A man rides past a destroyed tank in Mesobit, Ethiopia, on December 06, 2021. (Photo by Amanuel Sileshi/AFP Photo)

The granddaughter of one of the family members cries after the eviction from their home in El Raval neighbourhood, amid the coronavirus disease (COVID-19) pandemic, in Barcelona, Spain, May 12, 2021. (Photo by Nacho Doce/Reuters)

United States Air Force Academy graduates cheer as the United States Air Force Thunderbirds fly over the graduation for the Class of 2021 at Falcon Stadium on May 26, 2021 in Colorado Springs, Colorado. Chairman of the Joint Chiefs of Staff General Mark A. Milley gave the commencement address to the 1,019 graduates from the academy. (Photo by Michael Ciaglo/Getty Images)

A young girl sits on a mat, as worshippers arrive to pray to mark the Muslim Eid-al-Adha (Festival of Sacrifices) without observationg precautionary measures to curb the spread of COVID-19, in Kara, Ogun State in southwest Nigeria, on July 31, 2020. Nigerian Muslim faithfuls joined their counterparts across the world to celebrate Eid-El-Adha, Islamic festival of sacrifice. (Photo by Pius Utomi Ekpei/AFP Photo)

Two women in traditional kimonos wear face masks to help curb the spread of the coronavirus as they visit the Sensoji temple in Tokyo on Friday, August 7, 2020. (Photo by Hiro Komae/AP Photo)

Enthusiasts participate in the historical re-enactment of the Sevastopol Fortress assault, which took place during the Crimean War of 1853-1856, at a military historical festival in Sevastopol, Crimea, September 5, 2020. (Photo by Alexey Pavlishak/Reuters)

An Indian villager wearing a face mask as a precaution against the coronavirus sells his ware at market in Jammu, India, Friday, October 9, 2020. (Photo by Channi Anand/AP Photo)

Luis Hernan was always curious about how wireless technologies like radio are transmitted through the air. So after finishing up his studies in architecture, computer science, and design, Hernan decided to research these invisible signals through a PhD at Newcastle University. Hernan set up a system that turned the wireless signals around him into colourful, ghostlike images using long-exposure photography, allowing people to see the strength of the signals around them. (Photo by Luis Hernan)