Apr 27, 2016 05:12 PM
(This post was last modified: Apr 27, 2016 05:45 PM by C C.)
The flow of time is central to human experience. Why isn’t it central to physics?
Why doesn't physics help us to understand the flow of time?
https://aeon.co/essays/why-doesn-t-physi...ow-of-time
EXCERPT: [...] The flow of time is certainly one of the most immediate aspects of our waking experience. It is essential to how we see ourselves and to how we think we should live our lives. [...] Yet today’s physicists rarely debate what time is and why we experience it the way we do, remembering the past but never the future. Instead, researchers build ever-more accurate clocks. [...] Impressive, but it does not answer ‘What is time?’
To declare that question outside the pale of physical theory doesn’t make it meaningless. The flow of time could still be real as part of our internal experience, just real in a different way from a proton or a galaxy. Is our experience of time’s flow akin to watching a live play, where things occur in the moment but not before or after, a flickering in and out of existence around the ‘now’? Or, is it like watching a movie, where all eternity is already in the can, and we are watching a discrete sequence of static images, fooled by our limited perceptual apparatus into thinking the action flows smoothly?
The Newtonian and Einsteinian world theories offer little guidance. They are both eternalised ‘block’ universes, in which time is a dimension not unlike space, so everything exists all at once.
[...] Time’s flow appears nowhere in current theories of physics. For most of the past few centuries, conscious awareness has been considered beyond the pale for physics, a problem too hard to tackle, postponed while we dealt with other urgent business. As scientists drove ever deeper into the nucleus and out to the stars, the conscious mind itself, and the glaring contrast between our experience of time’s flow and our eternalised mathematical theories, was left hanging. How did that come to pass? Isn’t science supposed to test itself against the ground of experience? This disconnect might help to explain why so many students not only don’t ‘get’ physics, but are positively repulsed by it. Where are they in the world picture drawn by physicists? Where is life, and where is death? Where is the flow of time?
The Atomist Greek philosopher Democritus had already pointed out the conundrum here back in the 4th century BCE. By careful observation and reasoning, he argued, we come to the conclusion that the senses can fool us, but it is through evidence from the senses that we have come to that conclusion. [...] The phenomenology of experience, such as our internal perception of the passage of time, is an area owned by cognitive science and philosophy. The exterior world is traditionally the playground of physics. Yet to separate the inner and outer realms in this naive way is misleading. It is our brain that does physics, after all. In the end, the two sides strive to find bridges between them, if only through metaphor, to find connections between the myriad ways in which humans experience themselves in the world.
[...] Current cognitive science says that our memories are a kind of story that our brain creates [...] Some of the intuitions that infuse those memories are basic to our sense of the world: the smooth geometry of three spatial dimensions, the clear and obvious distinction between before and after, and the flow of time. Current physics calls into question the smoothness of space and time, the psychological flow of time, and even asks: why do we remember the past but not the future?
[...] Our experience of the ‘now’ is built out of a mix of recent memories and our current sense perceptions, what we see, hear, feel, taste and smell. Those sensory perceptions are not instantaneous [...] We usually don’t sense this mingling of near past and near future because our brain works quickly enough to obscure the process, but there are moments when it struggles to keep up.
[...] It’s possible that our experience of the flow of time is like our experience of colour. A physicist would say that colour does not exist as an inherent property of the world. Light has a variety of wavelengths, but they have no inherent property of ‘colour’. The things in the world absorb and emit and scatter photons, granules of light, of various wavelengths. It is only when our eyes intersect a tiny part of that sea of radiation, and our brain gets to work on it, that ‘colour’ emerges. It is an internal experience, a naming process, an activity of our brain trying to puzzle things out.
So the flow of time might be a story our brain creates, trying to make sense of chaos. In a 2013 paper, the physicists Leonard Mlodinow of Caltech and Todd Brun of the University of Southern California go even further and argue that any physical thing that has the characteristics of a memory will tend to align itself with the thermodynamic arrow of time, which in turn is defined by the behaviour of extremely large numbers of particles. According to this theory, it is no puzzle that we remember the past but not the future, even though the microscopic laws of nature are the same going forward or backward in time, and the past and future both exist. The nature of large systems is to progress toward increasing entropy – a measure of disorder, commonly experienced as the tendency of hot or cold objects to come into equilibrium with their surroundings. Increasing entropy means that a memory of the past is dynamically stable, whereas a memory of the future is unstable.
[...] Lee Smolin at the Perimeter Institute in Ontario argues that scientists must change tack, accepting the flow of time as real and building the church of a new physics upon that rock. The British physicist Julian Barbour takes an opposite stance; going beyond Newton and Einstein, in "The End of Time" (1999) he proposes that time itself is an illusion. Instead, the Universe consists of a collection of static moments, like a pile of unsorted photographs tossed into a shoebox. Each photo contains a snapshot of the world entire, a unique configuration of all things: planets, galaxies, bumblebees, people. Barbour gives the collection of all possible moments an evocative name: The Heap.
Because each instant in The Heap is a moment of the entire world, it contains references to all other moments, so the shoebox also contains an implied web of connections, branching threads of mutual association. Following a single thread, one would experience an apparent flow of time. Most threads would follow isolated paths that are without sense or meaning, but a very few threads and their neighbours follow paths that are mutually coherent. We might say that such paths tell a story, or that they include a sensible memory of the past at each step. The family of threads that are mutually coherent is robust, whereas the isolated and incoherent threads are fragile, with brittle associations providing no neighbouring reinforcement....
Henri Bergson’s debate with Albert Einstein reached and swayed the 1921 Nobel committee.
This Philosopher Helped Ensure There Was No Nobel for Relativity
http://nautil.us/issue/35/boundaries/thi...relativity
EXCERPT: On April 6, 1922, Einstein met a man he would never forget. He was one of the most celebrated philosophers of the century, widely known for espousing a theory of time that explained what clocks did not: memories, premonitions, expectations, and anticipations. [...] The meeting had been planned as a cordial and scholarly event. It was anything but that. The physicist and the philosopher clashed, each defending opposing, even irreconcilable, ways of understanding time. At the Société française de philosophie—one of the most venerable institutions in France—they confronted each other under the eyes of a select group of intellectuals. The “dialogue between the greatest philosopher and the greatest physicist of the 20th century” was dutifully written down. It was a script fit for the theater. [...]
The philosopher’s name was Henri Bergson. In the early decades of the century, his fame, prestige, and influence surpassed that of the physicist—who, in contrast, is so well known today. Bergson was compared to Socrates, Copernicus, Kant, Simón Bolívar, and even Don Juan. [...] The philosopher and historian of philosophy Étienne Gilson categorically claimed that the first third of the 20th century was “the age of Bergson.” He was simultaneously considered “the greatest thinker in the world” and “the most dangerous man in the world.”
[...] Bergson’s reputation was at risk after he confronted the younger man. But so was Einstein’s. The criticisms leveled against the physicist were immediately damaging. When the Nobel Prize was awarded to Einstein a few months later, it was not given for the theory that had made the physicist famous: relativity. Instead, it was given “for his discovery of the law of the photoelectric effect”—an area of science that hardly jolted the public’s imagination to the degree that relativity did. The reasons behind the decision to focus on work other than relativity were directly traced to what Bergson said that day in Paris.
The chairman for the Nobel Committee for Physics explained that although “most discussion centers on his theory of relativity,” it did not merit the prize. Why not? The reasons were surely varied and complex, but the culprit mentioned that evening was clear: “It will be no secret that the famous philosopher Bergson in Paris has challenged this theory.” Bergson had shown that relativity “pertains to epistemology” rather than to physics—and so it “has therefore been the subject of lively debate in philosophical circles.”
Einstein laid down the gauntlet by considering as valid only two ways of understanding time: physical and psychological.
The explanation that day surely reminded Einstein of the previous spring’s events in Paris. Clearly, he had provoked a controversy. These were the consequences. He had been unable to convince many thinkers of the value of his definition of time, especially when his theory was compared against that of the eminent philosopher. In his acceptance speech, Einstein remained stubborn. He delivered a lecture that was not about the photoelectric effect, for which he had been officially granted the prize, but about relativity—the work that had made him a star worldwide but which was now in question.
The invocation of Bergson’s name by the presenter of the Nobel Prize was a spectacular triumph for the philosopher who had lived his life and made an illustrious career by showing how time should not be understood exclusively through the lens of science. It had to be understood, he persistently and consistently insisted, philosophically. Why did two of the greatest minds of modern times disagree so starkly, dividing intellectual communities for years to come?...
Why doesn't physics help us to understand the flow of time?
https://aeon.co/essays/why-doesn-t-physi...ow-of-time
EXCERPT: [...] The flow of time is certainly one of the most immediate aspects of our waking experience. It is essential to how we see ourselves and to how we think we should live our lives. [...] Yet today’s physicists rarely debate what time is and why we experience it the way we do, remembering the past but never the future. Instead, researchers build ever-more accurate clocks. [...] Impressive, but it does not answer ‘What is time?’
To declare that question outside the pale of physical theory doesn’t make it meaningless. The flow of time could still be real as part of our internal experience, just real in a different way from a proton or a galaxy. Is our experience of time’s flow akin to watching a live play, where things occur in the moment but not before or after, a flickering in and out of existence around the ‘now’? Or, is it like watching a movie, where all eternity is already in the can, and we are watching a discrete sequence of static images, fooled by our limited perceptual apparatus into thinking the action flows smoothly?
The Newtonian and Einsteinian world theories offer little guidance. They are both eternalised ‘block’ universes, in which time is a dimension not unlike space, so everything exists all at once.
[...] Time’s flow appears nowhere in current theories of physics. For most of the past few centuries, conscious awareness has been considered beyond the pale for physics, a problem too hard to tackle, postponed while we dealt with other urgent business. As scientists drove ever deeper into the nucleus and out to the stars, the conscious mind itself, and the glaring contrast between our experience of time’s flow and our eternalised mathematical theories, was left hanging. How did that come to pass? Isn’t science supposed to test itself against the ground of experience? This disconnect might help to explain why so many students not only don’t ‘get’ physics, but are positively repulsed by it. Where are they in the world picture drawn by physicists? Where is life, and where is death? Where is the flow of time?
The Atomist Greek philosopher Democritus had already pointed out the conundrum here back in the 4th century BCE. By careful observation and reasoning, he argued, we come to the conclusion that the senses can fool us, but it is through evidence from the senses that we have come to that conclusion. [...] The phenomenology of experience, such as our internal perception of the passage of time, is an area owned by cognitive science and philosophy. The exterior world is traditionally the playground of physics. Yet to separate the inner and outer realms in this naive way is misleading. It is our brain that does physics, after all. In the end, the two sides strive to find bridges between them, if only through metaphor, to find connections between the myriad ways in which humans experience themselves in the world.
[...] Current cognitive science says that our memories are a kind of story that our brain creates [...] Some of the intuitions that infuse those memories are basic to our sense of the world: the smooth geometry of three spatial dimensions, the clear and obvious distinction between before and after, and the flow of time. Current physics calls into question the smoothness of space and time, the psychological flow of time, and even asks: why do we remember the past but not the future?
[...] Our experience of the ‘now’ is built out of a mix of recent memories and our current sense perceptions, what we see, hear, feel, taste and smell. Those sensory perceptions are not instantaneous [...] We usually don’t sense this mingling of near past and near future because our brain works quickly enough to obscure the process, but there are moments when it struggles to keep up.
[...] It’s possible that our experience of the flow of time is like our experience of colour. A physicist would say that colour does not exist as an inherent property of the world. Light has a variety of wavelengths, but they have no inherent property of ‘colour’. The things in the world absorb and emit and scatter photons, granules of light, of various wavelengths. It is only when our eyes intersect a tiny part of that sea of radiation, and our brain gets to work on it, that ‘colour’ emerges. It is an internal experience, a naming process, an activity of our brain trying to puzzle things out.
So the flow of time might be a story our brain creates, trying to make sense of chaos. In a 2013 paper, the physicists Leonard Mlodinow of Caltech and Todd Brun of the University of Southern California go even further and argue that any physical thing that has the characteristics of a memory will tend to align itself with the thermodynamic arrow of time, which in turn is defined by the behaviour of extremely large numbers of particles. According to this theory, it is no puzzle that we remember the past but not the future, even though the microscopic laws of nature are the same going forward or backward in time, and the past and future both exist. The nature of large systems is to progress toward increasing entropy – a measure of disorder, commonly experienced as the tendency of hot or cold objects to come into equilibrium with their surroundings. Increasing entropy means that a memory of the past is dynamically stable, whereas a memory of the future is unstable.
[...] Lee Smolin at the Perimeter Institute in Ontario argues that scientists must change tack, accepting the flow of time as real and building the church of a new physics upon that rock. The British physicist Julian Barbour takes an opposite stance; going beyond Newton and Einstein, in "The End of Time" (1999) he proposes that time itself is an illusion. Instead, the Universe consists of a collection of static moments, like a pile of unsorted photographs tossed into a shoebox. Each photo contains a snapshot of the world entire, a unique configuration of all things: planets, galaxies, bumblebees, people. Barbour gives the collection of all possible moments an evocative name: The Heap.
Because each instant in The Heap is a moment of the entire world, it contains references to all other moments, so the shoebox also contains an implied web of connections, branching threads of mutual association. Following a single thread, one would experience an apparent flow of time. Most threads would follow isolated paths that are without sense or meaning, but a very few threads and their neighbours follow paths that are mutually coherent. We might say that such paths tell a story, or that they include a sensible memory of the past at each step. The family of threads that are mutually coherent is robust, whereas the isolated and incoherent threads are fragile, with brittle associations providing no neighbouring reinforcement....
Henri Bergson’s debate with Albert Einstein reached and swayed the 1921 Nobel committee.
This Philosopher Helped Ensure There Was No Nobel for Relativity
http://nautil.us/issue/35/boundaries/thi...relativity
EXCERPT: On April 6, 1922, Einstein met a man he would never forget. He was one of the most celebrated philosophers of the century, widely known for espousing a theory of time that explained what clocks did not: memories, premonitions, expectations, and anticipations. [...] The meeting had been planned as a cordial and scholarly event. It was anything but that. The physicist and the philosopher clashed, each defending opposing, even irreconcilable, ways of understanding time. At the Société française de philosophie—one of the most venerable institutions in France—they confronted each other under the eyes of a select group of intellectuals. The “dialogue between the greatest philosopher and the greatest physicist of the 20th century” was dutifully written down. It was a script fit for the theater. [...]
The philosopher’s name was Henri Bergson. In the early decades of the century, his fame, prestige, and influence surpassed that of the physicist—who, in contrast, is so well known today. Bergson was compared to Socrates, Copernicus, Kant, Simón Bolívar, and even Don Juan. [...] The philosopher and historian of philosophy Étienne Gilson categorically claimed that the first third of the 20th century was “the age of Bergson.” He was simultaneously considered “the greatest thinker in the world” and “the most dangerous man in the world.”
[...] Bergson’s reputation was at risk after he confronted the younger man. But so was Einstein’s. The criticisms leveled against the physicist were immediately damaging. When the Nobel Prize was awarded to Einstein a few months later, it was not given for the theory that had made the physicist famous: relativity. Instead, it was given “for his discovery of the law of the photoelectric effect”—an area of science that hardly jolted the public’s imagination to the degree that relativity did. The reasons behind the decision to focus on work other than relativity were directly traced to what Bergson said that day in Paris.
The chairman for the Nobel Committee for Physics explained that although “most discussion centers on his theory of relativity,” it did not merit the prize. Why not? The reasons were surely varied and complex, but the culprit mentioned that evening was clear: “It will be no secret that the famous philosopher Bergson in Paris has challenged this theory.” Bergson had shown that relativity “pertains to epistemology” rather than to physics—and so it “has therefore been the subject of lively debate in philosophical circles.”
Einstein laid down the gauntlet by considering as valid only two ways of understanding time: physical and psychological.
The explanation that day surely reminded Einstein of the previous spring’s events in Paris. Clearly, he had provoked a controversy. These were the consequences. He had been unable to convince many thinkers of the value of his definition of time, especially when his theory was compared against that of the eminent philosopher. In his acceptance speech, Einstein remained stubborn. He delivered a lecture that was not about the photoelectric effect, for which he had been officially granted the prize, but about relativity—the work that had made him a star worldwide but which was now in question.
The invocation of Bergson’s name by the presenter of the Nobel Prize was a spectacular triumph for the philosopher who had lived his life and made an illustrious career by showing how time should not be understood exclusively through the lens of science. It had to be understood, he persistently and consistently insisted, philosophically. Why did two of the greatest minds of modern times disagree so starkly, dividing intellectual communities for years to come?...
