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)

A child, from Municipal school Parana, poses during the project “Fencing School” in Rio de Janeiro, Brazil, March 30, 2016. Children in Rio de Janeiro lift their sights and their swords to new idols, as a round of fencing workshops takes to public schools. The International Fencing Federation, together with the Brazilian and state federations, will reach 40 public schools in March and April. The aim is to whip up a following for the Olympic sport, little known in the soccer-mad nation, as Rio sets the stage for the Summer Games in August. (Photo by Sergio Moraes/Reuters)

Italian artist Maurizio Cattelan poses with his creation “Him” (2001) prior to the opening of the exhibition “Not Afraid of Love” at the Hotel de la Monnaie in Paris, France, October 17, 2016. From October 21, 2016 to January 8, 2017, “Not Afraid of Love”, curated by Chiara Parisi, director of Cultural Programs, sets Maurizio Cattelan’s “comeback at work” in one of the most beautiful Palaces on the river Seine. (Photo by Philippe Wojazer/Reuters)

A photograph of a dog taken from underneath on December 2016 in VA, Canada. Forget the cats, itÌs just raining dogs! A creative duo have come up with an innovative way to raise money for animal welfare; photographing dogs as youÌve never seen them before. Professional photographer Jason Kenzie and designer Tania Ryan have created a unique set of images from the underside of dogs, named The Underdogs Project. The project will be featured as a 2017 calendar, with each month belonging to a quirky canine. (Photo by The Underdogs Project/Barcroft Images)

Afghan policemen take position at the site of a suicide attack followed by a clash between Afghan forces and insurgents after an attack on a Shi'ite Muslim mosque in Kabul, Afghanistan on Friday, August 25, 2017. Gunmen stormed a Shiite mosque in the Afghan capital while worshippers were at Friday prayers, setting off an explosion that killed a security guard outside and pushing into the shrine, officials said. (Photo by Omar Sobhani/Reuters)

Documentary photographer William E. Crawford was one of the first Western photographers to gain access to North Vietnam after the war ended. He has photographed the capital, Hanoi, at regular intervals since 1985, concentrating on the colonial and indigenous architecture, urban details, landscapes and intimate portraits of people in their home settings, street scenes and the city’s surrounding countryside. Here: 54 Hàng Ga (Chicken Street), 1994. (Photo by William E. Crawford from the book “Hanoi Streets 1985-2015: In the Years of Forgetting”)

A landscape photographer turned the camera on himself to take a set of incredible selfie while visiting some of the world's most beautiful destinations. Paul Zizka, 39, from Alberta, Canada, has been a photographer for nine years, and thought that featuring in his own pictures would emphasize the nature surrounding him and create a more unique shot. Here: Lake Minnewanka, Banff National Park, Alberta, Canada. (Photo by Paul Zizka/Caters News Agency)

An anti-government protester shouts at a police officer in downtown Caracas, Venezuela, Wednesday, May 10, 2017. Opponents of President Nicolas Maduro will attempt to march to the Supreme Court to protest its decision to gut the opposition-controlled congress of its powers, a ruling that was quickly rescinded under a barrage of international criticism but that set off weeks of political unrest that have left some three dozens killed. (Photo by Fernando Llano/AP Photo)