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 woman uses the Aurasma app on an iPad which displays a virtual 3D animation of a Thundercat character which her colleague pretends to fight at the 2012 London Toy Fair at Olympia Exhibition Centre on January 24, 2012 in London, England. The annual fair, which is organised by the British Toy and Hobby Association, brings together toy manufacturers with retailers from around the world. (Photo by Oli Scarff/Getty Images)

French artist Gino rides the “Celestial Cyclo” tricycle built by him in Le Marais neighbourhood in Paris, France, August 15, 2015. (Photo by Pascal Rossignol/Reuters)

People take part in a sunset ceremony on the lower slopes of Glastonbury Tor as they celebrate Samhain at the Glastonbury Dragons Samhain Wild Hunt 2017 in Glastonbury on November 4, 2017 in Somerset, England. To celebrate Samhain, the Glastonbury Dragons, alongside Gwythyr Ap Greidal, the Summer King and the Winter King, (Photo by Matt Cardy/Getty Images)

Members of rival teams fight with oranges during an annual carnival battle in the northern Italian town of Ivrea, Italy on February 11, 2018. Established in 1808, the Carnival of Ivrea is one of the oldest and most particular festivals in the world. (Photo by Alessandro Bianchi/Reuters)

Brazilian graffiti artist Eduardo Kobra (C) puts the final touches to his piece of art in tribute to Brazilian architect Oscar Niemeyer, next to his assistants, at the financial center on Sao Paulo's Avenida Paulista January 22, 2013. Kobra created the 56-metre (61-yard) tall graffiti artwork as a tribute to Niemeyer, one of the 20th century's most influential modernist architects. Niemeyer died in December 2012, aged 104. (Photo by Andre Penner/AP Photo)

Dressed for the traditional New Year's festival known as “La Diablada”, in Pillaro, Ecuador, Friday, January 5, 2018. Thousands of singing and dancing devils take over the mountain town for six days of revelry in the streets. Local legend holds that anyone who adopts a costume for the celebration and wears it at the event six years in a row will have good luck. (Photo by Dolores Ochoa/AP Photo)

At the Krasnopresnenskaya station, the benches come from the Cathedral of Christ-Sauveur, which was built from 1839 to 1883 in memory of the victory of Russia against the army of Napoleon I. The cathedral was destroyed under Stalin in 1931, but the benches remained intact. Metro architects decided to install them in some stations. (Photo by Didier Bizet/The Washington Post)