Morse telegraph operators clicks radio tones sound patterns

Morse operators learned to hear the message

Early Morse telegraph receivers printed marks on paper, but operators learned to read the receiver’s clicks directly, so the paper tape was no longer needed. With radio tones, operators learned each character as a whole sound pattern instead of working out separate dots and dashes.

Greenland ice records a rise in Roman lead pollution

4× prehistoric levels

Lead trapped in Greenland ice preserves a record of ancient air pollution. During the Roman Imperial period, lead levels rose to about four times prehistoric levels before falling again later. The pollution provides a clue to the scale of Roman metal production.

Tiny black holes made in collisions would disappear almost instantly

≈10⁻²⁵ s to evaporate

If particle collisions could create tiny black holes, they would lose their energy and disappear in about 10⁻²⁵ seconds. They would vanish instead of growing by collecting matter, so they would not threaten Earth.

Like this? There’s a whole feed of it. Replace empty scrolling with things worth knowing.

Download Hence for free

Morse telegraph operators clicks radio tones sound patterns

Morse operators learned to hear the message

Keep exploring