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Is explaining consciousness in the realm of physics?

Detailed question:

We know that consciousness exists. Or rather, I know that I have it. The rest of you may not be conscious, but I know that I am, so it exists. Since it's the job of physics to explain everything in the universe (even indirectly), I feel that sooner or later, we have to tackle how consciousness arises.

With other phenomena, yes. Physics does answer them. We see a straightforward link between the fundamental laws of physics and the phenomena in question.

Examples:

Economics → human psychology → evolutionary biology → biology → chemistry → physics
Climate science → thermodynamics/weather/geology, etc. -> physics
Fluid mechanics → collected movements of particles → physics

So with all other phenomena, we see the links between them and physics. The links may be too numerous to compute, but there's nothing mysterious about these links. We can easily observe and measure these links, no problemo.

With consciousness however, there appear to be no links to explain how subjective experience can possibly arise from the interaction of particles. It seems to be the only phenomena in nature for which we have zero inkling of how it arises. I feel that this is a challenge that physics should not ignore.

But there are some physicists who feel it's not in the domain of physics to explain how consciousness arises.

What do you think? Is consciousness in the domain of physics, or is it outside?

Some say that the physics only deals with experiments reproducible by others. This would imply that a single person by themselves could never, ever be scientific, which I think is inaccurate. It converts physics into a social science field.

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  • Comments are not for extended discussion; this conversation has been moved to chat.
    – Geoffrey Thomas
    Sep 23 at 8:50
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    ...it's the job of physics to explain everything in the universe... - No it isn't. Wherever did you get that idea? Sep 23 at 13:29
  • While it's certainly common for physics to deal with questions of the physical ontology, it certainly isn't constrained. However, what the discipline of physics should or shouldn't study is normative and thus an opinion. If I were you, I would disregard this question and post one regarding how the ontology of physics accommodates non-physical phenomena, if at all. An eliminative materialist rejects consciousness entirely, and a subjective idealist rejects physical phenomena exist independent of experience. On its face, consciousness is generally the business of psychologists, not physicists.
    – J D
    Sep 24 at 15:30
  • This is obviously a valid question for the site, as it covers defining physics, & establishing whether consciousness is in that remit. Closing the topic seems crazy to me. Voted to reopen.
    – CriglCragl
    Sep 25 at 11:08

10 Answers 10

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The concepts on your question are largely biased. Physics describes, does not explain. See below.

Since it's the job of physics to explain everything in the universe (even indirectly)

False. The goal of physics is to find quantitative laws that describe nature. Explanations are the task of philosophy. Newton never tried to explain gravity, he explicitely said "...to us it is enough that gravity does really exist and behaves according to these laws". If any, his explanation of gravity would be God.

With other phenomena, yes. Physics DOES answer them. We see a straightforward link between the fundamental laws of physics and the phenomena in question.

False. Quantum mechanics describe quantum systems, it does not explain them. Explanations (QM interpretations) are part of philosophy (specifically, metaphysics, because QM interpretations try to explain reality based on QM).

Economics -> human psychology -> evolutionary biology -> biology -> chemistry -> physics Climate science -> thermodynamics/weather/geology etc -> physics Fluid mechanics -> collected movements of particles -> physics

False. That's naive. You've proposed ONE LINEAR dependency of economics from the movement of particles. But there are literally INFINITE dependencies, and they are mostly NON-LINEAR. You can't describe economics based on the physical movement of particles. Just try. In order to do so, you will be forced to make trillions of philosophical assumptions. If things were so simple, economic issues would be solved just by moving nine dials. But you know that in order to solve a single economic issue, there are hundreds of elements to consider. The amount grows exponentially if you address the problem from your second link, human psychological interactions; etc.

So with all other phenomena, we see the links between them and physics. The links may be too numerous to compute, but there's nothing mysterious about these links.

False. If things were so simple, we would all be rich.

We can easily observe and measure these links, no problemo.

False. You can't observe psychological dynamics. You can't describe biological behaviors, etc.; science is very, very far from that.

With consciousness however, there appear to be no links to explain how subjective experience can possibly arise from the interaction of particles. It seems to be the only phenomena in nature for which we have zero inkling of how it arises. I feel that this is a challenge that physics should not ignore.

False: Consciousness is just another behavior qualified as "emergent", like biology is an "emergent" behavior. We just don't have no explanations for most natural phenomena. Science is just a superficial, partial and incomplete description of a small amount of phenomena.

But there are some physicists who feel it's not in the domain of physics to explain how consciousness arises.

They are right. Specifically, such is a metaphysical and epistemological issue (philosophy is said to have four main branches: epistemology, the study of knowledge, metaphysics, the study of reality, logics, the study of reason and ethics, the study of moral principles).

What do you think? Is consciousness in the domain of physics, or is it outside?

If you want to describe consciousness, get your pen, and write the formulae. Otherwise, explaining it is a philosophical task.

Edit: Some say that the physics only deals with experiments reproducible by others. This would imply that a single person by themselves could never, ever be scientific, which I think is inaccurate. It converts physics into a social science field.

See Karl Popper, or just https://en.wikipedia.org/wiki/Reproducibility

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  • Comments are not for extended discussion; this conversation has been moved to chat.
    – Geoffrey Thomas
    Sep 23 at 8:52
  • I think that with emergent and nonlinear you identified the main flaws of the argument. Nevertheless, "if you want to describe consciousness, get your pen, and write the formulae. Otherwise, explaining it is a philosophical task" is too flippant. Until 1828 people thought that there is something special to "organic" chemistry, some mysterious life ingredient. I think relegating brain functions to philosophy involves the same fallacy. Sep 24 at 14:18
  • Even though biology as a science of emergent phenomena is better suited to describe the material side of life than quantum physics there is no doubt that all biology in the end is based on suitable arrangements of elementary particles and channeling energy flows. I don't see a reason that there should be anything special about brain functions (of which consciousness is just one). This does not contradict the fact that because of nonlinearity and complexity, quantum physics is less suited to describe people's minds than psychology. Sep 24 at 14:23
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As a biologist working in neuroscience with many physicists, I used to get this question a lot. Many physicists seem to believe that prime principles + computational power = infinite explanatory power up to chemistry, biology, sociology and on.

The best analogy I have been able to come up with is that physics is to biology as typography is to literature: it is trivially true that you can describe all literature through a complete knowledge of letter forms, and also trivially useless 1. A characteristic of emergent systems is that their information content can arise at a fundamentally different level than its pre-emergence elements. In the gap between physics and biology (which is the one I am most familiar with), there is also the fundamental disconnect of contingency: the feature space of life which is possible within given physical constraints is enormously larger than the life which does exist, because historically some things happened and other didn't. Replicating this from prime principles would require as much complexity as the universe has - a map as large as the land2, and so, again, trivially useless.

As to whether it is the job of physicists to explain consciousness, a lot of them sure seem to think it is, and they certainly seem to feel qualified to do so. As a neuroscientist, I actually don't feel it's even my job, except in the uninformatively descriptive way that Sean Carrol uses: there is little evidence that the phenomenon that we self-perceive as consciousness is anything particularly remarkable or peculiar from a neurological perspective, and the reason we attach so much importance to this otherwise mundane phenomenon is something that philosophers and psychologists will have to explain to me.

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    The fact that we have experiences is mundane? Sep 24 at 14:21
  • @AmeetSharma I'm sure that was the neuroscientist speaking, somewhat tongue-in-cheek: They look, say, at the neurotransmitter levels at synapses and see no difference between men and mice: It's the same boring glutamate, whether you think about the Categorical Imperative or follow the cheese smell. That level, already an order of magnitude or two more abstract than quantum dynamics, still has no explanatory power. For that, you need "philosophers and psychologists". Sep 24 at 14:36
  • I love your examples and the "trivially true = trivially useless" mantra. Well done. From the realization that the "substrate science" (quantum dynamics or even neuro-biology) is unable to explain anything follows that the emergent phenomenon is, in fact, substrate-independent. Human psychology would look the same if our organisms were not running on a carbon- but a silicon-based chemistry, or on a synthetic substrate like a constructed computer. Sep 24 at 14:42
  • @Peter-ReinstateMonica, So if I'm understanding correctly, the neuroscience can't explain anything to distinguish consciousness from other neurological phenomena. So isn't the natural route to go down to lower levels like quantum physics? Weak emergence won't explain consciousness. Strong emergence is magic. Sep 24 at 14:53
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    @Peter-ReinstateMonica: Of course there's no difference, because mice can think too! They have the cheese imperative.
    – user21820
    Sep 24 at 18:06
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In seeking to describe the 'truths of nature', natural philosophy that focused on physika, 'the natural things', came to mean explicitly not animals (biology) or minds (philosophy). But physics has been on a journey of unification, which is better thought of as having arrived at the power of the 'languages' of energy and information, as discussed here: Is the idea that "Everything is energy" even coherent?

David Deutsch made the case in The Fabric Of Reality that we need four strands, styles of approach, to account for the universe at large. With his Constructor Theory he is aiming to provide an integrated picture for the four strands, a shared language, which could then specifically integrate information theory with wider physics. Conway's Game Of Life, which is Turing complete and can simulate universal Turing constructors, gives an intuitive example of a very simple picture out of which information and things reminiscent of life can be constructed, illustrating the process.

Consciousness as presented in the Hard Problem, as qualia, is dangerously close to metaphysics. If no one else can really 'get' something about your experience, it is not part of the shared domain, expressible in these universal languages of energy and information, that build up a picture of complex behaviours from simple things. It is unverifiable. Qualia as usually defined, just isn't part of physics. It may be real, though physicalists don't generally think so, but as something intrinsically personal it doesn't relate to this wider picture.

It's kind of funny to ask if physics should explain consciousness, when we call it a biological phenomenon, and have neuroscience and other specialisms focusing on our brains, synthetic ones and so on. But chemistry has been completely 'folded in' to physics, integrated with the picture of fundamental building blocks and the energy-information mode of prediction. We have no reason to think biology won't follow, though it's a lot more complicated a lot has already. But still biology won't be physics, neither will consciousness - but we expect they will be integrated with this physics picture in the same way chemistry has.

Should physics be focused on explaining consciousness? It's been estimated that with very small VonNeuman replicator probes humans could colonise our galaxy using technology we understand now and currently achievable speeds, in less than 10,000 years. So the impact of life will become very important in shaping the future evolution of the cosmos at the large scale, even without life elsewhere. At the small scale, quantum biology proved essential to understanding how chlorophyll works, and OrchOR theory proposes a role for quantum behaviour in neurons. So, while explaining consciousness is not an explicit goal of physics, the journey of unification seems to point towards inevitably requiring understanding consciousness, or at least the fundamental mechanisms, and widest impacts.

Popper would certainly not accept that science is only about the reproducible. He regarded the idea science is based on induction as a myth, and focused on experiments as testing models. Treating a specific persons illness, would not be science by the former model, as their unique predicament can't be replicated. But it could be by the latter model.

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    Wow, thanks for the amazing links! Particularly the one on constructor theory. So you feel that eventually physics will make inroads into how consciousness is generated. I also appreciate the pointing to David Deutsch - a few more books for me to look at! Sep 22 at 4:28
  • The unification you point to in your links is the unified physical description of the universe, not the unification of philosophy and science. The concept of the 'language of energy' has no sense for me. Can you please provide references (not to posts of your own)?
    – RodolfoAP
    Sep 23 at 5:22
  • @RodolfoAP: "not the unification of philosophy and science" Why would it be? Unification in physics is a well understood term. As far as consciousness is a physical process, we expect it will be fitted into the physical picture. Plenty of questions for philosophy, like how to live the good life, will never be part of physics. The 'language of energy' point is my own, raised specifically to address the idea everything 'is' energy, which I don't think is really a coherent stance ontologically.
    – CriglCragl
    Sep 23 at 13:20
  • Since the diameter of our galaxy is estimated to be 100,000 light years, it seems more than a little optimistic to think we could colonize it in less than 10,000 years.
    – D. Halsey
    Sep 23 at 18:18
  • @D.Halsey: Yes fair point, that does sound unworkable, & I can't locate where I read it. With probes at 0.1c, it's been estimated possible in 500,000 years: rfreitas.com/Astro/ComparisonReproNov1980.htm
    – CriglCragl
    Sep 24 at 10:35
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The job of physics is to explain what it can. It's not obvious a priori what that is.

Natural philosophers pondered big questions like the origin of the Earth and the stars for millennia without coming up with the correct answer. What led to the correct answer was pondering small questions: how materials on Earth behave, how light behaves, how objects roll down an inclined plane.

Future big answers from physics, if any, will also appear as a result of studying small problems, because there aren't any other methods available to physics.

Physicists are uninterested in your suggestion that they work on consciousness not because they aren't interested in consciousness, but because the suggestion isn't useful. They work on whatever they can, and consciousness isn't one of those things, yet.

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  • I'm not blaming physicists for not knowing how to solve consciousness obviously. I'm asking whether it it's in the domain of physics in the first place. Even when physicists couldn't explain the stars, no one ever said that it's not in the domain of physics. They only said we don't know for now (and we don't know how to find out). Never did they say "It's not our job to try and find out". That's all I'm asking - "Is it physics' job to find out what consciousness is?" They might fail at the job, sure. But is it their job at all? Sep 21 at 18:46
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    @BhagwadJalPark I'm not a historian, but as far as I know, people did say such things. Before Hubble's law, no one expected that we'd be able to probe the origin of the universe. It seemed a hopeless problem; there was no way to attack it. Finding the chemical composition of stars seems like a hopeless problem, but it turned out to be possible by analyzing atomic absorption lines. The heavenly spheres seemed much more otherworldly and inaccessible before Newton discovered universal gravitation. Today, consciousness is in many people's obviously-hopeless bag, but who knows.
    – benrg
    Sep 21 at 19:38
  • You're right. If anything, your example shows us that we shouldn't discount something from physics merely because it seems impossible to answer right now. The only question is "Is it a legitimate problem"? For example, ethics is outside physics' purview. Regardless of future technology, it will always be outside the purview of physics. My question is only asking whether or not consciousness is a legitimate problem for physics. Sep 21 at 21:40
  • "They work on whatever they can" isn't a coherent definition, or even picture, of physics
    – CriglCragl
    Sep 22 at 3:19
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It is indeed the desired goal of physics to show how the laws of physics imply phenomena at a level of magnification higher than that of elementary particles and fundamental forces. (Even if "explain" is not necessarily the appropriate word.)

Since consciousness is obviously present in the universe, and since its existence has so far defied our ability to derive this existence from other, simpler phenomena, it would be ideal if physics could indicate how the laws of physics provide for the existence of consciousness.

We have no reason to believe, so far, that there is any phenomenon in the universe that is not entirely governed by the laws of physics. So it seems plausible that consciousness, as well, corresponds to certain arrangements of physical entities: particles and waves and fundamental forces.

And yet, there seems to be no way to bridge the gap between the language of physics and anything that could possibly be called consciousness.

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welcome to the flock! You've already got many deep answers, but this is philosophy, so I'll chip in any way.

Firstly, anything to do with science is anybody's job, IMO; we are all allowed to have opinions, at least, and as a scientist you often have a background that allows you to have thoughtful opinions on many different things.

As for explaining consciousness (or biology for that matter), I think physics is still far too immature to come up with real answers; the necessary (mostly mathematical) tools don't exist yet for dealing with the complexities involved. I believe there is some research going on into the field of emerging properties that may one day be relevant - an emerging property, as I understand it, is a property that exists for large assemblies of 'objects' (~ particles, neurons, ...) that no single object has - like temperature: a bottle of water has a temperature, but no single water molecule does, at least in the common sense. Consciousness may turn out to be (a set of) emerging properties of large neural networks.

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I will be bold and say Consciousness deserves it's own field of study rather than relying on physics or economics for crying out loud. Is there a connection between observed physical motion and Human consciousness? Of course. Is there a connection between physical motion and the economic infrastructure of a nation? Of course. Hence, is there a connection between Human consciousness and economic infrastructure? Of course, as you'd expect. Do these conclusions point towards an explanation that explains one in terms of each other? No, at least, not so fast.

It is a scientific fact about biology, which I know of, that DNA and other biological processes contain more information than the mere parts that make it up. In other words, the information required to make biology work might not simply exist in a reduced level of physics or chemistry.

The bottom line is, Human consciousness is tied in with everything so intricately, and so fundamentally, that if you ever encounter an opinion that claims to be a very fine one but irrelevant to Human consciousness, your best bet would be to discard the opinion and turn away from the person immediately.

What entails Consciousness getting it's own field of study? Well, first of all you come up with a separate set of simples. For example in QFT, the simples that a physicist would likely entertain are quantum fields and transformations which live in their own nebulous abstract universe. The second would be to employ the scientific method, which means coming up with hypotheses about Consciousness and testing them against cold reality to see if they survive. A question could be phrased, about one's own consciousness, does the sensation of hot chocolate make me want more hot chocolate? A simple yes or no could be spit out and then noted down for future reference. A rudimentary example, but nonetheless a demonstration of scientific study of Consciousness.

So if you are hoping to use the tools developed by physicists in order to study a structure to study or rather answer the question of hot chocolate, then you are mistaken friend, for you're simply using the wrong tool for the job.

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The only empirical data we have about consciousness is our own personal experience of it coupled with other people's reports about their own experience. According to this, we have to make a fundamental distinction between on the one hand the quality of our subjective experience, for example the painfulness of pain, the redness of red colours etc., and on the second hand, the information content of the human mind. It is trivially apparent that the information content of our mind is correlated to events in our physical environment. Given the nature of our brain, the most plausible theory is that all the information content of our mind is the direct consequence of the neurological processes taking place in our brain. It should be expected that the cognitive sciences will improve our understanding of what goes on in our mind as a consequence of neuronal activity. It probably won't ever be easy, but if our technology keeps making progress, we should at some point get enough data to understand the detailed nature of the human mind.

In this context, the information content of the human mind is trivially understood as a state of matter. We can go even further in this respect by making a close analogy between the human brain and a computer as both information processing "machines".

This facet of the problem can be explained because it is not a fundamental property and we have plenty of empirical data. The working of the brain should in this respect be understood as a particular aspect of life processes and, more generally, of natural processes.

Still, this leaves open the question of the quality of our experience of the information processed by our brain, that is to say, qualia.

Personally, I don't see that there is any similar need to explain qualia. I also don't think it is even possible. The reasoning for that is the same as the reasoning which says that reality (as a whole) cannot possibly be explained. The quality of our subjective experience plays the same role for our consciousness as do the truly fundamental components of the material world if they exist. Such components are not explainable.

This should not be particularly surprising. There is no good reason to believe that human intelligence should be able to solve all the mysteries of the nature. Our intelligence is not magical. It is the natural result of natural selection. We should obviously expect that it helped us survive and prosper in our natural environment, but there is no mechanism which would have made our intelligence capable of explaining reality as a whole or the quality of our subjective experience. In this context, I don't see how qualia could possibly be explained in terms of material things, or in terms of anything for that matter.

So, it is definitely the job of science to explain the informational content of the human mind, but most plausibly not to explain the quality of our subjective experience.

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  • If I'm understanding you, you appear to be saying that because we're probably not smart enough to explain how subjective experiences arise, it's not the job of physics to try. Is that right? Sep 21 at 16:27
  • @BhagwadJalPark No, not at all. It has nothing to do with our limited intelligence. It is a fundamental problem. Even God could not explain it. Sep 21 at 16:37
  • I think I might accept that if we could prove rigorously that we can't explain consciousness. But I personally think physics needs to explain all of reality. Even if not directly, then at least indirectly. Since consciousness is part of reality, I feel that physics should at least take a stab at the problem and show us the connections by which we could start to measure it, or generate it. Sep 21 at 16:54
  • @BhagwadJalPark "physics needs to explain all of reality" No. It is logically impossible to explain the whole of reality. We just explain what we can, and it is not so much explaining real things, it is rather explaining our perception of real things, and only in terms of our perception of other real things. It works up to a point and only because our brain is the result of natural selection and therefore adapted to our environment. Maybe you need to come down to Earth. Sep 21 at 17:54
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If consider the issue with the help of decoherence and coherence violation, then, in quantum theory, there is even such a thing as "quantum consciousness".

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If physics wants to explain consciousness, then it would ultimately need to discover possible measurable properties.

In my mind, this comes down to finding those attributes of consciousness that may or may not happen to be exactly (or at least approximately) identical for every individual.

Unfortunately, we currently have no faith in such a discovery, because we consider consciousness a metaphysical construct, which is even contrary to science.

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