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The Arrow of Time
In our century, the subject of time has become an area of serious inquiry for science. Theories that contain time as a simple quantity form the basis of our understanding of many scientific disciplines, yet the debate rages why does there seem to be a direction to time, an arrow of time pointing from past to future?
In The Arrow of Time, a major bestseller in England, Dr. Peter Coveney, a research scientist, and award-winning journalist Dr. Roger Highfield, demonstrate that the commonsense view of time agrees with the most advanced scientific theory. Time does in fact move like an arrow, shooting forward into what is genuinely unknown, leaving the past immutably behind. The authors make their case by exploring three centuries of science, offering bold reinterpretations of Newton's mechanics, Einstein's special and general theories of relativity, quantum mechanics, and advancing the insights of James Gleick's Chaos.
In The Arrow of Time, a major bestseller in England, Dr. Peter Coveney, a research scientist, and award-winning journalist Dr. Roger Highfield, demonstrate that the commonsense view of time agrees with the most advanced scientific theory. Time does in fact move like an arrow, shooting forward into what is genuinely unknown, leaving the past immutably behind. The authors make their case by exploring three centuries of science, offering bold reinterpretations of Newton's mechanics, Einstein's special and general theories of relativity, quantum mechanics, and advancing the insights of James Gleick's Chaos.
377 pages, Paperback
First published January 1, 1988
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April 21, 2020
It's the Spring of 2020, the year of the Coronavirus. At this moment I, like you, am quarantined in my home and admonished about any outside contact. Naturally, I began thinking about time, not just what to do with it but, more importantly, what is it? This led me to The Arrow of Time: A Voyage Through Science to Solve Time's Greatest Mysteries (1990) by Peter Coveney and Roger Highfield.
The Arrow of Time is a very interesting exposition of the history of science, much of it not relating directly to the notion of the arrow of Time. For those who want a review of scientific advances from Newton forward, it is an excellent read. But I've traveled that path several times and my interest is in the basic questions that led me to the book: What is Time? Is Time irreversible? What do those questions even mean?
So this review focuses on those questions, which are the subject of the books. I also read portions of Brian Greene's excellent new book Until the End of Time just to be sure I got it right.
So here goes. All errors are due to my wife.
The Philosophy of Time
Our understanding of Time is inextricably linked to our culture and to our understanding of the world around us (our science). The Mayans thought of Time as a rotating wheel, like a clock, that returns to its original place, thus starting another 260-year cycle. To them, time was repetitive—each cycle simply reproduced earlier cycles. Thus the future was known by the past: if you record events during one cycle, you know them for future cycles. The Mayans were great record keepers!
But today we sense an Arrow of Time—Time inexorably proceeds from the past into the future. Is this an illusion, as Einstein suggested? Is time simply thee in a complete sequence with all possibilities already determined, so we just experience what must be experienced? Is Time reversible so we can go back? Newtonian mechanics offers no assistance on these questions: for Newtonian physics time is reversible: you can run his equations backward to pinpoint the location of a celestial object at any previous time. The same is true of Maxwell's equations of electromagnetism.
If Time is, or is not, reversible, why should that be? The bidirectional Arrow of Time, deeply embeded in early science and in science fiction, is unsettling. Our observations are always that the Arrow of Time points from the past toward the future; no matter how long you wait you'll never find yourself back before you started waiting; if you spill coffee from a cup, you never see it climb back into the cup.
Philosophical paradoxes are said to arise if we can reverse our path in time, going to the past to correct mistakes or leverage successes. Are these paradoxes simply a moral caution not to go back so as not to screw up the past and, therefore, the present? Or are they signs of something deeper? In scientific work the appearance of a paradox sometimes means that you've encountered the impossible. Perhaps traveling back in time is simply impossible—the arrow always points ahead.
The Notion of Entropy
Let's begin with the slippery concept of entropy, the idea that all energy—whether organized in matter or in electromagnetic radiation—inexorably becomes more disorganized with the passage of time. For example, with all of its atoms massed in a clump the human body is very organized—it has extremely low entropy. But a human corpse is in the process of releasing those atoms back into the cloud—its entropy, or the degree of disorganization in its atoms, is and ultimately its atoms will all be dispersed and the body will be totally disorganized (have maximum entropy).
In his Until the End of Time (2020) the physicist Brian Greene gives a good simple example of the statistical foundation of entropy. Suppose you flip ten coins in a row and count the number of heads that come up. There are 210 = 1,024 possible ways the ten coins can come down, ranging from ten heads to no heads. There is only one possible way that all heads (or no heads) can occur, so the probability of all-heads or no-heads is a remote 2-10 = .000977, about one-tenth of one percent. But there are 252 ways that exactly five heads can appear among the ten coins, giving a five-heads probability of .246094 or about 25 percent. This is the result that a statistician would predict, knowing as she does that the probability of a head on a single flip is ½.
The all-heads or no-heads outcomes are said to be "highly organized" (or "low entropy") in the statistical sense that they are so unlikely to occur that it appears as if someone or something organized the event. In contrast, the five-heads result is highly likely to occur by chance, occurring almost 25 percent of the times the experiment is run, so if a five-heads result occurs it's a ho-hum event and you would likely conclude that it occurred purely by chance. Stated differently, the five-heads result shows no particular organization and is a high-entropy outcome perfectly consistent with chance.
A similar result might occur if you observe snowflakes falling outside you house. randomly throw snowflakes into a box. If you see a snow man emerging you would be surprised and term the clump of snow as having low entropy. You would not attribute it to chance but to some higher force, a designer. But if the scattering of snow is very diffuse you would call it high-entropy and attribute it purely to chance.
In the same sense, the Empire State Building is a collection of atoms that in their free state were once randomly distributed and therefore had high entropy. You would never expect the random collection of atoms to organize itself into such a building—you know that it required the application of energy in the form of mechanical and human power to develop such low entropy.
Heat and and Entropy: Thermodynamics
Thus, lumpiness like in our bodies, our planets, our stars, and our galaxy is associated with low entropy while random diffusion like the atoms in celestial dust is high entropy. And low entropy—high organization—is unlikely to occur spontaneously. It could happen by chance, but that is highly unlikely.
To get from entropy to an Arrow of Time requires a theory of energy transfer, and that gets us to Thermodynamics, the transfer of energy in the form of heat. So let's introduce Thermodynamics.
The First Law of Thermodynamics states that within any closed physical system like the universe, energy is conserved though it might change its form from pure energy (E) to matter according to the equation E=mcˆ2. Thus, burning gasoline (matter) in an auto engine creates mechanical energy and heat from friction and combustion. But all the energy to drive the automobile is due to the energy in the gasoline that drove the process. Running an auto engine simply converts the energy from one form to another.
This First Law also tells us that all the energy in our universe was there at the outset, compressed into "the primordial stew." The universe once had extremely high entropy, with all of its energy stuffed into an infinitely small space.
The Second Law of Thermodynamics states that everything progresses from an initial state of low entropy (high lumpiness) to an ultimate state of high entropy (high diffusion). Our bodies, our planet, our solar system, our galaxy, and our universe have low entropy because they are highly organized into clumps of matter and energy. But as time passes, entropy must increase unless some outside force (God?) intervenes to reorganize the dispersing atoms, an act that would require an injection of additional energy.
The Third Law of Thermodynamics says that the entropy of a closed system (like the universe) approaches a constant level as the temperature approaches absolute zero. At absolute zero there can be no change in the universe's degree of organization.
The necessary indicator of an increase in entropy is a transfer of heat. If you heat the handle of a low-entropy object like a spoon to near-melting temperature, the heat accumulated in that spoon will dissipate into the air around it—it will move from a low-entropy state to a high-entropy state. If you ignite a stick of TNT the initial concentration of heat in the explosion will dissipate from the low-entropy clump of TNT to the surrounding high-entropy air. Any change in entropy requires a change in heat, and vice-versa.
The Arrow of Time
The Arrow of Time drops directly out of the Second Law of Thermodynamics.. When we say that time is passing we mean that change is occurring, and that change is known to us by the increasing disorganization of energy: a constant degradation of the quality of energy. Buildings decay, living organisms die. Each of these releases the energy it contained in its low-entropy state to be randomly distributed in a high-entropy environment.
Of course, the reverse process would also give rise to time: an increase in lumpiness—evidenced perhaps by the autonomous rise of office buildings out of thin air and other spontaneous lumpiness would give us a sense of passing through time. But that would obviate the laws of Thermodynamics telling us (First Law) that the universe began as a highly concentrated bundle of energy and then dissipated into randomness as it transfered its energy to an expanding space, and (Second Law) that the universe inevitable loses its form as its atoms disperse into a uniform distribution. And the Third Law tells us that entropy increases until the universe hits an absolute temperature of zero degrees and all motion stops.
Until Congress repeals the Laws of Thermodynamics we will have an Arrow of Time that points only in one direction. To reverse that requires an input of energy from some external source.
The Primordial Stew and the Big Bang
It's commonly acknowledged that the universe began with a Big Bang, in which a dense bundle of energy exploded and condensed into matter while it's energy created an expansion in space that is still continuing, apparently at an increasing rate. So the Arrow of Time requires an explanation of how this static bundle of energy became unstable and exploded.
In 1979 a physicist named Alan Guth developed the theory that has become the strongest story to date. According to Guth, the answer is in the types of energy that comprised the primordial stew, the way it was held together for eons (there really wasn't time yet), and the source of the instability that led to the Big Bang about 14 billion years ago, give or take a month.
In its initial state the universe was infinitely small and consisted of enormous amounts of energy potentials—atoms, quarks, and so on didn't exist yet. These potentials would become antimatter (particles composed of antiprotons, antineutrons, and antielectrons), matter (composed of protons, neutrons and electrons), attractive forces of gravity ("gravitons," the quantum of quantum gravity), and repulsive force of antigravity (ïnflatons," the quantum of antigravity). These opposing types of energy potentials balanced each other and maintained a neutral and static universe. This was all gathered as potential energy, just as the TNT stick is a lump of potential energy.
But the energy in that miniscule area was subject to quantum uncertainty: each type of energy potential could randomly jump to higher intensity or fall to lower intensity. As statistical analysis would predict, the random variations offset each other and stasis prevailed: it was highly unlikely that one energy form would dominate its opponent, just as it was unlikely that the all-heads or no-heads outcome would occur in coin tosses.
All might have stayed that way forever except for one fact. Quantum mechanics tells us that all energy levels particles are subject to quantum uncertainty: they randomly jump around. Thus, the primordial stew jiggled and the quantum jiggles produced pockets of gravitons and of inflatons. Following statistical principles, the vast majority of these jiggles were sufficiently minor to prevent unstable imbalances: the sizes of these opposing pockets remained in balance and stasis was maintained.
The possibility of destabilizing imbalances always existed, but eventually—like the all-heads coin toss—a sufficiently great jiggle occurred and inflation pockets became sufficiently larger than graviton pockets. Cosmic inflation took over—the size of the universe instantly expanded from an infinitely small radius with an infinitely high temperature. At 10-43 seconds after ignition the temperature was a blistering 10ˆ32 degrees Kelvin and the universe's radius was 10ˆ-35 meters; after one second the radius of the universe had increased to 10ˆ18 meters, about 620 billion miles, and the temperature had fallen to a balmy 10ˆ10 degrees Kelvin.
The result is the still-expanding universe we know and the dissipation of the original heat in the process we know as entropy. Over time the process stars and planets formed as energy converted into matter and gravity caused lumpiness. This lumpiness didn't violate the Second Law of Thermodynamics because it simply represented a conversion of the already lumpy heat energy into matter. Ultimately the story is dismal—entropy will continue until the absolute temperature of the universe falls to zero Kelvin. Put on your warm and woolies!
Wait! Wait! Don't Tell Me!
So goes the standard story, but perhaps there are variations on it. The Laws of Thermodynamic apply in a state of physical equilibrium, when the relationship between entropy and time is on a steady-state path. But, the authors ask, what if it is not in equilibrium?
Suppose that the entropy level at present is above the equilibrium level. Will it tend to move toward equilibrium, so and stay along that path? Will entropy increase further in an unstable process? Will entropy cycle around the equilibrium as we follow the equilibrium path? This would break the link between entropy and time by allowing an increase in entropy (more lumpiness) as time passes.
Well, maybe. The problem is that with unstable dynamics anything can happen, and we don't know which of the possibilities to key on My training leads me to place a great weight on equilibrium. Until we know more about possible instability in the dynamics of entropy, I sign on to the standard story.
I'm putting my parka on.
The Arrow of Time is a very interesting exposition of the history of science, much of it not relating directly to the notion of the arrow of Time. For those who want a review of scientific advances from Newton forward, it is an excellent read. But I've traveled that path several times and my interest is in the basic questions that led me to the book: What is Time? Is Time irreversible? What do those questions even mean?
So this review focuses on those questions, which are the subject of the books. I also read portions of Brian Greene's excellent new book Until the End of Time just to be sure I got it right.
So here goes. All errors are due to my wife.
The Philosophy of Time
Our understanding of Time is inextricably linked to our culture and to our understanding of the world around us (our science). The Mayans thought of Time as a rotating wheel, like a clock, that returns to its original place, thus starting another 260-year cycle. To them, time was repetitive—each cycle simply reproduced earlier cycles. Thus the future was known by the past: if you record events during one cycle, you know them for future cycles. The Mayans were great record keepers!
But today we sense an Arrow of Time—Time inexorably proceeds from the past into the future. Is this an illusion, as Einstein suggested? Is time simply thee in a complete sequence with all possibilities already determined, so we just experience what must be experienced? Is Time reversible so we can go back? Newtonian mechanics offers no assistance on these questions: for Newtonian physics time is reversible: you can run his equations backward to pinpoint the location of a celestial object at any previous time. The same is true of Maxwell's equations of electromagnetism.
If Time is, or is not, reversible, why should that be? The bidirectional Arrow of Time, deeply embeded in early science and in science fiction, is unsettling. Our observations are always that the Arrow of Time points from the past toward the future; no matter how long you wait you'll never find yourself back before you started waiting; if you spill coffee from a cup, you never see it climb back into the cup.
Philosophical paradoxes are said to arise if we can reverse our path in time, going to the past to correct mistakes or leverage successes. Are these paradoxes simply a moral caution not to go back so as not to screw up the past and, therefore, the present? Or are they signs of something deeper? In scientific work the appearance of a paradox sometimes means that you've encountered the impossible. Perhaps traveling back in time is simply impossible—the arrow always points ahead.
The Notion of Entropy
Let's begin with the slippery concept of entropy, the idea that all energy—whether organized in matter or in electromagnetic radiation—inexorably becomes more disorganized with the passage of time. For example, with all of its atoms massed in a clump the human body is very organized—it has extremely low entropy. But a human corpse is in the process of releasing those atoms back into the cloud—its entropy, or the degree of disorganization in its atoms, is and ultimately its atoms will all be dispersed and the body will be totally disorganized (have maximum entropy).
In his Until the End of Time (2020) the physicist Brian Greene gives a good simple example of the statistical foundation of entropy. Suppose you flip ten coins in a row and count the number of heads that come up. There are 210 = 1,024 possible ways the ten coins can come down, ranging from ten heads to no heads. There is only one possible way that all heads (or no heads) can occur, so the probability of all-heads or no-heads is a remote 2-10 = .000977, about one-tenth of one percent. But there are 252 ways that exactly five heads can appear among the ten coins, giving a five-heads probability of .246094 or about 25 percent. This is the result that a statistician would predict, knowing as she does that the probability of a head on a single flip is ½.
The all-heads or no-heads outcomes are said to be "highly organized" (or "low entropy") in the statistical sense that they are so unlikely to occur that it appears as if someone or something organized the event. In contrast, the five-heads result is highly likely to occur by chance, occurring almost 25 percent of the times the experiment is run, so if a five-heads result occurs it's a ho-hum event and you would likely conclude that it occurred purely by chance. Stated differently, the five-heads result shows no particular organization and is a high-entropy outcome perfectly consistent with chance.
A similar result might occur if you observe snowflakes falling outside you house. randomly throw snowflakes into a box. If you see a snow man emerging you would be surprised and term the clump of snow as having low entropy. You would not attribute it to chance but to some higher force, a designer. But if the scattering of snow is very diffuse you would call it high-entropy and attribute it purely to chance.
In the same sense, the Empire State Building is a collection of atoms that in their free state were once randomly distributed and therefore had high entropy. You would never expect the random collection of atoms to organize itself into such a building—you know that it required the application of energy in the form of mechanical and human power to develop such low entropy.
Heat and and Entropy: Thermodynamics
Thus, lumpiness like in our bodies, our planets, our stars, and our galaxy is associated with low entropy while random diffusion like the atoms in celestial dust is high entropy. And low entropy—high organization—is unlikely to occur spontaneously. It could happen by chance, but that is highly unlikely.
To get from entropy to an Arrow of Time requires a theory of energy transfer, and that gets us to Thermodynamics, the transfer of energy in the form of heat. So let's introduce Thermodynamics.
The First Law of Thermodynamics states that within any closed physical system like the universe, energy is conserved though it might change its form from pure energy (E) to matter according to the equation E=mcˆ2. Thus, burning gasoline (matter) in an auto engine creates mechanical energy and heat from friction and combustion. But all the energy to drive the automobile is due to the energy in the gasoline that drove the process. Running an auto engine simply converts the energy from one form to another.
This First Law also tells us that all the energy in our universe was there at the outset, compressed into "the primordial stew." The universe once had extremely high entropy, with all of its energy stuffed into an infinitely small space.
The Second Law of Thermodynamics states that everything progresses from an initial state of low entropy (high lumpiness) to an ultimate state of high entropy (high diffusion). Our bodies, our planet, our solar system, our galaxy, and our universe have low entropy because they are highly organized into clumps of matter and energy. But as time passes, entropy must increase unless some outside force (God?) intervenes to reorganize the dispersing atoms, an act that would require an injection of additional energy.
The Third Law of Thermodynamics says that the entropy of a closed system (like the universe) approaches a constant level as the temperature approaches absolute zero. At absolute zero there can be no change in the universe's degree of organization.
The necessary indicator of an increase in entropy is a transfer of heat. If you heat the handle of a low-entropy object like a spoon to near-melting temperature, the heat accumulated in that spoon will dissipate into the air around it—it will move from a low-entropy state to a high-entropy state. If you ignite a stick of TNT the initial concentration of heat in the explosion will dissipate from the low-entropy clump of TNT to the surrounding high-entropy air. Any change in entropy requires a change in heat, and vice-versa.
The Arrow of Time
The Arrow of Time drops directly out of the Second Law of Thermodynamics.. When we say that time is passing we mean that change is occurring, and that change is known to us by the increasing disorganization of energy: a constant degradation of the quality of energy. Buildings decay, living organisms die. Each of these releases the energy it contained in its low-entropy state to be randomly distributed in a high-entropy environment.
Of course, the reverse process would also give rise to time: an increase in lumpiness—evidenced perhaps by the autonomous rise of office buildings out of thin air and other spontaneous lumpiness would give us a sense of passing through time. But that would obviate the laws of Thermodynamics telling us (First Law) that the universe began as a highly concentrated bundle of energy and then dissipated into randomness as it transfered its energy to an expanding space, and (Second Law) that the universe inevitable loses its form as its atoms disperse into a uniform distribution. And the Third Law tells us that entropy increases until the universe hits an absolute temperature of zero degrees and all motion stops.
Until Congress repeals the Laws of Thermodynamics we will have an Arrow of Time that points only in one direction. To reverse that requires an input of energy from some external source.
The Primordial Stew and the Big Bang
It's commonly acknowledged that the universe began with a Big Bang, in which a dense bundle of energy exploded and condensed into matter while it's energy created an expansion in space that is still continuing, apparently at an increasing rate. So the Arrow of Time requires an explanation of how this static bundle of energy became unstable and exploded.
In 1979 a physicist named Alan Guth developed the theory that has become the strongest story to date. According to Guth, the answer is in the types of energy that comprised the primordial stew, the way it was held together for eons (there really wasn't time yet), and the source of the instability that led to the Big Bang about 14 billion years ago, give or take a month.
In its initial state the universe was infinitely small and consisted of enormous amounts of energy potentials—atoms, quarks, and so on didn't exist yet. These potentials would become antimatter (particles composed of antiprotons, antineutrons, and antielectrons), matter (composed of protons, neutrons and electrons), attractive forces of gravity ("gravitons," the quantum of quantum gravity), and repulsive force of antigravity (ïnflatons," the quantum of antigravity). These opposing types of energy potentials balanced each other and maintained a neutral and static universe. This was all gathered as potential energy, just as the TNT stick is a lump of potential energy.
But the energy in that miniscule area was subject to quantum uncertainty: each type of energy potential could randomly jump to higher intensity or fall to lower intensity. As statistical analysis would predict, the random variations offset each other and stasis prevailed: it was highly unlikely that one energy form would dominate its opponent, just as it was unlikely that the all-heads or no-heads outcome would occur in coin tosses.
All might have stayed that way forever except for one fact. Quantum mechanics tells us that all energy levels particles are subject to quantum uncertainty: they randomly jump around. Thus, the primordial stew jiggled and the quantum jiggles produced pockets of gravitons and of inflatons. Following statistical principles, the vast majority of these jiggles were sufficiently minor to prevent unstable imbalances: the sizes of these opposing pockets remained in balance and stasis was maintained.
The possibility of destabilizing imbalances always existed, but eventually—like the all-heads coin toss—a sufficiently great jiggle occurred and inflation pockets became sufficiently larger than graviton pockets. Cosmic inflation took over—the size of the universe instantly expanded from an infinitely small radius with an infinitely high temperature. At 10-43 seconds after ignition the temperature was a blistering 10ˆ32 degrees Kelvin and the universe's radius was 10ˆ-35 meters; after one second the radius of the universe had increased to 10ˆ18 meters, about 620 billion miles, and the temperature had fallen to a balmy 10ˆ10 degrees Kelvin.
The result is the still-expanding universe we know and the dissipation of the original heat in the process we know as entropy. Over time the process stars and planets formed as energy converted into matter and gravity caused lumpiness. This lumpiness didn't violate the Second Law of Thermodynamics because it simply represented a conversion of the already lumpy heat energy into matter. Ultimately the story is dismal—entropy will continue until the absolute temperature of the universe falls to zero Kelvin. Put on your warm and woolies!
Wait! Wait! Don't Tell Me!
So goes the standard story, but perhaps there are variations on it. The Laws of Thermodynamic apply in a state of physical equilibrium, when the relationship between entropy and time is on a steady-state path. But, the authors ask, what if it is not in equilibrium?
Suppose that the entropy level at present is above the equilibrium level. Will it tend to move toward equilibrium, so and stay along that path? Will entropy increase further in an unstable process? Will entropy cycle around the equilibrium as we follow the equilibrium path? This would break the link between entropy and time by allowing an increase in entropy (more lumpiness) as time passes.
Well, maybe. The problem is that with unstable dynamics anything can happen, and we don't know which of the possibilities to key on My training leads me to place a great weight on equilibrium. Until we know more about possible instability in the dynamics of entropy, I sign on to the standard story.
I'm putting my parka on.
January 9, 2013
Tough sledding but worth the effort. Coveney tackles the anomaly of time. Other aspects of physics submit to equations that work mathematically which means that they work in either direction. Time is different. Many physicists sidestep this issue, not Coveney who devotes this book to analyzing the problem and introducing leading theories about why time travels in only one direction.
February 25, 2009
The authors, one a science writer and the other a physicist - both British - provide a popular but robust survey of the current representation of time in scientific research. Basic physical theories of the cosmological and the microscopic contain no arrow of time as humans experience it. Newtonian mechanics, general relativity, and quantum mechanics are time invariant in the sense that the systems these theories describe are reversible. But thermodynamics, the authors argue, particularly exploration of the Second Law, offers a path to reintroduce to physical theory the irreversible arrow of time evident in chemical and biological systems as well as human experience. To the question whether there is in the universe an objective arrow of time they answer an emphatic 'yes' though as of their writing a grasp of irreversible time seemed yet to elude physical science. They recommend particularly the exploration of non-linear dynamical or chaotic systems as models of cosmological, macroscopic, and microscopic phenomena as well as the interfaces between these. One particularly fruitful observation they make in their shift against a strictly reductionist scientific program involves the role of numbers in measurement. The problem of measurement admits an array of difficulties. Not least, measurement is a critical interface between subjective and objective systems. Measurement converts physical phenomena to numbers in some manner. Resulting measures, though, are limited not only by subjective considerations attached to the act of measuring or objective considerations attaching to the measurement mechanism. Measurement also is intrinsically limited by the properties of numbers. For example, measurement mechanisms and our means for computing with measure-derived numbers are limited in the precision to which we can handle irrational numbers or even infinitely repeating rational numbers such as 1/3.
June 22, 2013
It could have been a great book, but fell far short:
1) The writing style was turgid,
2) Too much credit was given to Ilya Prigogine and his Brussels School, and
3) They talked endlessly about "dissipative irreversible systems" without showing how they might explain the arrow of time, rather than being merely evidence for it.
In more detail:
I just finished slogging through this book. It was not much fun, and neither was it terribly enlightening. I found the writing style to be rather turgid; there was no ability to enliven the reader's appreciation of the subject by conveying a sense of enthusiasm. Instead, the style was too academic, and tended to focus endlessly on the work of the Brussels school, led by Ilya Prigogine (who won the 1977 Nobel Prize in Chemistry for his work in dissipative structures and their role in thermodynamic systems far from equilibrium). Prigogine was mentioned so many times that it became annoying, regardless of how well one might regard Prigogine and his work.
The book contains many interesting topics, including lots of examples of dissipative, irreversible systems in chemistry and biology and beyond. However, the writing made these topics less interesting than they should have been, and it was by no means clear how such dissipative, irreversible systems could explain why the arrow of time flows (points?) in one direction only. It seems more likely that they provide yet more evidence that it does, but shed little light on why.
The book jacket says "... Picking up where Stephen Hawking's "A Brief History of Time" left off, ... ". I guess they were trying to ride the coat-tails of Hawking's deservedly very successful and delightful book. Don't be fooled; this book is a very different animal indeed.
Ilya Prigogine (who died in 2003) wrote a foreword for the book, in which he is quoted: "I warmly welcome this book, which is written on a high scientific level while being accessible to a wide public." I beg to differ; the book is not very accessible at all. I really had to work hard and grit my teeth to get through it, and I have a Ph.D. in Physics. A truly lay reader would likely have more difficulty.
Recently, I have been reading a lot of books about the latest discoveries in Physics and Cosmology (and the history of these discoveries, back to Galileo and beyond). There are many interesting and engaging books on these subjects. This is not one of them. The sad truth is that this book could have been (and should have been!) so much better.
Not recommended.
1) The writing style was turgid,
2) Too much credit was given to Ilya Prigogine and his Brussels School, and
3) They talked endlessly about "dissipative irreversible systems" without showing how they might explain the arrow of time, rather than being merely evidence for it.
In more detail:
I just finished slogging through this book. It was not much fun, and neither was it terribly enlightening. I found the writing style to be rather turgid; there was no ability to enliven the reader's appreciation of the subject by conveying a sense of enthusiasm. Instead, the style was too academic, and tended to focus endlessly on the work of the Brussels school, led by Ilya Prigogine (who won the 1977 Nobel Prize in Chemistry for his work in dissipative structures and their role in thermodynamic systems far from equilibrium). Prigogine was mentioned so many times that it became annoying, regardless of how well one might regard Prigogine and his work.
The book contains many interesting topics, including lots of examples of dissipative, irreversible systems in chemistry and biology and beyond. However, the writing made these topics less interesting than they should have been, and it was by no means clear how such dissipative, irreversible systems could explain why the arrow of time flows (points?) in one direction only. It seems more likely that they provide yet more evidence that it does, but shed little light on why.
The book jacket says "... Picking up where Stephen Hawking's "A Brief History of Time" left off, ... ". I guess they were trying to ride the coat-tails of Hawking's deservedly very successful and delightful book. Don't be fooled; this book is a very different animal indeed.
Ilya Prigogine (who died in 2003) wrote a foreword for the book, in which he is quoted: "I warmly welcome this book, which is written on a high scientific level while being accessible to a wide public." I beg to differ; the book is not very accessible at all. I really had to work hard and grit my teeth to get through it, and I have a Ph.D. in Physics. A truly lay reader would likely have more difficulty.
Recently, I have been reading a lot of books about the latest discoveries in Physics and Cosmology (and the history of these discoveries, back to Galileo and beyond). There are many interesting and engaging books on these subjects. This is not one of them. The sad truth is that this book could have been (and should have been!) so much better.
Not recommended.
August 7, 2019
Gran introducción a la entropía en los sistemas físicos y biológicos. A pesar de que los choques atómicos son reversibles y viendo dos átomos chocar no sabemos si nos están pasando una película hacia atrás hacia delante, parece que todos los procesos sólo pueden ir en una dirección. Ese es el efecto de la entropía. La introducción es clara y muy completa. Cosas que al principio parecen esotéricas van cobrando forma y, sin ecuaciones, uno llega a sentirse cómodo con el proceso de aumento de desorden que nos cuentan los autores una y otra vez. Al final aprendemos algo de termodinámica y todo, a pesar de la fama de hueso que tiene la materia. Muy buen libro.
March 31, 2024
I read the book 12 months before I write this review. I don't remember anything about it. I am sure I read it till the end because the arrow of time is a subject important to me. I just flipped through it now and saw about 20 sentences underlined but nothing important enough to write in this review.
There would have been mistakes I would probably remember.
There would have been mistakes I would probably remember.
June 10, 2025
Second time through...makes a little more sense. Although there have been many changes in cosmology since I last read this.
May 15, 2023
Seguramente lo habré comprado en la librería de la UAM-I. Recuerdo vagamente su contenido. Me es más memorable su efecto, muy similar al que me causara «Breve historia del tiempo»*, de Stephen Hawking. Digamos que lo que uno fue en Cosmología, el otro lo fue en termodinámica y sistemas complejos. Tal vez esta lectura me haya preparado para una mejor apreciación de «Jurassic Park», la novela de Michael Crichton. ¿O habrá sido al revés?
* El capítulo 9 del clásico de Hawking se titula, «La flecha del tiempo». El concepto debió quedar en mi mente y resonar al leerlo en la portada de este libro en aquel santuario de la UAM Iztapalapa.
* El capítulo 9 del clásico de Hawking se titula, «La flecha del tiempo». El concepto debió quedar en mi mente y resonar al leerlo en la portada de este libro en aquel santuario de la UAM Iztapalapa.
October 7, 2014
The author mentions Ilya Prigogine even more often than Mr Collins refers to Lady Catherine de Bourgh in Pride and Prejudice, and in a manner that reminds me of Mr Collins!!!
However there are some very good points in the book, but it felt repetitive towards the end. I learned something interesting about irrational numbers too
However there are some very good points in the book, but it felt repetitive towards the end. I learned something interesting about irrational numbers too
February 14, 2008
Time seems, in our perception, to "flow" from past to future, although nothing in classical physics, relativity, or quantum mechanics requires that this be so. So what's the dilly-o? This is the question that this book explores. Be warned: it gets pretty science-y.
July 15, 2010
An excellent book that tries to answer the question of what is time and can it flow backwards?
Essentially humans depend on circadian clocks to conceive and understand time, this clock is irrelevant to the rest of the universe, possibly time does not exist.
Essentially humans depend on circadian clocks to conceive and understand time, this clock is irrelevant to the rest of the universe, possibly time does not exist.
March 17, 2012
I read it many many years ago! It is a very good book. I recommend it to anyone who is interested in Time and Physics.
May 26, 2013
Interesting overview of time as it applies to broader science.
April 7, 2015
AWESOME!!
Read
January 20, 2016not finished
June 8, 2010
A pleasant mind fuck. Kinda boring though.
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