Einstein's dreams, de Lightman

Uno de los libros que más me han gustado de los que leí este verano, la verdad es que hasta ahora lo que he leído de Lightman es estupendo...En este caso, nos muestra, con historias muy cercanas y emotivas, las implicaciones de mundos con distintas leyes de la física. Así, Lightman cree que, cuando el tiempo es circular, habrá bastantes desgraciados. O que, cuando el tiempo tiene tres dimensiones, la responsabilidad de las decisiones es complicada de gestionar. La historia de cuando el mundo va a terminar está, sorprendentemente, llena de paz. Ojalá nos enfrentáramos así a la muerte...Todas las historias valen la pena, aquí van algunos extractos de casi todas:

El tiempo es circular

In the world in which time is a circle, every handshake, every kiss, every birth, every word, will be repeated precisely. So too every moment that two friends stop becoming friends, every time that a family is broken because of money, every vicious remark in an argument between spouses, every opportunity denied because of a superior's jealousy, every promise not kept.
And just as all things will be repeated in the future, all things now happening happened million times before. Some few people in every town, in their dreams, are vaguely aware that all has occurred in the past. These are people with unhappy lives, and they sense that their misjudgments and wrong deeds and bad luck have all taken place in the previous loop of time. In the dead of night these cursed citizens wrestle with their bedsheets, unable to rest, stricken with the knowledge that they cannot change a single action, a single gesture.

El tiempo tiene tres dimensiones:

These three chains of events all indeed happen, simultaneously. For in this world, time has three dimensions, like space. Just as an object may move in three perpendicular directions, corresponding to horizontal, vertical and longitudinal, so an object may participate in three perpendicular futures. Each future moves in a different direction of time. Each future is real. At every point of decision, whether to visit a woman in Fribourg or to buy a new coat, the world splits into three worlds, each with the same people but with different fates for those people. In time, there are an infinity of worlds.
Some make light of decisions, arguing that all possible decisions will occur. In such a world, how could one be responsible for his actions? Other hold that each decision must be considered and committed to, that without commitment there is chaos. Such people are content to live in contradictory worlds, so long as they know the reason for each.

El tiempo pasa más despacio en las alturas:

A small number of residents in each city have stopped caring whether they age a few seconds faster than their neighbors. These adventuresome souls come down to the lower world for days at a time, lounge under the trees that grow in the valleys, swim leisurely in the lakes that lie at warmer attitudes, roll on level ground. They hardly look at their watches and cannot tell you if it is Monday or Thursday. When the others rush by them and scoff, they just smile.
In time, people have forgotten the reason why higher is better. Nonetheless, they continue to live on the mountains, to avoid sunken regions as much as they can, to teach their children to shun other children from low elevations. They tolerate the cold of the mountains by habit and enjoy the discomfort as part of their breeding. They have even convinced themselves that thin air is good for their bodies and, following that logic, have gone on spare diets, refusing all but the most gossamer food. At length, the populace have become thin like the air, bony, old before their time.

El tiempo no pasa:

There is a place where time stands still...As a traveler approaches this place from every direction, he moves more and more slowly
Some say it is best not to go near the center of time. Life is the vessel of sadness, but it is noble to live life, and without time there is no life. Other disagree. They would rather have the eternity of contentment, even if that eternity were fixed and frozen, like a butterfly mounted in a case. 

El tiempo avanza a saltos:

This is a world of changed plans, of sudden opportunities. Time flows not evenly but fitfully, and as consequence, people receive fitful glimpses of the future.
Thus, in this world of brief scenes from the future, few risks are taken. Those who have seen the future do not need to take risks, and those who have not yet seen the future wait for their vision without taking risks.

Who would fare better in this world of fitful time? Those who have seen the future and live only one life? Or those who have not seen the future and wait to live life? Or those who deny the future and live two lives?

El futuro está predeterminado:

In a world of fixed future, life is an infinite corridor of rooms, one room lit at each moment, the next room dark but prepared. We walk from room to room, look into the room that is lit, the present moment, then walk on. We do not know the rooms ahead, but we know we cannot change them. We are spectators of our lives.