"What is a world line?"
Rasul walked with Mia and Miel on the damaged streets, explaining it to the two young girls.
"A world line is the world under probability distribution."
"When you toss a coin, the probability of it landing heads up or tails up is both close to 50%."
"However, when the coin lands, there can only be one outcome, either heads up or tails up."
Rasul flicked a coin with his finger and covered it with the back of his hand, "Guess, which side is up?"
"I guess heads," said Miel.
"Then I'll guess tails," Mia said.
Rasul removed his hand that covered the coin.
It was heads up.
"What is the probability of it being heads up now?" Rasul asked Miel.
"The probability now?" Miel puzzled, "Isn't it already determined? 100%?"
"That's right," Rasul said. "Why did the probability of heads up change from an initial 50% to now 100%?"
