The Invisible Worlds All Around Us

Imagine the world before the microscope.

From Robert Hooke's "Micrographia"

Imagine that all humans knew about the world around them was what they could see with their naked eyes. Imagine a world without microscopes  It's hard to return to that condition. It's just so crazy to think that all the world consisted of what we could perceive with our somewhat limited visual perception.

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In a feature for Aeon Magazine, Philip Ball digs into what happened when people first gained access to the previously hidden worlds at the microscopic scale.

The implications were theological as much as they were scientific.

Invisibility comes in many forms, but smallness is the most concrete. Light ignores very tiny things rather as ocean waves ignore sand grains. During the 17th century, when the microscope was invented, the discovery of such objects posed a profound problem: if we humans were God's ultimate purpose, why would he create anything that we couldn't see?

The microworld was puzzling, but also wondrous and frightening. There was nothing especially new about the idea of invisible worlds and creatures -- belief in immaterial spirits, angels and demons was still widespread. But their purpose was well understood: they were engaged in the Manichean struggle for our souls.

Absent a way of interpreting all the wonders of the microscopic world, people drew on what they knew, religion, superstition, or even simply human life. Check out this idea that floated around during the late 19th century:

The physicist George Johnstone Stoney declared in 1891 that the physical universe is really an infinite series of worlds within worlds. The scientist Edmund Fournier d'Albe developed these ideas in Two New Worlds (1907), where he envisaged an 'infra-world' at a scale below that which microscopes could register, peopled, like Leeuwenhoek's drop of water, with creatures that 'eat, and fight, and love, and die, and whose span of life, to judge from their intense activity, is probably filled with as many events as our own'. The human body, he estimated, could play host to around 10 to the 40th power of these 'infra-men', experiencing joys and woes 'without the slightest net effect on our own consciousness'.

From a medical perspective, of course, the invention and refinement of the microscope helped humans figure out that bacteria could cause infection. But this piece of biomedical technology has not received a sufficient amount of attention as a probe for meaning. People often say in wonder, "Think of all the stars and galaxies that we now know exist!" But it's much more rare for people to marvel at the incomprehensible amount of life that exists invisibly right in front of them.