The problem of defining exactly what is meant by the signal velocity, which cropped up as long ago as 1907, has not been solved. - Hans Christian von Baeyer

Entropy is not about speeds or positions of particles, the way temperature and pressure and volume are, but about our lack of information.

Time has been called God's way of making sure that everything doesn't happen at once. In the same spirit, noise is Nature's way of making sure that we don't find out everything that happens. Noise, in short, is the protector of information.

The smell of subjectivity clings to the mechanical definition of complexity as stubbornly as it sticks to the definition of information.