I On the relation between physics and philosophy

[A. Neumaier]

A lattice regularization defines a mathematically consistent description.

... but of an approximation to the standard model only, not to the standard model as defined in the textbooks.

 

[A. Neumaier]

I talked about the SM as a physical theory, and there it's very successful and also mathematically sound in the sense of renormalized perturbation theory. Maybe the lack of a consistent math for a fully self-consistent interacting QFT is also a hint at how to find a more comprehensive formulation, though all attempts for the last 70 years or so failed so far :-(.

Well, consistency means logically consistency, and this includes mathematical consistency.

At present, the standard model is not a fully consistent scheme but a large collection of very successful theroretical and computational recipes related to ill-defined foundations by means of ill-defined approximations.

I believe that the mathematical obstacles that so far prevented finding a consistent formulation of QED are also the obstacles that prevent finding the correct unification with gravity.

 

[Demystifier]

Then the "interpretations" have weak points, don't blame QM!

The weak point of QM is that it does not contain its own interpretation.

 

[vanhees71]

Which physical theory contains its own interpretation? It's not clear to me, what you mean by this.

 

[Elias1960]

... but of an approximation to the standard model only, not to the standard model as defined in the textbooks.

If on follows Wilson, so what? Field theories are large distance approximations of unknown low distance theories, and using a lattice theory as a straightforward example for such a low distance theory is not worse than presenting nothing at all for the limit of very small distances.

If we look for logical consistency of QFT as an effective field theory, one toy construction of a more fundamental theory so that both can be evaluated for consistency (the lattice theory as a theory itself, the field theory as its consistent large distance approximation) is sufficient.

For the textbooks, it would be also much better to teach, first, a model known to be consistent and easy to understand - as a field theory which approximates a lattice theory, similar to condensed matter theory approximating atomic theory would be, and together with a quite universal way to compute something - and then, if necessary or useful, to criticize for whatever reasons this approach and to argue why one wants more, namely a field theory working for all distances or so, or some numerically better even if conceptually dubious approximation schemes like dimensional regularization.

 

[Elias1960]

The weak point of QM is that it does not contain its own interpretation.

I would reformulate it in the following way: There is no straightforward interpretation of QT where it is a fundamental theory of everything.

The Copenhagen interpretation is quite natural - a statistical scheme of predicting things in a domain where we simply cannot see what really happens. One has to get rid of its fundamentalist claims, namely that it is complete, in the sense that there is no more fundamental theory which describes more. (Maybe one has really misinterpreted Bohr, and he has in fact meant with "completeness" something weaker, namely internal consistency.) In this case, Copenhagen becomes simply an interpretation where we have restricted abilities to prepare states and therefore can prepare only states where we can make only statistical predictions.

And there is the "classical part" where we can access information which quantum theory does not give (like if Schrödinger's cat is dead or alive). So, this interpretation contains parts which show that QM is not complete, thus, cannot be the fundamental theory.

 

[atyy]

Ok, add "and a condensed matter interpretation of the fields":

But some attempts are published in rather mainstream fora.
https://arxiv.org/abs/cond-mat/0407140
https://arxiv.org/abs/1106.4501 (see section 9 for speculation on how some parts of string theory could come out of "emergent relativity")

Of course there are some attempts that are not yet published in any peer-reviewed place: https://arxiv.org/abs/1809.11171

But overall one can't say that this is a forbidden line of work, when it is quite mainstream.

 

[Demystifier]

Which physical theory contains its own interpretation? It's not clear to me, what you mean by this.

By interpretation, I mean claims on ontology (or on the lack thereof). Classical mechanics, for instance, has a clear ontology in the sense that particles have positions at any time, irrespective of their measurement. Relativity theory (in the Minkowski formulation) has an explicit claim on the lack of ontology, in the sense that space and time do not exist separately unless they are measured.

 

[vanhees71]

The natural sciences don't give any ontology at all. They aim at a most accurate description of the observable objective facts about nature. No more no less. I don't see, why the mathematical abstract concepts of Newtonian mechanics should provide "more ontology" than that used in relativistic physics or even quantum theory. Math has been found to be the (so far only) adequate description of what's objectively observable in nature, no more no less!

 

[Lord Jestocost]

And there is the "classical part" where we can access information which quantum theory does not give...

What the heck are now "classical parts"?
All informations which are relevant for your subjective experience are given by quantum theory! Knowledge you might lack it is simply not there to be known.

 

[zonde]

The natural sciences don't give any ontology at all. They aim at a most accurate description of the observable objective facts about nature. No more no less.

This is plain wrong. Chemistry is clear counterexample. It started with ontology. It's success grew on ontology. And it grew to the level that nowadays it's ontology most of the people would consider observable facts.

 

[Elias1960]

But some attempts are published in rather mainstream fora.
https://arxiv.org/abs/cond-mat/0407140
https://arxiv.org/abs/1106.4501
But overall one can't say that this is a forbidden line of work, when it is quite mainstream.

A few papers which move, in small steps, toward a forbidden direction do not make this direction "quite mainstream".

The first paper defines some sorts of phonons in condensed matter theory, which is in itself unproblematic. The second one is protected by its relation to AdS/CFT, which is a quite popular mainstream fad. Moreover, "speculation on how some parts of string theory could come out of" whatever have support from the powerful string community. So they have both some sort of plausible deniability and some good enough connection to a mainstream background.

Let's not forget that some such small steps have been done many times by a lot of people. One can even say that the condensed matter analogy has been very fruitful for both sides almost all the time. Some of those who have used it gained Nobel prices (Dirac, Wilson). Nonetheless, the anathema remained, and remains today too.

Then, just to clarify: I do not claim that something is completely forbidden. Just that publishing it becomes much harder, even extremely hard if you openly support the anathema.

Moreover, publishing is not everything - if not cited, publications are not worth a lot. Moreover, there are no large groups studying such things, so that this also does not help on the job market or to get grants. These are objective problems of the actual way to organize science which forces, in general, young scientists to follow the actual mainstream fads instead of trying something completely different. The anathema simply adds even more to this general problem.

 

[atyy]

These are objective problems of the actual way to organize science which forces, in general, young scientists to follow the actual mainstream fads instead of trying something completely different. The anathema simply adds even more to this general problem.

Why is that a problem? They should follow mainstream fads, like John Bell, who followed mainstream fads to discover the chiral anomaly before he discovered Bell's theorem

 

[Demystifier]

The natural sciences don't give any ontology at all. They aim at a most accurate description of the observable objective facts about nature. No more no less.

Natural sciences do not aim at anything. It is natural scientists (that is, humans who study natural sciences) who aim at something. Typically, they aim at more than you claim. They aim at giving
(i) description,
(ii) explanation and
(iii) prediction
of observable objective facts about nature. The scientific explanations often involve objects that are not observable at the time when the scientific theories are proposed. A nice example are atoms as an explanation of chemistry and thermodynamics, much before the atoms have been observed. At that time nobody were saying that atoms are just a computational tool to predict the macroscopic behavior of chemicals and steam engines. Scientists who believed that atoms make any sense at all, believed that they actually exist despite the fact that nobody observed them (at that time).

 

[gmax137]

At that time nobody were saying that atoms are just a computational tool to predict the macroscopic behavior of chemicals and steam engines.

I don't know about that. I seem to recall that as recently as 1900 people doubted that atoms "really' exist. Including physicists like Ernst Mach.

 

[Elias1960]

Why is that a problem? They should follow mainstream fads, like John Bell, who followed mainstream fads to discover the chiral anomaly before he discovered Bell's theorem

If it is not a problem, then do it consistently, and stop financing fundamental physics at all. Then they all do the everyday job of condensed matter physics or experimental physics or whatever, that means, something useful (and in this case, it does not matter if it is mainstream fad or not), before they in their free time develop some fundamental theories.

 

[martinbn]

By interpretation, I mean claims on ontology (or on the lack thereof). Classical mechanics, for instance, has a clear ontology in the sense that particles have positions at any time, irrespective of their measurement. Relativity theory (in the Minkowski formulation) has an explicit claim on the lack of ontology, in the sense that space and time do not exist separately unless they are measured.

How is quantum mechanics different?

 

[lavinia]

I don't know much about either philosophy or physics so consider the following to be naive.

It seems that one goal of Physics is to come up with Physical principles such as "the speed of light is constant in all inertial frames of reference." Where did this goal come from if not from some philosophical bias?

- Pure observation suggests that a body in motion if not subjected to outside forces comes to its natural state of rest. Roll a ball. It eventually stops. Keep on pushing a wagon if you want to keep it moving. Why would one make such a conclusion from pure observation? Why not just say "I rolled the ball and it came to rest?".

- The Ptolemaic system for describing the orbits of planets, though approximate, can be calibrated to be extremely accurate and to give good predictions for long periods of time. When it goes noticeably wrong it can be adjusted back into line. Why not stick with this empirical method which is stable and can be made as accurate as one wants? Why invent the Copernican system and then Kepler's theory?

- It seems Physics is searching for a unity which that will reveal in some sense the "true Nature" of creation. To me this is intrinsically a philosophical if not an outright teleological goal. Mere description of phenomena even when it employs predictive rules, cannot tell you the answer.

- It seems that Quantum Mechanics and Classical Physics by themselves indicate that there is no such unity to creation. Some new way of thinking is needed. I think Physicists are well aware of this. To me this why merely accepting Quantum Mechanics as a set of rules that work - much like the Ptolemaic System - is unappealing. This even though Quantum Mechanics seems precise rather than approximate.

Here is a relevant lecture by Leonard Susskind

 

[martinbn]

If it would need a preferred frame, it would be rejected as Lorentz ether crackpot nonsense. Independent of the question if it would be really nonsense or not.

You are forgetting that papers are also rejected by journals simply because they aren't good enough for the journal, not because of their topic.

 

[martinbn]

I don't know much about either philosophy or physics so consider the following to be naive.

It seems that one goal of Physics is to come up with Physical principles such as "the speed of light is constant in all inertial frames of reference." Where did this goal come from if not from some philosophical bias?

Other things were tried. This one worked. If it didn't people wouldn't insist on it.

- Pure observation suggests that a body in motion if not subjected to outside forces comes to its natural state of rest. Roll a ball. It eventually stops. Keep on pushing a wagon if you want to keep it moving. Why would one make such a conclusion from pure observation? Why not just say "I rolled the ball and it came to rest?".

For a long time that was what people thought. From Aristotle till about Newton's time. Or in other words from the time of philosophy till the birth of science.

- The Ptolemaic system for describing the orbits of planets, though approximate, can be calibrated to be extremely accurate and to give good predictions for long periods of time. When it goes noticeably wrong it can be adjusted back into line. Why not stick with this empirical method which is stable and can be made as accurate as one wants? Why question invent the Copernican system and then Kepler's theory?

The motivation was simplicity. It was an easier model.

- It seems Physics is searching for a unity which that will reveal in some sense the "true Nature" of creation. To me this is intrinsically a philosophical if not an outright teleological goal. Mere description of phenomena even when it employs predictive rules, cannot tell you the answer.

It doesn't seem to me that way at all.

- It seems that Quantum Mechanics and Classical Physics by themselves indicate that there is no such unity to creation. Some new way of thinking is needed. I think Physicists are well aware of this. To me this why merely accepting Quantum Mechanics as a set of rules that work - much like the Ptolemaic System - is unappealing. This even though Quantum Mechanics seems precise rather than approximate.

I don't get this part.

 

[PeroK]

I don't know much about either philosophy or physics so consider the following to be naive.

It seems that one goal of Physics is to come up with Physical principles such as "the speed of light is constant in all inertial frames of reference." Where did this goal come from if not from some philosophical bias?

- Pure observation suggests that a body in motion if not subjected to outside forces comes to its natural state of rest. Roll a ball. It eventually stops. Keep on pushing a wagon if you want to keep it moving. Why would one make such a conclusion from pure observation? Why not just say "I rolled the ball and it came to rest?".

- The Ptolemaic system for describing the orbits of planets, though approximate, can be calibrated to be extremely accurate and to give good predictions for long periods of time. When it goes noticeably wrong it can be adjusted back into line. Why not stick with this empirical method which is stable and can be made as accurate as one wants? Why invent the Copernican system and then Kepler's theory?

- It seems Physics is searching for a unity which that will reveal in some sense the "true Nature" of creation. To me this is intrinsically a philosophical if not an outright teleological goal. Mere description of phenomena even when it employs predictive rules, cannot tell you the answer.

- It seems that Quantum Mechanics and Classical Physics by themselves indicate that there is no such unity to creation. Some new way of thinking is needed. I think Physicists are well aware of this. To me this why merely accepting Quantum Mechanics as a set of rules that work - much like the Ptolemaic System - is unappealing. This even though Quantum Mechanics seems precise rather than approximate.

I don't get any of this!

 

[Rollo]

Leaving aside quantum foundations, which is an active area of interdisciplinary research involving physicists and philosophers, there are a number of other live questions in contemporary physics where I think a philosophically informed perspective is valuable.

For example: the soundness and significance of anthropic arguments; the role of aesthetic and other qualitative factors in theory evaluation.

As others have pointed out, historically philosophical considerations were certainly important in significant scientific discoveries such as relativity (Einstein himself talked about the influence of Hume on his work, see here: https://aeon.co/essays/what-Albert-einstein-owes-to-david-humes-notion-of-time). More generally - most of the physicists of that vintage would have been knowledgeable about philosophy: this would have been the case with anyone educated to that level in the European university system of the time.

Further back, of course, the distinction between the disciplines becomes murkier (e.g. Newton would have regarded himself as a philosopher).

 

[PeroK]

Leaving aside quantum foundations, which is an active area of interdisciplinary research involving physicists and philosophers, there are a number of other live questions in contemporary physics where I think a philosophically informed perspective is valuable.

For example: the soundness and significance of anthropic arguments; the role of aesthetic and other qualitative factors in theory evaluation.

As others have pointed out, historically philosophical considerations were certainly important in significant scientific discoveries such as relativity (Einstein himself talked about the influence of Hume on his work, see here: https://aeon.co/essays/what-Albert-einstein-owes-to-david-humes-notion-of-time). More generally - most of the physicists of that vintage would have been knowledgeable about philosophy: this would have been the case with anyone educated to that level in the European university system of the time.

Further back, of course, the distinction between the disciplines becomes murkier (e.g. Newton would have regarded himself as a philosopher).

The question is, assuming modern physicists lack the philosophical knowldege of their predecessors, is this holding them back? Or, despite the success of Einstein, did philosophical considerations in the past hold back physics for many decades? Perhaps preventing many 19th century physicists breaking free.

You could certainly make a case that, for example, religious and philosophical ideas inhibited Darwin from publishing the Origin of the Species.

Even in mathematics, complex numbers were suppressed for philosophical reasons.

I'm not convinced by the argument that philosophy has eased the path of science. I believe you could make a stronger case that, quite the reverse, philosophical preconceptions have repeatedly held science and mathematics back.

 

[Elias1960]

You are forgetting that papers are also rejected by journals simply because they aren't good enough for the journal, not because of their topic.

No. I predicted the fate of a paper proposing a theory of quantum gravity which needs a preferred frame and a condensed matter interpretation. I did not make assumptions about its other qualities, thus, those other qualities are irrelevant for my prediction.

 

[PeterDonis]

I predicted the fate of a paper proposing a theory of quantum gravity which needs a preferred frame and a condensed matter interpretation.

You predicted that such a paper would not be published in peer-reviewed journals. But, as I have already pointed out, the physicist whose paper you linked to has had papers proposing such a theory published in peer-reviewed journals, as a simple check of his web page will show you.

You have now been banned from further posting in this thread.

 

[Julius Ceasar]

You could certainly make a case that, for example, religious and philosophical ideas inhibited Darwin from publishing the Origin of the Species.

Religion for sure has inhibited scientific ideas throughout history and used its philosophy to do so. I mean are you telling the whole story here and philosophy just the unintentional patsy.

 

[Demystifier]

I don't know about that. I seem to recall that as recently as 1900 people doubted that atoms "really' exist. Including physicists like Ernst Mach.

Mach was completely against atoms, he didn't say that they are just a "computational tool".

 

[Demystifier]

How is quantum mechanics different?

Quantum mechanics "itself" (as opposed to what we call interpretations of quantum mechanics) does not say whether the wave function exists irrespective of measurement, to give just one example.

 

[vanhees71]

Classical mechanics does not say whether position and momentum vectors exist irrespective of measurement either...

 

[Demystifier]

The question is, assuming modern physicists lack the philosophical knowldege of their predecessors, is this holding them back?

The problem for the work in foundations of physics is not the lack of philosophical knowledge. The problem is the lack of philosophical mode of thinking. A physicist does not need to know what Kant or Aristotel or Hume said to be a good philosopher of physics. What he needs is to be able to be in a mode of thinking in which the sentence "Is wave function real?" does not sound like a meaningless gibberish.

 

[martinbn]

Quantum mechanics "itself" (as opposed to what we call interpretations of quantum mechanics) does not say whether the wave function exists irrespective of measurement, to give just one example.

Because the question doesn't make sense.

 

[martinbn]

The problem for the work in foundations of physics is not the lack of philosophical knowledge. The problem is the lack of philosophical mode of thinking. A physicist does not need to know what Kant or Aristotel or Hume said to be a good philosopher of physics. What he needs is to be able to be in a mode of thinking in which the sentence "Is wave function real?" does not sound like a meaningless gibberish.

Good philosophy helps you to see that the question is gibberish.

 

[Demystifier]

Because the question doesn't make sense.

It seems that quantum mechanics is the only branch of physics that contains questions which "don't make sense".

 

[Demystifier]

Good philosophy helps you to see that the question is gibberish.

Which philosophy is that? Logical positivism?

 

[martinbn]

It seems that quantum mechanics is the only branch of physics that contains questions which "don't make sense".

You can ask that question in any branch. Why just QM, I don't know, you tell me.

 

[martinbn]

Which philosophy is that? Logical positivism?

No, just basic philosophy.

 

[Demystifier]

No, just basic philosophy.

Which is that? Where can I read the book "Basic philosophy for physicists"?

 

[Demystifier]

Why just QM, I don't know, you tell me.

I already did.

 

[Rollo]

The question is, assuming modern physicists lack the philosophical knowldege of their predecessors, is this holding them back? Or, despite the success of Einstein, did philosophical considerations in the past hold back physics for many decades? Perhaps preventing many 19th century physicists breaking free.

You could certainly make a case that, for example, religious and philosophical ideas inhibited Darwin from publishing the Origin of the Species.

Even in mathematics, complex numbers were suppressed for philosophical reasons.

I'm not convinced by the argument that philosophy has eased the path of science. I believe you could make a stronger case that, quite the reverse, philosophical preconceptions have repeatedly held science and mathematics back.

In terms of philosophical knowledge holding back vs. advantaging physicists, a few thoughts:

1. One of the difficulties here is disentangling formal philosophical commitments from philosophical background assumptions and ideas that we all have. For example (off the top of my head not researched) - the uptake of the big bang hypothesis was probably slowed by people finding the idea of the universe coming into being ex nihilo absurd. This is of course a philosophical thought of long pedigree, but also a perfectly natural intuition that people might have absorbed without specific exposure to it, or arrived at themselves.

2. I wouldn't necessarily assimilate people being resistant to new ideas because they conflict with philosophical principles with their being reluctant to contradict religious doctrines - either because they themselves hold to these or because of social pressure. These *could* be similar but are probably often not. Being reluctant to contradict received opinion has nothing specifically to do with philosophy.

3. More generally - my instinct is that this probably in part relates to the distinction between Kuhnian normal vs revolutionary science. I.e. in a period of 'normal' science, solving problems within a for-the-moment unquestioned framework, knowledge of philosophy is neither helpful nor unhelpful, and probably no more relevant to the practice of science than, e.g., what type of music the scientists listen to. However in a period of 'revolutionary' science , when a new paradigm is being formed, philosophical beliefs may inspire (as in the case of Einstein or Bohr) or hinder this process.

On a personal note, my background is in philosophy (I'm recreationally self-studying physics), and one of the things that I have noticed re this is that thinking about philosophy does cultivate a facility for what I'd call intuitive flexibility, basically being open to new ideas even if they are 'weird'. Crudely - if you spend a bit of time trying to think yourself into what it's like to hold, e.g., the metaphysics of Leibniz's Monadology or Spinoza's Ethics, then ideas like Everettian QM, or the world being 11 dimensional, don't seem that odd anymore!

 

[A. Neumaier]

If on follows Wilson, so what? Field theories are large distance approximations of unknown low distance theories

This doesn't change the fact that all effective theories of interest in high energy physics are relativistic quantum fields theories and not lattice theories! Wilson's lattice ideas don"t play any role there - except in one of several approaches to QCD, which is only a small part of the standard model.

 

[RUTA]

I’ve been working closely with a philosopher of science in foundations of physics for the past 25 years. When we first met, I was trying to answer Mermin’s challenge (1981 Am. J. Phys. paper “Quantum mysteries for anybody”) as a typical theoretical physicist, i.e., induced spacetime metrics from uniform spaces over group structures. Really cool math, but absolutely worthless physics. His ideas and questions got me to abandon my technical approach and find a real physics answer. Answering Mermin’s challenge has been the highlight of my career and I owe it to a philosophical method of inquiry that my training in physics did not provide.

 

[gleem]

You cannot be a physicist without being a philosopher since you have a specific view of knowledge. Another physicist looks at the relation of philosophy to physics

https://www.scientificamerican.com/article/physicists-are-philosophers-too/Rovelli gave a lecture at the Center of Philosophy of Natural and Social Science of the London School of Economics. It is the same content as the OP cited publication but has a different feel something a paper cannot reproduce.

https://www.artandeducation.net/classroom/video/197528/carlo-rovelli-why-physics-needs-philosophy

 

[Julius Ceasar]

Philosophy may well invite the weirdos with some ulterior motive they are perusing but it is an adolescent child that refuses help when they're stuck because they must do it all themselves.

 

[Julius Ceasar]

Thanks gleem I read the whole article, "physicists are philosophers too" i liked it a lot. See this excerpt-
"Philosophers from the time of Plato and Aristotle have claimed that knowledge about the world can be obtained by pure thought alone. As Tyson explained, such knowledge cannot be obtained by someone sitting back in an armchair." I would never endorse working out what's true by pure thought alone but to suppose it can't ever be useful is ridiculous to me. Pure thought alone is a great tool for ruling out what is least likely.
Krauss is the author of a book called, "A Universe from Nothing", nothing begets nothing, pure thought alone tells me this.

 

[PeroK]

Pure thought alone is a great tool for ruling out what is least likely.

And that is precisely the problem. It does no such thing. Physics you learn from what nature tells you.

For example: why, using pure thought alone, is gravity attractive and not repulsive?

 

[Julius Ceasar]

As for your example I would never endorse working out what's true by pure thought alone. Getting something from nothing? Not very likely but still I would go with the evidence because the use of philosophy does not preclude using science.

 

[PeroK]

As for your example I would never endorse working out what's true by pure thought alone. Getting something from nothing? Not very likely but still I would go with the evidence because the use of philosophy does not preclude using science.

In other words, you can only deduce from pure tought what turns out to be true when you do an experiment! So, you have no way to tell, until you do an experiment, which of your pure thoughts represents nature and which do not.

"Getting something from nothing" has no scientific meaning. Sitting in a room debating a question like that is pointless. That's not science.

 

[Julius Ceasar]

when you do an experiment!

what experiment?

 

[PeroK]

what experiment?

To test your pure thought against nature.

 

[Julius Ceasar]

Sorry i wanted to know what experiment you could come up with to show how you can get
"a universe from nothing" as per the title of krauss's book.