Can we speak intelligibly about non-physical entities?

[Ionian_Tradition]

To borrow from Hempel's dilemma, to posit "Physicalism" one must first provide a comprehensive definition of the term "physical". If one asserts that the term "physical" refers to that which is revealed through the various scientific theories which encapsulate our contemporary understanding of the "physical" world (quantum mechanics, general relativity, atomic theory, etc), one has failed to provide an adequate definition of the the term "physical" given that our contemporary understanding of the physical world is demonstrably incomplete. An example of this would be the fundamental conflict existing between the theory of relativity and quantum theory which presently drives the search for a "Grand unified theory". If one asserts that a future "complete physics" will round out our understanding of the physical world in its totality, one has appealed to a circular form of reasoning which states that all phenomena are explicable in terms of physics because a proper understanding of physics is that which explains all phenomena (including abstract thought, which begs the question that abstractions can be understood in terms of physics). Moreover, if one attempts to define the term "physical" in reference to a physics yet to be developed, has one truly said anything meaningful given that one cannot truly know what new physics will emerge? A cursory review of scientific developments made over the course of our species' history does not instill confidence that our "physics of the future" is guaranteed to reflect a physics similar to physics as it is presently known.

Given this, how is it that we can speak intelligibly of "non-physical" entities given that the term itself implies the understanding of that to which the term is antithetical ("physical" entities)? We have seen that we do not yet, and may never, possess a comprehensive understanding of the term "physical", how then can we speak intelligibly of things which are the opposite of that which has yet to be properly defined?


Questions for debate:

1. Can the term "physical" be comprehensively defined so as to provide meaning to the term "non-physical"?

[Divine Insight]

Are you arguing that the term "physical" is relegated to only that which can be understood by our present day understanding of the physical world? There was a time when modern physics was unknown to our species. Shall we then consider the present day findings we might consider "physical" to have been, at one point, "non-physical" by virtue of the fact that they were not encapsulated by the prevailing model of the day ? When you argue that "non-physical" refers to that which can never be encapsulated by a future model of physics, do you not realize that perhaps the same argument could have been made by our ancestors regarding the findings we take for granted at present that were at one time completely unknown to those who came before us?

You clearly do not understand the relevance of Quantum Theory. (see below)

Do you not think it somewhat presumptuous to assume that our present day understanding of the physical world represents the limits of our understanding?

It's not presumptuous at all. It's demanded by Quantum Mechanics.

Apparently you don't appear to understand that significance between Classical Physics and Modern Physics if you think that same sort of classical thinking can still be applied today.

At best, you can hope (against scientific evidence), that Quantum Mechanics will actually fail, allowing us to surpass it in a normal classical sense. However, if that's what you are hoping for, then you are indeed entertaining a dream that is not currently supported by Modern Physics.

Although, don't feel alone in that. There are actually many physicists who themselves hold out hope that Quantum Mechanics will indeed ultimately fail in some way. But like I say, that's not truly science. That's just a hope that our current scientific understanding is all wrong.

Are you quite sure that what you deem "non-physical" today will not be considered the text book physics of tomorrow? I'm not sure how you would go about demonstrating that you're asserting here is in fact the truth of the matter. Of course I see you have a ready made retort in the form of the following:

It has already been proven that this cannot possible be done in a conventional "Classical Way".

Therefore, if future physics textbooks of tomorrow someday explain the "non-physical" what will have actually happened is that we will have changed our definition and understanding of what we mean by "physical".

In fact, if spirit does indeed 'exist' then by that very proclamatoin it must have rules of existence that define it, (thus it must have it's own sort of "physics") even if alien to our way of thinking.

In short, if the "non-physical" actually "exists" then it's actually "Physical" in terms of it's own set of rules (i.e. The Natural Laws of the Non-Physical).

If you disagree that Quantum Mechanics is a complete description of "physical" reality and you think that someday Quantum Mechanics will fail and we will move beyond it, they you're probably not going to accept my model of reality because you are holding out for an imagined dream of something yet to come.

I can't argue with that, other than to point out that at this point in time all you have is a dream.

I'm basing my model on what we actually currently believe to know.

I'm not sure this is much of an argument. Of course you can appeal to what is known today, but what bearing does that have on our future capacity to add more to our understanding than you claim is possible? You can't argue that we'll never know more than we know today simply by appealing to the fact that today we only know X. This smacks of non-sequitur.

That's not the principle I'm appealing to.

Apparently you don't yet understand the difference between "Classical Physics" and "Modern Physics".

Modern Physics isn't merely an extension of "Classical Physics". It's a whole new ball-game. In fact, to be more precise it's a "Ball-less Game".

In Classical Physics the idea was that physical reality was indeed made up of particles in motion. It was basically a "billiard ball" description of reality. With nothing barring us from learning as much as we like.

Time and space where also believed to be "infinitely divisible" with nothing barring us from dividing up the universe as fine as we like.

That has all changed with Quantum Mechanics.

With Quantum Mechanics science has "lost it's balls".

And according to Quantum Mechanics, they are lost beyond hope of ever grabbing onto them firmly again.

So it's not just a matter of "learning more".

Quantum Mechanics actually predicts that we are at a "Dead End" in terms of classical style of investigation.

Like I say, apparently you don't fully appreciate this yet, or you wouldn't be suggesting that we can just "keep on plugging along" like we used to in the days of Classical Physics.

[Divine Insight]

I agree with some of what you say, but I would object that experiments verify that Quantum Mechanics is "true" only in the sense that limited experimental observations agree well with calculations. The question of "why?" is another matter entirely. The famous "Copenhagen interpretation" of Neils Bohr simply evades the question by saying, in effect, "Just do the calculations and don't ask questions." Even the experimental verification of Bell's Theorem explains nothing, only adds to the mystery.

I agree complete with your assessments above. The "Copenhagen interpretation" does not explain anything and like you say it just says, "Just do the calculations and don't ask questions."

Bell's Theorem also doesn't explain anything SAVE for showing us that the EPR "hidden local variables" can't work.

After more than 80 years, there is still no coherent broad theory behind the mathematical results. We have theories with no mathematics or experiment. and we have mathematics with no theory. The multiverse of String Theory is an example of very elegant mathematics with no possible experimental verification or coherent theory.

Well not only that but String Theory never even promised to "explain Quantum Mechanics" on the contrary it just accepts the Copenhagen Interpretation basically. The only thing String Theory has promised to do is meld together Quantum Mechanics and General Relativity, and thus far it has been nothing but an empty promise.

I had great hopes for Everett's "Many Worlds" interpretation in the 1950s, but that seems to have been ignored for decades in favor of the multiverses of String Theory, a quite different concept. Both ideas depend on multiple spatial dimensions beyond the three our brain can observe. Who is to say that these extra dimensions are not equally real and equally "physical" simply because they are separated from us by a tiny "distance" in a "direction" our 3-D brain is incapable of perceiving?

The "Many Worlds" interpretation has never impressed me as being a solution. While it can't be disproved, it certainly violates Occam's Razor to be sure. Rather than explaining the nature of reality it merely proclaims that nature is far weirder than we can ever possibly imagine. How does that help with anything?

May as well just say "God does it". The "Many Worlds" interpretation is basically no different from religion or mythology. It's purely a GUESS.

But you skipped the most reasonable interpretation of all. The "Hidden Variables" interpretation of David Bohm. Remember, these are NOT the EPR "hidden variables". David Bohm's "hidden variables" are non-local.

In other words, with David Bohm's interpretation you have to give up the idea of conventional classical "Cause and Effect" order underneath the quantum level.

I'll grant you that this may, at first glance, seem intuitively impossible. But there are actually ways to make sense of this interpretation. In fact, this interpretation is actually far more in harmony with General Relativity than any of the other interpretations.

These kinds of conversations are interesting, but unfortunately I'm about to cancel my Internet connection, so if I disappear mid-conversation you'll know what happened.

[JohnPaul]

I agree with some of what you say, but I would object that experiments verify that Quantum Mechanics is "true" only in the sense that limited experimental observations agree well with calculations. The question of "why?" is another matter entirely. The famous "Copenhagen interpretation" of Neils Bohr simply evades the question by saying, in effect, "Just do the calculations and don't ask questions." Even the experimental verification of Bell's Theorem explains nothing, only adds to the mystery.

I agree complete with your assessments above. The "Copenhagen interpretation" does not explain anything and like you say it just says, "Just do the calculations and don't ask questions."

Bell's Theorem also doesn't explain anything SAVE for showing us that the EPR "hidden local variables" can't work.

After more than 80 years, there is still no coherent broad theory behind the mathematical results. We have theories with no mathematics or experiment. and we have mathematics with no theory. The multiverse of String Theory is an example of very elegant mathematics with no possible experimental verification or coherent theory.

Well not only that but String Theory never even promised to "explain Quantum Mechanics" on the contrary it just accepts the Copenhagen Interpretation basically. The only thing String Theory has promised to do is meld together Quantum Mechanics and General Relativity, and thus far it has been nothing but an empty promise.

I had great hopes for Everett's "Many Worlds" interpretation in the 1950s, but that seems to have been ignored for decades in favor of the multiverses of String Theory, a quite different concept. Both ideas depend on multiple spatial dimensions beyond the three our brain can observe. Who is to say that these extra dimensions are not equally real and equally "physical" simply because they are separated from us by a tiny "distance" in a "direction" our 3-D brain is incapable of perceiving?

The "Many Worlds" interpretation has never impressed me as being a solution. While it can't be disproved, it certainly violates Occam's Razor to be sure. Rather than explaining the nature of reality it merely proclaims that nature is far weirder than we can ever possibly imagine. How does that help with anything?

May as well just say "God does it". The "Many Worlds" interpretation is basically no different from religion or mythology. It's purely a GUESS.

But you skipped the most reasonable interpretation of all. The "Hidden Variables" interpretation of David Bohm. Remember, these are NOT the EPR "hidden variables". David Bohm's "hidden variables" are non-local.

In other words, with David Bohm's interpretation you have to give up the idea of conventional classical "Cause and Effect" order underneath the quantum level.

I'll grant you that this may, at first glance, seem intuitively impossible. But there are actually ways to make sense of this interpretation. In fact, this interpretation is actually far more in harmony with General Relativity than any of the other interpretations.

These kinds of conversations are interesting, but unfortunately I'm about to cancel my Internet connection, so if I disappear mid-conversation you'll know what happened.

I have heard of David Bohm's ideas, but know little about them. I will do a little research before I comment.

[JohnPaul]

Divine Insight wrote:

The "Many Worlds" interpretation has never impressed me as being a solution. While it can't be disproved, it certainly violates Occam's Razor to be sure. Rather than explaining the nature of reality it merely proclaims that nature is far weirder than we can ever possibly imagine. How does that help with anything?

I disagree that the "Many Worlds" interpretation does not offer explanations. I read many ideas and explanations derived from it years ago, but nothing recently. All of them were speculation, of course, but so is almost any idea about Quantum Physics.

If we think of reality as a very large number of 3-D worlds (universes), similar to our own, arranged side-by-side and separated only by a very small or zero distance in a 4th spatial "direction," like 3-D pages of a 4-D book, then we can think of all objects and events we see around us in our world as merely 3-D "slices" of a larger 4-D reality.

A 3-D model of this 4-D reality would be like a tree or bush immersed in a block of ice and then sliced into many very thin 2-D slices and arranged like the pages of a book. Each page would be a separate 2-D universe separated from the others by a tiny distance in a 3rd dimension (direction) invisible and unimagined by the 2-D inhabitants of each 2-D page/world/universe. Got that?

Each page would be equally real and would simultaneously exist. Then we can think of our conscious awareness as continuously occupying or "scanning" through nearby pages until it randomly and temporarily "locks on" to a particular page, perhaps a version of our world containing a particular result of a quantum experiment we have just performed. It is not the quantum result which is random, it is our consciousness which randomly locks on to a world with a particular result out of many available worlds. This new world would also already contain all "entangled" quantum events, even very distant ones, related to that result, so no faster-than-light signals would be required to explain them.

In this interpretation, it is possible, although very improbable as predicted by quantum mathematics, that our randomly scanning consciousness would land on a very distant page that is very different from our familiar world. We would not be aware of this change, since all our memories contained in the new 3-D "slice" of our 4-D body in that new world would be memories of that new world. The researcher standing beside us in that world might be a Klingon, but we would not be surprised. In our new memories, he had always been there.

I will not ramble on here. You get the idea of the possibilities provided by "many worlds" available to us.

[Divine Insight]

I will not ramble on here. You get the idea of the possibilities provided by "many worlds" available to us.

Yes, I do understand the "Many Worlds" interpretation. But surely you can see that it has its own problems.

For example you say:

Each page would be equally real and would simultaneously exist. Then we can think of our conscious awareness as continuously occupying or "scanning" through nearby pages until it randomly and temporarily "locks on" to a particular page, perhaps a version of our world containing a particular result of a quantum experiment we have just performed. It is not the quantum result which is random, it is our consciousness which randomly locks on to a world with a particular result out of many available worlds. This new world would also already contain all "entangled" quantum events, even very distant ones, related to that result, so no faster-than-light signals would be required to explain them.

That almost sounds plausible until you realize that it truly makes no sense in the Many Worlds interpretation unless consciousness itself also splits.

You say that "our consciousness locks onto a particular page". But that implies that there is only a single consciousness that does this. But, if that were the case, that would render the "Many Worlds" interpretation useless. You'd be right back at square one with "random selection of a single outcome" again.

The whole idea of the "Many Worlds" interpretation is to avoid having to have only one outcome be chosen over the others.

So it's actually wrong to think of it as a single consciousness "locking onto a single page". What the "Many Worlds" needs is for consciousness itself to spit into every possible outcome so that all outcomes are realized and experienced unbeknownst to each other.

So not only would the universe itself be infinitely splitting into "Many Worlds", but consciousness itself would also need to be splitting into "Many Consciousnesses" .

This is why I don't even bother with the "Many Worlds" interpretation. It's just way too bizarre, IMHO. Not saying that it can't be reality. Just saying that I personally don't find it satisfying.

And it really should be called the "Many Consciousnesses" interpretation because that's what it requires. Otherwise it would be basically reduced to just one random event being chosen over the others. But that's precisely what it was trying to avoid. The "Many Worlds" interpretation requires that all outcomes are realized. And that requires that consciousness itself continually splits into many consciousnesses.

David Bohm's model looks a lot more inviting to me.

[JohnPaul]

I will not ramble on here. You get the idea of the possibilities provided by "many worlds" available to us.

Yes, I do understand the "Many Worlds" interpretation. But surely you can see that it has its own problems.

For example you say:

Each page would be equally real and would simultaneously exist. Then we can think of our conscious awareness as continuously occupying or "scanning" through nearby pages until it randomly and temporarily "locks on" to a particular page, perhaps a version of our world containing a particular result of a quantum experiment we have just performed. It is not the quantum result which is random, it is our consciousness which randomly locks on to a world with a particular result out of many available worlds. This new world would also already contain all "entangled" quantum events, even very distant ones, related to that result, so no faster-than-light signals would be required to explain them.

That almost sounds plausible until you realize that it truly makes no sense in the Many Worlds interpretation unless consciousness itself also splits.

You say that "our consciousness locks onto a particular page". But that implies that there is only a single consciousness that does this. But, if that were the case, that would render the "Many Worlds" interpretation useless. You'd be right back at square one with "random selection of a single outcome" again.

The whole idea of the "Many Worlds" interpretation is to avoid having to have only one outcome be chosen over the others.

So it's actually wrong to think of it as a single consciousness "locking onto a single page". What the "Many Worlds" needs is for consciousness itself to spit into every possible outcome so that all outcomes are realized and experienced unbeknownst to each other.

So not only would the universe itself be infinitely splitting into "Many Worlds", but consciousness itself would also need to be splitting into "Many Consciousnesses" .

This is why I don't even bother with the "Many Worlds" interpretation. It's just way too bizarre, IMHO. Not saying that it can't be reality. Just saying that I personally don't find it satisfying.

And it really should be called the "Many Consciousnesses" interpretation because that's what it requires. Otherwise it would be basically reduced to just one random event being chosen over the others. But that's precisely what it was trying to avoid. The "Many Worlds" interpretation requires that all outcomes are realized. And that requires that consciousness itself continually splits into many consciousnesses.

David Bohm's model looks a lot more inviting to me.

I am sure the "Many Worlds" interpretation has more than a few problems! I will try to address just a couple. First, the universe does not "split" (that is a different interpretation) with each new quantum event, and neither is a particular quantum result "chosen." The 4-D reality simply exists statically (although time passes equally in each page) and all possible results actually occur and exist simultaneously on different pages within the larger 4-D reality.

The concept of human consciousness is a big problem in itself. Perhaps it would be better to simply call it the "observer" occupying a similar "slice" of body on each page. Each "slice" thinks it is the only one, and thinks its universe is the only one, and that the quantum result has somehow been selected for it alone. Each slice of observer in adjoining pages is simultaneously observing slightly different results. Whether their is one big supervisory observer over all of them I won't even attempt to guess. Anyway, all possible 3-D observers exist equally and simultaneously, side-be-side in the larger 4-D reality, separated only by a very tiny distance (perhaps a Planck Length?) from each other in an invisible 4th "direction," but completely unimagined by each other.

I am only getting in deeper here, so I will give up for now. Some of this I read years ago and some is my own fill-in. The big problem with the "Many Worlds" and also the Multiverse is the almost impossible task of wrapping the mind around and truly visualizing the meaning of additional space dimensions which cannot be directly perceived or visualized by the human mind. Only four space dimensions are needed for Many Worlds, and 10 (or is it 11) for the multiverse. If we could truly visualize even one additional dimension, our concept of reality would instantly explode.

I still have not looked at David Bohm, but it is on my list of things to do, soon. Anything you have to say about his ideas would be appreciated.

John

[Ionian_Tradition]

Are you arguing that the term "physical" is relegated to only that which can be understood by our present day understanding of the physical world? There was a time when modern physics was unknown to our species. Shall we then consider the present day findings we might consider "physical" to have been, at one point, "non-physical" by virtue of the fact that they were not encapsulated by the prevailing model of the day ? When you argue that "non-physical" refers to that which can never be encapsulated by a future model of physics, do you not realize that perhaps the same argument could have been made by our ancestors regarding the findings we take for granted at present that were at one time completely unknown to those who came before us?

You clearly do not understand the relevance of Quantum Theory. (see below)

Do you not think it somewhat presumptuous to assume that our present day understanding of the physical world represents the limits of our understanding?

It's not presumptuous at all. It's demanded by Quantum Mechanics.

Apparently you don't appear to understand that significance between Classical Physics and Modern Physics if you think that same sort of classical thinking can still be applied today.

When have I argued that a classical interpretation of physics ought to be conducive with our present understanding of Quantum Theory?

At best, you can hope (against scientific evidence), that Quantum Mechanics will actually fail, allowing us to surpass it in a normal classical sense. However, if that's what you are hoping for, then you are indeed entertaining a dream that is not currently supported by Modern Physics.

I "hope" for nothing of the sort. Again, I'm not sure where you've acquired the notion that I am hopeful that Quantum Mechanics will fail. You've more or less asserted that QM represents the limits of our understanding, thus it is incumbent upon you to demonstrate this is true. If you prove successful, I will be more than glad to accept your claim. However, at present I remain skeptical of your ability to do this given that your assertion rests primarily upon the a priori assumption that QM represents the ultimate limit of our understanding..The veracity of which you've, as yet, failed to demonstrate. You're essentially arguing "X is all we will ever know because X is all we can claim to currently know." I don't find this a particularly compelling argument.

Although, don't feel alone in that. There are actually many physicists who themselves hold out hope that Quantum Mechanics will indeed ultimately fail in some way. But like I say, that's not truly science. That's just a hope that our current scientific understanding is all wrong.

What? Who "hopes" that our current scientific understanding will prove wrong? Care to substantiate this claim by citing a source? Skepticism regarding QM's capacity to describe the physical world in its totality, especially in light of its present incompatibility with General Relativity, is not an unscientific desire to see QM fail. Skeptical/critical examination of any scientific theory is science at work.

Are you quite sure that what you deem "non-physical" today will not be considered the text book physics of tomorrow? I'm not sure how you would go about demonstrating that you're asserting here is in fact the truth of the matter. Of course I see you have a ready made retort in the form of the following:

It has already been proven that this cannot possible be done in a conventional "Classical Way".

I'm not sure I ever argued that such a thing must be accomplished in a manner conducive with Classical physics. Where did you gather that I did?

Therefore, if future physics textbooks of tomorrow someday explain the "non-physical" what will have actually happened is that we will have changed our definition and understanding of what we mean by "physical".

Indeed, but you've not adequately demonstrated that you yourself understand what the term "physical" truly entails aside from arbitrarily asserting that it corresponds only with that which can presently be described by our modern understanding of physics...As if our present understanding of the universe represented absolute knowledge of the physical world in its totality. I doubt the vast majority of practicing physicists would be inclined to share your sentiment.

In fact, if spirit does indeed 'exist' then by that very proclamatoin it must have rules of existence that define it, (thus it must have it's own sort of "physics") even if alien to our way of thinking.

In short, if the "non-physical" actually "exists" then it's actually "Physical" in terms of it's own set of rules (i.e. The Natural Laws of the Non-Physical).

Then it would seem you grant that it is possible that our modern understanding of physics does not constitute complete knowledge regarding what the term "physical" truly entails given that the term "physical" could very well apply to phenomena foreign to what is presently understood within the framework of modern Physics (and Quantum Mechanics in particular). Why then argue that the term "physical" is relegated only to that which can be understood by modern Physics? Sounds to me like you've contradicted yourself here.

If you disagree that Quantum Mechanics is a complete description of "physical" reality and you think that someday Quantum Mechanics will fail and we will move beyond it, they you're probably not going to accept my model of reality because you are holding out for an imagined dream of something yet to come.

I can't argue with that, other than to point out that at this point in time all you have is a dream.

I'm basing my model on what we actually currently believe to know.

I'm not sure this is much of an argument. Of course you can appeal to what is known today, but what bearing does that have on our future capacity to add more to our understanding than you claim is possible? You can't argue that we'll never know more than we know today simply by appealing to the fact that today we only know X. This smacks of non-sequitur.

That's not the principle I'm appealing to.

Apparently you don't yet understand the difference between "Classical Physics" and "Modern Physics".

Modern Physics isn't merely an extension of "Classical Physics". It's a whole new ball-game. In fact, to be more precise it's a "Ball-less Game".

In Classical Physics the idea was that physical reality was indeed made up of particles in motion. It was basically a "billiard ball" description of reality. With nothing barring us from learning as much as we like.

Time and space where also believed to be "infinitely divisible" with nothing barring us from dividing up the universe as fine as we like.

That has all changed with Quantum Mechanics.

With Quantum Mechanics science has "lost it's balls".

And according to Quantum Mechanics, they are lost beyond hope of ever grabbing onto them firmly again.

So it's not just a matter of "learning more".

Quantum Mechanics actually predicts that we are at a "Dead End" in terms of classical style of investigation.

Like I say, apparently you don't fully appreciate this yet, or you wouldn't be suggesting that we can just "keep on plugging along" like we used to in the days of Classical Physics.

There you go again charging me with appealing to Classical Physics when I've done no such thing. Please stop misrepresenting my position by disingenuously asserting that I do not recognize the distinction between Quantum and Classical physics. Never have I argued that we require a classical or conventional method of investigation in order to further our understanding of the physical world. The very fact that QM is distinct from classical physics denotes that a classical understanding of physics is not the "end all" in terms of advancing our scientific understanding of the universe at large. With that said, it is somewhat presumptuous to assume that, given our incomplete understanding of even the quantum world, QM is itself the "end all" in regard to our understanding of the physical world.

[Divine Insight]

What? Who "hopes" that our current scientific understanding will prove wrong?

Anyone who is still clinging to an idea that physics can move beyond Quantum Mechanics. That's "hope" that is not supported by current modern "science" because Quantum Mechanics is current modern science.

Care to substantiate this claim by citing a source?

The Heisenberg Uncertainty Principle. (a mathematical relationship that is part of Quantum Mechanics)

Skepticism regarding QM's capacity to describe the physical world in its totality, especially in light of its present incompatibility with General Relativity, is not an unscientific desire to see QM fail.

Perhaps not from a philosophical point of view, but as a practical matter it is.

Besides, maybe it's General Relativity that's incompatible with QM, did you ever think of that? After all, QM is the most successful theory in all of science.

Skeptical/critical examination of any scientific theory is science at work.

Using that ideal, you're basically handing "spiritualists" and "supernaturalists" a silver platter proclaiming that they are indeed "doing Science" by refusing to accept current scientific knowledge in the hopes that they can move beyond it.

I'm not sure I ever argued that such a thing must be accomplished in a manner conducive with Classical physics. Where did you gather that I did?

You implied it when you compared our present day knowledge with previous eras of science and suggested that we moved forward from those ideas so why can't we do it again.

The reason we can't do it again is precisely because of the Heisenberg Uncertainty Relationship (or the discovery of complementarity as Neils Borh prefers to call it).

So for you to suggest that we could just keep plugging along like we did back in the days of Classical Physics implies to me that you don't fully understand why that principle no longer holds.

Indeed, but you've not adequately demonstrated that you yourself understand what the term "physical" truly entails aside from arbitrarily asserting that it corresponds only with that which can presently be described by our modern understanding of physics...As if our present understanding of the universe represented absolute knowledge of the physical world in its totality. I doubt the vast majority of practicing physicists would be inclined to share your sentiment.

You're simply misunderstanding what I've said. Go back and re-read my first post to this thread, specifically the following three paragraphs:

I personally believe that it not only can be, but that it already is sufficiently defined via the mathematics of Quantum Mechanics. Granted, a definition that may not be readily accessible intuitively to the man on the street. Or any non-mathematician, for that matter.

{snip}

Having said all of the above, if we then allow the mathematics of Quantum Mechanics to "define" precisely what we deem to be "physical", then clearly there must exist a "non-physical" reality beneath the "physical world".

This "non-physical" reality would only be "non-physical" in the very precise sense that it simply cannot be described by "physics" or any laws of "physics" that we can determine. And in that sense it makes perfect sense to speak of the "non-physical" as still being "real" and having obvious properties and behavior that we can know exists, but cannot define precisely in terms of "physics".

I've already given my "working definition" of what I define as "physical" based on science.

If you wish to contest that, so be it. But then please offer your own definition of what you consider to be "physical". Otherwise your very question has no meaning.

I'm actually appealing to Quantum Mechanics (our current most successful scientific mathematical description of what we mean by "physical" yet)

Therefore I have a very precise definition of what I mean by "physical" and therefore I can speak in an intelligent way about 'non-physical' entities. Entities that most likely exist because they have an affect on our physical reality, but cannot themselves be considered to be "physical" by our current scientific definition of what we mean by 'physical' according to physics, (i.e. Quantum Mechanics).

There you go again charging me with appealing to Classical Physics when I've done no such thing. Please stop misrepresenting my position by disingenuously asserting that I do not recognize the distinction between Quantum and Classical physics. Never have I argued that we require a classical or conventional method of investigation in order to further our understanding of the physical world. The very fact that QM is distinct from classical physics denotes that a classical understanding of physics is not the "end all" in terms of advancing our scientific understanding of the universe at large. With that said, it is somewhat presumptuous to assume that, given our incomplete understanding of even the quantum world, QM is itself the "end all" in regard to our understanding of the physical world.

But that was precisely what the Einstein/Bohr debates were entirely about.

"Can a Quantum-Mechanical Description of Physical Reality Be Considered Complete?"

They both wrote papers using precisely this same title.

Einstein said, "No", while Bohr said, "Yes".

In fact, Bohr argued that the Heisenberg Uncertainty Principle (or the principle of what Bohr calls "Complementarity" demands that it necessarily must be complete. At least complete in the sense that it is as far as we can ever go.

Einstein's objections were based on his suspicion that "hidden local variables" could potentially be discovered at some point to further our understanding of QM.

However, John Stewart Bell changed all that with "Bell's Theorem", which was experimentally testable, and fell in favor of Borh, and proved that Einstein's "hidden local variables" could not be used to further explain QM.

And that's where we stand today.

In other words, we stand at a point where QM must be "complete" in the sense that we can never know more about the nature of the "physical" world than we already know.

That's where we are right now.

Some people appeal to String Theory as possibly going beyond this, but even String theory doesn't truly promise to go beyond this. All string theory does is accept QM and promise to potentially describe General Relativity in terms of QM.

But even that promise has never been realized to day. So far it's just an empty promise. But even if it did come to pass, it wouldn't have made any progress deeper into the mysteries of QM.

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I'm not trying to misrepresent your position at all.

I'm just trying to respond to your question, "Can we speak intelligibly about non-physical entities?".

I can, because I have very methodically defined what I mean by "physical" by simply accepting QM as a final mathematical definition for that. Therefore when I consider potential processes beneath the quantum level I can meaningfully refer to those processes as being "non-physical" and rightfully so. Because when speaking of processes in the realm, the laws of "physics" go out the window.

For one thing we move from a "local" environment (i.e. an environment governed by the speed limit of light), to a "non-local" environment (i.e. an environment where there are no propagation delays (and thus no conventional classical sense of "cause and effect").

A very strange realm to be sure, and thus deserving of being called "non-physical" IMHO.

Yet, we have very good reasons for believing that such a non-physical realm exists.

Just like John and I were discussing,... even if that ends up requiring "Many Worlds". Although I personally feel that there are even better pictures to be had, like the picture proposed by David Bohm and make almost "intuitive" by Richard Feynman independently via his insight into his concept of "Sum Over Histories".

Anyway, I'm not even remotely attempting to misrepresent you. I was addressing your notion that we should be able to just "Keep on plugging along as before". That's what appears to be "Classical thinking" to me.

QM says, nope, we're done from that local perspective. To "move forward" requires a whole different perspective (i.e. a non-local perspective).

And that's going to be totally different from what we currently think of as being "physical". So we may as well be prepared now to refer to this new realm as being a "non-physical" realm.

[asymptotic freedom]

How about the distinction between concrete and abstract objects? Concrete objects enter into causal relationships with each other, abstract ones don't, they are inert. We assume that concrete objects will obey some type of physical that we can investigate, at least hypothetically, and be able to understand their interactions. That is a result of their being in causal relations, whether probabilistic or deterministic, with other concrete objects.

[JohnPaul]

Divine Insight wrote:

And that's going to be totally different from what we currently think of as being "physical". So we may as well be prepared now to refer to this new realm as being a "non-physical" realm.

Why call it "non-physical"? Even if multiple space dimensions exist, as both Many Worlds and String Theory claim, why should they be any less "physical" than what our feeble brains see around us now?

What about virtual particles which pop into existence out of nowhere and then vanish, leaving no trace? Where do they come from? Where do they go? What happens to their mass and energy? I have read that QM allows all this to happen throughout the universe around us by saying that such particles exist for such a short time that the laws of physics can't catch up with them. Really? Reeealy? The Heisenberg Uncertainty Principle can't be sure they really exist, so ignores them?