Time Reborn - Lee Smolin

Introduction

 

The excellent book « Time Reborn » written by Lee Smolin proposes the rebirth of a real time, in the sense where whatever is real in our universe is real only in a moment of time, the past was real but is no longer real, the future does not yet exist and is therefore open.

This vision of the time as well as my theory are going against the relativity of simultaneity and against the block-universe stemming from Einstein’s theories of special and general relativity.

 

Sum up of the concepts defended by Lee Smolin

 

- Embracing time means believing that reality consists only of what’s real in each moment of time

- Whatever is real in our universe is real in a moment of time

- The past was real but is no longer real

- The future does not yet exist and is therefore open

- The usual arguments for a predetermined future are wrong scientifically

- Time must be a consequence of change; without alteration in the world, there can be no time

- Time will turn out to be the only aspect of our everyday experience that is fundamental.

 

The fact that it is always some moment in our perception, and that we experience that moment as one of a flow of moments, is not an illusion. It is the best clue we have to fundamental reality.

We have to deconstruct the erroneous arguments, in particular the Einsteinian arguments, stemming from the theories of special and general relativity:

  - The relativity of simultaneity

  - The block-universe picture of spacetime.

 

The argument for the block universe rests on the relativity of simultaneity (which is erroneous).

This implies a universal, physical notion of simultaneity that includes distant events and, indeed, the whole universe. This can be called a preferred global time (“global” here meaning that the definition of time extends throughout the universe).

A preferred global notion of time implies a preferred observer, whose clock measures that preferred time.

This means giving up the relativity of simultaneity and embracing its opposite: that there is a preferred global notion of time.

 

The philosopher John Randolph writes: “The block universe gives a deeply inadequate view of time. It fails to account for the passage of time, the pre-eminence of the present, the directedness of time and the difference between the future and the past.”

Extracts from Lee Smolin’s book which reinforce the fundations of my theory

Time Reborn – From the Crisis in Physics to the Future of the Universe     Lee Smolin

 

Preface

 

Embracing time means believing that reality consists only of what’s real in each moment of time.

When, in the pages that follow, I assert that time is real, what I am saying is that:

  - Whatever is real in our universe is real in a moment of time, which is one of a succession of moments.

  - The past was real but is no longer real. We can, however, interpret and analyze the past, because we find evidence of past processes in the present.

  - The future does not yet exist and is therefore open. We can reasonably infer some predictions, but we cannot predict the future completely. Indeed, the future can produce phenomena that are genuinely novel, in the sense that no knowledge of the past could have anticipated them.

  - Nothing transcends time, not even the laws of nature. Laws are not timeless. Like everything else, they are features of the present, and they can evolve over time.

 

 

Introduction

Einstein’s theories of relativity make even stronger arguments that time is inessential to a fundamental description of the world, as I’ll discuss in chapter 6. Relativity strongly suggests that the whole history of the world is a timeless unity; present, past and future have no meaning apart from human subjectivity. Time is just another dimension of space, and the sense we have of experiencing moments passing is an illusion behind which is a timeless reality.

These assertions may seem horrifying to anyone whose worldview includes a place for free will or human agency. This is not an argument I will engage in here; my case for the reality of time rests purely on science. My job will be to explain why the usual arguments for a predetermined future are wrong scientifically.

In part I, I will present the case from science for believing that time is an illusion. In part II, I will demolish those arguments and show why time must be taken to be real if fundamental physics and cosmology are to overcome the crises they currently face.

Laws, then, are not imposed on the universe from outside it. No external entity, whether divine or mathematical, specifies in advance what the laws of nature are to be. Nor do the laws of nature wait, mute, outside of time for the universe to begin. Rather the laws of nature emerge from inside the universe and evolve in time with the universe they describe.

As I will explain in chapter 3, it follows from Leibniz’s great principle that there can be no absolute time that ticks on bindly whatever happens in the world. Time must be a consequence of change; without alteration in the world, there can be no time.

The main message of this book is that this requires embracing the ideas that time is real and laws evolve.

Time will turn out to be the only aspect of our everyday experience that is fundamental. The fact that it is always some moment in our perception, and that we experience that moment as one of a flow of moments, is not an illusion. It is the best clue we have to fundamental reality.

 

 

Chapter 6 - Relativity and Timelessness

 

This is well and good, but it only matters if the block universe is a correct description of nature. Other philosophers doubt that it is. John Randolph Lucas writes:

“The block universe gives a deeply inadequate view of time. It fails to account for the passage of time, the pre-eminence of the present, the directedness of time and the difference between the future and the past.”

 

 

Interlude - Einstein’s Discontent

 

The block universe of Einstein’s theories of relativity was the definite step in the expulsion of time from physics. But Einstein himself was ambivalent about the disappearance of time from the conception of nature he had done so much to build. We saw how he found consolation in the block-universe picture of the timeless cosmos – yet it appears that Einstein was not content with its implications. We know this from the Intellectual Autobiography of the Viennese philosopher Rudolf Carnap, who reported a conversation with Einstein on time:

Once Einstein said that the problem of the Now worried him seriously. He explained that the experience of the Now means something special for man, something essentially different from the past and the future, but that this important difference does not and cannot occur within physics. That this experience cannot be grasped by science seemed to him a matter of painful but inevitable resignation.

If Einstein was reflective, Carnap had no doubt where he himself stood:

“I remarked that all that occurs objectively can be described in science.”

A scientific theory, to be successful, must explain to us the observations we make of nature. Yet the most elemental observation we make is that nature is organized by time. If science must tell a story that encompasses and explains everything we observe in nature, shouldn’t that include our experience of the world as a flow of moments?

Everything we experience, every thought, impression, action, intention, is part of a moment. The world is presented to us as a series of moments. We have no choice about this. No choice about which moment we inhabit now, no choice about whether to go forward or back in time. No choice to jump ahead. No choice about the rate of flow of the moments. In this way, time is completely unlike space. One might object by saying that all events also take place in a particular location. But we have a choice about where we move in space. This is not a small distinction; it shapes the whole of our experience.

In part I, we traced nine steps in the expulsion of time from the physicists’ conception of nature, beginning with Galileo’s discoveries about falling bodies and on up to Julian Barbour’s timeless quantum cosmology.

 

Shortly we will see time reborn, but first we have to deconstruct the apparently strong arguments given in Part I.

Einsteinian arguments, stemming from the theories of special and general relativity:

  - The relativity of simultaneity

  - The block-universe picture of spacetime.

 

These arguments lead to a view of nature that denies the reality of the present moment and instead speaks of nature in terms of the block universe picture in which what is real is only the entire history of the world taken as one.

In these theories (the Newtonian mechanics and Einstein’s relativity), time is not real, in the sense I defined in the preface when I asserted that all that is real is such in a moment of time. To make the contrast vivid I will refer to such theories as timeless.

The strongest arguments for the elimination of time have come from relativity theory. In chapter 14, we will break these down. Once we have deconstructed the case for the elimination of time, we will consider what physics and cosmology gain from the hypothesis that time is real.

 

 

Chapter 14 - Time Reborn from Relativity

 

We have seen that the reality of time opens up new approaches to understanding how the universe chooses its laws while making possible a new resolution of the mysteries of quantum mechanics. But we still have to surmount a big obstacle, which is the formidable argument from special and general relativity in favor of the block-universe picture. This argument concludes that what is real is only the history of the universe as a timeless whole.

The argument for the block universe rests on the relativity of simultaneity, which is an aspect of the theory of special relativity (see chapter 6). But if time is real, in the sense of a real present moment, there is a boundary all observers can agree on between the real present and the not yet real future. This implies a universal, physical notion of simultaneity that includes distant events and, indeed, the whole universe. This can be called a preferred global time (“global” here meaning that the definition of time extends throughout the universe).

 

The purpose of this chapter is to resolve the conflict in favor of the principle of sufficient reason. This means giving up the relativity of simultaneity and embracing its opposite: that there is a preferred global notion of time. Remarkably, this does not require overthrowing relativity theory; it turns out that a reformulation of it is enough.

A preferred notion of global time picks out a family of observers, spread though the universe, whose clocks measure it. This implies a preferred state of rest, reminiscent of the Aristotelian notion of rest, or the aether of the 19th century physics, both of which Einstein punctured with his invention of special relativity. For physicists before Einstein, this aether was necessary, because light waves needed a medium within which to propagate. Einstein demolished it, because his principle of the relativity of simultaneity implies that there is no aether, no state of being at rest.

A preferred global notion of time implies a preferred observer, whose clock measures that preferred time.

General relativity, it turns out, can be reformulated in a beautiful way as a theory with a preferred notion of time. This reformulation is just another way to understand general relativity, but it reveals a physically preferred synchronization of clocks throughout the universe. Furthermore, the choice of that preferred synchronization depends on the distribution of matter and gravitational radiation throughout the universe, so it is not a throwback to Newton’s absolute time.

Chapter 19 - The Future of Time

The most radical suggestion arising from this direction of thought is the insistence on the reality of the present moment and, beyond that, the principle that all that is real is so in a present moment. To the extent that this is a fruitful idea, physics can no longer be understood as the search for a precisely identical mathematical double of the universe. That dream must be seen now as a metaphysical fantasy that may have inspired generations of theorists but is now blocking the path to further progress. Mathematics will continue to be a handmaiden to science, but she can no longer be the Queen.

  • Facebook Classic
  • Twitter Classic
  • c-youtube

FOLLOW ME

© 2015 créé par Olivier Pignard

This site was designed with the
.com
website builder. Create your website today.
Start Now