I am giving an informal talk soon on the subject of physics and reality, and in it I plan to pose the question: "Do we design physics to be able to conceptualize reality, or do we conceptualize reality so that physics will work on it?". I'd appreciate the thoughts of people on here who have given this general topic some consideration. Note that I'm not suggesting that any old physics could be posited and some reality could be found wherein it worked, I think that would require an obviously bogus definition of reality. What I really mean is, we have an approach to doing physics, which in turn controls the kinds of questions we can get answers to. The answers to those questions in turn affects our concept of reality. So was the reality there first, and we are just using physics to map it like Lewis and Clark, or is our concept of reality more like the concept of the terrain that you can see from a canoe?

Physics is the language of reality. Its a language that grows and evolves as we better understand what reality is. New terms are created as new forces are identified, old terms for processes no longer relevent are discarded, or sometimes, they evolved along with the knowledge they attempt to define.

Reality is what it is. Electrons bind to Protons, fires radiate heat, planets orbit stars (sometimes ), and the Universe exapands around us, whether we know exactly how to describe it or not. Physics is the expression of the how and why, and sometimes when, of the universe around us.

I don't think its fair to say either Physics defines Reality or Reality defines Physics any more than a noun defines a verb or a verb defines a noun.

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The last time I felt a warm fuzzy feeling, I was informed by my doctor that it was just gas.

I'll join in. I think Physics is best described as our version of reality. We see something and do our best to characterize its attributes with our current knowledge. This is blatantly obvious when our theories are forced to change due to new information and better understanding.

IMO Our goal in science, as you can see in my signature, is to understand the physical world without error. Of course that is a lofty goal. So, from where I stand the world is (or laws thereof are) fixed and we want to figure them out. Physics is our best approach to do so.

Unlike Lewis and Clark however I don't see physics changing as geology changes. I think it stays the same, and only our perception changes as our understanding grows. Physics is of course our tool; the better we use that tool the more we know.

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Very often, our physics changes because we come up with some new way of conceptualizing the world. The canonical example of this is relativity theory. In the 1905 paper, Einstein revolutionizes our idea of time by pointing to physical processes of determining simultaneity. Holding this fast, he then proceeds to point out aspects of time and space that would otherwise conflict with our intuition of these concepts.

Thanks for your thoughts. To give you something more concrete to chew on, you might also wish to consider the question against the backdrop of the example concepts of space and time. Are these "real" entities that physics has led us to an understanding of, or did we manually imbue reality with these qualities so we could better conceptualize our physics? Or is it more like the "chicken and egg" aspect of Doodler's comments, that we developed physics even as we were imbuing reality with these concepts that worked hand-in-hand with the physics we were developing?

Perhaps, somewhat along the lines of Doodler's post, it's a false dichotomy?

Perhaps "physics" plays "nature" and "reality" plays "nurture" (or vice versa)?

Or perhaps, since they're both 'just' mental constructs, the questions can only be answered via neuroscience?

Or, to the extent that we are social beings, they are both 'just' social constructs, the questions can be answered best by sociology?

I expect that the above is more noise and distraction than possibly helpful inputs.

So, narrowing the focus somewhat ...

We 'design physics' to find cool new experiments and observations to conduct. Or, rather, we should - the apparently blind alley string theory (etc) has lead us into is, in this view, an aberration. Its relationship with reality is, today, merely incidental.

Our concepts of reality are, today, pretty much defined by physics (in the broad sense - if no physicist has, or could, imagine it, then it's not real), an early 20th century revolution that was completely successful - Kwalish Kid made half this case above.

Taking a more data driven approach - a key driver is neither conceptualisations of reality nor the ease of doing physics, but rather some resonance of brain circuits - the beauty of the idea, the glimpses of sublime elegance, and so on. A.k.a. the string theory swamp which too many of us are mired in today.

Our posts crossed ...

In this particular revolution, the chicken and egg reign.

In the other early 20th century revolution, our minds still baulk at what the physics seems to say about what the underlying reality might (or should) be. In this example, the questions in the OP are somewhat irrelevant ...

As a non-physicist but avid reader of same, I'll toss out the idea that physics is our best model of reality. The universe would be here without us to pontificate upon it so I subscribe to the idea that reality came first.

My big question is: "Why is it so stinkin' complex?" Why so many disparate forces, particles, possible dimensions and non-intuitive aspects to the universe? One would think that a universe would unfold in a reasonably simple manner.

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"The universe is a big place, perhaps the biggest."

-Kilgore Trout

The 13.7 billion dollar question.

The determinist would say, "Because that's how it works."

The relativist would say, "Because stuff happens."

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The last time I felt a warm fuzzy feeling, I was informed by my doctor that it was just gas.

science is a bit like a blind man walking through the world feeling his way trying to make a mental model of the world. He might have a certain model and then bam he walks into a lamp post thus ending his model of roads that are clear but boarded by walls.

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Hum,
The Buddhist would say, "everything is an illusion."

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`Irony` actually does mean `metal like`...

Don't sell the Buddhist's short. They developed some quite interesting logic. (I have the Dover 2 volume set in my library, but I haven't yet had time to read it.)

Following from some of the later Hindu philosophy, their illusion is, I suspect, a different kind of illusion that that we think of in the West. The illusion from that tradition is more akin to perspective. Sure, what we see of the world is not the ultimate truth, but it is the world as we experience it, and thus it is a part of us and through that a part of the world as it really is. This supports a very interesting and sophisticated tolerance.

Perhaps this is relevant to the topic at hand.

A false dichotomy, that might indeed be a good way to approach that question (it wasn't actually intended to have a clear-cut answer, but note that most "knee-jerk" kinds of reactions to what physics is would tend to suggest it did). Your "nature" vs. "nurture" idea is also promising, and indeed I would say ironic, when reality finds itself on the side of nurture not nature! That in a nutshell is why I'm asking the question.

Interestingly, I don't think that approach will ever lead to an answer. I don't think neuroscience will ever do philosophy, either. It's like asking someone who knows how to build computers to run a program without turning the computer on!
That's a really sticky one, to try and trace how society controls the kinds of questions we ask. We are talking about objective reality here, so it's difficult for sociology to add to that, because by definition what is objective cuts across societal boundaries. But there is the issue of what objective questions are subjectively deemed to be worth answering, so sociology might indeed have something to say here.

Not at all, the attention should indeed be placed on the framing of the question, or it will not be ready to look for an answer!

That is true, I was really focusing on theoretical physics. I see the experiments as the kinds of questions we are allowed to ask (like "yes or no" questions in the 20 questions game), and physics and reality are the concepts we build up from the answers. I think most scientists tend to view reality as the person giving the answers, the experiments as the questions, and physics as the solution to the puzzle. But the interesting thing about "20 questions" is that you can't tell if the person really had an answer in mind all the time, or if they are constantly narrowing the possibilities with each answer, waiting until the end to choose a solution consistent with all answers given! So the OP is like asking, which type of "20 questions" are we playing, and how can you tell the difference?

Yes, this is very much where I'm coming from as well-- in other words, the physics can get out in the lead of our views of reality, such that our current view of reality depends not just on the sum of all the answers we've gotten, but it also depends on the questions we've asked. It may be a false dichotomy to focus on only one or the other, but it is enough to note that our impression of reality has come from both the allowable questions and the answers. Following the 20 questions analogy a bit farther, how often have you played that game, and someone has asked you what seemed like a yes or no question, but you wanted to say "usually" or "not in the way you probably think". But if you are only allowed to say "yes" or "no", you can see how the very questions asked, as much as the answer, could start to limit the ability to find the solution.

I also have in mind string theory as the ultimate example of physics leading reality, so it will be especially interesting to see if future tests can establish this as physics following reality in a prescient kind of way, or simply physics trying to define reality to kind of aggrandize itself.

I think this is kind of the "standard model" of what physics tries to be, but it is also what I am questioning.
That's an interesting perspective, because I generally see it from the opposite point of view-- why is it understandable at all? In other words, what business do relatively intelligent apes have predicting the behavior of hydrogen atoms they have zero personal experience with to better than a part in a million? How on Earth have we been able to construct the history of the entire universe, and figure out how we came to be here? How fair is it that many came before these were known, and how fair is it to us that many more may come later and be involved in revolutions of thought about reality that would make our heads swim? In short, how is it possible that our best minds have become so deeply "plugged in" to the fabric of reality that we have started talking about a "theory of everything"? At some level, I get a sense we are looking into a mirror, and saying, "look, I have that guy so figured out, I can anticipate his every move."

This would have been a startling insight into the "Science vs. Religion" thread. I wish I had said it so well, especially if you are talking about subjective experience, some part of which we may assume is also a shared objective experience but not necessarily all. I presume that is the source of the "tolerance" you refer to, which is what that thread was all about.

This topic always makes me think of Hermann Weyl's The Open World, one of the best short works on this subject. It was originally a series of semi-public lectures, so it's very accessible.

A particular quote always comes to mind...
http://www-groups.dcs.st-and.ac.uk/~...roduction.html

You might want to take a look at this paper in the abstract archive:
On the intelligibility of the universe and the notions of simplicity, complexity and irreducibility
G.J. Chaitin
http://arxiv.org/abs/math.HO/0210035

I only mention it because it contains some great stuff from Hermann Weyl, who would recommend but his good stuff (The Open World, The Philosophy of Mathematics and Natural Science) is hard to find. Though the intro to Space, Time, Matter is pretty good.

It is my opinnion that there is "a" reality (an "absolute reality" if you will) underlying the universe that we "see". Physics is the tool we use to probe what we see to determine the underlying reality. Our understanding is far from complete, but we have made tremendous progress in the last few centuries (especially the last one), but we still have a long way to go.

A good example is the "wave/particle duality" of electromagnetic radiation. Today, when we look for (set up experiments to find) waves, that's what we find. Conversely, when we look for particles, we find particles. Some day we may find the true underlying reality that will explain why we find what we are looking for.

Another: Today, we have two great theories - GR and QM. Both work very well within limits, but they don't "mesh". It's all the same universe, so our understanding must be incomplete. Again, some day we will find a way to make them work together

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

Reading some Thomas Kuhn might be inspirational.

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"A witty saying proves nothing" Voltaire.
"All your bias are belong to us" Ara Pacis.

The way I see it, our concept of reality is bound to our concept of physics. Physics & mathematics are inventions of the human mind, and are themselves dependent on how our brains function, and especially on the fact that our thoughts tend to be dominated by language rather then imagery. We are only able to discover realities that are discoverable through physics, as we have designed it, so a strong selection effect is at work.

Whether or not the philosphers "true reality" exists outside ourselves is irrelevant; if it is not a reality amenable to physics, we will never know. But I suspect that this philosopher's "true reality" really exists, and is the primary reason why physics gets as complicated as it does, once we are removed from the realm of common experience. We can only approximate "true reality" with the models of reailty that we build from the tools at hand (physics). Hence, to follow the Kaptain's lead, waves & particles are all we have to work with, so we model everything in the universe as waves & particles (and fields perhaps). "True reality" is not waves or particles, so a rough approximation is all we get.

The result of all this is that we close in on "true reality", but never quite get there. We approach it asymptotically, creating models that we call "reality", for want of a better word. But "true reality" remains so elusive that we cannot even be reliably certain that there is such a thing. Unless of course, like Descartes, you are satisifed with cogito ergo sum.

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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell

I refute it thus! [kicks a huge stone - ouch]

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What brings us together is stronger than what pulls us apart

This seems like a good argument to the contrary, to me. What you are saying about the wave/particle duality sounds a lot like the version of "20 questions" I was talking about where the answerer awaits the questions before deciding on the solution to the game. When the questions determine the perception of reality, then the reality seems to be created "on the fly" to make the questions make sense. We may already have as much as we'll ever get-- the wave function, and that may be as deeply into it as reality goes. I agree that it doesn't seem like reality in the "normal" way we view it, that's part of why we can ponder these questions.
How do you know? You're assuming what we have yet to determine about reality. Maybe there is simply no way to unify them, just as one cannot completely unify a wave and a particle picture. Maybe as long as those are the questions we are asking, those are the answers reality will give us-- or more to the point, our concept of reality will always have that "hole" because it is a result of those questions.

You have probably read more about the wave-particle duality than I will in my entire life already, but I found this a couple of days ago and figured what the heck?...

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"A witty saying proves nothing" Voltaire.
"All your bias are belong to us" Ara Pacis.

Tim's statement is interesting, but he's easily refuted by my first post here. Forces operate by rules, whether we're aware of the rules and forces involved or not. What is imperceptable now will not always be imperceptable, if we continue answering the questions by defining the unknowns. One question at a time, one rule at a time, the language of physics is deciphered. Math is nothing but a Rosetta stone that gives us a start point. The alphabet to the language.

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The last time I felt a warm fuzzy feeling, I was informed by my doctor that it was just gas.

And yet horribly, horribly misleading. Kuhn is quite popular. Indeed, his Structure of Scientific Revolutions is the most popular english language textbook, I believe. However, his popularity is not among philosophers of science, who tend to take a dim view of both his history of science, his sociological conclusions, and his philosophical conclusions.

Edited to remove grammatical error. Thanks Nereid.

Hear! hear!

(I think you meant 'those who study the philosophy of science', but it's equally true, I think, among scientists ...)

And scientists, today, also take a dim view of his descriptions of what they actually do ... (not that it's all wrong, but that it omits much, and seems to focus on the wrong sorts of things ... as well as being wrong in places).

Glad you liked it.

That the question does not have - or, perhaps, cannot have - a clear-cut answer may be the most satisfying conclusion.Perhaps as mind-stretchers, or 'a more general set of considerations' these two might be interesting.

In the scope of your talk, I'd guess they are just too far off-track.I feel the experimental side is oft overlooked or overshadowed.

Why not consider the doing of the experiments as at least partly an end in itself?

Or why not consider that the experiments may open new doors to reality which neither our perceptions of it nor physics (theory) hithertofore had even hinted had existed?

I'm reminded of something ngc3314 (I think it was him) said - re proposals for HST/Chandra/XMM-Newton/etc telescope time: the allocation committees ranked them A, B, or C, according to criteria that we may summarise as 'answer well-formulated questions in current theories'.

While most (perhaps nearly all) A and B proposals did indeed return good results (when evaluated a year or so later), the impetus for the really interesting new/future areas of research often came from the C proposals.

Physics as discovery or physics as serendipity doesn't quite fit nicely into your question, but (I feel) is an important aspect.This might be worth exploring further ... instead of GR, let's use quantum theory (QT) as the example.

The 'reality' that QT seems to paint is notoriously difficult for us to grasp, yet the experimental validation is truly astonishing.

I don't think that particular physics was 'designed to conceptualise reality', it is just too wild.

Nor do I think we can conceptualise reality in any helpful way, the better for us to do (QT) physics.

In this case, I think the '20 questions' game is being played in a code that has clear questions (the experiments), reality supplying the answers, but physics being Searle's Chinese Room.The point I was trying to make is that string theory is physics as narcissism, which is perhaps a form of 'physics leading reality'.

Perhaps Ken G will come up with a brand new refutation of Kuhn.

I am not Kuhn's biggest fan, either, but when it comes to whether "we design physics [and science in general] to be able to conceptualize reality, or [...] conceptualize reality so that physics will work on it", his notion of paradigm is definitely pertinent.

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"A witty saying proves nothing" Voltaire.
"All your bias are belong to us" Ara Pacis.

Of course do we make physics in order to conceptualize reality!!!
But the inverse of it is more true, than i think you think( Ken G).
Think of a certain Quantum Cat. You do a 50/50 photon experiment on her. Whilst the apparatus is running through it's preprogrammed routine, you use the idle time to ponder as to the reality in the closed box. As you are learned, you will come up with some mixed state conception of sorts. Now your little doughter unforseen enters the scene and smells some poison stuff.............You will have a hard time explaning to her that you really arn't cruel or something, but just doing science. Your silly offspring has definitively a quite naive conception of reality. She can't yet fully grasp the notion of a physical observable and just empathizes with that little creature in the box. In her youthful mind she simply doesn't realize, that pain is afterall not fundamental but just a secondary, derived entity. Now Penrose does his appearence, inviting you to a talk in the caffeteria....

i think i will go for a tea

Wrt the scope of Ken G's question (and talk), I think we can safely say that, at this level, reality and physics are seamless.

With classical physics and quantum theory (and its experimental verification!), there's little in the way of stones you could stub your toe on that are not just as much physics ... and that includes the pain signals that travel to your brain!

The kind of reality and physics that Ken G's question refers to is beyond the ken of any of us in our daily lives, unless, perhaps, we are doing leading edge physics research or are cosmologists (I'll cover possible exceptions later in this post).

There are, of course, plenty of gaps to plug and interesting questions still to answer - I recently read that we now have some good answers to how coffee rings form, and that this new understanding lead to an improved process or three in the fabrication of semiconductors (IIRC) - but 'new physics' likely won't have any direct impacts on any of us.

Now for the exceptions (well, a sample of them anyway):

* neutrinos: do flavours matter?

* cosmic rays, especially the very high energy ones: is there a wonderous new world hidden in the primaries that are the parents of the ones passing through your body?

* dark matter: what is it?

* Pioneer anomaly: awaiting a mundane explanation, or a hint of something profoundly new?

* dark energy: what is it?

The first three may well be 'just' a part of whatever subsumes the Standard Model (of particle physics); perhaps all five will be too. Perhaps what's beyond the Standard Model will lead to some magic as transforming as lasers and semiconductors ... and a new conceptualisation of reality to boot.

Nereid,

Is this meant as an aside to my piece above ?
In the science and religon thread Ken G allows, that the human existence "must be viewed as the most importent of all" (true so). There are certain who think the thinking is informing us about our existence (cogito ergo sum). Others meight argue, pain can be doing that the fast lane. In the sensing of pain, the acuteness of this expirience seems to be the more real part. "Signals going along the nerves" seems the conceptualisation part here.
The natural scope of physics causes it to put things on it's head. The elementary building blocks of nature are only of secondary importance to nature herself. She seems very angry with her own initial bubbeling -quntum -chaos sort of state, and hurries to form Structures. In mathematics for constructing new objects, you often start out with a "fundamental set" E of elements and than change to ExE=E^2=Set(all the(e1,e2)). The new elements (e1,e2) are equaly fundamental as the e1,e2,e3,....Via QT nature CAN do the trick to, build new fundamental enteties of Reality. This is the crossroads of QT, Neuroscience and Platonism...
That the physical world model will never be complete (if not thru the rule of the Taliban) is a truism. The advent of dark this and dark that should serve as a reminder.

( I didn't mean the string clique, when mentioning the Taliban)