Inflating the tube strains the mesh, providing a powerful pulling force.

ECONOMIST: Mechanical hand seeks dangerous, dirty and dull jobs

It has at least three factions, and they disagree on many things, so it will have a hard time pulling itself together into a truly cohesive legislative force.

FORBES: Sizing Up Leadership in America

The tractor would intercept the asteroid from just 48m away and exert a small gravitational force on it, pulling the rock towards it.

BBC: British plan to tackle asteroids

Finally, it might take a shock like pulling out of the World Cup to force England to deal with the thugs.

ECONOMIST: England��s shame

But exactly what's driving that expansion - the force responsible for pulling the Universe apart, and for want of a better description, dubbed dark energy - remains a mystery.

BBC: Getting the measure of dark energy