"The double-slit experiment exemplifies the wave-particle duality of light, as well as quantum physics itself. It demonstrates that light interferes with itself in passing through a pair of slits. It also shows that even single electrons - proceeding one by one - interfere. Richard Feynman is said to have remarked that it contains everything you need to know about quantum mechanics.
[...] The double-slit experiment with electrons possesses all of the aspects of beauty most frequently mentioned by readers. [...] It is transformative, being able to convince even the most die-hard sceptics of the truth of quantum mechanics. [...] the concepts are readily understandable, despite its revolutionary result. It is also deep play: the experiment stages a performance that does not occur in nature, but unfolds only in a special situation set up by human beings. In doing so, it dramatically reveals - before our very eyes - something more than was put into it.
The quantum-mechanical world is likely to remain counterintuitive to human beings, no matter how well-versed or confident we are in the theory. The double-slit electron-interference experiment brings its reality before our eyes in a dramatic, economical and materially embodied way. It is therefore likely to remain in the pantheon of beautiful experiments for a long time to come."
In the inside pages we shall consider some examples of how the beauty of an experiment might be perceived, interviewing both people involved in research and people not conversant with science.