Scientists and their supporters have taken to the streets across the country in a march of defiance as fears of a post-fact age loom large over academia.
Physicists, biologists and astronomers were joined by celebrities in the March for Science as the crowd prepared to walk past London's most celebrated research institutions.
The march in London is just one of hundreds of similar events taking place around the world, from Australia to the US, in a celebration of scientific endeavour.
Doctor Who star Peter Capaldi was photographed mingling with activists at the event, where comedian Robin Ince was also scheduled to talk.
Concerns about how research might be affected in future flared after former cabinet minister Michael Gove said last year that the public have "had enough of experts".
Organisers said that "fake news" and the growth of misinformation meant it was needed to highlight "the vital role that science plays in each of our lives and the need to respect and encourage research that gives us insight into the world".
In London, supporters gathered outside the Science Museum with placards supporting science and research.
The Commons Science and Technology Committee stressed earlier this month that allowing scientists and experts into the UK after Brexit was important.
It followed several warnings from influential figures in the scientific community that Brexit could have a crippling impact on research and prompt an exodus of talent.
In March, Nobel Prize winning scientist Sir Paul Nurse told the Press Association: "I don't think there's anything in Brexit that helps universities, either in teaching or research, but we are where we are...we have to make the best of it."