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Post by robinpike on Dec 13, 2010 20:10:34 GMT 1
A lot of the arguments discussions that occur on this board come about because there is disagreement as to whether something has been proved or not. It seems to me that fundamental explanations are very difficult to prove. What seems to happen is that we build up more and more evidence in favour of one explanation over another, and that explanation becomes more probable - but without understanding what light, electrons, protons etc are, and the mechanisms behind the electric force, gravity etc, it is very difficult to be absolutely sure that we have proved one explanation over another. But the position that physicists seem to portray, is that we do understand all the fundamental things - certainly all the things in the standard model - but that just isn't true is it? For example, the CERN website public.web.cern.ch/public/en/science/StandardModel-en.html introduces the standard model with these pictures of the standard model particles. If the standard model contains everything about these particles, why then are the particles portrayed as spherical shapes with hearts, spades and other shapes on them? if we know what these things are, why not just show them as they are, and show how they interact with each other etc etc? So what is the standard model really a proof of? Attachments:
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Post by abacus9900 on Dec 13, 2010 20:51:36 GMT 1
A lot of the arguments discussions that occur on this board come about because there is disagreement as to whether something has been proved or not. It seems to me that fundamental explanations are very difficult to prove. What seems to happen is that we build up more and more evidence in favour of one explanation over another, and that explanation becomes more probable - but without understanding what light, electrons, protons etc are, and the mechanisms behind the electric force, gravity etc, it is very difficult to be absolutely sure that we have proved one explanation over another. But the position that physicists seem to portray, is that we do understand all the fundamental things - certainly all the things in the standard model - but that just isn't true is it? For example, the CERN website public.web.cern.ch/public/en/science/StandardModel-en.html introduces the standard model with these pictures of the standard model particles. If the standard model contains everything about these particles, why then are the particles portrayed as spherical shapes with hearts, spades and other shapes on them? if we know what these things are, why not just show them as they are, and show how they interact with each other etc etc? So what is the standard model really a proof of? Big problem is that we can only go so far in testing theories because ideas tend to outpace what can be currently experimentally observed. For example, string theory is a beautiful mathematical explanation of what underlies all of the forces and matter in the universe (at least those we know of) but is it really correct? We will have to wait before that question can be answered (if ever). I suppose theories can at least point us to what to look for and this is the case with the LHC where experiments will be performed that should provide data that either supports some current ideas about physics or does not. You have to remember that although it is natural to try to visualize quantum objects in terms of familiar concepts this is really very misleading because the way quantum objects behave are based on mathematical models and, therefore, are not really able to be represented very well by everyday analogies. One can only test and re-test scientific theories through experiments and this should be the only criteria with which to judge weather a theory is reliable or not. That does not mean to say it will always be the case, but it is all science can do.
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Post by robinpike on Dec 14, 2010 1:06:11 GMT 1
One can only test and re-test scientific theories through experiments and this should be the only criteria with which to judge whether a theory is reliable or not. That does not mean to say it will always be the case, but it is all science can do. But I think there is more to just having a theory that agrees with experiment - for what about explanations? For example: Take the simple experiment of light passing through a block of glass. The speed at which the light goes through the glass can be measured, and the speed of the light after it has left the glass can be re-measured. What is found is that the light slows down while it is in the glass, and speeds up after leaving the glass. Easy enough to put together a theory that agrees with the results, and how can the theory be disproved if it agrees with the experimental results? But surely, a theory should be more than just agreeing with the results, it must explain the results. For example: If the explanation involves the light going slower while passing the electrons and protons in the glass, then what is the explanation as to how it speeds up after leaving the glass? If the explanation involves the light not slowing down while it is going past the electrons and protons in the glass, then how is the light's slower speed in the glass explained? So theories should not be stated as proved if they simple agree with experiment - they should have a (believable) explanation as well. And this is where we get into arguments about whether a theory is "right" or "wrong".
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Post by speakertoanimals on Dec 14, 2010 1:28:30 GMT 1
First off, physics doesn't go for proof, leave that to the mathematicians!
Physics is about explanations, and explanations that explain a lot of seemingly disparate phenomena within one simple package.
The problem with this is that it assumes there is such an answer which is immediately obvious.
The second point is we do have an answer -- photons are the quanta of the em field. Electrons are the quanta of the electron field. The electric force is just another aspect of the quantum field that gives us photons.
All these fields are written in terms of quantum field theories.....
And so on. We have taken light, electrons, protons, em forces, weak forces, and the strong nuclear force (that holds protons together), and put them into a single framework, the standard model.
It does tell us what photons, electrons, protons are, what the mchanisms are that describe the weak, em anmd strong forces. It explains a lot. But it is also not complete, we know that, it doesn't do gravity.
Because that is just a diagram -- you can't draw a picture of what an electron REALLY is, because you just can't draw it! Just as you can't draw a picture that gives the temperature at every point of a flowing fluid, AND the way that the fluid flows, ANd what every molecule in that fluid is doing, and so on and so on.
But we caqn compute it, and use those results to predict what the fluid will do. Just as we can compute what an electron will do. We can draw limited parts of the results of that computation, but not all of it.
Why should you expect what the electron IS (it isn't a little biliard balls for starters) to be something that you can draw anyway? Drawing is just one way of describing something, and in some cases, drawings aren't enough, we have to use the language of maths instead.
It's not a proof of anything, its an explanation, and a rather concise explanation of a whole load of stuff, from why protons, to why atoms, to why nuclei, to why exactly what elements we see and what properties they have, to why radioactive nuclei decay, to why neutrons decay, to why light passes through glass but not rock, and so on and so on. In principle, the standard model encompassess all of that.
It doesn't deal with why apples fall off trees, but still, not bad!
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Post by nickcosmosonde on Dec 14, 2010 3:40:43 GMT 1
It's not beautiful at all, it's a mess. That's why hardly anyone believes it's anything other than a provisionally interesting effort.
Also, the mathematical content of a theory does not explain. It describes at best - it indicates the invariant relations in the system concerned. An explanation attempts to show why those relations are as they are in the first place. Sometimes a deeper mathematical description can do this, but this is simply pushing the explantory process a further step backwards - or rather, nearly always (unless the system is a self-contained delimited one, where the relations are enumerable - as the structure of DNA might be, for example) what occurs is the original explanation is shown to be completely ungrounded, and the new one recasts the observed relations in an entirely different conceptual framework. It's a very mysterious process, logically speaking - inasmuch as it doesn't seem logical at all, in fact, but something more akin to artistic creation. This is why Einstein called it the most mysterious fact in the universe - not that it's mysterious, but that we can comprehend anything at all (the most incomprehensile thing about the universe is its comprehensibility, I think is the most famous of the many, many ways he expressed this.)
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Post by nickcosmosonde on Dec 14, 2010 3:53:16 GMT 1
I think that was a good overall respose, StA.
But here's a good example of the limits of the explanatory power of any theory. Eventually we arrive in our analysis of the terms we're using at end concepts that are themselves unobservable and unanalysed. We need these concepts in order to explain the mathematical relations in our descriptive system of equations, but they themselves are not definable in terms of anything else - until a new broader theory comes along. In this case we have the impression that our theory "tells us" what electrons, protons etcetera "are" - the "quanta" of whatever "field." But if one asks, what are these elements in our explanation - what is a "quanta" or a "field" - there is nowhere for us to refer to to deduce their meaning.
Does this "explanation" therefore "explain" anything, in fact? Yes, if you're asking what a proton, electron etcetera might be - or "how they work", which is probably a better choice of phrase. But no, if you think that this explanation works reflexively, in both directions as it were. Understanding particle interactions in terms of quantal fields is one thing - we cannot do it vice versa. We understand nothing about what quantal fields might be. For that we need another theory - and until that comes along, all we have to rely on, to give an illusion of understanding, is an interpretation, a speculative framework of what these terms might mean.
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Post by robinpike on Dec 14, 2010 14:29:18 GMT 1
Because that is just a diagram -- you can't draw a picture of what an electron REALLY is, because you just can't draw it! What this is, is really a theory in its own right: that an electron cannot be depicted using a visual image. And as a theory is not necessarily straight forward to prove to be correct. And this is how discussions can become at cross purposes, because some will sense these underlying assumptions in a theory and question whether the overall theory therefore is complete, whereas some will not see it as an assumption at all and wonder why anyone is questioning the standard model of the electron (in this example), since the standard model theory of the electron agrees with experiment.
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Post by speakertoanimals on Dec 14, 2010 14:46:40 GMT 1
What this is, is really a theory in its own right: that an electron cannot be depicted using a visual image. Why do you call everything a theorem and demand proof? Stop being daft with language! Not exactly an earth-shattering revelation -- especially when you ralise that visual images, in essence, are just approximations of what we can SEE. Since visible light can't see things that small anyway.......... And then once you see that measurements on the electron say that it is pointlike, how can you draw a point? ANd if you do, not very informative................. Rubbish. If we define them mathematically, that is as good as you are ever going to get! There can be nothing else to refer to, at the root.
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Post by robinpike on Dec 14, 2010 15:05:32 GMT 1
What this is, is really a theory in its own right: that an electron cannot be depicted using a visual image. Why do you call everything a theorem.......... And then once you see that measurements on the electron say that it is pointlike, how can you draw a point? And if you do, not very informative................. But that is the exact problem. In this example, some one sees the statement as a theory - and therefore considers whether it may be correct, or may not be correct, and therefore interested in considering both of those possibilities. Whereas some one else sees it as a statement of fact and therefore considers only that it is true. The electron may well have a shape, even if we cannot measure it, and if it does, then the standard model is missing that aspect of the eelctron, and therefore missing the possibility that its shape may give rise to some of its properties, etc etc..
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Post by abacus9900 on Dec 14, 2010 15:49:29 GMT 1
"Some cosmologists are drawn to M-Theory because of its mathematical elegance and relative simplicity. Physicist and author Michio Kaku has remarked that M-Theory may present us with a 'Theory of Everything' which is so concise that its underlying formula would fit on a t-shirt. Stephen Hawking originally believed that M-Theory may be the ultimate theory but later suggested that the search for understanding of mathematics and physics will never be complete." en.wikipedia.org/wiki/Introduction_to_M-theory#StatusThere it is, in black and white. "M-Theory is not yet complete, but the underlying structure of the mathematics has been established and is in agreement with not only all the string theories, but with all of our scientific observations of the universe. Furthermore, it has passed many tests of internal mathematical consistency that many other attempts to combine quantum mechanics and gravity had failed." en.wikipedia.org/wiki/Introduction_to_M-theory#StatusAgain, there it is in black and white. Now, if you have a more convincing theory please feel free to present it, but of course, we all know you have not, so please stop making a fool of yourself.
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Post by abacus9900 on Dec 14, 2010 15:54:01 GMT 1
One can only test and re-test scientific theories through experiments and this should be the only criteria with which to judge whether a theory is reliable or not. That does not mean to say it will always be the case, but it is all science can do. If you do not test ideas by conducting experiments how do you know whether your theories are correct? Proof of the pudding and all that....
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Post by abacus9900 on Dec 14, 2010 15:58:20 GMT 1
So what do you propose that we use instead of the scientific method? Anything sensible to say?
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Post by speakertoanimals on Dec 14, 2010 18:04:31 GMT 1
Why do you keep repeating such NONSENSE, calling everything at random a theorem..................
The measurements made on electrions see them as pointlike -- that's not a theorem, just a simple report of experiment -- to a certain resolution, electrons look like points.
Now when it comes to theories, certain theories (such as the standrad model) treat electrons as points. Others, such as string theory, do not.
An electron being pointlike is not necessarily something that cajn be proved -- our resolution alwats limited. Not being pointlike can, in principle, be proved (or at least the converse disproved).
None of which has much to do with your seeming need for a pretty picture of an electron................
So? WE all KNOW that the standard model is not complete, no news there, and since string theory explicitly goes beyind the pointlike description for ALL particles (kind of the whole point of string theory), that's not news either. So I fail to see what your point is (if any).
Just PLEASE stop calling everything at random a theorem, and go look it up before you come back again...................
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