Quantum physics in three sentences?

[skippy1729]

R. Clifton, J. Bub and H. Halvorson did, in fact, reduce (finite dimensional) quantum mechanics into three statements:

1. No superluminal transfer of information.

2. No cloning. (actually they use no broadcasting of mixed systems)

3. No unconditionally secure bit commitment.

Infinite dimensional representations (if they really exist) can be approximated by large finite dimensional systems. The equivalence is proved in the domain of physical systems which can be represented by C* algebras (which includes, among other things, classical mechanics).

Although simple statements, I don't see them giving much immediate clarity to things like the two-slit experiment. Although the statements are non-mathematical, the proof of the theorem is not.

reference: Foundations of Physics 33, 1561-1591 (2003)
http://arxiv.org/abs/quant-ph/0211089

 

[mysearch]

The closest thing to a denial of reality you can legitimately do is to deny that quantum theories describe what's actually happening to physical systems at all times. The fact that quantum theories make excellent predictions is undeniable. Some people like to take this as a definition of what statements like "the theory describes reality" or "the theory is telling us what's actually happening" mean. If we define the terms that way, then we certainly can't deny that QM describes reality. But we can leave the term "describes" undefined, and argue that our intuitive understanding of what the term means is good enough. Then we can deny that QM is telling us what's actually happening on a microscopic level.

Thanks for a very logical and constructive argument, which appears to be based on a 'premise' leading to a 'conclusion'. As such, it would seem to encapsulate a number of possible variants, e.g.
1) QM is incomplete/wrong, therefore cannot fully ‘describe’ any objective reality?
2) QM is complete/right, therefore it must ‘describe’ some sort of quantum reality?
3) QM is verifiable, but the scope of its ‘description’ maybe limited to a subjective reality?
4) etc.

So the debate has raged for eons.

As it would appear that the debate is still far from any obvious conclusion, I would like to return to one aspect related to the science, and not the philosophy, of QM that was originally raised in post #15 and still puzzles me at a very basic level:

According to the standard formalism of QM, there's no more distinction between particles and waves, as these 2 concepts, as I said before, actually pertain to classical physics, namely the mechanics of point particles and waves (including electromagnetism). So <quantum waves> as a concept does not exist. The fundamental concepts of QM are: (quantum) system, states and observables of a system and virtual statistical ensembles. The rest is essentially mathematics.[/

If I have understood this comment, it would appear to suggest that classical concepts of particles and waves, including EM waves, do not align to the QM description at the quantum level of existence, i.e. they cease to be meaningful? However, if I take the inference that quantum waves are essentially a mathematical construct, I am left wondering as to what, if anything, is left on which any form of physical quantum reality could be built, i.e. what transports energy and momentum from A to B?

 

[DevilsAvocado]

Looks like Stephen Hawking could help us to sort out what constitutes a scientific theory:

Stephen Hawking – A Brief History of Time

A theory is a good theory if it satisfies two requirements: It must accurately describe a large class of observations on the basis of a model that contains only a few arbitrary elements, and it must make definite predictions about the results of future observations.
...
Any physical theory is always provisional, in the sense that it is only a hypothesis; you can never prove it. No matter how many times the results of experiments agree with some theory, you can never be sure that the next time the result will not contradict the theory. On the other hand, you can disprove a theory by finding even a single observation that disagrees with the predictions of the theory.

P.S. Fredrik & Ken G, will respond ASAP.

 

[Fredrik]

Looks like Stephen Hawking could help us to sort out what constitutes a scientific theory:



P.S. Fredrik & Ken G, will respond ASAP.

I suppose I should say something, since that's a question that I've spent a lot of time thinking about. The term "theory" means a lot of different things to different people, for example:

1. Something that's believed to be true.
2. An explanation of a fact.
3. An approximate description of (some aspect of) our universe.
4. An exact description of a fictional universe that resembles our own.
5. An assignment of a unique probability to each member of some set of verifiable statements.

These "definitions" are all useful in some context. #1 is how the word is used by non-scientists. Since that's almost everyone, I'm not going to say that what they're doing is wrong. They're just wrong to think that the word means the same thing to a scientist. To someone who likes to talk about the theory of evolution, #2 is probably the most appropriate one. #3 or #4 is more appropriate for classical mechanics, but classical theories can also be considered theories of type #5 (with all the probabilities associated with pure states equal to either 0 or 1).

For quantum mechanics, I think only #5 is good enough. It's just not clear that what QM describes even resembles our universe. (I think QM can be said to describe several different things, including a much larger system such that a universe is just an "aspect" of some of its properties, and a single universe in which some of the usual laws of logic don't apply. It probably also describes lots of things I haven't even thought of yet).

Hawking's definition of "theory" is certainly good enough for a book like that.

 

[DevilsAvocado]

I suppose I should say something ...

Very interesting Fredrik, my "time machine" is running backwards today = I will answer later...

However, theory of evolution and #2 reminds me of this nice quote:

Evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts. Facts do not go away when scientists debate rival theories to explain them. Einstein's theory of gravitation replaced Newton's, but apples did not suspend themselves in mid-air, pending the outcome. And humans evolved from ape-like ancestors whether they did so by Darwin's proposed mechanism or by some other yet to be discovered.

— http://en.wikipedia.org/wiki/Stephen_Jay_Gould" ​

 

[jewbinson]

Doing maths, I find it strange that people mix up the words "theorem" and "theory". But I can understand it.

In maths, there is a clear and "obvious" distinction between a (rigorous) proof/theorem, and a theory (something which is a hypothesis but has not yet been proved).

In physics, everything is in "theories" not "theorem" because sometimes a "better theory" will come along, e.g. GR and QM are more accurate theories than Classical Mechanics. I think this transition from a "worse" theory to a "better" theory is always occurring in physics (throughout history). I guess you could argue that what a "better theory" is is subjective, but I am avoiding these philosophical thoughts and trying to present an intuitive view point. There are - and never will be - a theorem in physics unless a greater being (God) gives us a supernatural ability such that we can understand the universe in a way that we cannot even imagine now. Bu until then, we will always have theories (and good prediction), not fact.

In maths, once a theory is proved, it becomes a theorem and it stays a theorem forever.

 

[DevilsAvocado]

In maths, once a theory is proved, it becomes a theorem and it stays a theorem forever.

Well, you should call Gödel and tell him what you’ve found!

This sentence is false.

 

[Ken G]

There are - and never will be - a theorem in physics unless a greater being (God) gives us a supernatural ability such that we can understand the universe in a way that we cannot even imagine now.

Or another way to say something similar is that physics only has theorems when it becomes mathematics. There is usually a step like that in any physical theory-- the theory sets up a mathematical structure, enters that structure, and proves theorems in that structure (what Fredrik means by an exact description of a fictitious universe that resembles ours-- the fictitious universe is not another real universe that is close to ours, it is a mathematical universe, a different type of entity altogether unless you are a complete rationalist). Sometimes the "proofs" used within mathematical physics have a weaker degree of rigor than pure math is accustomed to, but there are usually mathematical physicists who are willing to work on shoring up the rigor in the background, while physicists closer to the "front lines" of experimental research are not as concerned about that-- they just want a prediction they can test, regardless of whether or not it stems from a rigorous mathematical structure.

The reason that the need for rigor is much less clear in physics is that physics is only tested empirically, and empirical facts are not "pure" facts, they have "error bars" and generally require some degree of interpretation. So there is never an experimental "proof", there is only experimental evidence of the usefulness of a theory. But rationalists tend to believe that the universe "really is" some type of mathematical structure within which the things of interest to physicists "really are" true, and can be proven true within that structure. There's actually very little evidence, from the history of physics, that this is anything but a kind of pipe dream, but what is eminently clear is that treating the universe as if it were a mathematical structure, Fredrik's "fictional universe", has reaped huge rewards. Why that holds is certainly the deepest mystery of physics, and the task of understanding why it is true is probably outside the purvey of physics itself. The real question for us is, in the context of framing quantum mechanics' relationship with objective reality: how literally shall we take that all-important "as if"?

In other words, we discover that before we can begin to answer whether or not quantum mechanics is consistent with a concept of objective reality, we must do a lot more work around what we think we mean by "objective reality" in the first place. Since physics was essentially invented as our means of saying things about objective reality, this task requires that we decide what we think physics is supposed to be doing. Interestingly, after centuries of doing physics quite effectively, we now discover (what has probably always been true) that even physicists themselves do not really agree on what they think physics is supposed to be doing. Thankfully, they can do it, all the same!

 

[Fredrik]

Doing maths, I find it strange that people mix up the words "theorem" and "theory". But I can understand it.

In maths, there is a clear and "obvious" distinction between a (rigorous) proof/theorem, and a theory (something which is a hypothesis but has not yet been proved).

In physics, everything is in "theories" not "theorem" because sometimes a "better theory" will come along, e.g. GR and QM are more accurate theories than Classical Mechanics. I think this transition from a "worse" theory to a "better" theory is always occurring in physics (throughout history). I guess you could argue that what a "better theory" is is subjective, but I am avoiding these philosophical thoughts and trying to present an intuitive view point. There are - and never will be - a theorem in physics unless a greater being (God) gives us a supernatural ability such that we can understand the universe in a way that we cannot even imagine now. Bu until then, we will always have theories (and good prediction), not fact.

In maths, once a theory is proved, it becomes a theorem and it stays a theorem forever.

I don't think I've seen anyone confuse the words "theory" and "theorem", except maybe as a typo. I don't think anyone in mathematics uses the term "theory" to refer to a statement that hasn't been proved yet. It usually refers to a collection of theorems and definitions. For example, "group theory" is the part of mathematics that deals with groups.

I'm not sure what you mean by the last statement. If you're thinking of theorems as objectively true statements, I would disagree, because they are only guaranteed to be true in the formal system defined by a set of axioms, for example the axioms of ZFC set theory and an associated proof theory.

 

[jewbinson]

I don't know much about Godel's Incompleteness Theorems in depth, but I thought all they say is that for any system of facts, there are some statements that cannot be determined to be true or false. I don't see how this means that some theorems cannot be proved.

Ken G - I kind of agree with some of what you're saying, apart from there being an objective reality... but anyway, I don't want to get into a lengthy discussion on the philosophy of reality...

Fredrik - sometimes mathematicians use the word "theory" for unproven theorem - it is not that uncommon. But yes, "group theory" is more common. Anyway, the meaning is context dependent and it is usually obvious what is meant, so it doesn't really matter...

When I say a theorem is true I mean precisely that it is true in the formal system defined by a set of axioms. Whether or not it is objectively true is again philosophy...

 

[Ken G]

The connection with Godel is that the meaning of "true" and the meaning of "provable" can never be the same thing in mathematics. Thus the words cannot be used interchangeably, which was the fervent hope of pre-Godel mathematicians. Our first problem is we cannot know the truth of the axioms, but even if we assume the axioms are true, perhaps in some definitive way (and therefore we must also assume they are consistent), Godel says there must be something that is true but unprovable by those axioms. Or, if we require that the meaning of "true" be "provable from the axioms", perhaps on the rationalistic grounds that within some axiomatic system, "true" can have no other meaning, then Godel says the axioms must be inconsistent. In other words, any attempt within some given axiomatic system to require that "true" be the exact same thing as "provable from the axioms" must fail (for interestingly rich axiomatic systems).

Thus, if we connect "knowing" with "proving", we find that the mathematician has an imperfect relationship between what can be known and what can be true. This problem is of course much worse for the physicist, who cannot really be said to "know" anything at all, but this doesn't stop physicists from adopting a kind of effective meaning of the term "know", often connected with "what can be seen to play out in a reproducible and objective way." It is in quantum mechanics where the physicist confronts most inescapably the question, is the set of everything that we can know to be true defined by the set of everything that actually is true (which is what we'd like to believe), or is the set of everything that is true simply defined by the set of what we can know to be true? We must choose, it simply isn't coherent to adopt the stance that there are true things we cannot know to be true, because in physics, there is no proving-- so that which can be known is all we have to even talk about the meaning of the word "true." No other definition of the word means anything in physics.

 

[PatrickPowers]

It so happens that I have read Godel's original proof. I would recommend that anyone with an interest do that: it is easier to read than any of the "explanations" that I have come across. But if you want another explanation, here it is.

In those days Hilbert thought that it was possible to have a few axioms and derive all of mathematics from that. It was quite a reasonable idea. There are logical systems that can be built up this way. Kurt Godel proved that when the system became complex enough that there were sentences that could not be proved this way. Later it was found that the requirements are: infinite sets, second-order logic (you have to be able to make statements about properties of every element of an infinite set), and being able to have exponents be variables, as in y = 2^x. If you had that then you could make circular statements that can't be traced down to the fundamental axioms. Nobody wanted to give up any of the three requirements, so mathematics went on its way happily unselfproved, just as it had always done.

So how does this apply to physics. In physics there is no requirement that anything be traceable down to a few axioms. The test is experiment. If it works within its domain of definition is all that is asked. In actual practice physicists try to follow the axiomatic model in order to keep excess complexity at bay. There ARE theorems in physics, but those are of the type "Joe's theory is equivalent to Alice's theory." That can be a theorem because it does not assume that either theory is correct.

Note that Godel's result could be avoided by simply giving up on infinite sets. Humans are finite so we can never observe an infinity. So all you would have to do would be to specify smallest and largest quantities and a finest resolution and you would have a system that was immune to Godel's attack. But no one is concerned enough about Godel to do this. There are better things to do.

As to whether there is an objective reality, I'm puzzled by that debate. The way I see it, if there were no objective reality then instead we would have a kind of chaos with no patterns at all, so there could be no mathematics that describes reality. We have such mathematics, therefore by my definition there is an objective reality. Humans may find it peculiar, hard to understand, or even illogical, but such opinions are beside the point.

 

[nazarbaz]

Doing maths, I find it strange that people mix up the words "theorem" and "theory". But I can understand it.

In maths, there is a clear and "obvious" distinction between a (rigorous) proof/theorem, and a theory (something which is a hypothesis but has not yet been proved).

In physics, everything is in "theories" not "theorem" because sometimes a "better theory" will come along, e.g. GR and QM are more accurate theories than Classical Mechanics. I think this transition from a "worse" theory to a "better" theory is always occurring in physics (throughout history). I guess you could argue that what a "better theory" is is subjective, but I am avoiding these philosophical thoughts and trying to present an intuitive view point. There are - and never will be - a theorem in physics unless a greater being (God) gives us a supernatural ability such that we can understand the universe in a way that we cannot even imagine now. Bu until then, we will always have theories (and good prediction), not fact.

In maths, once a theory is proved, it becomes a theorem and it stays a theorem forever.

If you want a god to teach you... Become one... That's the crux of the "anti-humanist" tradition from Nietzsche to Foucault...

 

[Len M]

As to whether there is an objective reality, I'm puzzled by that debate. The way I see it, if there were no objective reality then instead we would have a kind of chaos with no patterns at all, so there could be no mathematics that describes reality. We have such mathematics, therefore by my definition there is an objective reality. Humans may find it peculiar, hard to understand, or even illogical, but such opinions are beside the point.

I’m afraid that I am puzzled by you puzzlement. Objective reality refers to a reality that is independent of the mind. Intuitively we think of objects and facts associated with those objects as having a degree of (or complete) similarity to what we observe, directly or indirectly.

But that intuition stems from the only thing we have – our minds. How can we possibly formulate any kind of procedure in which to step outside of our minds in order to look at what exists outside of that mind?

So any attempt to be definitive about what objective reality actually refers to entails entering the world of philosophical thought, which by definition is endlessly debatable.

From my philosophical perspective, it seems perfectly reasonable to consider objective reality to be part and parcel of our minds – the stone observed by us in terms of space and time is a construct of our minds that is “our” reality. Not that it is an illusion; it’s just what “is”. What lay “underneath” that construct is quite properly the domain of mind independent reality – and that is a reality that is beyond the scientific method – it is an area where objectivity breaks down because we cannot access this reality independently of our minds.

To invoke only scientific or mathematical reasoning in order to remove the uncertainty of mind independent reality with no reference to it being primarily a philosophical question I think is wrong. For me, philosophically, mind independent reality could be a “something” with no patterns as we would think of them, and not even existing in space or time (notions that I think of as being constructs of our minds). Emerging (not in any familiar sense of the word “emerging” of course) from that could be our reality, and within that reality mathematics can describe the consistent physical patterns that we also observe. That process I think of as invoking the scientific method – it is a method that is used extremely effectively to describe “our” reality and it is objective because of intersubjective agreement that exists between all of us. But note that word “intersubjective” - our reality, as a whole, is entirely subjective, we cannot step outside of ourselves, so what we do instead is accept (without realising it) the subjective nature of our reality, but within that subjective reality we look for consistent patterns that we all perceive to be the same. But no where in that procedure is there any definitive means that enables us to step outside of that whole procedure (i.e. our minds) in order to examine if the mathematics (or observation) does describe mind independent reality. Thus whatever our position on the question of what objective reality ultimately refers to, it is a philosophical position, and can only ever be that way. There is room for debate ranging from strong realism to strong idealism - you can be anywhere on this sliding scale, but the whole scale is essentially a philosophical platform, not a scientific or mathematical one.

So I don’t think you should be puzzled by the debate over what objective reality refers to, I can’t think how it could be otherwise.

 

[jewbinson]

Fine, let's do some philosophy. Last week I held the view that all you can know is "your mind"/"your subjectiveness".

At the moment I am uncertain about subjectivity being the only reality.

There are arguments for it, but they all seem to contain some sort of "actual accepting" of an objective reality, even if the person making the argument claims they do not. It doesn't really make sense to say "I think therefore I am" without making reference to something other than yourself. If all you are is truly your subjective mind - the "ego", and/or the "intellect" - which, by the way, I think is the same thing as the ego (most philosophers do not - but I do not understand this), then what are you subjective relative to? How did you come to the conclusion that all you are is your mind's subjectivity? Somewhere along the way you must have experienced some sort of objectivism so that your "subjectiveness" has any meaning.

 

[PatrickPowers]

I’m afraid that I am puzzled by you puzzlement. Objective reality refers to a reality that is independent of the mind. Intuitively we think of objects and facts associated with those objects as having a degree of (or complete) similarity to what we observe, directly or indirectly.

But that intuition stems from the only thing we have – our minds. How can we possibly formulate any kind of procedure in which to step outside of our minds in order to look at what exists outside of that mind?

So any attempt to be definitive about what objective reality actually refers to entails entering the world of philosophical thought, which by definition is endlessly debatable.

From my philosophical perspective, it seems perfectly reasonable to consider objective reality to be part and parcel of our minds – the stone observed by us in terms of space and time is a construct of our minds that is “our” reality. Not that it is an illusion; it’s just what “is”. What lay “underneath” that construct is quite properly the domain of mind independent reality – and that is a reality that is beyond the scientific method – it is an area where objectivity breaks down because we cannot access this reality independently of our minds.

To invoke only scientific or mathematical reasoning in order to remove the uncertainty of mind independent reality with no reference to it being primarily a philosophical question I think is wrong. For me, philosophically, mind independent reality could be a “something” with no patterns as we would think of them, and not even existing in space or time (notions that I think of as being constructs of our minds). Emerging (not in any familiar sense of the word “emerging” of course) from that could be our reality, and within that reality mathematics can describe the consistent physical patterns that we also observe. That process I think of as invoking the scientific method – it is a method that is used extremely effectively to describe “our” reality and it is objective because of intersubjective agreement that exists between all of us. But note that word “intersubjective” - our reality, as a whole, is entirely subjective, we cannot step outside of ourselves, so what we do instead is accept (without realising it) the subjective nature of our reality, but within that subjective reality we look for consistent patterns that we all perceive to be the same. But no where in that procedure is there any definitive means that enables us to step outside of that whole procedure (i.e. our minds) in order to examine if the mathematics (or observation) does describe mind independent reality. Thus whatever our position on the question of what objective reality ultimately refers to, it is a philosophical position, and can only ever be that way. There is room for debate ranging from strong realism to strong idealism - you can be anywhere on this sliding scale, but the whole scale is essentially a philosophical platform, not a scientific or mathematical one.

So I don’t think you should be puzzled by the debate over what objective reality refers to, I can’t think how it could be otherwise.

So would a completely alien intelligence come up with similar mathematics or not? Perhaps some day we shall find out. Not that that would end the debate :-)

 

[nazarbaz]

So would a completely alien intelligence come up with similar mathematics or not? Perhaps some day we shall find out. Not that that would end the debate :-)

While waiting for aliens or gods , we just have to avoid intellectual shortcuts on the nature of matter : as to say it's unknowable per se, it doesn't exist at all or that science is not about it any way but about paradigms and interpretations... The outcome of "empiricism" would be completely "idealist" if not...

 

[Len M]

we just have to avoid intellectual shortcuts on the nature of matter : as to say it's unknowable per se, it doesn't exist at all or that science is not about it any way but about paradigms and interpretations... The outcome of "empiricism" would be completely "idealist" if not...

Well I can't see how science will be able to step outside of the framework that produces that science, the framework of course being us and our reality. I can't even foresee a time when we will be able to model the brain, mind and consciousness such that we can mitigate for it and thus determine the nature of a reality that may exist outside of the brain, mind and consciousness, I mean to say, who will have created that model - it will be our brain, mind and consciousness.

Idealism is philosophical, realism is philosophical. Science operates within our reality - to extrapolate that science to mind independent reality, fully, partially or not at all is to operate on a sliding scale between strong realism and strong idealism. And that sliding scale is a philosophical platform, and each persons position on that sliding scale is a philosophical one, not a scientific one in terms of the objective scientific method.

Empiricism is a product of our reality, it describes our reality, is objective and extremely powerful within the scientific method. But it is not a scientific description of mind independent reality, to "describe" mind independent reality is a philosophical exercise.

 

[PatrickPowers]

Well I can't see how science will be able to step outside of the framework that produces that science, the framework of course being us and our reality. I can't even foresee a time when we will be able to model the brain, mind and consciousness such that we can mitigate for it and thus determine the nature of a reality that may exist outside of the brain, mind and consciousness, I mean to say, who will have created that model - it will be our brain, mind and consciousness.

Idealism is philosophical, realism is philosophical. Science operates within our reality - to extrapolate that science to mind independent reality, fully, partially or not at all is to operate on a sliding scale between strong realism and strong idealism. And that sliding scale is a philosophical platform, and each persons position on that sliding scale is a philosophical one, not a scientific one in terms of the objective scientific method.

Empiricism is a product of our reality, it describes our reality, is objective and extremely powerful within the scientific method. But it is not a scientific description of mind independent reality, to "describe" mind independent reality is a philosophical exercise.

Yes. Suppose you were able to step completely out of any human influence: how could you know that you had done so? If you did know it, how could you convince anyone else that you had done this? Neither seems possible.

 

[Ken G]

So would a completely alien intelligence come up with similar mathematics or not? Perhaps some day we shall find out. Not that that would end the debate :-)

Right, it would not, because even if some other alien that seemed very different from us formulated similar mathematical theorems that we do, and even if they found similar ways that their mathematics resonated with a certain order to their reality, it would not prove anything other than what we already know-- the resonances between our mathematics and our physical reality do exist. The real question persists: what are we to gather from the existence of such resonances? A dog creates some concept of what its master is, and achieves certain resonances by it, but would we not be shocked by how far from our own picture of ourselves is a dog's picture of its master? If a cat creates a picture of its master that resembles the picture the dog creates, all it means is the picture encompasses the pet/owner relationship in some way, it does not convince us that somehow the dog and cat know us better than we know ourselves.

In that light, earlier you argued that the existence of the resonances requires that there be an objective reality, but I don't see what axioms you take as true that can lead to that conclusion. We can say there needs to be something, but what do we mean by "objective reality", and what claims can we make on it? One approach you might take is to simply define the concept of objective reality around the empirically demonstrated resonances between mathematics and common experience, and I'd say that is more or less the standard approach used in physics. But that's also pretty much what Len Moran is talking about-- we cannot choose a philosophical definition of objective reality that is somehow separate from the methods of science, and then use science to discover how such a reality works, because science doesn't exist on the side of that philosophical construct, it exists on the side of the scientific approaches to answering questions. As Bohr said, physics is not about nature, it is about what we can say about nature. That might be a lot more like what a dog or cat can say about its master than what its master can say about themself.

So science is always forced to create its own concept of objective reality, around the patterns of common experience that resonates with our mathematics. We have no access to any other concept of objective reality in physics, so it is purely tautological to claim that science has somehow shown that objective reality exists. What it really shows is that the scientific concept of objective reality affords us some power over, and understanding of, our environment. That power and understanding is all the scientist means by objective reality, just as our models of gravity are all we ever mean by the term gravity. But of course this always begs the question as to whether or not there "really is" any such thing as gravity outside of our scientific models of it, or whether any elements of our models exist anywhere but in those models.

Now, some say, there must be some real kind of gravity or else we couldn't model it successfully, but to them I would point out that the real kind of gravity they have in mind does not need to actually involve any of the attributes of our models. Similarly, if you demand that there be a thing called objective reality, I would point out that it need not actually involve a single one of the aspects that you attribute to it. So it is a kind of objective reality that need not be either objective or real, the instant you provide meanings to those words, and so calling it "objective reality" doesn't really mean a whole heck of a lot. Instead, what has meaning is saying "let's enter into a kind of pretense that there is a thing called objective reality with the following attributes, and let's just see how far it gets us, under no illusions that it is actually true." I would say that science works best when framed in just that way, and it certainly saves a lot of embarrassment hundreds or thousands of years later.

 

[nazarbaz]

Thinking goes far beyond subjectivity... Thought condition of possibility is by nature led to exceed itself... We're not condemned to solipsism... That's what a trained philospher could say to a scientist...
Science, the search for truth, is one modality of the very complex relations between us and the universe... Maybe our destiny is to get eternally closer without hitting the target, but to pretend that we're not dealing with the problem and winning some battles is just philosphical nonsense...
Here, criticizing the naive objectivism of the old epistemology takes us to kill the object itself and to adopt a naive subjectivism...

 

[DevilsAvocado]

... like the guy who commented a David Bowie video from the early 70's on youtube by saying that Bowie has no talent or originality, and just copies everything from Lady Gaga.

OMGLOL!

:rofl::rofl:

 

[UrBestFriend]

I hope this is an attempt to be funny, like the guy who commented a David Bowie video from the early 70's on youtube by saying that Bowie has no talent or originality, and just copies everything from Lady Gaga. (The picture is kind of funny). What you're saying about quantum physics and the scientific method is of course...uh...the picture on the right comes to mind.

Not really. The image on the left was the top perspective while the image on the right was the side perspective when some students tried to re-create the model using inflated latex. I just colored it brown in Photoshop. :tongue:

I think people should have the courage to criticize without fear of looking stupid. Well, I have long accepted that I'm stupid that's why I quest to learn. Anyway, the string theory as far as I know does not even provide any quantitative experimental predictions. What use is that? Also, if I'm not mistaken, subjects in quantum level cannot be separated from the measuring device, and the measuring device cannot be separated from the environment around it etc etc (Quantum non-locality and uncertainty principle).

And so when the elite physicist use their expensive toys in observation, what they are really observing is the effect of everything in the universe on the quantum subject. And that is quite different from the scientific method of observation wherein scientists try to localize and remove elements that introduce uncertainty in the experiment (i.e. effect of air drag on falling objects etc.).

But hey, since the elites control the multi-billion dollar tools (like the LHC) and there is no way that these tools can be reproduced by poor physicists such as us, these elites can churn theories after theories without fear that someone would be able to invalidate the results. Wasn't that what happened in the particles that is faster than the speed of light?

And thus I think people should be encouraged to scrutinize everything.

 

[Fredrik]

I actually started writing a point-by-point reply, but I realized that I have wasted enough time on people who just show up to make accusations about things they have absolutely no understanding of.

 

[Fredrik]

One point worth mentioning is that this is a physics forum, not a conspiracy theory forum. If you want to talk about how "the elite" is deceiving the masses, then you need to go somewhere else.

 

[Fredrik]

OK, it's possible that I got the wrong impression, but when you say things like "these elites can churn theories after theories without fear that someone would be able to invalidate the results", it sounds like you're going for the conspiracy theory.

 

[Ken G]

The outcome of that experiment, on either half, is predicted by quantum mechanics to be the same as if you just had a single slit and your right-angle screen, but half the intensity at the source. You could even use a mirror, instead of a screen, in the middle to get your doubling-over effect automatically, but again the outcome is predicted by wave theory and no one would expect the experiment to come out any differently. The point is, many trials with one photon must end up with the same co-added result as the classical wave result, or else the principle of superposition is violated-- a principle that has passed a thousand tests with flying colors. The photon is the "cleaner" particle to use for that, because it doesn't interact with other photons-- if you want to do it with electrons, you do have to worry about internal interactions unless you lower the intensity to one at a time. But quantum mechanics has passed a lot of tests like that already.

Now, you can certainly do the experiment to find out if quantum mechanics is right for both photons and electrons, there is no harm in actually testing it because you never really know if it might not be right. But no one would expect it not to be right, and I don't see why you wonder if it will be right or not. No one thinks the pattern is caused by interactions between elecrons (that has already been checked with one-at-a-time electron sources), and no one thinks the pattern is due to scattering off the edges of the slit (such scattering events are related to the width of the barrier used, and can be calculated and taken into account). I certainly think you should go ahead with such an experiment if you have the wherewithall, but I doubt you can convince anyone else to try it, because they will see a vanishighly small likelihood that quantum mechanics won't predict such an experiment bang on.

 

[Fredrik]

OMGLOL!

:rofl::rofl:

I thought it was funny too. He was the first internet troll I've appreciated. Most people seemed to think that he actually believed that David Bowie had stolen all his ideas from Lady Gaga. There were lots of frustrated replies that tried to explain to him how wrong he was, and of course a lot of people just yelled insults at him.

(I think the song was Ashes to Ashes. I looked it up, and it was released in 1980, so I should have said 80's, not 70's).

 

[Ken G]

Getting back to the topic at hand, we were wondering if physics works because there really is such a thing as objective reality, or if objective reality is just another physics model and when it doesn't work we just use some other physics model, or some more sophisticated version of what we mean by objective reality. I was saying that we shouldn't pin our faith in physics on some naive concept invented thousands of years ago, like the common notion of objective reality.

 

[DevilsAvocado]

I thought it was funny too. He was the first internet troll I've appreciated. Most people seemed to think that he actually believed that David Bowie had stolen all his ideas from Lady Gaga. There were lots of frustrated replies that tried to explain to him how wrong he was, and of course a lot of people just yelled insults at him.

(I think the song was Ashes to Ashes. I looked it up, and it was released in 1980, so I should have said 80's, not 70's).

Yeah, it’s hilarious! It’s not always easy to decide if you’re talking to a 'woozy kid' or a 'real troll'.

I don’t know if it’s http://www.youtube.com/all_comments?v=XXq5VvYAI1Q", but there are ~5,000 comments and a lot about Lady Gaga...

"I think he was a Lady Gaga of the 70s(and it's not an insult), and before you swear me for what I've said think about the reason why I said that,...it has a big point!"
...
"omg who ever said lady gaga wow hahahahaha WRONG WRONG WRONG WRONG WRONG WRONG"
...
"Lady Gaga is the god knows what love child of Britney Spears, Donald Trump, and a goat"
...
"Please, STOP talking about Lady Gaga!"​

Okay guys, enough off-topics, back to business...

I have a lot to ask/say, back soon... (hopefully)