Gravity the fountainhead of cosmic order

Of the four fundamental forces of nature only gravitation acts across cos-mological distances. In this sense, gravity powers the cosmos. It is responsible for bringing about the large-scale structure of the universe, and it is within this structure that the other forces act out their roles. It has long been appreciated by physicists and astronomers that gravity is peculiar in the way that it organizes matter. Under the action of gravity, a homogeneous gas is unstable. Minor density...

Driving a pendulum crazy

Limit Cycle

Random and unpredictable behaviour is by no means restricted to ecology. Many physical systems display apparently chaotic behaviour. A good example is provided by the so-called conical pendulum, which is an ordinary pendulum that is pivoted so as to be free to swing in any direction rather than just in a plane. The pendulum is the epitome of dynamical regularity as regular as clockwork, so the saying goes. Yet it turns out that even a pendulum can behave chaotically. If it is driven by applying...

Morphogenesis the mystery of pattern formation

Among the many scientific puzzles posed by living organisms, perhaps the toughest concerns the origin of form. Put simply, the problem is this. How is a disorganized collection of molecules assembled into a coherent whole that constitutes a living organism, with all the right bits in the right places The creation of biological forms is known as morphogenesis, and despite decades of study it is a subject still shrouded in mystery. The enigma is at its most striking in the seemingly miraculous...