Is Physics Complete?

There's a pretty popular argument in contemporary western philosophy that goes something like this:


Physics studies, and has at least some inkling of a theory for, everything that exists. Since this is so, everything that exists is a physical thing (since physics studies all physical things, by definition). Therefore, physicalism, which is the thesis that all that exists is physical stuff, is correct.


Is this argument right? Much more than people commonly realize hangs on this argument. I'm curious how it strikes you. Does it seem sound?

I don't think anyone suggests that we have theories to cover everything. We very clearly don't. Now, you're conflating this with the conclusion that there is nothing outside of physical existence. That one people do think, because no one has ever encountered credible evidence of anything non-physical. Ghosts and spirits do not appear to exist and do not leave behind any evidence. This is likewise why no one bothers with a theory that the oceans aren't made of marshmallows. There's no reason at all to think that they are.

It's complete and utter nonsense that no rational person can consistently abide by, since reason is itself not a physical thing.

ashurbanipal said:

There's a pretty popular argument in contemporary western philosophy that goes something like this:


Physics studies, and has at least some inkling of a theory for, everything that exists. Since this is so, everything that exists is a physical thing (since physics studies all physical things, by definition). Therefore, physicalism, which is the thesis that all that exists is physical stuff, is correct.


Is this argument right? Much more than people commonly realize hangs on this argument. I'm curious how it strikes you. Does it seem sound?

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When Einstein was developing his theory physicists thought physics was complete, anyway.

ashurbanipal said:

There's a pretty popular argument in contemporary western philosophy that goes something like this:


Physics studies, and has at least some inkling of a theory for, everything that exists. Since this is so, everything that exists is a physical thing (since physics studies all physical things, by definition). Therefore, physicalism, which is the thesis that all that exists is physical stuff, is correct.


Is this argument right? Much more than people commonly realize hangs on this argument. I'm curious how it strikes you. Does it seem sound?

Click to expand...

Physicist here (though I don't presume to speak for all of us!).

Regarding the bolded, I wouldn't say it's quite accurate. Physics studies everything that exists physically and that we have evidence for - either physical evidence (detected directly or via machine) or as the consequence of a theory which has proven true in other situations (eg a black hole, which were studied by theory long before evidence for their existence was discovered). However, what physics does not do is study social/psychological phenomena, for which a link to the physical world has yet to be found - phenomena such as the concepts of 'conciousness', 'free will', 'God', 'love', 'democracy' or 'capital'.

With that said, however, one of the most fascinating modules I did at university was called "Chaos and Complexity" The module looked at the staggering power of emergence - whereby simple micro-rules can lead to macroscopic phenomena which are both incredibly complex and hard to explain, and for which there is not an obvious link back to the micro-rules.

As such, both interpretations are currently open. Either physical matter is all there is and phenomena such as conciousness are simply emergent phenomena from the insane complexity of the human brain, or there is something else which allows these things to exist and cannot ever be explained by physical means - a Descartian dualism or something similar. Physics has yet to either come up with the answer, or to meet and discover it's limits in the field.

Paschendale said:

I don't think anyone suggests that we have theories to cover everything. We very clearly don't. Now, you're conflating this with the conclusion that there is nothing outside of physical existence.

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Let me see if I can clarify: the argument I presented (well, more like outlined at a very high level) leads to that conclusion. In discussion of physicalism, this has emerged as the strongest--or at least most often cited--argument in favor of physicalism. If physics studies everything there is, then everything there is, is physical.

I do not mean to suggest that this is the only argument one might adduce in support of physicalism. It does seem to be the most powerful.

Paschendale said:

That one people do think, because no one has ever encountered credible evidence of anything non-physical. Ghosts and spirits do not appear to exist and do not leave behind any evidence.

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This seems false to me. It's very easy to say this, and I used to believe it myself. However, I changed my mind after reading through some journals of parapsychology, and found nothing like the sloppy procedures and questionable conclusions I was expecting to find. I think it's become common for people who are committed to materialism to repeat this accusation, but I think it's just false.

That said, this doesn't mean that ghosts do exist--merely that there's evidence they do. It also doesn't mean that ghosts aren't physical phenomena.

Paschendale said:

This is likewise why no one bothers with a theory that the oceans aren't made of marshmallows. There's no reason at all to think that they are.

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Oh, sure. But there's some reason to think that physics is not complete--at least some such reasons are mentioned in this thread so far. Max Black may have posted the best version of what has come to be called the property argument, though I think Descartes deserves credit for it. Basically, physical objects (rocks, protons, clouds, planets, etc.) and mental objects (thoughts, dreams, motives, intentions, imaginings, etc.) seem to have radically different properties. I can hold a rock in my hand, discover its mass, take it apart to find its composition, and so on. I can do none of those things with an impression, an emotion, an intuition, a dream, an intention, and so on. This is because the properties of physical objects and mental objects seem to be entirely at variance. Presumably, properties that differ so radically must inhere in radically different substrata.

How much credence one gives to this argument--especially the last bit (cf. Chalmers' property dualism)--seems to vary with the strength of one's other comittments. I find it to be a reasonably strong argument. At least it's not obviously bad, which means the case is not open-and-shut.

Paleocon said:

It's complete and utter nonsense that no rational person can consistently abide by, since reason is itself not a physical thing.

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My tendency is to agree with the sentiment, though maybe not the exact wording, of this point. But let me play devil's advocate for a little while. The answer back would go something like this: reason is an emergent system by which information is managed by physical brains. Both information, and the management system itself, are just abstract terms that describe features of the physical system.

Here's an analogy: imagine 3 rocks on a table. What actually exists are these three rocks; we have invented an abstract concept (the number 3) to describe a feature of what exists.

JoG said:

When Einstein was developing his theory physicists thought physics was complete, anyway.

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This is an interesting point, and at least some physicists with good credentials and reputation have suggested that physics has already strained the commonsense definition of "physical," to the point that we really need an entirely new set of concepts before physics could be considered complete in the (epistemic) sense at issue in this thread.

In other words, Einstein and Bohr left us with entirely new concepts whose implications are still being worked-through. But we made need yet other new concepts before we can adequately describe minds.

iangb said:

Physicist here (though I don't presume to speak for all of us!).

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Nor I for all philosophers.

iangb said:

Regarding the bolded, I wouldn't say it's quite accurate. Physics studies everything that exists physically and that we have evidence for - either physical evidence (detected directly or via machine) or as the consequence of a theory which has proven true in other situations (eg a black hole, which were studied by theory long before evidence for their existence was discovered). However, what physics does not do is study social/psychological phenomena, for which a link to the physical world has yet to be found - phenomena such as the concepts of 'conciousness', 'free will', 'God', 'love', 'democracy' or 'capital'.

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I think this gets to the heart of my motive for posting this thread. I'm interested in public opinion about these matters, but professional opinion among philosophers is, if anything, even more fascinating to me. I've had a number of physicists tell me in private conversation that the notion that physics is epistemically complete (i.e. that if we know everything there is to know about physics, we would thereby know everything there is to know period) is questionable, at best. But many philosophers seem to advance it without the usual fear and trembling, which I find odd.

What I think is going on is that some philosophers seem to think that social and psychological phenomena will ultimately be reduce to physical phenomena. Physics is complete (so the story goes) because everything ultimately reduces to the subject matter of physics.

I'm not very convinced that this is so, however.

iangb said:

With that said, however, one of the most fascinating modules I did at university was called "Chaos and Complexity" The module looked at the staggering power of emergence - whereby simple micro-rules can lead to macroscopic phenomena which are both incredibly complex and hard to explain, and for which there is not an obvious link back to the micro-rules.

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I have a question about this:

Is it the case that there is no obvious link because no such link exists in principle, or is it only because we lack either the knowledge or computational or cognitive resources to establish the link?

In other words, for example, fluid dynamics is the study of how fluids behave. There are relations which describe how, say, water will flow over some object. What is in fact happening is that a gazillion water molecules are each moving over the object, but there's no way we could calculate a gazillion trajectories, and little point in doing so, since the relations we have describe the phenomena at a close enough approximation. Presumably, the behavior of the fluid is an emergent property of the beavhior of the gazillion water molecules. But in principle, we could build a computer powerful enough to calculate all those trajectories and have a fully worked-out reason why the fluid behaves as it does. The lack of an obvious link from micro to macro is caused by a lack of cognitive resources.

Similarly, one might say that the behavior of a spiral galaxy emerges from the behavior of many individual stars, nebulae, black holes, and so on. But in this case, in fact we lack knowledge, since apparent dark matter and dark energy play some role in that behavior, and we really don't have much idea what those could be. There's no obvious link from the macro back to the micro because we don't have the requisite knowledge.

On the other hand, it's possible to play the Game of Life on a stack of graph paper with a pencil. It takes a long time, but the various gliders and other patterns can be shown to be a direct result of the rules plus the starting conditions (and perhaps plus the presence of a conscious human observer). The emergent phenomena reduce neatly to those factors.

I'm not aware of another kind of emergence, though, and I've always wondered about this claim. There seems to be a strange kind of question-begging that often goes on. Some philosophers, for example, want to claim that consciousness emerges from the workings of the brain, but this happens in a non-nomic manner, so that working backward from consciousness to brain processes is simply impossible. But in the same breath, those philosophers want to insist that we know that consciousness emerges solely from brain processes.

There may very well be something I'm missing, or a good example of emergence that I'm discounting unduly or something, of course.

iangb said:

As such, both interpretations are currently open. Either physical matter is all there is and phenomena such as conciousness are simply emergent phenomena from the insane complexity of the human brain, or there is something else which allows these things to exist and cannot ever be explained by physical means - a Descartian dualism or something similar. Physics has yet to either come up with the answer, or to meet and discover it's limits in the field.

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This strikes me as correct, which is why I find the attitudes that some philosophers hold towards this argument a little odd.

ashurbanipal said:

There's a pretty popular argument in contemporary western philosophy that goes something like this:


Physics studies, and has at least some inkling of a theory for, everything that exists. Since this is so, everything that exists is a physical thing (since physics studies all physical things, by definition). Therefore, physicalism, which is the thesis that all that exists is physical stuff, is correct.


Is this argument right? Much more than people commonly realize hangs on this argument. I'm curious how it strikes you. Does it seem sound?

Click to expand...

quantum physcis has surpassed the classic physics which still forces some scientists to requestion their perception of reality and all other scientific claims made by materialists

ashurbanipal said:

My tendency is to agree with the sentiment, though maybe not the exact wording, of this point. But let me play devil's advocate for a little while. The answer back would go something like this: reason is an emergent system by which information is managed by physical brains. Both information, and the management system itself, are just abstract terms that describe features of the physical system.

Here's an analogy: imagine 3 rocks on a table. What actually exists are these three rocks; we have invented an abstract concept (the number 3) to describe a feature of what exists.

Click to expand...

Except that it's a basic principle of philosophy that a thing cannot give what it doesn't have. So no arrangement of matter could be sufficient to create an ability to consider universals (which are immaterial).

Paleocon said:

Except that it's a basic principle of philosophy that a thing cannot give what it doesn't have. So no arrangement of matter could be sufficient to create an ability to consider universals (which are immaterial).

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I'm not sure about this point qua basic principle. You seem to be appealing to a principle that effects must exist as potentials in their causes. Whether this is true is questionable.

However, I think in this case something like this is true. It's not easy to see how we'd ever get something like an intention out of non-intentional processes, no matter how we arranged those. Ditto consciousness, and a whole host of other mental phenomena.

Anyway, I'm not very good at playing devil's advocate on this, since it does seem there is a sharp distinction between reason as such, and the physical processes which we use to keep track of certain aspects of it. If this were not so, computers could exist in only a very limited collection of forms. But computers can be made of things as diverse as beads on wires, rocks in paper cups with numbers on them, vacuum tube arrays, magnetic cores, neural tissues, and of course silicon microchips. If reason were nothing over and above physical processes, we'd expect the physical processes which instantiate it to be more similar.

But there's a more subtle point to be made in favor of this point. Imagine the rocks-in-numbered-cups computer for a moment. Suppose there is a universe in which such a computer is the only thing that exists. It seems quite difficult to believe that, no matter how complex such a computer became, reason would come to exist in such a universe. Reasoning human beings invented such computers in order to keep track of certain processes of information. Without a person being present to interpret the results, all there would be is rocks moving in and out of cups here and there. Reason is reflected in such proceedings, rather than instantiated by them.

ashurbanipal said:

I'm not sure about this point qua basic principle. You seem to be appealing to a principle that effects must exist as potentials in their causes. Whether this is true is questionable.

However, I think in this case something like this is true. It's not easy to see how we'd ever get something like an intention out of non-intentional processes, no matter how we arranged those. Ditto consciousness, and a whole host of other mental phenomena.

Anyway, I'm not very good at playing devil's advocate on this, since it does seem there is a sharp distinction between reason as such, and the physical processes which we use to keep track of certain aspects of it. If this were not so, computers could exist in only a very limited collection of forms. But computers can be made of things as diverse as beads on wires, rocks in paper cups with numbers on them, vacuum tube arrays, magnetic cores, neural tissues, and of course silicon microchips. If reason were nothing over and above physical processes, we'd expect the physical processes which instantiate it to be more similar.

But there's a more subtle point to be made in favor of this point. Imagine the rocks-in-numbered-cups computer for a moment. Suppose there is a universe in which such a computer is the only thing that exists. It seems quite difficult to believe that, no matter how complex such a computer became, reason would come to exist in such a universe. Reasoning human beings invented such computers in order to keep track of certain processes of information. Without a person being present to interpret the results, all there would be is rocks moving in and out of cups here and there. Reason is reflected in such proceedings, rather than instantiated by them.

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How is its truth questionable? What examples are there of effects that do not exist as potentials of their causes?

Exactly.

Agreed.

Agreed.

ashurbanipal said:

There's a pretty popular argument in contemporary western philosophy that goes something like this:


Physics studies, and has at least some inkling of a theory for, everything that exists. Since this is so, everything that exists is a physical thing (since physics studies all physical things, by definition). Therefore, physicalism, which is the thesis that all that exists is physical stuff, is correct.


Is this argument right? Much more than people commonly realize hangs on this argument. I'm curious how it strikes you. Does it seem sound?

Click to expand...

Strawman

Paleocon said:

Except that it's a basic principle of philosophy that a thing cannot give what it doesn't have. So no arrangement of matter could be sufficient to create an ability to consider universals (which are immaterial).

Click to expand...

"To consider the matter A PRIORI, any thing may produce any thing" ~Hume, "A Treatise of Human Nature".

It is a rule of science, not philosophy, that things cannot give what they do not have - but even then, that all depends on how you measure 'what something has'. A neutral atom can give away a charged particle and in doing so give itself the opposite charge. Empty space can emit particles, vacuum can have pressure and a moving mirror with nothing shining on it will emit radiation (see 'virtual particles' and the static and dynamical Casimir Effect, respectively). Even in simple terms - a ball dropped off a cliff will gain kinetic energy; that energy merely existed beforehand as 'gravitational potential', not as something that you could measure by examining the ball alone. In science then, you must not only take into account what something has, but also what it has the potential to give. So who is to say that matter does not have the potential to consider the immaterial, despite not being immaterial itself?

ashurbanipal said:

I think this gets to the heart of my motive for posting this thread. I'm interested in public opinion about these matters, but professional opinion among philosophers is, if anything, even more fascinating to me. I've had a number of physicists tell me in private conversation that the notion that physics is epistemically complete (i.e. that if we know everything there is to know about physics, we would thereby know everything there is to know period) is questionable, at best. But many philosophers seem to advance it without the usual fear and trembling, which I find odd.

What I think is going on is that some philosophers seem to think that social and psychological phenomena will ultimately be reduce to physical phenomena. Physics is complete (so the story goes) because everything ultimately reduces to the subject matter of physics.

I'm not very convinced that this is so, however.

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The other most interesting module I did at uni was called the Philosophy of Science, and covered quite a lot of things on Hume, Popper, Kant etc. It was fascinating stuff - but it did disagree with the views you have described here that 'physics is all'. Science itself has a whole set of episemological problems, from sollipsism to Hume's Problem of Induction, and while I think those problems are not exactly of concern to the pragmatist, they don't point to a 'final answer' - yet, at least!

I have a question about this:

Is it the case that there is no obvious link because no such link exists in principle, or is it only because we lack either the knowledge or computational or cognitive resources to establish the link?

In other words, for example, fluid dynamics is the study of how fluids behave. There are relations which describe how, say, water will flow over some object. What is in fact happening is that a gazillion water molecules are each moving over the object, but there's no way we could calculate a gazillion trajectories, and little point in doing so, since the relations we have describe the phenomena at a close enough approximation. Presumably, the behavior of the fluid is an emergent property of the beavhior of the gazillion water molecules. But in principle, we could build a computer powerful enough to calculate all those trajectories and have a fully worked-out reason why the fluid behaves as it does. The lack of an obvious link from micro to macro is caused by a lack of cognitive resources.

Similarly, one might say that the behavior of a spiral galaxy emerges from the behavior of many individual stars, nebulae, black holes, and so on. But in this case, in fact we lack knowledge, since apparent dark matter and dark energy play some role in that behavior, and we really don't have much idea what those could be. There's no obvious link from the macro back to the micro because we don't have the requisite knowledge.

On the other hand, it's possible to play the Game of Life on a stack of graph paper with a pencil. It takes a long time, but the various gliders and other patterns can be shown to be a direct result of the rules plus the starting conditions (and perhaps plus the presence of a conscious human observer). The emergent phenomena reduce neatly to those factors.

I'm not aware of another kind of emergence, though, and I've always wondered about this claim. There seems to be a strange kind of question-begging that often goes on. Some philosophers, for example, want to claim that consciousness emerges from the workings of the brain, but this happens in a non-nomic manner, so that working backward from consciousness to brain processes is simply impossible. But in the same breath, those philosophers want to insist that we know that consciousness emerges solely from brain processes.

There may very well be something I'm missing, or a good example of emergence that I'm discounting unduly or something, of course.

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It's a big mix of lots of problems. I think (and I'd strongly recommend reading the first two of Pratchett's Science of the Discworld series, which have influenced me quite significantly in this opinion) that the problem is rooted in the way we describe the universe, in all it's chaos and complexity, with (to paraphrase) a language originally evolved to tell the other monkeys where the ripe fruit was. We explain the universe by telling stories ("the rock wants to be close to the ground so it falls", "the electrons move around the circuit and heat up the wire in the lightbulb so it glows" etc) but emergent processes do not naturally lend themselves to storytelling - eg "Given the laws of the Game of Life, why does Methusela patterns take so long to die?" or "Why does Langton's Ant build it's highway?". Even non-emergent sytems are proving increasingly complex - for example, how to interpret quantum mechanics so that it tells an understandable story is immensely difficult (and there are lots of different interpretations - eg Copenhagen, or many-worlds).

This problem is compounded by the two other things you mentioned - lack of knowledge (eg there is increasing evidence that our sense of smell, for example, uses quantum effects - we still don't fully know how the brain might use them) and sheer scale (billions and billions of rapidly interacting neurons). But I think the real problem is that many things do not work in a nice narrative way, and at the moment that's the overwhelmingly main way in which we understand things.

iangb said:

"To consider the matter A PRIORI, any thing may produce any thing" ~Hume, "A Treatise of Human Nature".

It is a rule of science, not philosophy, that things cannot give what they do not have - but even then, that all depends on how you measure 'what something has'. A neutral atom can give away a charged particle and in doing so give itself the opposite charge. Empty space can emit particles, vacuum can have pressure and a moving mirror with nothing shining on it will emit radiation (see 'virtual particles' and the static and dynamical Casimir Effect, respectively). Even in simple terms - a ball dropped off a cliff will gain kinetic energy; that energy merely existed beforehand as 'gravitational potential', not as something that you could measure by examining the ball alone. In science then, you must not only take into account what something has, but also what it has the potential to give. So who is to say that matter does not have the potential to consider the immaterial, despite not being immaterial itself?

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That man was just full of idiotic statements wasn't he? A finite being cannot create God, not even theoretically.

It is a rule of both. Your example does not alter the principle, as the potential energy is already present.

Paleocon said:

That man was just full of idiotic statements wasn't he? A finite being cannot create God, not even theoretically.

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There are a great many theoretical 'Gods' who have been created by finite beings such as ourselves - you don't believe in Gaia, do you? Or Thor?

Shine a laser at the sky. The beam has a finite source, but has the potential (barring obstacles, obvs) to continue infinitely.

You disagree with Hume - that doesn't lend weight to your argument that he is wrong, nor does stating your opinion lend it any more weight than it had the first time you stated it.

It is a rule of both. Your example does not alter the principle, as the potential energy is already present.

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'Potential' energy is not a property of an object itself, but only a property of the object when compared to other features. The kilogram mass on my desk has ~10J of GPE when compared to the floor in this room, ~100J of GPE when compared to the ground outside, 10 meters below. 'Potential' is not measurable by a direct study of the object, only by looking at what the object can do or by comparing it to something else which gives it that property.

With that in mind, there is no evidence that matter does not have the 'potential' to consider the infinite.

Is Physics Complete? Short answer, NO, nor will it ever likely be.
We have a rough understanding of things, call it a first approximation.
The pieces of the puzzle seem to fit, some even fit nicely.
But there are things out there, we do not fully understand.
Example: Dr Randell Mills thinks a ground state hydrogen atom,
still holds enough energy to emit a UV photon.
Is he wrong? His device does throw of UV at the right wavelength.
As we improve our ability to test and evaluate, and repeat said test,
we learn more.
Sometimes the old answers appear correct, sometimes just inaccurate,
sometimes they are wrong.

joG said:

When Einstein was developing his theory physicists thought physics was complete, anyway.

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They thought it was almost complete.

Einstein and the science of radioactivity changed that.