Is the ‘resolution’ of the human eye ‘infinite’?

No measurable physical quantity is ever infinite. In other words, only theoretical concepts can be definitively labeled as infinite. But that is perhaps an epistemological claim that is unnecessary here. So let’s dive into the nitty-gritty of how visual ‘resolution’ is actually measured. As we shall see, the number of light sensitive cells in the retina does not tell us what the ‘resolution’ of the visual system as a whole is. In some circumstances our visual ‘resolution’ exceeds that of the eye considered in isolation.

Visual acuity [1] is the sharpness with which we can distinguish patterns of light on the retina of the eye. This depends on the exact location of the light falling on the retina.

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Why can’t we perceive cells? Or atoms?

I was asked the following question on Quora:

Why can’t we see, touch, hear and smell on a cellular level? And what happens if we can?

Here’s what I wrote:

Essentially, we perceive the visible world in the way that we do because of our overall size, the shape of our eyes, and the sizes of objects in the world that are relevant to our voluntary behavior.

This question might seem silly, but a closely related question can serve as a springboard for us to think very deeply about physical scale, and how it relates to biological life and to the very concept of a scientific law.

But first lets deal with the basic question.

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