The Sub-Microscopic World

Abstract

For more than a century physicists have been exploring the world at smaller and smaller distances. They have found structures on smaller and smaller scales—molecules, atoms, nuclei, nucleons, quarks—but have never seen anything such as the world described in O’Brien’s tale. Some would say that’s a shame but, to my mind at least, the theories that describe the submicroscopic world are more interesting than the product of O’Brien’s imagination.

Appendices

Commentary

Fitz-James O’Brien, writing in 1858, was clearly as familiar as Robert Milne (see previous chapter) with the activities of spirit mediums. However, if we ignore the paranormal aspects of this story (as well as the offensive nature of the narrator) it is clear O’Brien had a passing acquaintance with the science—or at least the microscopy—of his day. With the obvious exception of the diamond lens itself, the instruments he describes were all working microscopes and the names he drops were all noted microscopists.

For example, Antonie Philips van Leeuwenhoek, whose voice plays a role in the story, is widely considered to be the first microscopist. He used a primitive sort of device—essentially just a small glass ball set in a metal frame—to discover “animalcules” (what we now call microorganisms). Christian Gottfried Ehrenberg, another noted microscopist mentioned in the story, spent three decades of his scientific career examining water, soil, and dust under magnification and he described countless new species. Félix Dujardin was an equally accomplished microscopist, as was Matthias Jakob Schleiden, who studied the structure of plants and was the co-founder of one of the most important principles of biology—namely, that organisms are composed of fundamental units called cells. And Charles Achilles Spencer was America’s first microscope maker to meet with success—his “Trunnion Microscope”, which O’Brien’s narrator purchases, was classed as one of the finest optical instruments of the mid-19th century.

Those early microscopes, although relatively simple, were advanced enough to provide sufficient magnification for the science of microbiology to develop. It turns out you don’t need a huge amount of magnification to observe various types of specimen. At a magnification of 40×, for example, you can see the larger types of biological cell. At a magnification of 100× you can make out bacteria as tiny dots. Increase the magnification to 400× and bacterial shapes become clearly visible while individual chromosomes can be seen within cells. So—given the state of microscopy in the mid-1850s, was O’Brien justified in imagining the miniature forest world inhabited by Animula? I’m not convinced he was.

Even Victorian instruments were sufficiently sophisticated to cast doubt on the notion that the microscopic world is like the everyday world, only smaller. To be sure, in the early days of microscopy Ehrenberg had argued that animalcules were “complete organisms”. In other words, there was an early view that all animals—from microscopic organisms through to elephants—possess complete organ systems: muscular system, circulatory system, lymphatic system, and so on. But as early as 1835, microscopic studies carried by Dujardin had disproved this idea. So, by the time O’Brien was writing, the world inhabited by Animula was more fantasy than science fiction.

Can we be entirely sure, however, that going to higher magnifications won’t uncover a hidden world of tiny people inhabiting tiny forests? Well, yes we can.

Consider how a miniature human such as Animula might function. Better still, think about one of those many other miniaturized humans that appear in science fiction from time to time: Scott Carey, the protagonist in Richard Matheson’s The Shrinking Man, provides perhaps the most famous example. Towards the end of Matheson’s novel, Carey concludes that he won’t simply disappear as he continues to shrink. He thinks: “If nature existed on endless levels, so also might intelligence.” Carey’s belief was the general philosophy behind all these stories, from O’Brien’s “The Diamond Lens” through to Matheson’s The Shrinking Man almost a century later. But how could an intelligent being such as Animula or the ever-dwindling Scott Carey possibly exist? The human brain contains about 100 billion neurons. If the miniature person must maintain the mass of all those neurons—not to mention all the other systems required by the human form—then he or she is going to have the density of a white dwarf star! This is simply not viable. As the person gets smaller, the only way to preserve the density that’s typical of biological organisms is to get rid of mass. But if Animula or Carey had 100 neurons, say, rather than 100 billion neurons … well, they’d be less like a human and more like a rotifer (one of the tiny animals seen by microscopists such as van Leeuwenhoek, Ehrenberg, and Dujardin; see Fig. 11.1). The venerable SF trope of humans in microscopic form has never made any sense.

Fig. 11.1

A rotifer of the genus Northolca. Most rotifers are between 0.1–0.5 mm in size, and so they are among the smallest animals; you need a microscope to study them. Many of the first rotifers to be described were identified by van Leeuwenhoek at the start of the 18th century. But van Leeuwenhoek was working when the techniques of optical microscopy were in their infancy; the beautiful image here, which clearly shows various body parts inside a shell-like protective outer covering, could only have been taken using modern techniques. Clearly, in an animal as small as this, there simply isn’t enough room to contain a nervous system that would support the behaviour exhibited by Animula in “The Diamond Lens” (Credit: Wiedehopf20)

The possibility of advanced life forms existing at the microscopic level is ruled out by observation as well as theory.

Nowadays, microbiologists have access to optical microscopes capable of magnifying up to about 1500×. (Beyond this magnification the object being viewed starts to appear fuzzy; the wavelength of light puts a limit on the clarity of images.) This is sufficient magnification to make out bacteria and the various constituents of a biological cell. And it’s clear that the microbial world does not contain creatures of the complexity of Animula. Unicellular organisms, yes; complex animals, no.

What about the world at even shorter distances? Might intricate structures exist at those length scales? Well, modern techniques permit microscopists to apply magnifications greatly beyond the limit of traditional optical microscopes and, again, observations rule out Animula.

In 1931, the German physicist Ernst Ruska developed the first transmission electron microscope (TEM). The TEM is similar in function to an optical microscope but uses electrons rather than light; where an optical microscope bends light rays with a glass lens, a TEM bends electron beams with an electromagnet. A modern TEM allows scientists to produce extremely high-resolution images at extremely high magnifications—thousands of times greater than optical telescopes permit. And four years after the invention of the TEM, Ruska’s colleague Max Knoll developed the scanning electron microscope (SEM). A SEM doesn’t have the same extremely high resolution of a TEM, but it has numerous other advantages: those spectacular photographs we see of the surface of microscopic creatures are usually SEM images (see, for example, Fig. 11.2). More recently microscopists have developed other techniques in addition to TEM and SEM. None of these approaches or techniques, when applied to biological systems, have found anything other than cells and the usual structures that are to be found in cells. The world of Animula doesn’t exist.

Fig. 11.2

A scanning electron microscope can take images that would be impossible using a traditional optical microscope. This image, for example, shows a white blood cell (yellow) engulfing anthrax bacteria (orange). The white line at the bottom indicates the scale of the image: the bar is 5 micrometers long. SEM and TEM images clearly demonstrate that the world described in “The Diamond Lens” does not exist at these distance scales (Credit: Volker Brinkmann)

Even a transmission electron microscope is limited in the magnification it can achieve. The world contains structures that are much smaller than can be seen by a TEM. Could there be creatures of interest existing at a scale that’s hidden even from the prying eyes of an electron microscope?

Again, the answer is: no.

One of the main strands in the story of twentieth century physics is the development of our understanding of the world as it appears on the very smallest scales. The story began, as much of twentieth century physics began, in 1905—when Albert Einstein solved a puzzle first highlighted by the botanist Robert Brown in 1827. Brown used a microscope to study tiny granules inside pollen grains suspended in water. He noticed the granules were in constant, random motion. Similar random motion was later seen to be exhibited by microscopic chips of glass and scraps of stone, and you can observe the same effect if you watch dust motes dancing in a shaft of light, so the explanation for the motion clearly does not lie in biology. Einstein explained how Brownian motion could be explained if the pollen grains were being buffeted by water molecules: it was the first convincing evidence for a long-standing but controversial idea—that matter consists ultimately of molecules and atoms.

The word “atom” comes from a Greek word meaning “indivisible”. But just a few years after Einstein’s seminal paper on Brownian motion had started to persuade the world of the existence of atoms, physicists learned how to divide the atom. Ernest Rutherford demonstrated that atoms have a structure. He showed that an atom is mainly empty space: it has a central nucleus, which contains nearly all of an atom’s mass, while a cloud of electrons orbit the nucleus at a distance.

The atomic nucleus also possesses a structure: it consists of particles called protons and neutrons. And just as the atom itself can be divided, so too can the atomic nucleus. In 1932, John Cockcroft and Ernest Walton succeeded in splitting the nucleus of a lithium atom by bombarding it with high energy particles. Over the following decades physicists continued with this approach—smashing particles together at ever greater energies and examining the debris—and it proved to be an exceptionally fruitful line of attack for investigating the subatomic world. It has been so successful that we now know—to some level of accuracy, at least—how the universe is put together. At the most fundamental level there are particles called electrons and quarks. Certain combinations of quarks are permitted and these allowed combinations form particles such as protons and neutrons. Protons and neutrons combine to form atomic nuclei. Atomic nuclei, when orbited by electrons, are the constituents of atoms. Atoms combine to form molecules. And molecules combine to form the complex structures we see around us—from microscopic organisms all the way up to macroscopic entities. Whether physicists are using a machine such as CERN’s Large Hadron Collider to investigate the properties of quarks, or an advanced atomic force microscope to investigate matter at the nanoscale, they are always able to explain their observations in terms of standard models of physics. Nothing has been discovered, at any distance scale, that would permit the existence of the world inhabited by Animula.

Quite by accident, however, one aspect of O’Brien’s story does strike a chord with modern readers: the title, “The Diamond Lens”. The UK possesses a national research facility called a synchrotron—a huge ring, 500 m in circumference, which accelerates electrons in such a way that intense beams of light are created. The synchrotron acts as a giant microscope, which scientists use to study fossils, and oil paintings, and archeological artefacts, and viruses, and jet engines … it’s an impressive operation. And the name of this giant microscope? Diamond!

For the final chapter we turn from speculations about what we might see through a microscope to speculations about what—if we’re unlucky—we might one day see through a telescope.

Notes and Further Reading

• For example, Antonie Philips van Leeuwenhoek—A quick online search will throw up numerous sites devoted to the history of microscopy. Rochow and Tucker (1994) is expensive, but if your library has it then you’ll find a good overview of the development of microscopy. Asimov (1964) contains potted biographies of many of the scientists mentioned in this chapter.

• to observe various types of specimen—Allen (2015) provides a concise account of what can be seen at different levels of magnification and of the various types of instrument.

• appear in science fiction from time to time—“The Diamond Lens” was published in Victorian times (O’Brien 1858); The Shrinking Man was published almost a century later (Matheson 1956); and such stories continued—Asimov (1966), who was of course aware of the impossibility of miniaturization, nevertheless tried to provide a veneer of scientific respectability to this idea in his novelization of the film Fantastic Voyage.

• microscopists have developed other techniques—The Nobel Prize committee has recognised various developments in microscopy over the decades, and their website gives a good account of techniques such as transmission electron microscopy. See Nobelprize.org (2014).

• much of twentieth century physics began, in 1905—In addition to publishing papers on special relativity, mass–energy equivalence, and the photoelectric effect (for which he was awarded the Nobel prize), this miraculous year saw Einstein publish his explanation of Brownian motion. See Einstein (1905) if you want to read the original paper.

• how the universe is put together—The Standard Model of particle physics gives us our best understanding of the subatomic world, and represents one of the pinnacles of human intellectual endeavor. Oerter (2006) gives a good overview of the historical development of the Standard Model, and is only slightly out of date. Carroll (2013), with its description of the hunt for the Higgs particle, brings the story up to date.