Soap Bubble Structures by Kym Cox. Bubbles optimise space and minimise their surface area for a given volume of air. This phenomenon makes them a useful tool in many areas of research, in particular, materials science and “packing” – how things fit together. Bubble walls drain under gravity, thin at the top, thick at the bottom, which interferes with travelling lightwaves to create bands of colour. Black spots show the wall is too thin for interference colours, indicating the bubble is about to burst. (Photo by Kym Cox/2019 Science Photographer of the Year/RPS)

A Spanish national police officer uses his club to hit a protester during a demonstration called the Catalan pro-independence left youth group “Arran” on October 19, 2019 in Barcelona, a day after nearly 200 people were hurt in another night of violent clashes in Catalonia. The deterioration came on the fifth consecutive day of protests in the Catalan capital and elsewhere over a Spanish court's jailing of nine separatist leaders on sedition charges over a failed independence bid two years ago. (Photo by Josep Lago/AFP Photo)

Protesters use fireworks against riot police during clashes in the Athens neighborhood of Exarchia, a haven for extreme leftists and anarchists, Thursday, December 6, 2018. New protest marches were underway in Greece Thursday evening on the 10th anniversary of the fatal police shooting of a teenager, hours after violent initial demonstrations where masked youths attacked police with firebombs and stones. (Photo by Yorgos Karahalis/AP Photo)

Girls in red neckerchiefs dance on Red Square, with the GUM, the State Department Store and the Historical Museum in the background, during a ceremony to celebrate joining the Pioneers organization and 100th anniversary of the All-Union Pioneer Organization, in Moscow, Russia, Sunday, May 22, 2022. Pro-Communist Russians are trying to preserve the Young Pioneers, which used to be the Communist league for pre-teens in the Soviet Union. (Photo by AP Photo/Stringer)

Swab Cadet Langton reads the Running Light guidebook as members of the US Coast Guard academy class of 2026 report for the first day of Swab Summer, a seven-week training programme designed to transform civilian students into military members, in Connecticut on June 27, 2022. The Swabs, as the new cadets are called, cycle through haircuts, uniform issue, drill practice and various administrative in-processing over the course of the day. (Photo by Sean D. Elliot/AP Photo)

A young woman looks at her smartphone sitting in front of a mannequin use to keep social distancing at a Chinese cuisine restaurant in Tokyo, Japan, 27 July 2020. Japan's total number of COVID-19 cases crossed the 30,000 line showing the new coronavirus pandemic is spreading across the country and not only in Tokyo and Osaka megalopolis. (Photo by Franck Robichon/EPA/EFE)

A demonstrator uses a TV case as a facemask during a protest to demand justice for Daniel Prude, on September 3, 2020 in New York City. Protests were planned in New York September 3 over the death of Daniel Prude, a black man that police hooded and forced face down on the road, according to video footage that prompted a probe from the state's attorney general. (Photo by Kena Betancur/AFP Photo)

Russian soldiers run along Red Square in central Moscow on September 29, 2022, as the square is sealed prior to a ceremony of the incorporation of the new territories into Russia. Russia will formally annex four territories of Ukraine its troops occupy at a grand ceremony in Moscow on Friday, the Kremlin has announced, after Russia suggested it could to use nuclear weapons to defend the territories. (Photo by Alexander Nemenov/AFP Photo)