Egypt book costs paper spread west

Egyptian books became cheaper

41 → 8 days’ wages

As paper spread west from China, cheap, portable Arab paper helped standardize Arabic script and raise literacy. Many places also moved from oral to written history. In Egypt, the average book cost fell from the equivalent of 41 days’ wages for an unskilled worker in the 11th century to eight days in the 13th.

Submarines can navigate without GPS

An inertial navigation system works out a submarine’s position from its motion sensors, without outside information once aligned. Weather and jamming do not disrupt it. But small errors build over time, so the system needs occasional position fixes.

Plastic waste could become hydrogen and graphene

Researchers have demonstrated a way to heat polyethylene—the plastic used in many bags and containers—so it breaks down into hydrogen gas and graphene, a form of carbon just one atom thick. The approach could turn waste plastic into two useful materials, although scaling it up remains a challenge.

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Egypt book costs paper spread west

Egyptian books became cheaper

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