› added 7 years ago

226

TIL of infrasound - a low-frequency sound (19Hz and below) that cannot be heard, but literally unsettles human beings. Some horror movie music composers use this sound to make audiences feel dread just before disturbing or scary images appears on the screen.

Read more atlasobscura.com

via reddit.com

ZpWLQ TIL that American Airlines created Sabre, the multi-airline reservation system. Knowing that more than 50% of travel agents chose the first flight they saw, American modified the ranking system to display its flights before those from rivals. The US outlawed such manipulation in 1984.
wowJ TIL the security guard who discovered a pipe bomb at the 1996 Olympics in Atlanta, alerted police, and helped evacuate the area was later considered a suspect by the FBI and presumed guilty by the media. He was exonerated when a homegrown terrorist confessed nine years later.
5YVAn Hot enough to boil oceans and vaporize rock. The highest terrestrial temperatures occurred more than four billion years ago, when a Mars-size proto-planet smashed into the Earth. (The debris from this collision formed our moon.) Within a millennium, the surface air temperature had dropped from a high of about 3,700°F down to 3,000°. Then the planet went into a period of slower cooling that lasted a few tens of millions of years.
9Y5P7 TIL of the sinking of the PS General Slocum, the second worst disaster in terms of lives lost in NYC, in which many people drowned because the life jackets had been filled with iron in order to meet minimum weight requirements of the time.
5Y8M8 TIL that the skin colour of apples darkens with exposure to UV