Wednesday, June 12, 2019

Guest Post: A conversation with Lee Smolin about his new book "Einstein’s Unfinished Revolution"

[Tam Hunt sent me another lengthy interview, this time with Lee Smolin. Smolin is a faculty member at the Perimeter Institute for Theoretical Physics in Canada and adjunct professor at the University of Waterloo. He is one of the founders of loop quantum gravity. In the past decades, Smolin’s interests have drifted to the role of time in the laws of nature and the foundations of quantum mechanics.]

TH: You make some engaging and bold claims in your new book, Einstein’s Unfinished Revolution, continuing a line of argument that you’ve been making over the course of the last couple of decades and a number of books. In your latest book, you argue essentially that we need to start from scratch in the foundations of physics, and this means coming up with new first principles as our starting point for re-building. Why do you think we need to start from first principles and then build a new system? What has brought us to this crisis point?

LS: The claim that there is a crisis, which I first made in my book, Life of the Cosmos (1997), comes from the fact that it has been decades since a new theoretical hypothesis was put forward that was later confirmed by experiment. In particle physics, the last such advance was the standard model in the early 1970s; in cosmology, inflation in the early 1980s. Nor has there been a completely successful approach to quantum gravity or the problem of completing quantum mechanics.

I propose finding new fundamental principles that go deeper than the principles of general relativity and quantum mechanics. In some recent papers and the book, I make specific proposals for new principles.

TH: You have done substantial work yourself in quantum gravity (loop quantum gravity, in particular) and quantum theory (suggesting your own interpretation called the “real ensemble interpretation”), and yet in this new book you seem to be suggesting that you and everyone else in foundations of physics needs to return to the starting point and rebuild. Are you in a way repudiating your own work or simply acknowledging that no one, including you, has been able to come up with a compelling approach to quantum gravity or other outstanding foundations of physics problems?

LS: There are a handful of approaches to quantum gravity that I would call partly successful. These each achieve a number of successes, which suggest that they could plausibly be at least part of the story of how nature reconciles quantum physics with space, time and gravity. It is possible, for example that these partly successful approaches model different regimes or phases of quantum gravity phenomena. These partly successful approaches include loop quantum gravity, string theory, causal dynamical triangulations, causal sets, asymptotic safety. But I do not believe that any approach to date, including these, is fully successful. Each has stumbling blocks that after many years remain unsolved.

TH: You part ways with a number of other physicists in recent years who have railed against philosophy and philosophers of physics as being largely unhelpful for actual physics. You argue instead that philosophers have a lot to contribute to the foundations of physics problems that are your focus. Have you found philosophy helpful in pursuing your physics for most of your career or is this a more recent finding in your own work? Which philosophers, in particular, do you think can be helpful in this area of physics?

LS: I would first of all suggest we revive the old idea of a natural philosopher, which is a working scientist who is inspired and guided by the tradition of philosophy. An education and immersion in the philosophical tradition gives them access to the storehouse of ideas, positions and arguments that have been developed over the centuries to address the deepest questions, such as the nature of space and time.

Physicists who are natural philosophers have the advantage of being able to situate their work, and its successes and failures, within the long tradition of thought about the basic questions.

Most of the key figures who transformed physics through its history have been natural philosophers: Galileo, Newton, Leibniz, Descartes, Maxwell, Mach, Einstein, Bohr, Heisenberg, etc. In more recent years, David Finkelstein is an excellent example of a theoretical physicist who made important advances, such as being the first to untangle the geometry of a black hole, and recognize the concept of an event horizon, who was strongly influenced by the philosophical tradition. Like a number of us, he identified as a follower of Leibniz, who introduced the concepts of relational space and time.

The abstract of Finkelstein’s key 1958 paper on what were soon to be called black holes explicitly mentions the principle of sufficient reason, which is the central principle of Leibniz’s philosophy. None of the important developments of general relativity in the 1960s and 1970s, such as those by Penrose, Hawking, Newmann, Bondi, etc., would have been possible without that groundbreaking paper by Finkelstein.

I asked Finkelstein once why it was important to know philosophy to do physics, and he replied, “If you want to win the long jump, it helps to back up and get a running start.”’

In other fields, we can recognize people like Richard Dawkins, Daniel Dennett, Lynn Margulis, Steve Gould, Carl Sagan, etc. as natural philosophers. They write books that argue the central issues in evolutionary theory, with the hope of changing each other’s minds. But we the lay public are able to read over their shoulders, and so have front row seats to the debates.

There are also working now a number of excellent philosophers of physics, who contribute in important ways to the progress of physics. One example of these is a group, centred originally at Oxford, of philosophers who have been doing the leading work on attempting to make sense of the Many Worlds formulation of quantum mechanics. This work involves extremely subtle issues such as the meaning of probability. These thinkers include Simon Saunders, David Wallace, Wayne Mhyrvold; and there are equally good philosophers who are skeptical of this work, such as David Albert and Tim Maudlin.

It used to be the case, half a century ago, that philosophers, such as Hilary Putnam, who opined about physics, felt qualified to do so with a bare knowledge of the principles of special relativity and single particle quantum mechanics. In that atmosphere my teacher Abner Shimony, who had two Ph.D’s – one in physics and one in philosophy – stood out, as did a few others who could talk in detail about quantum field theory and renormalization, such as Paul Feyerabend. Now the professional standard among philosophers of physics requires a mastery of Ph.D level physics, as well as the ability to write and argue with the rigour that philosophy demands. Indeed, a number of the people I just mentioned have Ph.D’s in physics.

TH: One of your suggested hypotheses, the next step you take after stating your first principles, is an acknowledgment that time is fundamental, real and irreversible, effectively goring one of the sacred cows of modern physics. You made your case for this approach in your book Time Reborn and I'm curious if you've seen a softening over the last few years in terms of physicists and philosophers beginning to be more open to the idea that the passage of time is truly fundamental? Also, why wouldn't this hypothesis be instead a first principle, if time is indeed fundamental?

LS: In my experience, there have always been physicists and philosophers open to these ideas, even if there is no consensus among those who have carefully thought the issues through.

When I thought carefully about how to state a candidate set of basic principles, it became clear that it was useful to separate principles from hypotheses about nature. Principles such as sufficient reason and the identity of the indiscernible can be realized in formulations of physics in which time is either fundamental or secondary and emergent. Hence those principles are prior to the choice of a fundamental or emergent time. So I think it clarifies the logic of the situation to call the latter choice a hypothesis rather than a principle.

TH: How does viewing time as irreversible and fundamental mesh with your principle of background independence? Doesn’t a preferred spacetime foliation, which would provide an irreversible and fundamental time, provide a background?

LS: Background independence is an aspect of the two principles of Leibniz I just referred to: 1) sufficient reason (PSR) and 2) the identity of the indiscernible (PII). Hence it is deeper than the choice of whether time is fundamental or emergent. Indeed, there are theories which rest on both hypotheses about time (fundamental or emergent). Julian Barbour, for example, is a relationalist who develops background-independent theories in which time is emergent. I am also a relationalist, but I make background-independent models of physics in which time and its passage are fundamental.

Viewing time as fundamental and irreversible doesn’t necessarily imply a preferred foliation; by the latter you mean a foliation of a pre-existing spacetime, specified kinematically in advance of the dynamical evolution. In our energetic causal set models there does arise a notion of the present, but this is determined dynamically by the evolution of the model and so is consistent with what we mean by background independence.

The point is that the solutions to background-independent theories can have preferred frames, so long as they are generated by solving the dynamics. This is, for example, the case with cosmological solutions to general relativity.

TH: You and many other physicists have focused for many years on finding a theory of quantum gravity, effectively unifying quantum mechanics and general relativity. In describing your preferred approach to achieving a theory of quantum gravity worthy of the name you describe why you think quantum mechanics is incomplete and why general relativity is in some key ways likely wrong. Let’s look first at quantum mechanics, which you describe as “wrong” and “incomplete.” Why is the Copenhagen (still perhaps the most popular version of quantum theory) school of quantum mechanics wrong and incomplete?

LS: Copenhagen is incomplete because it is based on an arbitrarily chosen division of the world into a classical realm and a quantum realm. This reflects our practice as experimenters, and corresponds to nothing in nature. This means it is an operational approach which conflicts with the expectations that physics should offer a complete description of individual phenomena, with no reference to our existence, knowledge or measurements.

TH: Your objections just stated (what’s known generally as the “measurement problem”) seem to me, even as an obvious non-expert in this area, to be fairly apparent and accurate objections to Copenhagen. If that’s the case, why is Copenhagen still with us today? Why was it ever considered a serious theory?

LS: I don’t think there are many proponents of the Copenhagen view among people working in quantum foundations, or who have otherwise thought about the issues carefully. I don’t think there are many enthusiastic followers of Bohr left alive.

Meanwhile, what most physicists who are not specialists in quantum foundations practice and teach is a very pragmatic, operational set of rules, which suffices because it closely parallels the practice of actual experimenters. They can get on with the physics without having to take a stand on realism.

What Bohr had in mind was a much more radical rejection of realism and its replacement by a view of the world in which nature and us co-create phenomena. My sense is that most living physicists haven’t read Bohr’s actual writings. There are of course some exceptions, like Chris Fuch’s QBism, which is, to the extent that I understand it, an even more radical view. Even if I disagree, I very much admire Chris for the clarity of his thinking and his insistence on taking his view to its logical conclusions. But, in the end, as a realist who sees the necessity of completing quantum mechanics by the discovery of new physics, the intellectual contortions of anti-realists are, however elegant, no help for my projects.

TH: Could this be a good example of why philosophical training could actually be helpful for physicists?

LS: I would agree, in some cases it could be helpful for some physicists to study philosophy, especially if they are interested in discovering deeper foundational laws. But I would never say anyone should study philosophy, because it can be very challenging reading, and if someone is not inclined to think “philosophically” they are unlikely to get much from the effort. But I would say that if someone is receptive to the care and depth of the writing, it can open doors to new ideas and to a highly critical style of thinking, which could greatly aid someone’s research.

The point I would like to make here is rather different. As I discussed in my earlier books, there are different periods in the development of science during which different kinds of problems present themselves. These require different strategies, different educations and perhaps even different styles of research to move forward.

There are pragmatic periods where the laws needed to understand a wide range of phenomena are in place and the opportunities of greatly advancing our understanding of diverse physical phenomena dominate. These kinds of periods require a more pragmatic approach, which ignores whatever foundational issues may be present (and indeed, there are always foundational issues lurking in the background), and focuses on developing better tools to work out the implications of the laws as they stand.

Then there are (to follow Kuhn) revolutionary periods in science, when the foundations are in question and the priority is to discover and express new laws.

The kinds of people and the kinds of education needed to succeed are different in these two kinds of periods. Pragmatic times require pragmatic scientists, and philosophy is unlikely to be important. But foundational periods require foundational people, many of whom will, as in past foundational periods, find inspiration from philosophy. Of course, what I just said is an oversimplification. At all times, science needs a diverse mix of research styles. We always need pragmatic people who are very good at the technical side of science. And we always need at least a few foundational thinkers. But the optimal balance is different in different periods.

The early part of the 20th Century, through around 1930, was a foundational period. That was followed by a pragmatic period during which the foundational issues were ignored and many applications of the quantum mechanics were developed.

Since the late 1970s, physics has been again in a foundational period, facing deep questions in elementary particle physics, cosmology, quantum foundations and quantum gravity. The pragmatic methods which got us to that point no longer suffice; during such a period we need more foundational thinkers and we need to pay more attention to them.

TH: Turning to general relativity, you also don’t mince your words and you describe the notion of reversible time, thought to be at the core of general relativity, as “wrong.” What does general relativity look like with irreversible and fundamental time?

LS: We posed exactly this question: can we invent an extension of general relativity in which time evolution is asymmetric under a transformation that reverses a measure of time. We found two ways to do this.

TH: You touched on consciousness as a physical phenomenon and a necessary ingredient in our physics in your book, Time Reborn (as have many other physicists over the last century, of course). You spend less time on consciousness in your new book — stating “Let us tiptoe past the hard question of consciousness to simpler questions” — but I’m curious if you’ve considered including as a first principle the notion that consciousness is a fundamental aspect of nature (or not) in your ruminations on these deep topics?

LS: I am thinking slowly about the problems of qualia and consciousness, in the rough direction set out in the epilogue of Time Reborn. But I haven’t yet come to conclusions worth publishing. An early draft of Einstein’s Unfinished Revolution had an epilogue entirely devoted to these questions, but I decided it was premature to publish; it also would have distracted attention from the central themes of that book.

TH: David Bohm, one of the physicists you discuss with respect to alternative versions of quantum theory, delved deeply into philosophy and spirituality in relation to his work in physics, as you discuss briefly in your new book. Do you find Bohm’s more philosophical notions such as the Implicate Order (the metaphysical ground of being in which the “explicate” manifest world that we know in our normal every day life is enfolded, and thus “implicate”) helpful for physics?

LS: I am afraid I’ve not understood what Bohm was aiming for in his book on the implicate order, or his dialogues with Krishnamurti, but it is also true that I haven’t tried very hard. I think one can admire greatly the practical and psychological knowledge of Buddhism and related traditions, while remaining skeptical of their more metaphysical teachings.

TH: Bohm’s Implicate Order has much in common with physical notions such as the (nonluminiferous) ether, which has been revived in today’s physics by some heavyweights such as Nobel Prize winner Frank Wilczek (The Lightness of Being: Mass, Ether, and the Unification of Forces) as another term for the set of space-filling fields that underlie our reality. Do you take the idea of reviving some notion of the ether as a physical/metaphysical background at all seriously in your work?

LS: The important part of the idea of the ether was that it is a smooth, fundamental, physical substance, which had the property that vibrations and stresses within it reproduced the phenomena described by Maxwell’s field theory of electromagnetism. It was also important that there was a preferred frame of reference associated with being at rest with respect to this substance.

We no longer believe any part of this. The picture we now have is that any such substance is made of a large collection of atoms. Therefore the properties of any substance are emergent and derivative. I don’t think Frank Wilczek disagrees with this, I suspect he is just being metaphorical.

TH: He doesn’t seem to be metaphorical, writing in a 1999 article:“Quite undeservedly, the ether has acquired a bad name. There is a myth, repeated in many popular presentations and textbooks, that Albert Einstein swept it into the dustbin of history. The real story is more complicated and interesting. I argue here that the truth is more nearly the opposite: Einstein first purified, and then enthroned, the ether concept. As the 20th century has progressed, its role in fundamental physics has only expanded. At present, renamed and thinly disguised, it dominates the accepted laws of physics. And yet, there is serious reason to suspect it may not be the last word.” In his 2008 book mentioned above, he reframes the set of accepted physical fields as “the Grid” (which is “the primary world-stuff”) or ether. Sounds like you don’t find this re-framing very compelling?

LS: What is true is that quantum field theory (QFT) treats all propagating particles and fields as excitations of a (usually unique) vacuum state. This is analogized to the ether, but in my opinion it’s a bad analogy. One big difference is that the vacuum of a QFT is invariant under all the symmetries of nature, whereas the ether breaks many of them by defining a preferred state of at rest.

TH: You consider Bohm’s alternative quantum theory in some depth, and say that “it makes complete sense,” but after further discussion you consider it inadequate because it is generally considered to be incompatible with special relativity, among other problems.

LS: This is not the main reason I don’t think pilot wave theory describes nature.

Pilot wave theory is based on two equations. One, which is the same as in ordinary QM-the Schrödinger equation, propagates the wave-function, while the second-the guidance equation, guides the “particles.” The first can be made compatible with special relativity, while the second cannot. But when one adds an assumption about probabilities, the averages of the guided particles follow the waves and so agree with both ordinary QM and special relativity. In this way you can say that pilot wave theory is “weakly compatible” with special relativity, in the sense that, while there is a preferred sense of rest, it can’t be measured.

TH: If one considers time to be fundamental and irreversible, isn’t there a relativistic version of Bohmian mechanics readily available by adopting some version of Lorentzian or neo-Lorentzian relativity (which are background-dependent)?

LS: Maybe — you are describing research to be done.

TH: Last, how optimistic are you that your view, that today’s physics needs some really fundamental re-thinking, will catch on with the majority of today’s physicists in the next decade or so?

LS: I’m not but I wouldn’t expect any such call for a reconsideration of the basic principles would be popular until it has results which make it hard to avoid thinking about.

66 comments:

  1. I noticed a couple of typos, presumably in your source but which you might like to correct:

    About 80% through the text the paragraph starting with "The important part of the idea of the ether was that ..." is the start of Lee's reply and should therefore commence with an "LS: ".

    And in Lee's penultimate response "LS: Maybe — you are describing research do be done" the "do" should clearly be "to".

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    1. Hi Mike,

      Thanks for your attentive reading. I have fixed that.

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  2. I'm reading Smolins book at the moment so, thank you very much for posting this interview (^_-)

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  3. I think it is incorrect to say that Bohr is an antirealist about quantum objects. It is often thought that when he says “There is no quantum world” he denies the reality of the world. I like to think that his view is compatible with realism about the world, just that we cannot say the world is quantum in itself. More precisely: Quantumness is the result of our description of the world, when we have no choice but to use classical objects as measuring instruments of the micro objects.
    We cannot see the world directly, only through instruments that possess certain properties (those that produce an outcome in each run). Bohr was saying, When we try to use these instruments to see the microworld, we end up in weird descriptions that are noncommutative, i.e. a quantum description. It is in this sense we cannot say the microworld is itself quantum.

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  4. Great stuff. Spotted typos "Therefor" and "w while" if interested.

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  5. It isn't that "The Ether" do not Exist, Instead, Its Existence that can not grasp The Ether ...

    Therefore, As existent entities inside existence, What can we do about "The Ether" un-graspable and Unnatural "Nature" ??

    Build a Network of Synced Vacuum Chambers all around the planet ... Just to try to get The Instruments of the Network Synced will be a technological challenge that can change the outdated local physics-approaches ...

    Of course, That Will not inform about The Ether's Existence but at least, provide more room for physical research ...

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    1. Funny thing that the question of ether is still open in physics.

      History: In 1916 Einstein received a letter from H. Lorentz about a (Gedanken) experiment regarding rotation. Lorentz' argument: Rotation can physically not be understood without an ether. Einstein fully agreed! He gave an own example saying: The Foucault pendulum is not understandable without the existence of an ether. But then he added: I can anyway not except an ether because it is in conflict with a principle my theory is based on. - So Einstein has clearly neglected observable facts which contradict his theory.

      I have recently asked several professors of relativity if there is any new state of this discussion. --> There is none.
      So, why does no one see the necessity to clarify this point? I would say that this question (and others of this kind) have priority before doing much philosophy on top of it.

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    2. Lorentz' argument: Rotation can physically not be understood without an ether.

      That's inaccurate. Lorentz merely noted the well-known fact that the first-order Sagnac effect (for a waveguide cable circling the earth) is consistent with a stationary ether, although he agreed that it is also consistent with Einstein’s theory of relativity. Lorentz argued that Einstein’s relativistic interpretation is not the only possible one. Also, since we can detect absolute rotation, Lorentz argued that we cannot simply assume that it’s impossible to detect absolute translation. This (he said) can only be established by observation. Of course, he agreed that observation so far supports the principle of relativity, but he cautioned that “future observations may force us to abandon this hypothesis”. This is why he preferred to maintain the ether interpretation.

      Einstein fully agreed!

      Not at all. Einstein, writing in a conciliatory way to Lorentz (who he revered), went so far as to say that one could refer to the spacetime metrical field as “the ether”, especially in general relativity where the metric becomes a dynamical element of the theory. However, “this new ether theory would not violate the relativity principle any more, for the state of the guv=ether would not be that of a rigid body in an independent state of motion”. He went on to correct Lorentz’s scenario, by mentioning that the metric field in the vicinity of the rotating earth would actually not be perfectly stationary (as Lorentz supposed), but would rotate, albeit very slightly… referring to what is now called the Lense-Thirring effect.

      He gave an own example saying: The Foucault pendulum is not understandable without the existence of an ether.

      He said no such thing. He merely pointed out that, because of the Lense-Thirring effect, Focucault’s pendulum would also precess, by about 0.01”/year, and lamented that it was too small to measure.

      But then he added: I can anyway not except an ether because it is in conflict with a principle my theory is based on.

      No, what he actually said was “I prefer the guv [metrical] interpretation to an incomplete comparison with anything material [i.e., Lorentz’s ether]”. He explained his view of this much more fully in the famous Leiden lecture a few years later.

      So Einstein has clearly neglected observable facts which contradict his theory.

      There is no mention in these letters, either by Lorentz or Einstein, of any observable facts contradicting Einstein’s theory.

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  6. "I don’t think there are many proponents of the Copenhagen view among people working in quantum foundations, or who have otherwise thought about the issues carefully. I don’t think there are many enthusiastic followers of Bohr left alive." There's definitely a *neo*-Copenhagenism out there. Anyone interested in foundations of QM who's up to the math should IMO read Klaas Landsman's "Foundations of Quantum Theory: From Classical Concepts to Operator Algebras", Springer, 2017, at least as a counterpoint to other approaches. There are others. Neo-Copenhagenism is in the process of finding a mathematical grounding.
    There is a substantial body of philosophy of QFT that Smolin effectively doesn't mention by his choice of Philosophers. Simon Saunders and David Wallace have distinctively different approaches to other work on QFT, precisely because of their focus on Many Worlds that Lee Smolin mentions. How can one mention philosophers of physics without mentioning Hans Halvorson or Laura Ruetsche, not that they should be first from a long list of others? Since about 2000, my sense is that every philosophy of physics student wants to work on QFT even if they don't, quite possibly because they have been scared off by their supervisors or by the impenetrability of the physics literature. In addition, many mathematical physicists working on algebraic QFT and similar approaches have a distinctive philosophical bent.

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  7. Even if one stone makes one complete revolution, so what if it has spin-1 ?

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  8. I've never understood why, from the beginning, "observers" and "measurements" were not just considered special cases of the millions of possible natural environmental conditions that can cause the wavefunction to collapse into a singular eigenstate.

    I think it was Penrose that suggested a threshold of mass superposition that might cause that, and proposed a practical (realizable) test for that. If it isn't a sharp threshold, it could be an asymptotic probability that is a function of the mass/energy involved.

    I've never understood the insistence upon any consciousness or observer or "measurement" per se. Both consciousness and qualia have easy explanations due to the way we already know the brain functions subconsciously. We don't know half of all we'd like to know, but we know enough to dismiss any notion these are supernatural mysteries or require any special physics or forces at all; that is all voodoo religion concocted by people that fear the obvious truth.

    Like all things in nature, we can take what occurs naturally but rarely, and engineer methods to make it occur reliably. In this case, the rare phenomenon is a wavefunction collapse that has a significant macro-world (human scale) observable consequence.

    But that is all a measurement device does. And a brain interprets its sensors, which are also just measurement devices. The critical issue would be entangling enough mass to force a wavefunction collapse due to something like gravitational superposition (I do not rule out other candidates).

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    1. Decoherence of quantum states is modeled not according to spooky ideas of consciousness. Instead decoherence is just how a large action S = Nħ system that is classical on a coarse grain level takes the quantum phase from a small system. In this way the quantum phase of a measured wave function is not destroyed, but is "randomized" into a system with large number of quanta. In this way the apparent reduction of a wave function in a measurement is no different from the interaction of a cosmic ray with quartz that leave a track. We observers just happen to find this millions of years later. There is little reason to think our observing this track has some wave function collapsing properties due to consciousness.

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  9. What is your opinion on theories of time, that mainly exist in the humanities, where time is considered to be a subjective matter. Round 1900 Henri Bergson doubted on every issue, that was put under an a priori law, even the phenomenon of time. He said chronological time is such an a priori law and he wasn’t even sure whether it existed. For him passage of time was merely an interval between A and B. With measuring the passage of time one wouldn’t be able to grasp the essence of time. Can one measure the phenomenon of time that lies behind the interval?

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  10. At this stage in my amateur studies (30 years of adult contemplation), I'm starting to suspect that the restrictions of consciousness lead to the confusion over why the math has so many more degrees of freedom than we experience (quantum probabilities rather than linear determinism).
    We don't know what consciousness is, while treating it like a fish treats water ... as a given. What if an arrow of time is merely a special perspective necessary to be conscious in the way that we are conscious. We only have faith in the past because we have a MEMORY of an ordered past, which we then PROJECT into a "future" that we never reach.
    Memory and anticipation ... these might be the prerequisites for our kind of consciousness (which always resides in "now").
    The universal wave function includes ALL ways to remember, and ALL possible predictions. We tend to experience a world of rules because consciousness is only possible for solutions to the wave function that "make sense" ... that reside in near the center of the normal distribution of possibilities (all the air molecules COULD be on one side of the room, or the shattered cup COULD rise from the floor and reassemble on the table... but don't plan on it.)

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    1. Len Arends: We do know what consciousness is and don't treat it like a fish treats water.

      We can interrupt consciousness by interrupting brain function; this can be done with physical shock, by chemical interference, perhaps even by electromagnetic interference. We can do it by fuel deprivation; blocking the flow of blood to the brain or depriving it of oxygen. It can be done by internal interference; an accumulation of waste products in neurons interfering with their operation and leading to sleep; during which the blood vessels expand to flush this waste into the blood stream, but the pressure on the neurons they serve prevents them from proper operation. Thus the necessity of unconsciousness (although the dolphins have evolved a clever system of shutting down 1/2 of their brain for "cleaning" at a time, thus sustaining 24/7 consciousness).

      The fact that we can interfere with consciousness in so many ways, and chemically alter consciousness in so many ways, is all the proof we need to say consciousness is a function of physical brain operation.

      We don't treat consciousness "as a given", we treat it as a product of the mechanical operation of a device called the "brain". Nor is there any need to claim humans are special in this regard, many species exhibit behavior that is only plausibly explained by consciousness.

      Consciousness is a progression of thought; without significant outside stimulus it is a progression of self-stimulus in the brain; thoughts trigger thoughts, endlessly (or until consciousness is interrupted by the above methods, or the death of the brain). With outside stimulus, consciousness is generally focused on processing that. Most of our lives it is a combination of both outside and internal stimulation.

      I find nothing particularly mysterious or magical or supernatural about consciousness (or qualia) itself.

      I will grant that consciousness requires time, without time there can be no change of state, and because consciousness is entirely dependent upon neurons processing electrochemical inputs and producing electrochemical outputs, it is entirely dependent upon billions of changes of state per second. But there is nothing fundamentally different about the passage of time for a living brain versus the passage of time for a kilo of carbon-14 or uranium; in both cases they will experience changes of state over time.

      And of course we reach the "future", I planned to write this sentence before I wrote it, and I have reached that future.

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    2. Dr Castaldo:

      Lee Smolin says:
      "I am thinking slowly about the problems of qualia and consciousness, in the rough direction set out in the epilogue of Time Reborn. But I haven’t yet come to conclusions worth publishing."

      It's not that simple.

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    3. Mike: Yes, it is that simple. I don't accept Dr. Smolin as an expert on this topic.

      Just like trying pretty mathematical tricks to posit new particles that never showed up in the LHC, speculating about qualia and consciousness without reference to the thousands of experimental results on actual brain function and organization, particularly in damaged brains, is pointless fantasizing.

      However, when grounded in such experiments, the clues they give us to how consciousness works, and how the subconscious works and supports that, give us enough information to see the explanation of both does not require anything new in fundamental physics, or time, or space, or anything else.

      I work on the (currently) fastest supercomputer in the world; Summit, but the interactions between its trillions of parts is very closely defined. It is engineered that way. The brain is not engineered, and its interactions between parts is not closely controlled at all, its present form is the result of evolution and millions of "whatever seems to work right now" randomized additions and changes.

      The result is a patchwork of spaghetti code, legacy bugs that didn't matter when they were coded and can't be corrected now that they matter, and broadcast communications that influence parts that have nothing to do with the problem at hand.

      Read up on psychological "priming" experiments for examples of how completely unrelated minutia can influence decisions that can have real life consequences. What is behind those "priming" errors in thinking is broadcast information to all parts of the brain, so neural modules with even a weak supportive link to a word or feeling (like 'cold') become more likely to feel like the "right answer" versus neural modules that would respond to the opposite ('warm'). They are 'primed' by the broadcast to be more responsive.

      That gives us a clue to qualia: Subconsciously our brain state consists of millions of subconscious neural "models" that have been processing information from the outside environment and other internal models, and are in various states of excitation. My qualia of "red" is the state of having everything I know about "red" primed, and everything anti-red not primed. That includes related emotions. It can influence my thoughts, making some neural models more likely to respond than others.

      There is no evidence the brain does anything more than this, or requires any kinds of forces or physics beyond what we already understand.

      Claiming it feels different is not a convincing or logical argument, it is the equivalent of saying ice feels different than water, thus ice must be a different substance than water. Wrong. The solidity of ice (or the liquidity of water, depending on how you want to look at it) are emergent properties of H2O that depend on the temperature and density of H2O molecules.

      Qualia and consciousness are explainable emergent phenomena of a neural system complex enough to fall into self-triggering loops. Disrupt the signaling and disrupt consciousness (but not necessarily the subconscious activity). Thoughts are broadcast signals that prime neural modules and thus trigger other parts of the brain; thus more thoughts, more qualia, more feelings, in a feedback loop until something external takes priority, or we run low on energy and have to sleep (to clean the brain of waste products it produces in the operation of neurons).

      These conclusions are not hard to reach. I can't say what Dr. Smolin is having trouble explaining, I will wait and see if what he publishes is consistent with what we already know of brain operation.

      I personally don't regard the broad outlines of brain operation as particularly difficult to comprehend, or glossing over any critical observed phenomena. It really is that simple.

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    4. Dr Castaldo

      You say:
      "Qualia and consciousness are explainable emergent phenomena of a neural system complex enough to fall into self-triggering loops."

      Okay, so please do explain. Just how does consciousness emerge? Just how complex? Are there equations? What is the ACTUAL physical correlate of your qualia of red? As opposed to green? As opposed to a color-blind person? As opposed to your qualia of a salty taste? As opposed to not noticing a color at all?

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    5. Mike: Sure, let me give you a few semester courses in experimental psychology, neurobiology and artificial intelligence in comment box.

      Read my comments related to neurons and consciousness and pattern processing in Dr. Hossenfelder's other thread; http://backreaction.blogspot.com/2019/05/how-to-live-without-free-will.html?showComment=1557524019377

      Here's the "Father Guido Sarducci's 5 Minute University" version.

      Neurons, individually, are pattern matchers; they respond when certain patterns of input occur within a window of time determined by electrochemical decay of signals. They are teachable by exposure to patterns.

      Neurons compose into networks to model patterns and signal recognition to other neurons. This is efficient because we tend toward decomposable and hierarchical patterns. My brain contains a model of a "wheel" that can itself be a component of many larger models: Carts, cars, baby carriages, trains, pulleys, lawnmowers, unicycles, bicycles, tricycles, ad infinitum. What do they have in common? Not much universally, a circle that turns and somehow bears a weight. Wheels are composed of may-be-present sub-models: spokes, tires and rims, hubs, brakes.

      If you want another example, consider the myriad manifestations of "door". You can even have a door IN a door; e.g. to look out of, or to let the dog in and out.

      This approach is efficient because the combinatorial explosion of features for a "door" reduces the info load to be carried from every door you have ever experienced to a generalized model that can be 'decorated' with specific features to represent a specific door; perhaps with a specific "handle", and "lock", and means of moving out of the way (up on rails like a garage door, sliding sideways on wheels like a hidden door, opening from an edge on hinges, dilating parts like on a space station, spinning on a central axle, etc).

      This also has the beneficial effect of letting us recognize as doors combinations we have never seen; or even mechanisms we have never seen. In a fantasy show Joe uses a knocker mounted on a solid brick wall, someone yells "come in!" and we see the wall vanish, and reappear after Joe walks through the opening. That is still a 'door'.

      Our brain is composed of millions of these interconnected models. They work backward and forward. Their likelihood of signaling is changed, temporarily, when some of their inputs match the pattern, but not all of them. When I say (to most Americans) “Red, White and”, their neural model of BLUE has been primed so strongly by these three words they will almost undoubtedly finish this sentence with the word “blue” (which is one input to their neural model of BLUE) as the most probable next word. It isn't the only possible word; I can add different priming and defeat that result: “There are three principle varieties of wine, Red, White, and” (and nobody says “blue”).

      The physical correlates of the qualia “Red” are all the many thousands of neural models being primed (electrochemically readied for short-term firing) by the mention of the word Red. This will include visual models where one has seen red, audio models if one has heard “red”, but even in the blind and deaf it would include all mental models in which “red” is considered a component.

      But not every model is equally primed; some models have nothing to do with red, and do not become more likely representations of reality if “red” is seen, heard or sensed. They may become less likely. The physical qualia of “red” is this collection of priming which has a physical electrochemical component within trillions of neurons, and often firing (due to previous priming with other senses/words), which will include emotional content (also a product of neurons). We feel something about “red”, technically unique to each of us, but by similar experiences in the world, we have much in common too.

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    6. Dr Castaldo
      It seems you have never heard about the problem of zombies, have you?
      And have you dared to think about that a bit longer, without your professional prejudices?
      Best regards,
      Wojciech

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    7. @Wojciech: I am aware of the non-problem of zombies, I do not regard it as a valid argument. If you had bothered to read what I wrote, here and on the "free will" thread; you would probably have gathered this.

      The proposition is a being that acts like us, but lacks conscious experience or sentience, but behaves as if it has both. I reject that out of hand, it is as false a premise as proposing an ax that has no handle or blade, yet chops wood just like a real ax. It is magical thinking and as pointless an argument as debating how many angels can dance on the head of a pin.

      It is not how the brain works and contrary to observations and facts.

      Asserting I have "professional prejudices" because I disagree with you is actually the fallacy of arguing from authority; or that I am wrong "because you said so."

      Instead of insulting my integrity with "prejudices" or implying I am uninformed or stupid, you can just say you disagree with me.

      Or you might pretend you are a scientist and provide a logical refutation of my argument, or a logical challenge.

      But I understand if you cannot; insults are the go-to strategy for people that have run out of rational argument, so their emotions step in to take up the battle.

      I have presented plenty of material here for laymen that are actually worth challenging and arguing about, we don't have to debate the existence of fairies.

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    8. My head is with Costaldo, but my heart is elsewhere: I'd really like to be believe that consciousness is a special ontological category, but the scientific evidence is against it.

      But if consciousness were special in some way, might that make it possible to accept a naive Copenhagen (or von Neumann) interpretation of QT?

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    9. Andrew: If consciousness is NOT special in any way, then an "observer" is just a component of the environment and it follows that wavefunction collapse is, at least in some circumstances, environmentally caused.

      But every particle is in some environment, so environmentally induced collapse must involve some kind of threshold; and that becomes a research direction.

      Perhaps there is a limit on how much mass can be in superposition, or entangled. Perhaps, as Dr. Hossenfelder has mentioned before, there is an issue with conflicting gravitational fields of a mass in super-position that is in more than one place at once.

      Trying the two-slit experiment with larger and larger masses is one route to exploring such a limit.

      To answer your broader assertion: When I claim consciousness is just the operation of the brain obeying the known laws of physics; I am not asserting that minds, emotions and pains (of people and animals) are dismissible; in fact I'd say in the end I prioritize those over just about anything else.

      The reverence I have for life, love and happiness does not demand they have a supernatural or magical component beyond comprehension. In fact dismissing any magical component broadens our research horizons so we can find and address the physical issues standing in the way of consciousness and quality of life.

      IMO, consciousness does not have to be magical to be viewed as a special condition deserving its own set of rules for how we behave toward things with it, and without it. I feel the same thing about pain and emotions in our fellow animals.

      Consciousness is already special. For me that specialness does not have to be justified by any new physics, nor does it have to be an unfathomable mystery.

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  11. In reading this I am a bit relieved to see that Smolin is not trying to appeal to the pilot wave Bohm QM interpretation. I usually think that when people try to devise a classical underpinning to QM that they have fallen off the horse. Some luminaries, 't Hooft for example, have gone this route. Smolin did not seem to make that sort of appeal.

    When it come to the nature of time there have been those who argue time is not real, such as Barbour and those who do say it is real, Carroll and Smolin thinks time is real, but irreversible. General relativity is a bit “schizoid” on this. On the one hand the differential equations of general relativity are second order, which is a clear signature of a theory invariant under a Z_2 time direction change. On the other hand we have black holes with the area theorem that suggests an irreversible nature to time. Of course a black hole with the delay or tortoise time t' = t - 2m ln|1 - 2m/r|, r = ct, suggests that all the information that enters a black hole is still there. The only thing we have available to us are the most UV of quantum spectra, which are Planck or string scale quantum gravity modes. These in our more ordinary world are not accessible to us. A duality between UV and IR physics would then be

    (q-gravity UV physics) = (IR physics of gauge fields and fermionic matter)

    This is a way of writing Einstein's field equation!

    If we are to appeal to philosophy and philosophers I would tend to invoke Immanuel Kant. He told us that what we observe is a domain of phenomena, but there is an underlying noumena that is fundamental. In a funny way the breaking of symmetry in the standard model is of this nature, for the false vacuum of symmetry and the symmetry of the Lagrangian are not directly accessible to us, but rather the physical vacuum physics restricted away from the symmetry of the Lagrangian. With quantum gravitation something similar is maybe afoot. The global theory of a grand symmetry may simply be unstable, and what we can only directly observe are local symmetries of a more restricted nature. In this sense then time is a local process. For instance, in a multiverse setting with an inflationary manifold it may not make sense that time here can to extended by parallel transport everywhere. So while in Kant's sense there may be a global meaning to time that is reversible, in a local setting what we measure as time is not reversible --- at least FAPP.

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    1. "In reading this I am a bit relieved to see that Smolin is not trying to appeal to the pilot wave Bohm QM interpretation. I usually think that when people try to devise a classical underpinning to QM that they have fallen off the horse."

      And what horse would that be, mathematicism? Seriously, the primary objection to the Bohmian model seems to come from theorists who object to the fact that it retains the the classical concepts of waves and particles, making the quantum realm fully contiguous with the rest of physical reality.

      The problem with that apparently, is that it puts a crimp in the the cottage industry of scientifically baseless metaphysical speculations such as MWI. Realism is such a drag on the theoretical imagination.

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    2. Actually in his book Smolin spends a lot of time presenting pilot wave theory as a credible alternative.

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    3. Bohm wrote a paper in 1952 on how a form of quantum mechanics might be formulated as purely local. He wrote the wave function as ψ = Re^{-iS/ħ}, which is called a polar form because it is equivalent to how one represents a vector in the complex plane. This wave acted on by the Schrödinger equation gives a real valued differential equation that is a modified Hamilton-Jacobi equation

      ∂S/∂t = H - (ħ^2/2m)∇^2R/R.

      The last term is called the quantum potential, which is thought of as the quantum modification of this equation of classical mechanics. This is the dynamics for a classical-like particle that Bohm designated the beable, for “Be Able.” The imaginary part is a continuity equation for hydrodynamic flow that from memory is something like

      ∂R/∂t - (1/2m)[R∇^2S + 2∇R·∇S ] = 0.

      This is a conservation of the pilot wave, and one can derive so called guidance equation for the pilot wave from quantum currents undergraduate students compute in elementary quantum courses. There is nothing wrong with this. It is I think better to consider the unitary operators in polar form with the state being static, say taking a Heisenberg picture of this. Still there is nothing completely wrong with this, but it has “issues.”

      What Bohm tried to do is to show that this means QM is purely local. John Bell was in fact highly motivated by this and tried to prove that this is the case. He failed, and I give a brief description of Bell's theorem at the end here. This effectively torpedoed the idea that Bohm's representation of QM demonstrates a more fundamental locality. It has other problems, where if you try to do the Klein-Gordon equation this way you find the classical-like beable actually moves faster than light. Yet we can look at matters of quantum chaos, and I think Bohm's QM has great utility there, and I think aspects of quantum chaos lie with quantum gravitation. However, it does not really appear to tell us in any way that quantum mechanics is “wired up” on some substratum by classical principles.

      I had read that Smolin appealed to Bohmian QM to try to satisfy Einstein's objections. This is is a problem I can see with his program and why if I read his book it will be borrowed. I tend to think that people who appeal to Bohmian QM as a way to restore a classical objectivity to physics have in some ways lost their way.

      Since 1809 we've know from experiment that Malus's law always works, that is to say the amount of light polarized at 0 degrees that will make it through a polarizing filter set at θ degrees is cos^2θ. For example if θ = 30 degrees then the value is .75; if light is made of photons that translates to the probability any individual photon will make it through the filter is 75%. The Bell inequality with polarizers is if one polarizer is set 30 degrees relative to the other, then think of the photons as polarized in the way a nail has a direction. 30 degrees is a third of a right angle, and so if we think of the photons as being like nails aligned in a certain direction, then at least 1/3rd of these nails would be deflected away. This is why an upper bound of 2/3rds of the photons in a classical setting will make it through, or less will by attenuating effects etc. But the quantum result gives 3/4. This is a violation of the Bell inequality, and with polarizers it is found in a "quantization on the large." Of course sensitive experiments work with one photon at a time, but the same result happens. This is done to insure there are not some other statistical effect at work between photons.

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    4. My reading of Smolin's book does not jibe with "I had read that Smolin appealed to Bohmian QM to try to satisfy Einstein's objections." I did not see an appeal in relation to Bohm. Following is a brief excerpt from The Singular Universe where Bohm's work is referred to in a limited way on page 488. Perhaps this will encourage you to reconsider looking beyond what you read.

      "[t]he goal must be to discover the cosmological theory that quantum mechanics approximates, but it channels that search in a certain direction. It is notable that the hypothesis of a preferred global time coming from our program is consistent with the need for a global time to express a non-local hidden-variables theory. This has been seen explicitly in relativistic versions of Bohmian mechanics [88] and spontaneous collapse models [90] which reproduce the Poincare invariance of the predictions of quantum field theory while breaking that invariance for predictions that diverge from those of standard quantum theory."

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    5. What Bohm tried to do is to show that this means QM is purely local. John Bell was in fact highly motivated by this and tried to prove that this is the case. He failed, and I give a brief description of Bell's theorem at the end here. This effectively torpedoed the idea that Bohm's representation of QM demonstrates a more fundamental locality."

      I don't know where you got this idea but you are seriously mistaken:

      ...all such "hidden-variable" completions of quantum mechanics must either be nonlocal (as the Bohm interpretation is)... -

      https://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory#Quantum_entanglement,_Einstein%E2%80%93Podolsky%E2%80%93Rosen_paradox,_Bell's_theorem,_and_nonlocality

      and

      Bohmian mechanics is manifestly nonlocal....Thus Bohmian mechanics makes explicit the most dramatic feature of quantum theory: quantum nonlocality -

      https://plato.stanford.edu/entries/qm-bohm/#Nonl

      With regard to Bell's inequality, it showed that local hidden variables would predict results differing from those of QM. Subsequent experiments bore out the QM predictions, meaning that local hidden variable theories were ruled out. Bohmian mechanics has non-local hidden variables and violates Bell's inequality in exactly the same way that standard QM does.

      Other than expressing aesthetic dissatisfaction with pilot-wave theory, while exhibiting a basic misunderstanding of it, you don't seem to have any substantive objection. This suggests that you perhaps simply prefer metaphysical interpretations of QM, like MWI. You seem to dislike Bohmian mechanics because it is realistic.

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    6. John Bell derived his inequalities in 1964 in a paper titled On the Einstein Rosen Podolsky Paradox, where he formulated a hidden variable in a way that satisfied realism and locality. His original intention was to show that QM satisfied these two conditions. However, it was not that difficult to show QM failed to do so. Bell was a panegyric for Bohm's QM and wanted to to show there was locality in QM as was thought to be the case for a beable in the pilot wave.

      I do not "hate" Bohm's QM so much as I see it as a quantum interpretation with limited scope. It is considered nonlocal because to model measurements the quantum potential is modified "by hand" in a way that is a sort of collapse.

      I can't comment too much more on Smolin's book outside of reviews I have read. It does appear Smolin is trying to answer Einstein's objections to QM in a way that restores classical objectivity.

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    7. There is nothing in the paper you cite, On the Einstein Rosen Podolsky Paradox, that supports your claim that Bell's "...original intention was to show that QM satisfied these two conditions" (realism and locality). Here are the opening sentences of that paper:

      THE paradox of Einstein, Podolsky and Rosen was advanced as an argument that quantum mechanics could not be a complete theory but should be supplemented by additional variables. These additional variables were to restore to the theory causality and locality. In this note that idea will be formulated mathematically and shown to be incompatible with the statistical predictions of quantum mechanics.

      I do not "hate" Bohm's QM so much as I see it as a quantum interpretation with limited scope.

      This begs the question, compared to what do you consider it limited in scope, a metaphysical interpretation like many-worlds?

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  12. I think there still is the great danger of beauty leading physics astray, once again. Philosphy may be an inspiration for a new model, maybe it can also be a guide to develop it further, but it cannot fully replace math and observation.

    And philosophy can also be worn as a mask by intuition to sneak into science and poison it from within, because scientists can be "all too human".

    So when there are different competing models based on the same original mathematical physics, and one of them gets the support from philosophy, it gets easy to reject competing models with sloppy reasoning. That can then become self-reinforcing: if one disallows defending a model that lost in the area of philosophy, then it's easy to "prove" that the competitors of the "winner" are mathematically wrong as well, so it is deemed to be the mathematical winner without having actually proven it. Which can become fatal if the winning model causes internal contradictions later on, when everyone has forgotten that the other models were cheated out of having their fair chance - and so they get cheated once again now that they are needed, since everyone believes they were disproven.

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  13. I agree that time is fundamental. In fact, I think it is THE fundamental. Considering Special Relativity, we see that approaching light speed, time draws to a halt and dimensions (ahead) tend to zero. My contention is that motion cannot directly affect dimensions (or space), but it apparently does directly affect the rate of passage of time (and in a circular way - Lorentz).The only way this can happen is for the passage of time to be somehow wavelike ( faster then slower then faster then,....etc). This would also explain the emission of photons in waves of varying numbers (light intensity). The wave nature of light would be a demonstration of the wave nature of time. I could go on but I would have to rewrite my book "The Binary Universe".

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    1. I suspect conciousness is the fundamental. All systems of physical relationships that allow our type of consciousness are realized "somewhere" in a highly multidimensional mathspace.
      The "arrow of time" may just be one of the restrictions necessary for our type of consciousness ... "memory" and "anticipation" interacting in an elusive "now."

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    2. Time is the geometry of consciousness. Particles are how we model events at the surface of intersection of consciousness and... some sort of possibility space... but today's physics wants to label these ideas "the measurement problem" and sweep them under a small rug.

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  14. During the first decades of the 20th century, some lively philosophical debates appeared about the concept of time (far from the scientific views of Einstein). To a certain extent, Henri Bergson and William James developed similar ideas independently. And Whitehead has been largely inspired by James’s ideas, particularly with what James called the ‘epochal theory of time’, which is based on Zeno's paradox, which traces back to the 5th century BC.
    It is related to the question of (infinite) divisibility of space and time. Curiously, while William James did not know nothing about QM, he ended up with the notion that becoming - or the flow of experience (not time per se) - must proceed with discrete units, ‘drops of experience’, or ‘discrete pulses of perception’. On a very different ground, It is difficult to avoid thinking about Max Planck…
    But this is only one aspect of a more extended thought, where several important concepts are tied together: time, process, becoming, continuity versus what they called then ‘atomicity’…
    Some meaningful consequences of this debate can be found in Whitehead’s more abstract ideas, for example through the distinction between genetic and coordinate analysis in 'Process and Reality'.
    A good article is available online about James’s ideas: ‘William James and the Epochal Theory of Time’, by Richard W. Field, 1983.

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    1. Great info, thanks. I've long been inspired by Whitehead in my work. https://medium.com/@aramis720/resonance-and-process-philosophy-e5b801045ca6

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  15. If a professor of English literature were to announce that for his discipline to progress a new language must be created with a new grammar and a new vocabulary and, furthermore, that new literary forms akin to our current epics, sonnets, novels, etc., must be created if there is to be further progress then we would likely view the study of English literature as having brought us to a dead end. Likewise, Dr. Smolin's desire for new "first principles" reminds one of Woody Allen's statement, "The only thing I regret in life is that I was not born somebody else." All of this, together, is a tacit admission of defeat in the application of physics to understanding the universe.

    One can understand the need to tinker here and there with any discipline: to amend, adjust, revise and revivify hypothesis in the light of new information. But, such remodeling, as occurs in all the sciences all the time, is different from scrapping everything in order to start over at Ground Zero. It is, furthermore, a ludicrous consul of perfection to suggest that we need can blithely summon a new physics from the "vasty deep" when what we are stuck with right now took better than three centuries to evolve.

    If three centuries of rigid materialism (or, if one prefers, "Naturalism") pushes us head-first into a brick wall with no further way in sight then perhaps it was the wrong path to take from the start. Thus, I am not surprised that Dr. Smolin sees possible value in a discipline long scorned by many physicists -- philosophy.

    I am advanced in years and will not live to learn whether Dr. Smolin's gets his new "first principles." But,physics seems at this moment to he like the ending of "Waiting For Godot" -- "We can't go on. We'll go on."

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    1. Well said A. Andros! Initially I didn’t interpret Smolin quite that literally — as in physics now needs a full reboot. I figured that his call for new first principles was just a bit of rhetoric. But given his advocacy of traditional philosophy I’m starting to think that he might have been speaking literally here as well.

      As I see it the problem with traditional philosophy is that it has not developed a respected community of professionals with their own generally accepted understandings to provide. Physics is quite the opposite. But how could philosophy help physics today when dedicated philosophers provide no agreed upon answers regarding the questions that they explore? Is he advocating some kind of Zen thing, or “journey” rather than “destination”?

      Actually I do consider the subject matter of philosophy important however. I believe that science suffers tremendously today without generally accepted principles of metaphysics, epistemology, and value from which to work (though our mental and behavioral sciences should suffer the most).

      My single principle of metaphysics states that to the extent that causality fails, nothing exists to discover. This would effectively put physicists who endorse Heisenberg’s uncertainty principle as and ontological rather than epistemic void in causality, into a supernaturalist camp.

      Also pertaining to physics is my second principle of epistemology. It proposes one exclusive process by which anything conscious, consciously figures anything out: It takes what it thinks it knows (or evidence), and uses this to assess what it’s not so sure about (or a model). If generally accepted then all sorts of suspect practices should be penalized, such as eschewing empirical evidence for mathematical beauty.

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  16. I basically agree with the L. Smollin's views, but I would like to add some further input:

    - Having paradoxes and "brick walls" in the current theories of physics is unavoidable and good, since they indicate what is the domain of aplicability of those theories. For example, a 19-th century physcist would be puzzled with the Rudeford atom model, since according to the classical EM theory the atom would be unstable. So even without any experiments he would conclude that at atomic distances a different theory is needed. Similarly, if we assume that the standard QM applies to the whole universe, there is a problem of the observers and the measurement of the wavefunction of the universe, as well as the problem of how to define probabilities for a universe. The current QG theories do not address this problem, and they are essentially concerned with a problem of how to incorporate GR into a QFT framework.

    - As far as the role of philosophy in formulating new theories of physics, so far, it was not essential, but as we expand the dominion of aplicability, it will be helpful to understand the concepts of metaphysics, as well as the basics of formal logic.

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  17. “Reality is nothing but a mathematical structure, literally”.

    That is your first principle.

    From the simplest structure that relates set of numbers to others the whole of the physics of reality falls out,QM,QFT,GR, space, time ,energy all one one coherent system.

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    1. Your first principle is nothing but the ubiquitous mathematicism (https://en.wikipedia.org/wiki/Mathematicism) that is the primary cause of the dead-end state of modern theoretical physics. Mathematicism is an ill-considered philosophical belief that has no basis in science, mathematics, or logic.

      Physics is the study of physical things and events; it is not (or not supposed to be) the study of the abstract mathematical musings of reality challenged individuals who seem incapable of distinguishing between their mathematical fantasies and empirical reality.

      But for the sake of argument let's grant you your first principle. And on the basis of that first principle, I request that you provide, for each of matter, energy, space and time, a definition that is coherent, concise, and consistent empirical observations.

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    3. Thanks Bud for your reply. As you know giving references on Bee's blog is like shooting oneself in the head. However, if you google the main sentence with FQXI plenty of information will come up (or simple click you know where:)) on the subject that has been thoroughly discussed in FQXI contest with two camps.
      https://fqxi.org/community/forum/category/31424

      I am not the first to come up with the idea (the idea is been around in some form since Plato), but I have developed it independently with substantial "proof". Thanks again.

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  18. Time, Time is on my side.....yes it is...

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  19. I wished Smolin had mentioned some of the other benefits of philosophy to scientists: A greater willingness to question one's deeply held assumptions, a greater drive to examine (non-mathematical) arguments for fallacious reasoning, and most importantly, a greater awareness of one's philosophical biases before they turn into cognitive biases.

    Everyone has philosophical biases, but not everyone is aware of what they are, and this lack of awareness can facilitate the descent into cognitive bias.

    This all probably sounds nice in the abstract, but I don't think people know what do with this until they see a concrete example. An example I consider highly salient is as follows:

    I consider the belief that there has to be a deeper theory unifying GR with the SM a belief which reflects a particular philosophical bias, one historically well-grounded in past successful unifications and supported by reasonable theoretical arguments, but still reflecting a philosophical bias.

    What happens when one does not recognize it for what it is, i.e. a belief reflecting a particular philosophical bias?

    One is liable to mistake it for a "fact" about the world, in the sense that, say, gravity itself is a fact about the world.

    What it would take to consider quantum gravity a "fact" about the world is an observation or experiment in which gravity is observed to be quantized. Absent that, an experiment or observation in which a system which obeys quantum laws is shown to produce a gravitational field would also do.

    At this time, we have neither.

    (Continued in next post)

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  20. (Continued from previous post)

    Experiments or observations in which quantum systems are affected by gravity (e.g. gravitational bending of light) will not do, because they can be explained by a rival hypothesis: QFT in curved spacetime. So long as observations which suggest there must be a theory of quantum gravity can be also explained by a rival hypothesis, we cannot be conclusively certain that quantum gravity is in fact the correct explanation and therefore we cannot use them to promote it from a belief to a "fact" about the world.

    (It might not be clear how QFT in curved spacetime works in strong gravitational regimes, but since we have no relevant observations in such regimes, this can only be considered at best as an additional theoretical argument in support of the belief.)

    Yet, as best as I can tell, lack of awareness of this philosophical bias has caused almost an entire community of physicists for multiple generations now to consider the existence of an as yet undiscovered theory of quantum gravity a fact.

    Some even mistake the gravitational bending of light as a conclusive argument for quantum gravity, a mistake I attribute to cognitive bias caused by lack of awareness of one's philosophical bias.

    This conflation of belief with fact has real consequences because it closes off various other possibilities for advancing our fundamental understanding of nature. If the physics community were more skeptical of quantum gravity, then that would likely spur a stronger drive to come up with ideas to experimentally test it independent of the particular model or experimental approach.

    For example, I think it would be very challenging and expensive, but doable, to measure the gravitational field of an ultra high energy beam or pulses of light.

    The beauty of such an experiment would be that even if the result comes out exactly as expected, it would still be a resounding success, something that cannot be said of a particle accelerator slightly larger than the LHC.

    Just like the discovery of the Higgs boson, which added to our knowledge even though it was completely expected, the detection of a gravitational field produced by light exactly as expected would add to our knowledge by promoting a fundamental belief about the world into a fact, namely quantum gravity.

    But if one already considers quantum gravity a fact about nature, then such experiments would seem nearly pointless or at least not worth the effort. Consequently, there is, as far as I can tell, no strong push for this kind of experiment.

    Getting back to my main point, philosophy can help us not just by the ways Smolin described but also by helping us question our most deeply held and therefore most "obvious" assumptions, by helping us think clearly and especially be helping us recognize how our philosophical biases frame our understanding of the world.

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    1. Sabine has posted on detecting quantum superpositions of spacetime variables http://backreaction.blogspot.com/2019/04/comments-on-quantum-gravity-in-lab-in.html This is focused on the Aspelmeyer group experiments. I read a paper a couple of months ago which proposed a way of looking at superpositions of metric configurations. I would have to spend some time looking that up again. Roger Penrose in his Road to Reality proposes an experiment that connects wave function collapse with quantum gravitation. I am less certain about that, for his so called R-process I doubt is fundamental and more a phenomenology, but he may be right at the phenom-level.

      In a nutshell these ideas are all forms of the Cavendish experiment. This is the torsional bar with two masses suspected between two other masses so a light reflected off a mirror on the bar is measured to find the strength of the gravity force. This was used to find Newton's G = 6.67×10^{-11}Nm^2/kg^2. The Aspelmeyer group uses a mass on a spring, but the idea is essentially the same. We might think of the Cavendish experiment where there is some quantum superposition of the metric configuration with these masses. A laser beam reflecting off this mirror is then in a superposition of two different, or should I say very slightly different, directions. This is then tacitly a sort of beam splitter.

      In an exercise I did many years ago I looked at a three body problem with one large mass, a medium sized mass and a very small test mass. The two larger masses have Newtonian dynamics and gravity, with the test mass is close to the largest mass and exhibits general relativistic effects. Think of the sun, Jupiter and Mercury, and ignoring the other planets. The upshot, which seemed to be working out, is that GR breaking of the invariance of the Lense vector or the periapsis shift of the orbit in the tiny mass amplified the Lyapunov exponent in the chaotic dynamics one would get with just Newtonian mechanics. I never did anything with this. However, for the purposes of detecting quantum gravitation we might consider the double pendulum. This has for swing angles sufficiently large chaotic dynamics. So for this in a Cavendish-like experiment might then illustrate some amplification of chaos that bears signatures of quantum gravity.

      These sorts of experiments are important for motivating quantum gravity physics. They are just the start. These experiments are tough to accomplish. As I think spacetime is a sort of coherent state configuration of entangled states, these are then a classical-like subspace of the Hilbert space, which may be one reason spacetime is so obstinate in revealing quantum properties. However, remember Einstein's coefficients, where the emission of any set of quantum states will have both A and B coefficients. This means that even if there are primarily coherent states there will still be some mixed states as well. We will then be trying to measure these as small fluctuations.

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  21. My thanks to all three of you for creating and posting this interview, which was one of the most intriguing ones I've read in a long time. Lee Smolin, please keep at it. While I am just a poor bewildered information specialist, my understanding of search spaces tells me you are on the trail of something quite important.

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  22. Also, I'll add one remark about the concept of a "unique" foliation: From an information perspective, I have been persuaded over the past couple of decades that our universe is both hugely more (a) efficient and (b) devious than the models we use to describe it.

    What I am suggesting is that many of the seemingly "universal" features of physics are what computer science would call virtual. That is, while they do adhere to a very strict set of internal, mutual, and temporal self-consistency rules, they do not actually exist until "funded" by the insertion of energy. Planck foam would be a good example of an, um, seriously underfunded virtual physics concept.

    Applied consistently, virtualization allows finite resources (finite mass-energy) to pose convincingly as all sorts of seemingly universal effects, when in fact those effects are nothing more than highly localized virtual charades that exist only because enough energy came together for a while to instantiate them... and even then, only to the level of detail possible at those energies.

    Virtualization has significant implications for issues such as vacuum density, the block universe, and the detailed nature of foliations.

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  23. Moved this comment. I improperly nested it as a reply to a comment.

    Smolin: The point is that the solutions to background-independent theories can have preferred frames, so long as they are generated by solving the dynamics. This is, for example, the case with cosmological solutions to general relativity.

    This is at best a dodgy claim. It may be valid mathematically while being invalid in the context of physical reality. If the cosmos is not, in fact, a unitary entity with a preferred frame, the ability to fashion such a mathematical model means that the so-derived model will not accurately describe the underlying physical reality.

    Given the reality-challenged nature of the LCDM description of the cosmos, with its stable of undetectable entities and events, that indeed appears to be the case. Smolin wants new physics from the same old failed methodology of prioritizing mathematical abstractions over empirical reality.

    And so Smolin reifies the relational concept of time as a solution to the correctly perceived crisis in physics? That's like trying to cure a headache by banging your head on the wall.

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    1. Laser coherent states are a subspace in Hilbert space with a symplectic and classical-like structure. Maybe spacetime is from a quantum mechanical perspective built up from coherent states, or a large N entanglement of states. It might then be the preference for background dependency stems from this.

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    2. Physical reality does not stem from mathematical formalisms. Mathematical formalisms are supposed to provide reasonably accurate, qualitative descriptions of physical reality. The current standard models do not provide reasonably accurate descriptions of physical reality.

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    3. The standard model does pretty well. The theory with color and flavor changing interactions, known as weak and strong nuclear, the intertwining of the weak with electromagnetism in hypercharge and the weak angle, the Higgs particle and so forth are pretty much on the money.

      The entry here on the muon g - 2 is one place where there may be deviations from the standard model. Of course Bee is right to point out that nature is not that obligated to follow our sense of aesthetics, but the standard model has a very kludge aspect to it. It is not entirely unreasonable to think there is something beyond the standard model, certainly as one reaches quantum gravitation energy.

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    4. When I say the standard models do not provide reasonably accurate descriptions of physical reality I mean, very specifically, that both models have a significant number of entities and events that are not part of empirical reality. A partial list would include quarks, gluons, the w, Z and Higgs bosons, dark matter, dark energy, substantival space, time and/or spacetime, the inflaton field, and the big bang event itself.

      None of these things are observables; they are not part of empirical reality. They are all either axiomatic or model dependent inferences. The models simply do not resemble the physical reality we observe (detect).

      If you are going to claim that I don't understand the way modern science works, my response is that I understand how it works quite well. And it is specifically the way it works that I am criticizing.

      Even more specifically, I would say that the general methodological approach of modern theoretical science which prioritizes mathematical models over empirical reality is deeply flawed, fundamentally unscientific, and the root cause of the "crisis in physics".

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    5. I guess I do not understand entirely what you mean. Quarks, gluons, W and Z bosons etc are observable. At least the predicted results of their existence are detected. The presence of dark matter is observed by its gravitational effects. Dark energy is inferred from the accelerated expansion of the universe, and the big bang is inferred from the CMB.

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    6. @Lawrence Crowell; bud rap: Even gravity is only observed by its effects, we have not found any particles for it. It is a mathematical model.

      Does this make our theories of gravity (all mathematical models) fundamentally unscientific?

      I don't think so.

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    7. Quarks, gluons, W and Z bosons etc are observable. At least the predicted results of their existence are detected.

      No to the first sentence, Yes to the second. Those sentences are mutually exclusive. Observation and inference are not the same thing and they do not carry the same scientific weight. Quarks, gluons, the W, Z and Higgs bosons, are inferred, not observed entities.

      Dark matter is a failed hypothesis that was put forth to compensate for the inability of theorists to derive formalisms appropriate to galactic and cosmological scale systems. Keplerian and Newtonian formalisms that were derived in the context of the solar system do not, self-evidently, work.

      It is hard to understand why anyone would think that they should work given the completely dissimilar physical structures of the larger-scale systems. Another gift of mathematicism, I suppose. Dark matter is a failed hypothesis because there is no empirical evidence for its existence. It doesn't matter that it makes an inappropriate model(s) work.

      Dark energy is inferred from the assumption that a discrepancy between SnIa supernovae luminosity and redshift distances is caused by the acceleration of the "universal" expansion that is, itself, inferred from the 90 year old assumption that the redshift-distance relationship observed by Hubble is caused by some form of recessional velocity.

      None of those assumptions and inferences rest on, or are supported by, any empirical evidence. In fact, assumptions and inferences would not be necessary, if there were empirical evidence for the claims being made. As an inferential chain grows longer without empirical evidence it also grows scientifically weaker.

      The CMB was a prediction of the big bang model, although various predictions by well-known cosmologists, ranged over an order of magnitude right up until its 1965 discovery. See:

      https://en.wikipedia.org/wiki/Cosmic_microwave_background#Timeline_of_prediction,_discovery_and_interpretation

      Note that predictions based only on thermodynamic considerations were generally more accurate. "Cosmic Microwave Radiation" is the more accurate empirical description - the "background" designation is just another model-dependent inference.

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    8. Dr Castaldo,

      You are correct, our mathematical models of gravity tell us nothing about the mechanism that produces the gravitational effect. The models' scientific value is as as calculational tools; they have no explanatory value. If modern theoretical research were serious about the "fundamentals" this would be a prime topic of research rather wasting time and money on scientifically inert string theory.

      By comparison, I can't think of any useful calculations provided by LCDM, and while QM provides such tools it offers no coherent physical explanation for the outcomes it calculates. It is more unsatisfactory than the gravitational models because it invites endless metaphysical speculations that have no scientific value whatsoever.

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  24. Whenever I read "Einstein" in a book title, I reach for my water pistol...

    Seriously, I do not quite know what to make of Smoling's musings on the foundation of physics. It's all a fair of "perhaps this and perhaps that, and what if this and what if that". Take this statement, for instance (it is by TH, but summarizes well Smolin's approach): "the next step you take after stating your first principles, is an acknowledgment that time is fundamental, real and irreversible".
    Now Sabine, be honest. If someone had posted a comment like this on your blog, he/she would have got one of your snappy responses: "well then, go and build a mathematically consistent theory of time, publish it, and win a Nobel prize". Smolin is just more articulate and experienced and he can drag on for a whole book about it (I've read Time reborn), but in the end he is no better than your average layperson comment on this blog.
    I had appreciated "The trouble with physics", which was right in spurring physicists not to ignore the the current problems of foundational theories. But since, I have the impression Smolin is just trying to compensate for his lack of concrete ideas with some woolly "philosophical" thinking.

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    1. You need to read Smolin's peer-reviewed publications. His real ensemble theory does *attempt* to build a mathematically consistent theory of QM within a non-reversible model of time. I applaud that effort, and his explicit commitments to "naive realism" and empirical test. It's an effort that is in some ways heroic, or perhaps quixotic, inasmuch as physicists continue to get funding to work the same failed paradigms. As long as they do so, there will be no kuhnian crisis to remedy.

      Since cold war institutionalization and bureaucratization of funding controlled by those who benefit from these same funding mechanisms, it is much more difficult to tip academic communities into recognition of crisis. Smolin and a few others recognize the crisis and make halting attempts to remedy it. The new book's epilog is a poignant recitation of regret that he did not do more.

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  25. It is anything but trivial to regard space and time as physical "objects". Space and time are primarily "order patterns of the mind". In order to "create" physics from these mind-patterns, a phenomenological examination and explanation are absolutely necessary. To really start over here, no one is able to do that using existing formalisms primarily based on mathematics (needs).

    An example of a really different approach: The “secret” of very weak gravitation in relation to the electrical interaction and strong interaction is based on the false assumption that there is generally a mass decoupled space existing. If one considers inherent space that elementary particles and macroscopic bodies contain, by their object expansions and by their radius of interactions, then it becomes clear that the "missing" energy is (in) the space itself. To create space(-energy) space-coupled mass(-energy) must be transformed in such. One consequence, inflation is ruled out. Another consequence of the observed “real object physics” is, the “massless concept” of the SM is ruled out.

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  26. I like Lee Smolin's natural philosopher approach, we really should bring physical intuition and philosophy back to physics. Symmetry tricks work well up to a point,but they abstract out the fundamental concepts that underlie the symmetry. I know this sounds like a rant against Copenhagenism, but Lee is correct that our historical path through physics has been most successful when physical intuition has been our guide. The worst thing that can happen to physics (and I think it already has) is that we discover a beautiful mathematical formula from abstract concepts that has limited predictive power (because we don't understand it's fundamental concepts). Perturbative analysis coupled with renormalization are the enemies of progress in understanding nature.

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  27. @Bio_interloper
    As to "work (on) the same failed paradigms": those people like Smolin who, for almost a century now, have been trying unsuccessfully to build some consistent relist model of QM are a clear example of "failed paradigm".

    As to the first part of your comment, I agree, I checked the references, and indeed he has published on this. Whether it is interesting, I do not know yet.
    I wonder how these considerations about irreversible time compare with work done by Prigogine a few decades ago. By the way, tPrigogine's work was completely ignored by other physicists and long forgotten now.

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