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.

"I was very curious about this idea of the invisible signals that surround us all the time so I wanted to explore that," Hernan told Business Insider. "I was really interested in how they would look if we were able to see them."

Hernan set up a system that turned the wireless signals around him into colorful, ghostlike images using long-exposure photography, allowing people to see the strength of the signals around them. He custom-built a device that translates WiFi signal strength into colors and then leverages long-exposure photography to create the results, which are all documented in his project called "Digital Ethereal."