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)

In this file photo taken on Saturday May 1, 1993, an elderly communist woman clutches her head as police on horseback patrol the streets in Moscow. When Alexander Zemlianichenko started working as an AP photographer in Moscow, the Soviet Union was nearing its demise. (Photo by Alexander Zemlianichenko/AP Photo)

Steam rises from Lake Superior as the ship St. Clair comes to harbor during some of the coldest temps of the year, Sunday, December 31, 2017, at Canal Park in Duluth, Minn. The St. Clair is a self-unloader built in 1976 at Sturgeon Bay, Wis., and is 770 feet long and has 26 hatches that open into 5 cargo holds, providing a load capacity of 45,000 tons. (Photo by David Joles/Star Tribune via AP Photo)

Warriors from the Suri tribe in Ethiopia still stage the savage “Donga” battles – even after many fighters have been died from their injuries. Donga stick fights take place after the harvests, the Surmas count days owing to knots on a long stem of grass or jags on the trunk of a tree dedicated to that specific use. Here: A tribeswoman sporting a huge lip plate and wearing a skinned animal carcass on her head. (Photo by Eric Lafforgue/Exclusivepix Media)

A woman wears glasses in support of late Venezuelan President Hugo Chavez during a caravan to carry Chavez's cadet saber and his dagger to the mausoleum where the politician's remains are laid to rest, in Caracas on March 15, 2023. The caravan traveled some 9 kilometers through the streets of Caracas to the Cuartel de la Montaña, also known as the Cuartel 4 de Febrero, as a reminder of the date of the failed coup led by Chavez on February 4, 1992. (Photo by Miguel Zambrano/AFP Photo)

A bakery worker carries fresh bread in Cairo, Egypt on August 1, 2021. (Photo by Amr Abdallah Dalsh/Reuters)

Israeli security forces arrest an Ultra Orthodox Jewish man as they close a synagogue in the Mea Shearim Ultra-Orthodox neighbourhood in Jerusalem, on March 30, 2020, amid efforts to curb the spread of the COVID-19 coronavirus pandemic. (Photo by Ahmad Gharabli/AFP Photo)

A police officer chases shoppers to clear the streets of the Red Light market on the first day of lockdown to stop the spread of the coronavirus disease (COVID-19) in Monrovia, Liberia on April 11, 2020. (Photo by Derick Snyder/Reuters)