Quotes About Past

The difference between past and future only exists when there is heat. The fundamental phenomenon that distinguishes the future from the past is the fact that heat passes from things that are hotter to things that are colder.

This means we can say that on Mars there are events that in this precise moment have already happened, events that are yet to happen, but also a quarter-of-an-hour of events during which things occur that are neither in our past nor in our future.

For a hypothetically supersensible being, there would be no "flowing" of time: the universe would be a single block of past, present, and future.

The key fact that Einstein understood is that this quarter of an hour is inevitable: there is no way of reducing it. It is woven into the texture of the events of space and of time: we cannot abbreviate it, any more than we can send a letter to the past.

This is what Boltzmann understood. The difference between past and future does not lie in the elementary laws of motion; it does not reside in the deep grammar of nature. It is the natural disordering that leads to gradually less particular, less special situations.

There is our past: all the events that happened before what we can witness now. There is our future: the events that will happen after the moment from which we can see the here and now. Between this past and this future there is an interval that is neither past nor future and still has a duration: fifteen minutes on Mars; eight years on Proxima b; millions of years in the Andromeda galaxy. It is the expanded present.28 It is perhaps the greatest and strangest of Einstein's discoveries.

Heat, entropy, and the lower entropy of the past are notions that belong to an approximate, statistical description of nature.

Time has lost another of its crucial components: the intrinsic difference between past and future. Boltzmann understood that there is nothing intrinsic about the flowing of time. That it is only the blurred reflection of a mysterious improbability of the universe at a point in the past. The source of Rilke's "eternal current" is nothing other than this.

In tutti i casi in cui non viene scambiato calore, infatti, oppure quando il calore scambiato è trascurabile, noi vediamo che il futuro si comporta esattamente come il passato.

The crucial point here is the difference from what happens with falling bodies: a ball may fall, but it can also come back up, by rebounding, for instance. Heat cannot. This is the only basic law of physics that distinguishes the past from the future.

In the elementary equations of the world,13 the arrow of time appears only where there is heat.* The link between time and heat is therefore fundamental: every time a difference is manifested between the past and the future, heat is involved. In every sequence of events that becomes absurd if projected backward, there is something that is heating up.

The difference between past and future does not lie in the elementary laws of motion; it does not reside in the deep grammar of nature. It is the natural disordering that leads to gradually less particular, less special situations.

The possibility of predicting something in the future obviously improves our chances of survival, and consequently, evolution has selected the neural structures that allow it. We are the result of this selection. This being between past and future events is central to our mental structure. This, for us, is the flow of time.

This is the flow of time familiar from our experience. It is inside there that it nestles. Inside of us. The utterly crucial presence of traces of the past in our neurons. Proust could not be more explicit on this matter. Writing in the first book, "Reality is formed only by memory" and memory in its turn is a collection of traces-an indirect product of the disordering of the world.

Only where there is heat is there a distinction between past and future. Thoughts, for instance, unfold from the past to the future, not vice versa—and, in fact, thinking produces heat in our heads. . . .

The expanded present is the set of events that are neither past nor future: it exists, just as there are human beings who are neither our descendants nor our forebears.

Even the distinction between present, past, and future thus becomes fluctuating, indeterminate. Just as a particle may be diffused in space, so, too, the differences between past and future may fluctuate: an event may be both before and after another one.

At the precise moment when heat is produced, the process is irreversible: the past differs from the future. It is always heat and only heat that distinguishes the past from the future. This is universal. A burning candle is transformed into smoke, the smoke cannot transform into a candle-and a candle produces heat. A boiling hot cup of tea cools down and does not heat up: it diffuses heat. We live and get old: producing heat through friction.

But on the moon, the duration of the "extended present" is a few seconds, and on Mars it is a quarter of an hour. This means we can say that on Mars there are events that in this precise moment have already happened, events that are yet to happen, but also a quarter-of-an-hour of events during which things occur that are neither in our past nor in our future.

But the past, he concluded, was as dead as a smashed Victrola record. "Chasing yesterdays," said he, "is a bum show".

Memory is the most potent truth. Show me history untouched by memories and you show me lies.

The hard truth about leadership and success is that it can never be taken for granted. It must always be invested in. When companies—or countries for that matter—begin to rest on their laurels and take comfort in their past triumphs or their present performance, the future begins to dim just a bit. The past is not prologue to the future. The future must always be built.

There is nothing new except what is forgotten. —Rose Bertin

When no one is left to tell what happened, family histories keep their secrets.