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The result, obtained last August, is an image. But it is not a photo. The difference is in how the picture gets made.

The wavelength of visible light varies, from the shortest violet to the longest red, but is about 500 nanometres, give or take.

The average atom is hundreds, even thousands of times smaller than that.

The upshot is that you cannot bounce light off an atom, in the way you can bounce light off a person or a cat to capture their image.

Photo by David Nadlinger / University of Oxford

Nadlinger’s image shows a single atom of strontium, positively charged, held in place in a vacuum by the electromagnetic field produced by two metal electrodes a mere two millimetres apart.

This device is called an ion trap, and it is a key part of research into the development of quantum computers, and in the operation of atomic clocks. In both cases, the trap is useful because it allows physicists to measure and manipulate the highly regular behaviour of atoms at the smallest scale.

At the sub-atomic scale, on the level of electrons and protons, the problem of observation goes even deeper.

Electrons, for example, are never exactly here or there. They exist in varying potentials all over the place. If you were to measure precisely where a single electron is at a given time, the wave function that describes its behaviour would collapse. In other words, you would not really be seeing the electron in all its quantum uncertainty.

What you can do, however, is make an atom glow, like a stove element on high.