Evolution and ecology: The pace of life

Abstract

We consider the influence of physics on the development of the microscope, using the unusual approach of working backwards in time from the present day to the earliest times. Modern microscopes use techniques including stimulated emission depletion microscopy and near-field scanning optical microscopy that relies on the properties of evanescent waves. These instruments allow optical instruments greatly to exceed conventional concepts of resolution, and they rely on computers to drive the system. High-resolution objective lenses, meanwhile, are now being made at very high cost using aspheric lenses. These are not used by microscopists, but are essential for the systems of photollithography used in the printing of microcircuits on computer chips. Apochromatic objectives resulted from the theoretical physics elaborated by Ernst Abbe in the nineteenth century, yet before the development of the color-corrected lens, simple (i.e., single-lens) microscopes were capable of resolving surprisingly fine details. Microscopes made by Bancks of London were used by Darwin, Brown, Bentham, and Hooker and—with careful adjustment—can reveal remarkably fine detail that seems to defy the constraints of the theoretician. Simple microscopes were used by Leeuwenhoek in the Netherlands in the seventeenth century, and here we will see that the design—widely described as a “Leeuwenhoek microscope”—was actually a concept of the London philosopher, Robert Hooke. The chapter will conclude at the earliest days of the microscope, throwing new light on the earliest microscopic descriptions in the literature of science. We learn how the theoretical constraints of physics can be challenged by the use of personal preference and experience.