Tara West signals to her partner Natalie Cook during the Bronze final match during the Australian Beach Volleyball Championships at Glenelg Beach on March 13, 2011 in Adelaide, Australia.

A member of the German wireless police picks up signals on the radio equipment he carries on his back, while his colleague takes notes. (Photo by General Photographic Agency/Getty Images). Circa 1925

The Haʻikū Stairs, also known as the Stairway to Heaven or Haʻikū Ladder, is a steep hiking trail on the island of Oʻahu. The trail began as a wooden ladder spiked to the cliff on the south side of the Haʻikū Valley. It was installed in 1942 to enable antenna cables to be strung from one side of the cliffs above Haʻikū Valley to the other. A building to provide a continuous communication link between Wahiawā and Haʻikū Valley Naval Radio Station was constructed at the peak of Puʻukeahiakahoe, elevation about 2,800 feet (850 m). The antennae transmitted very low frequency radio signals from a 200,000-watt Alexanderson alternator in the center of Haʻikū valley. The signals could reach US Navy submarines as far away as Tokyo Bay while the submarines were submerged.

People wear masks to help guard against the Coronavirus in downtown Tehran, Iran, Sunday, February 23, 2020. On Sunday Iran's health ministry raised the death toll from the new virus to 8 people in the country, amid concerns that clusters there, as well as in Italy and South Korea, could signal a serious new stage in its global spread. (Photo by Ebrahim Noroozi/AP Photo)

A dancer from the Trisha Brown Dance Company performs during “Roof Piece” above the High Line park June 9, 2011 in New York City. Roof Piece (1971) consists of nine dancers performing improvised movement signals to each other in a chain on various rooftops overlooking the city. This presentation marked the first full performance of the piece since 1973. (Photo by Mario Tama/Getty Images)

A man wearing the traditional Carnival Neapolitan mask of Pulcinella performs on Via Caracciolo avenue in Naples, Italy, Saturday, November 14, 2020. The regions of Campania and Tuscany were designated red zone on Friday, signaling the dire condition of a hospitals struggling with a surge of new admissions. (Photo by Gregorio Borgia/AP Photo)

People walk through Ginza’s shopping district in Tokyo, Japan, 15 December 2025. Japan’s economic focus is on the upcoming Bank of Japan (BOJ) meeting where the central bank is expected to raise its policy rate to combat inflation. The BOJ signaled a rate hike bar is cleared with the wage momentum still intact. (Photo by Franck Robichon/EPA)

Pinot noir vineyards in the famed Sta. Rita Hills AVA turn a vivid red, orange, and yellow, signaling the end of the grape harvest and approach of winter as viewed on November 26, 2023, near Buellton, California. Following the notoriety from the Academy Award-winning film Sideways, this buccolic farming region north of Santa Barbara has become a popular Wine Country stop for global and domestic tourists traveling between San Francisco and Los Angeles. (Photo by George Rose/Getty Images)