“Time goes forward because energy itself is always moving from an available to an unavailable state. Our consciousness is continually recording the entropy change in the world around us. We watch our friends get old and die. We sit next to a fire and watch it's red-hot embers turn slowly into cold white ashes. We experience the world always changing around us, and that experience is the unfolding of the second law. It is the irreversible process of dissipation of energy in the world. What does it mean to say, 'The world is running out of time'? Simply this: we experience the passage of time by the succession of one event after another. And every time an event occurs anywhere in this world energy is expended and the overall entropy is increased. To say the world is running out of time then, to say the world is running out of usable energy. In the words of Sir Arthur Eddington, 'Entropy is time's arrow'.”