But hes not always sure. Admitting that the neurophysical facts shed only a monochrome light on human experience, he extols art as another dimension. We gain access to worlds otherwise uncharted, he says. As Proust emphasized, this is to be celebrated. Only through art, he noted, can we enter the secret universe of another, the only journey in which we truly fly from star to star, a journey that cannot be navigated by direct and conscious methods.

Two main themes run through this story. The first is natural selection, the endless inventive process of evolution that keeps molding organisms into more and more complex arrangements and codependencies. The second is what Greene calls the entropic-two step. This refers to the physical property known as entropy. In thermodynamics it denotes the amount of heat wasted energy inevitably produced by a steam engine, for example as it goes through its cycle of expansion and contraction. Its the reason you cant build a perpetual motion machine. In modern physics its a measure of disorder and information. Entropy is a big concept in information theory and black holes, as well as in biology.

We are all little steam engines, apparently, and everything we accomplish has a cost. That is why your exhaust pipe gets too hot to touch, or why your desk tends to get more cluttered by the end of the day.

In the end, Greene says, entropy will get us all, and everything else in the universe, tearing down what evolution has built. The entropic two-step and the evolutionary forces of selection enrich the pathway from order to disorder with prodigious structure, but whether stars or black holes, planets or people, molecules or atoms, things ultimately fall apart, he writes.

In a virtuosic final section Greene describes how this will work by inviting us to climb an allegorical Empire State Building; on each floor the universe is 10 times older. If the first floor is Year 10, we now are just above the 10th (10 billion years). By the time we get to the 11th floor the sun will be gone and with it probably any life on Earth. As we climb higher we are exposed to expanses of time that make the current age of the universe look like less than the blink of an eye.

Eventually the Milky Way galaxy will fall into a black hole. On about the 38th floor of the future, when the universe is 100 trillion trillion trillion years old, protons, the building blocks of atoms, will dissolve out from under us, leaving space populated by a thin haze of lightweight electrons and a spittle of radiation.

In the far, far, far, far future, even holding a thought will require more energy than will be available in the vastly dissipated universe. It will be an empty and cold place that doesnt remember us. Nabokovs description of a human life as a brief crack of light between two eternities of darkness may apply to the phenomenon of life itself, Greene writes.

In the end it is up to us to make of this what we will. We can contemplate eternity, Greene concludes, and even though we can reach for eternity, apparently we cannot touch eternity.

Original post:
Just a Few Billion Years Left to Go - The New York Times