The mathematics of music means piano strings can never be in perfect harmony

Unlike with guitars and violins, pianos’ strings can never be perfectly tuned to one another. The solution? As this short animation from MinutePhysics explains, the instrument’s 88 strings across more than seven octaves means tuning a piano using harmonic intervals will inevitably lead to notes being fractionally off-pitch, with the issue compounding across octaves. So instead of using harmonics, piano-tuners generally keep octaves perfect, while leaving every other interval out of tune by just a tiny fraction. This workaround forsakes the appealing mathematical patterns of harmonics, but makes it possible to keep the kind of uniformity that is so valued in an era of mass production and reproduction of music.

When skipping school for a day at the beach is to be torn between the present and the future

On the Monday after prom, a bit before graduation, getting to class is the last thing on the minds of high-school seniors from the small industrial city of Pahokee in Florida. Instead, they’re off on a 60-mile drive to have a celebratory day at the beach. In between selfies and shenanigans, they reflect on their diverging paths, including friendships, romances and plans for the future. With intimacy and ease, Skip Day moves among these young people on the cusp of enormous changes, eliciting the mixed emotions and uncertainties that so frequently accompany coming of age. A favourite on the film festival circuit in 2018, Skip Day won the Illy Prize for best short film at the Directors’ Fortnight in Cannes, among other honours.

Along with The Rabbit Hunt, the short is part of a group of documentaries by the filmmakers chronicling the lives of teens in Pahokee.

The mysterious ‘something’ behind the accelerating expansion of the Universe

Dark energy is the term that scientists have given to the mysterious ‘something’ deemed responsible for the accelerating expansion of the Universe. However, unlike gravity, which pulls things together, physicists and cosmologists still can’t explain what dark energy really is or how it does what it does, despite the fact that it theoretically makes up a substantial part of everything. In this upbeat animation, Pedro Ferreira, professor of astrophysics at the University of Oxford, points to the scenarios that his field faces – the ‘incredibly exciting’ one and the ‘doomsday’ one – perhaps taking solace in knowing that there are only two. 

Abundance has made fat an enemy, but it’s been a friend to humans for millennia

Despite the modern Western obsession with bodyweight, the idea that fat bodies are unsightly and unhealthy is largely unprecedented in human history. Nevertheless, the thin ideal is spreading, permeating societies where ‘a little extra’ has been celebrated, even until very recently. But, as this short video collaboration between Aeon and SAPIENS explains, the idea of fat as something we should get rid of is a historical outlier. Playfully visualised by the London-based Kazakh animator Ermina Takenova, What Fat Is For probes the complex role of fat across human society, from mysterious Palaeolithic figurines to Jamaican dance halls, treating this vital component of our bodies with the complexity, even reverence, it deserves.

Meet your single-celled neighbours – a microbial tour of a metropolis

From an anthropocentric point of view, big cities are one of humanity’s most majestic achievements: massive, self-contained ecosystems built by, catering to, and inhabited by huge numbers of people. But you could forgive microorganisms for claiming that cities are actually theirs. After all, they outnumber humans in urban environments by the trillions. They also affect cityscapes in a far more tangible way: city planners and epidemiologists shape urban environments with pathogenic threats in mind. 

For his experimental short film The Big City, the Canadian filmmaker Evan Luchkow put the hidden lifeforms of downtown Vancouver’s main roads under the literal microscope, documenting the various microbes he found to reveal, in his words, ‘the blurry boundary between human society and the natural world’. The result is an extraordinary and enlightening glimpse of the vast biodiversity with which we share our cities.