People smoke marijuana in front of the Brandenburg Gate during the 'Smoke-In' event in Berlin, Germany, Monday, April 1, 2024. Starting 1 April, Germany has legalised cannabis for personal use. As per the new law, Adults aged 18 and over will be allowed to carry up to 25 grams of cannabis for their own consumption. (Photo by Ebrahim Noroozi/AP Photo)

Young men play basketball on an improvised court wedged between a construction site and the shells of once grand colonial homes in Havana, July 20, 2015. As much as the young in Cuba welcome political opening and economic reform, such changes are unlikely to filter down to their lives anytime soon. (Photo by Meridith Kohut/The New York Times)

A dog from the K9 Division of the Sri Lanka Army’s Commando Regiment performs during an event to mark International Children’s Day at a school in Welisara, Colombo, Sri Lanka, 01 October 2016. Sri Lanka marks the Children's Day on 01 October with more emphasis on prevention of child abuse. (Photo by M.A. Pushpa Kumara/EPA)

Canada's Marissa Papaconstantinou makes her way to the finish line after falling in the Women's 200m T44 Final during day ten of the IPC World ParaAthletics Championships 2017 at London Stadium on July 23, 2017 in London, England. (Photo by Peter Cziborra/Reuters)

Kids play in water to cool off during the scorching weather of a heatwave at a River Landing splash park in Saskatoon, Saskatchewan, Canada July 2, 2021. (Photo by David Stobbe/Reuters)

A biker carrying huge bags of recyclables travels on a street outside Phnom Penh, Cambodia on Saturday, March 27, 2021. (Photo by Heng Sinith/AP Photo)

Wags the dog wears a button featuring a photo of the moment after the attempted assassination on former president Donald Trump outside the Fiserv Forum during the third day of the 2024 Republican National Convention in Milwaukee, Wisconsin, on July 17, 2024. Days after he survived an assassination attempt Donald Trump won formal nomination as the Republican presidential candidate and picked Ohio US Senator J.D. Vance for running mate. (Photo by Nick Oxford/AFP Photo)

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)