Physicists find first direct proof of a metamorphosis between two of the three known types of neutrinos (scientificamerican.com)
The finding provides the first direct proof that microbes that leave the gut and travel to the rest of the body — a process called microbial translocation — is the mechanism that triggers these health complication in people with HIV. (newscientist.com)
In 1919, observations of an eclipse from Brazil and the African island of Príncipe offered the first direct proof of Einstein's theory of general relativity. (discovermagazine.com)