality, DNA is tightly wound around proteins called histones. It is probably already as compact as it can be, but that is beside the point. DNA which is tightly wound is functionally switched ‘off’, that is to say, the genes are not actively being expressed. If the body needed to access those genes to produce enzymes and proteins for any cellular operations, specialized protein complexes ‘unwind’ the relevant areas of DNA as needed. This is already how things normally function, so tightly winding everything would turn the entire genome off. You would die…instantly.
Fortunately for Kirk and crew, they were able to fix their predicament via the magic of the transporter. By readjusting everyone’s original pattern, the effects of the spiroid radiation was reversed. Since they were already so small, the entire Terratin city could be beamed aboard the ship and transported easily to a beautiful new planet. No one will be shrinking against their will anytime soon, but if they survive it, hopefully they remember to bring snacks.
Mortola, J. P. (2023). “The Mouse‐To‐Elephant Metabolic Curve: Historical Overview”. Comprehensive Physiology, 13(2), 4513-4558.
Hopeless Trekkie 