How long can a person go without sleep?

The number of hours is quite variable and difficult to be scientifically evaluated. “In the record books, the maximum time achieved was 164 hours”, says neurologist Flávio Alóe, from the Center for Sleep Studies at the Hospital das Clínicas at…

What is the origin of firearms?

The first firearms, still improvised, probably appeared in China shortly after the invention of gunpowder, in the 9th century. In bamboo tubes, this mixture of saltpeter, sulfur and charcoal that explodes in contact with fire was used to throw stones…