1What makes a rumor spread
Knowers tell more knowers — but there's only so many people
A rumor needs just two things. Watch each one:
Each knower tells a few more
Hear it, pass it on. One person tells a few friends, then they each tell a few — so the crowd of knowers feeds itself and grows. That's a feedback loop.
Fresh ears run out
The town is only so big, and nobody un-knows. "Fresh ears" are people who haven't heard yet. That tank only ever empties — telling someone twice does nothing.
2Same teller, two moments
When fresh ears are full vs nearly empty
The same person telling the same rumor does totally different things depending on how many fresh ears are left:
Almost everyone is fresh
Tell anyone and it lands on a new person. Every telling counts, so the rumor doubles and doubles. Explosive.
Almost everyone knows
Now most tellings hit someone who says "yeah, heard it." Tellers waste their breath and the spread crawls to a stop.
3Your turn — spread a rumor by hand
Tell one round at a time and watch the town fill
Pick how many people each knower tells, then push tell a round over and over. Watch the teal fresh ears turn coral — and watch how many tellings get wasted on people who already know as the town fills.
4Now predict the whole story
Lots of people know. How many can still spread it?
A fresh town has 126 people. Half already know the rumor, but only ONE of those 63 is still telling it. Each teller now makes just one contact attempt, then stops. A newly told person may pass it on once in the next round.
Guess before you let it spread
Could this town gain more than ONE new knower in a single round, even though 63 people already know?