Why is a theory able to predict a phenomena?

[Bodhi Dharma Zen]

Why does this system works? It is assumed that is BECAUSE the theories "reflect reality" (whatever that means), thats why we can make accurate predictions with (some of) them.

Still, take for instance gravity. Is it a force? Is it a distortion of the spacetime continuum? Newtonian mechanics still work, and will work to make a great number of accurate predictions, but this does not render the theory "a true reflection of reality".

Current theories are able to predict with a lot greater degree of accuracy the facts we later observe. Is this an indication of them being "truer"?

 

[TV's Frank]

Science is not some vague "quest for truth". It is simply a description of nature. General relativity is not "truer" than Newtonian gravity, it is simply a more accurate description of nature. In certain limits, both theories give identical results.

Theories can predict phenomena like this: suppose you have a theory, say Newtonian gravity. You use it to explain, say, the motions of the planets. The predictions of your theory match observations. Awesome. Well, except for the motion of Mercury. It's a little off. So, you wait a couple hundred years, and you come along with General Relativity. Wow! General Relativity correctly describes the motion of Mercury! Sweet! Now you start playing with the theory, looking at the math, seeing what else it predicts. You note, with some interest, that GR predicts that light will bend around massive objects, like the sun. This is something that Newton never even thought of. So, you conclude, if GR is REALLY correct, then not only should it explain the motion of Mercury (which is does), but we should ALSO see this bending of light. This is a never-before-observed phenomenon, so if we go looking for it, we should see it. And we did, and the amount of bending is exactly predicted by GR.

So, in short, scientists predict new phenomena by monkeying around with the mathematics of a theory, and seeing what happens.

 

[JoeTheJuggler]

"Phenomena" is plural.

As for your question: to some extent, you can say we are selecting better and better theories. The one's that don't predict as well are tossed in favor of the ones that work better.

I think your question is much more philosophical, though. More on the order of "Do our theories say anything about reality, or do they merely describe how our minds perceive reality?"

 

[Bodhi Dharma Zen]

Science is not some vague "quest for truth". It is simply a description of nature.

A description. The implicit postulate below a description is that we understand what is going on. Furthermore, that we understand it because there is a correspondency between our ideas and the world.

But, note that its also asumed that the correspodency is true because our ideas are a true representation of reality.

General relativity is not "truer" than Newtonian gravity, it is simply a more accurate description of nature. In certain limits, both theories give identical results.

More accurate. This implies that we can have several different descriptions and that some of them (maybe just one) is more accurate because its truer.

This is something that Newton never even thought of. So, you conclude, if GR is REALLY correct, then not only should it explain the motion of Mercury (which is does), but we should ALSO see this bending of light. This is a never-before-observed phenomenon, so if we go looking for it, we should see it. And we did, and the amount of bending is exactly predicted by GR.

GR is REALLY correct... until a new theory comes and render it obsolete (not in its predictive faculties, but our taking it in an epistemic way as "really correct". This is the whole point behind my questions, and any theory can fit. Scientists used to say that "eggs are bad for your heart", now they say otherwise. Mobile phones were considered as dangerous, now they are not... you get the idea.

 

[Bodhi Dharma Zen]

As for your question: to some extent, you can say we are selecting better and better theories. The one's that don't predict as well are tossed in favor of the ones that work better.

Exactly, we select the "better theories", and they are better because they predict better, nothing more. Can we claim that a theory is like a map (so its not and will never be the territory) and that the better or more accurate the map is the better predictions? At first sight yes, the answer is plain and simple.

But where does it end? Can we have a "final map"?

I think your question is much more philosophical, though. More on the order of "Do our theories say anything about reality, or do they merely describe how our minds perceive reality?"

Exactly, thank you for seeing it. You can add that Im curious about the relation of our language to that what we call "the world". What is an explanation? A set of words that, putted together in certain order, are a representation of our perceptions? Or are we drawing representations about "what is really there, outside our minds"?

 

[JoeTheJuggler]

A set of words that, putted together in certain order, are a representation of our perceptions? Or are we drawing representations about "what is really there, outside our minds"?

How about this: theories and language reflect our perceptions, but our perceptions evolved in the real world as successful for survival and reproduction. I think we can assume that there is correspondence.

For example, we have words for colors--they differ a little from culture to culture in how we divvy up the visible part of the EM spectrum, but no too much because human eyes are sensitive to the same range of wavelengths. We think of the world as what we see to a great extent. Other animals see, for example, into the UV range--so the world looks very different to them than it does to us. They can even see things that are there that we can't see (patterns on flower petals, for instance).

So our perceptions do reflect at least a part of reality--they're not totally arbitrary.

Our minds can reason out a great deal that we can't perceive (or even imagine--like 4 or more spatial dimensions). I think there is an objective reality that informs our perceptions (and by extension using reason to go farther).

If not, it would be a huge stroke of luck that what we think is reality isn't so far off that actual reality kills us.

 

[Jeff Corey]

As you probably know, theories cannot be proven to be true. Modus ponens, all that. They are considered to be confirmed if a massive amount of experimental or other empirical data confirm their predictions . Viz, evolution science.

 

[l0rca]

It seems like your question has elements of induction, philosphical realism/nominalism, and queiries into Popper's falsification ideas. There's a lot in this question, and at the moment, I don't know what approach to take to give you a satisfying answer.

If you're only interested in wondering why theories predict, and not if they have some kind of objective correspondance with reality, then the answer is simple, but hardly satisfying. We axiomize mathematics and logic, assume causes produce effects, as well as some vauge notion of "natural law". These are pure assumptions, though each of them helpful, if not entirely reasonable. Why they tend to work remains up for conjecture.

If you're wondering if science can come to a "soulful" understanding of reality: I don't think so. I think our very experience and understanding is built upon a number of biologically-determined biases about how to interpret and deal with the outside world. I don't think experience and understanding trancsends us at all. The correspondance we have with reality is empirical, yes, but the correspondance is never direct, and we've yet to draw entirely agreeable lines to where our experience of reality ends, and the reality we're experiencing begins. Getting down to it, we may never be able to draw this line, but only better understand the degrees involved.

Sorry for the hazy speculations. Up there's probably mostly psilosophical garbage, but I'm at work.

EDIT: Ehh. to add, it's entirely possible that the brain experiences its own experiences -- that is (if you know of the Multiple Drafts model and other similar material ideas) our consciousness is not continuous, but because of structure and mechanisms, at some point, either fundamental in matter or in a more macrocosmic referance, begins to experience itself on smaller scales -- not in a "cartesian theatre" central way. In such a way, our own experiences are shared, re-experienced, and proliferated throughout the brain. There's still much work to be done before a satisfying explanation for all this can be given, but it helps to open the idea of any material entity being able to, in some universal sense of scale, "experience".

 

[Schneibster]

Why does this system works? It is assumed that is BECAUSE the theories "reflect reality" (whatever that means), thats why we can make accurate predictions with (some of) them.

There are two reasons. First, our universe is such (so far as we've been able to determine) that it has consistency. That is, the most things happen the same way every time, and if they don't, it's because something we didn't notice is different; we can then go look for that something, and we always (so far) have found it. For example, if there's a rock outside my door on the ground today, it will still be there tomorrow unless it was moved by someone or something. If I pick it up and let go of it, it will fall, and it will fall the same way today as it would have last week, and as it will next week. This property of consistency is embodied in physics in symmetries. For example, if I pick the rock up and turn it around, and put it back down, it's still a rock. This illustrates the symmetries of translation (picking it up) and rotation (turning it around).

A brilliant theoretical physicist and mathematician named Emmy Noether showed that these symmetries (specifically, continuous symmetries) each imply a conservation law, and since this is a theorem, she proved it (which you can do with a theorem, being a mathematical construct, unlike a theory). Specifically, she showed (for example) that the symmetry of physical law over translation implies the conservation of momentum, and the symmetry of physical law over rotation implies the conservation of angular momentum.

You will have realized, of course, that the inbuilt consistency of mathematics reflects this apparent consistency of the universe. This is why mathematics is so useful for describing the universe. In fact, if we stick to a few simple rules in our math, if we discover some new way of manipulating the numbers, we almost always find some novel and interesting behavior in the universe that reflects this new way. The basic laws of mathematics, therefore, reflect some basic properties of the universe. And that's no surprise; we chose them carefully so that they would.

What happens is, someone looks at some behavior of the universe, and they develop some math to describe that behavior. This is called, if you will, a "conjecture." Then they explore implications of this conjecture in other areas than the one it was originally developed to explain, and see if they can find anything that makes it inconsistent with reality. If they fail, then it becomes, if you will, a "hypothesis." Finally, they look for implications of behavior that no one has ever checked before. The hypothesis is used to predict novel behavior. Once such a prediction can be made, then they go test it; they go looking for this novel behavior. If they find it, then the hypothesis becomes a theory.

Over time, more and more predictions of a theory are checked. If an inconsistency is found, it may result in a revision of the theory; it may result in the creation of a new theory; or it may result in the rejection of the original theory. The last is extremely unlikely at this stage of things; back in Newton's and Galileo's times, physics was very young, and new ideas were as likely to be completely rejected later as they were to survive. These days, we know enough that most of the theories we make might be revised, or a new theory that describes actions in extremes or conditions the original theory did not account for might be needed, but we rarely find it necessary to reject an entire line of thought.

And remember that as more and more predictions of a theory are checked, if they all come out true, the stronger the support for that theory is. For example, Gravity Probe B is currently checking for indications that Einstein's General Relativity Theory correctly or incorrectly predicts a phenomenon called "frame dragging." If it is correct, then it will be even more strongly supported than it is today; if it is not, then there will be some adjustment, but because GRT correctly predicts the precession of the orbit of Mercury, and correctly predicts the bending of starlight passing near the Sun during an eclipse, it won't be supplanted, it will almost certainly be supplemented.

To understand the genius of Newton and Galileo, consider that Einstein's SRT and GRT, although they are said to supplant the laws of motion and the theory of universal gravitation, in fact, supplement them; the laws of motion are unmeasurably incorrect at ordinary velocities. In other words, the difference between the predictions of the laws of motion and SR at velocities of any macroscopic object we have ever seen is minute enough to be essentially unmeasurable. The only objects we have ever seen moving at relativistic velocities are subatomic particles; and they obey the laws of SR. But for ordinary, everyday objects, the laws of motion are so close an approximation that it is not worthwhile using SR's more complex calculations; we could not measure the difference. Only by the use of the most sensitive measuring instruments are we able to see the effects predicted by GR and SR that differ from the predictions of the laws of motion; atomic clocks, for example.

The second reason that theories are able to predict phenomena is that they are deliberately constructed so that they do; and if they fail to, then they are rejected. We keep only those theories, in other words, that DO accurately describe reality. All others become not-theories.

Still, take for instance gravity. Is it a force? Is it a distortion of the spacetime continuum? Newtonian mechanics still work, and will work to make a great number of accurate predictions, but this does not render the theory "a true reflection of reality".

It was never intended to be "a true reflection of reality." It was intended to be an accurate description of reality. And it is. All of them are, within their areas of competency. Newtonian mechanics is not competent when velocities are very high; otherwise, it is. SR and GR are competent, as far as we can tell, for all velocities. Universal gravitation is not competent over very long periods, or in very strong gravity fields; GR is competent, as far as we can tell, for all periods and all field strengths. But SR and GR are very much more complex; so if Newtonian mechanics and universal gravitation give answers that are accurate enough to be useful, that is, if they are used within their areas of competence, then there is no need to use the more complex methods. The question is, how accurate an answer do you need? Choose your method accordingly.

Current theories are able to predict with a lot greater degree of accuracy the facts we later observe. Is this an indication of them being "truer"?

No, it is an indication of them being more accurate. But I think that was obvious from what I have already written.

 

[Dave1001]

Why does this system works? It is assumed that is BECAUSE the theories "reflect reality" (whatever that means), thats why we can make accurate predictions with (some of) them.

Still, take for instance gravity. Is it a force? Is it a distortion of the spacetime continuum? Newtonian mechanics still work, and will work to make a great number of accurate predictions, but this does not render the theory "a true reflection of reality".

Current theories are able to predict with a lot greater degree of accuracy the facts we later observe. Is this an indication of them being "truer"?

I'm also curious about tools we have to assess the degree to which these correlations might be completely random. I assume there's a possibity of this being the case that's greater than zero? How do we make or attempt to make these determinations?

 

[cafink]

Exactly, we select the "better theories", and they are better because they predict better, nothing more. Can we claim that a theory is like a map (so its not and will never be the territory) and that the better or more accurate the map is the better predictions? At first sight yes, the answer is plain and simple.

But where does it end? Can we have a "final map"?

As the late Carl Sagan explained it, the scientific method "helps us determine not absolute truth, only asymptotic approaches to the truth--never there, just closer and closer, always finding vast new oceans of undiscovered possibilities when we have made tiny forays into the island on this great sea of unknowing."

 

[Dave1001]

It seems like your question has elements of induction, philosphical realism/nominalism, and queiries into Popper's falsification ideas. There's a lot in this question, and at the moment, I don't know what approach to take to give you a satisfying answer.

If you're only interested in wondering why theories predict, and not if they have some kind of objective correspondance with reality, then the answer is simple, but hardly satisfying. We axiomize mathematics and logic, assume causes produce effects, as well as some vauge notion of "natural law". These are pure assumptions, though each of them helpful, if not entirely reasonable. Why they tend to work remains up for conjecture.

If you're wondering if science can come to a "soulful" understanding of reality: I don't think so. I think our very experience and understanding is built upon a number of biologically-determined biases about how to interpret and deal with the outside world. I don't think experience and understanding trancsends us at all. The correspondance we have with reality is empirical, yes, but the correspondance is never direct, and we've yet to draw entirely agreeable lines to where our experience of reality ends, and the reality we're experiencing begins. Getting down to it, we may never be able to draw this line, but only better understand the degrees involved.

Sorry for the hazy speculations. Up there's probably mostly psilosophical garbage, but I'm at work.

EDIT: Ehh. to add, it's entirely possible that the brain experiences its own experiences -- that is (if you know of the Multiple Drafts model and other similar material ideas) our consciousness is not continuous, but because of structure and mechanisms, at some point, either fundamental in matter or in a more macrocosmic referance, begins to experience itself on smaller scales -- not in a "cartesian theatre" central way. In such a way, our own experiences are shared, re-experienced, and proliferated throughout the brain. There's still much work to be done before a satisfying explanation for all this can be given, but it helps to open the idea of any material entity being able to, in some universal sense of scale, "experience".

Very well-written. This assessment most closely matches my own, although I doubt I'd be able to articulate it as elegantly as I0rca

 

[Bodhi Dharma Zen]

How about this: theories and language reflect our perceptions, but our perceptions evolved in the real world as successful for survival and reproduction. I think we can assume that there is correspondence... ... If not, it would be a huge stroke of luck that what we think is reality isn't so far off that actual reality kills us.

Good way to put it. I agree. Now, this would pressupose that our thinking is delimited by our biology. We have being able to think "outside our humanity" (so to speak) by extrapolating, deducing, creating tools to enhance our perceptions, etc. Still, our words are based on our natural ways for perception.

I believe this is why its so difficult to talk about, or understand, things like theoretical physics, GR and SR, Quantum mechanics, and so on. We simply lack the appropriate concepts because our "normal every day life and perceptions" limit what we can think, or our use of language.

That said, it is interesting this relation between language, meanings and the so called "external reality". And I put it in between " " because EXTERNAL REALITY is a concept, not a perception. We deduce its existence, but we cant see it or touch it or smell it.

 

[Bodhi Dharma Zen]

As you probably know, theories cannot be proven to be true. Modus ponens, all that.

But my point is that they are considered true. Of course, truth is truth, and an approximation to it is simply that, an approximation.

Now, the interesting part, IMO, is that when we say that we have an approximate truth, we are implying that there is a final truth, whatever that means.

I

 

[Bodhi Dharma Zen]

In such a way, our own experiences are shared, re-experienced, and proliferated throughout the brain. There's still much work to be done before a satisfying explanation for all this can be given, but it helps to open the idea of any material entity being able to, in some universal sense of scale, "experience".

I agree. This is the more natural explanation I can think of. That said, its intriguing the relation between the ideas generated by "something" that can arrange those experiences in a meaningful way, and their cause.

 

[Bodhi Dharma Zen]

... What happens is, someone looks at some behavior of the universe, and they develop some math to describe that behavior. This is called, if you will, a "conjecture."...

... The question is, how accurate an answer do you need? Choose your method accordingly.

Thoughtful post, I will try to answer you when I have more time. Just to brief comments. To the first paragraph, yes, I would say that all we have, and can aspire to have, are conjectures, nothing more. We can then build theories, but our theories are just succesful, or not, in explaining (predicting) observations. No "reality" nor "truth" can be deduced by them, which leads us to the last paragraph I choose from your response.

 

[Bodhi Dharma Zen]

I'm also curious about tools we have to assess the degree to which these correlations might be completely random. I assume there's a possibity of this being the case that's greater than zero? How do we make or attempt to make these determinations?

Exactly!

 

[Bodhi Dharma Zen]

As the late Carl Sagan explained it, the scientific method "helps us determine not absolute truth, only asymptotic approaches to the truth--never there, just closer and closer, always finding vast new oceans of undiscovered possibilities when we have made tiny forays into the island on this great sea of unknowing."

The problem with this view, IMO, is that we pressupose that there is something like "a final truth". I cant buy that. We can, or cant, predict what happens next, but only using artificial models, which happen to be related, somehow, to "that" what is "beyond us".

 

[cafink]

"That what is beyond us," as you put it, is the "final truth." As science advances, our models of this truth become increasingly accurate. We'll never know everything that there is to know about it, but we learn more and more every day, forever coming closer and closer to that truth.

 

[Bodhi Dharma Zen]

"That what is beyond us," as you put it, is the "final truth." As science advances, our models of this truth become increasingly accurate. We'll never know everything that there is to know about it, but we learn more and more every day, forever coming closer and closer to that truth.

How close? how do you measure this?

IMO, what is happening is similar to the old "the map is not the territory". It doesnt matter how well you can predict something, what you are doing is making a map about "that other thing", and this map (or collection of maps) will always be artificial, full of ad hoc conjectures and, to a point, arbitrary.