What Costs Nothing?

What costs nothing
but is worth everything,
weighs nothing, but can last a lifetime,
that one person can't own,
but two or more can share?


Check Braingle.com for the answer.

Cellulose, the main component of paper, can be turned into clear, waterproof objects such as cups that are almost indistinguishable from plastic, but break down more quickly

Cellulose, the main component of paper, can be turned into clear, waterproof objects such as cups that are almost indistinguishable from plastic, but break down more quickly

In the latest instalment of our Future Chronicles column, which explores an imagined history of inventions yet to come, Rowan Hooper reveals how brain-computer interface let us travel to Mars via robot avatars in the late 2020s

Feedback is delighted to hear from a reader who proposes an ingenious new unit of data – but we have some quibbles with the maths

Bed rest is commonly prescribed for high-risk pregnancies. It can't hurt and might help, right? Wrong, says Jacqueline Sears

Cuneiform, the oldest identified writing system, defied deciphering – until 1857. What happened then makes a terrific read, in Joshua Hammer's The Mesopotamian Riddle

Governments love asking what scientific research will bring society, but the most important discoveries come from wondering without direction

In the latest instalment of our Future Chronicles column, which explores an imagined history of inventions yet to come, Rowan Hooper reveals how brain-computer interface let us travel to Mars via robot avatars in the late 2020s

Feedback is delighted to hear from a reader who proposes an ingenious new unit of data – but we have some quibbles with the maths

Bed rest is commonly prescribed for high-risk pregnancies. It can't hurt and might help, right? Wrong, says Jacqueline Sears

Cuneiform, the oldest identified writing system, defied deciphering – until 1857. What happened then makes a terrific read, in Joshua Hammer's The Mesopotamian Riddle

Governments love asking what scientific research will bring society, but the most important discoveries come from wondering without direction

A new understanding of why some animals evolved to be loners, and the benefits that brings, shows that a social lifestyle isn’t necessarily superior

A new understanding of why some animals evolved to be loners, and the benefits that brings, shows that a social lifestyle isn’t necessarily superior

Amazon is aiming to launch its first operational satellites today to provide speedy internet connections in remote regions, but it will still take some time to catch up with its main competitor, SpaceX's Starlink  

Amazon is aiming to launch its first operational satellites today to provide speedy internet connections in remote regions, but it will still take some time to catch up with its main competitor, SpaceX's Starlink  

A map of part of a mouse brain, which is expected to be generalisable to people, could help scientists understand behaviours, consciousness and even what it means to be human

A map of part of a mouse brain, which is expected to be generalisable to people, could help scientists understand behaviours, consciousness and even what it means to be human

Ancient rocks reveal there were several humid spells in Arabia’s past, which might have given early hominins a route out of Africa long before our genus migrated