Soldier boys at Fort Dix, N.J., learn something about guns during their working hours, as they show their girlfriends at a camp dance, December 13, 1940. In front row, playing with the coin amusement gun, from left: Pvt. Tom D'Amato of West Orange; Rose Sinkewicz, behind gun site, of Trenton; Julia Ivans of Trenton, and Pvt. Vernon Landers of Kearney. Back row: Pvts. William Sargent and William Corlies of Philadelphia. (Photo by AP Photo)

British theoretical physicist Stephen Hawking, Cambridge University Professor and Fellow, circa 1985. Stephen Hawking, the brightest star in the firmament of science, whose insights shaped modern cosmology and inspired global audiences in the millions, has died aged 76. (Photo by Gemma Levine/Getty Images)

An ethnic Lisu man dances barefoot on hot charcoal embers to celebrate the annual Knife Pole Festival in Luzhang township of Nujiang Lisu Autonomous Prefecture in Yunnan province, China, March 29, 2018. (Photo by Aly Song/Reuters)

These friends took a tumble after sharing a hug in Leeds in northern England on May 17, 2021, as Covid-19 lockdown restrictions ease. (Photo by London News Pictures)

A young Iranian woman walks in Tehran on June 14, 2021, ahead of the June 18 presidential elections. Iran is gearing up for a presidential election on June 18 but many young people are more focussed on the daily struggle to survive and their dreams for the future. Jobs are scarce in a recession-hit economy battered by sanctions, a crisis exacerbated by the region's worst outbreak of the Covid pandemic. (Photo by Atta Kenare/AFP Photo)

A girl attends a performance hosted by the Ministry of the Interior that includes police, border guards, and rescuers celebrating International Children's Day in Kyiv, Ukraine on June 1, 2021. (Photo by Gleb Garanich/Reuters)

Fans of Croatia are seen during the UEFA Euro 2020 Championship Round of 16 match between Croatia and Spain at Parken Stadium on June 28, 2021 in Copenhagen, Denmark. (Photo by Antonio Bronic/Reuters)

Pakistan fans during the first one day international match at the Sophia Gardens, Cardiff on Thursday, July 8, 2021. (Photo by Bradley Collyer/PA Images via Getty Images)