Two mathematicians have proved that a straightforward question—how hard is it to untie a knot?—has a complicated answer.

April Wilkerson explains the safe angle for using a ladder that every DIYer should know. Trump’s shutdown win just landed ...

A world-famous light experiment from 1801 has now been carried out with sound for the first time. Research by physicists in ...

By using two propellers that rotate in opposite directions, a ship can use less energy to move forward. New knowledge means ...

Parallel lines are lines that never cross each other - they keep the same distance apart from each other. When two lines intersect, the opposite (X) angles are equal. On parallel lines, alternate (Z) ...