What is the differene between a model and a theory?

[NobleSavage]

Title says it all.

 

[Bomb#20]

Kepler had a model; Newton had a theory. Planck had a model; Einstein had a theory.

 

[NobleSavage]

I should have put this in the dumb questions thread. Thanks, Bomb but I'm still not comprehending.

 

[skepticalbip]

Models and theories are pretty much the same thing in common usage. But a model would be a verbal or mathematical representation of a particular process (think of the Copernican heliocentric model). A theory would be a mathematical description that explains the model and more. Think of Newton’s theory of gravity that not only describes the Copernican model but much more like the arc of an artillery round, an apple falling, the thrust needed for a probe to reach Mars, etc.

But then that is just my understanding.

 

[J842P]

Here's my attempt:

I don't think there is any real difference except that the words may have different connotations. Theory connotes an explanatory framework that accurately, as best as we can at least, models reality. Using the term model might connote that the explanatory framework is not attempting to be 100% accurate, that they are sacrificing accuracy for practicality.

Also, it might connote the scale of the explanatory framework. We might speak of Newton's theory of motion and gravitation, which would apply to the motion of any two bodies in the universe. However, when we speak of explanatory frameworks that are limited to our solar system, for example, we might call it a "model of the solar system."

Here's an interesting paper on the Hodgkin Huxley Theory (Model?) of the neuronal action potential. Notice that the word theory and model are used interchangeably.

http://www.psy.uni-muenster.de/impe...pe/freie_dokumente/occ_0809/hodgkinhuxley.pdf

 

[Underseer]

Kepler had a model; Newton had a theory. Planck had a model; Einstein had a theory.

Theories are models. They're just a specific kind of model that explains existing evidence and laws while making predictions about data that hasn't been gathered yet.

 

[beero1000]

A theory consists of hypotheses about reality that have been tested and verified sufficiently. They include things that we think are true, and simply leave out things about which we are uncertain.

A model is a way of thinking about the facts of a theory and incorporating them into a simplified mental and mathematical framework. Models are simplified, so they can include things that we know are not true (but in general are approximately true) as long as they simplify the calculation of predictions.

For example, we can can model the force on a pendulum using the small angle approximation for sin(x). This isn't true according to our theory of gravity, but is a useful way of simplifying the predictions of the theory that is valid for small values of x.

 

[spikepipsqueak]

I would put it differently though I think everybody is talking about roughly the same knowledge building process.

When you think you have identified some previously unrecognised Fundamental Truth, you construct a simplified version of the world which illustrates the thing you are investigating. In building a model you try to identify and account for every factor that affects the process you are trying to explain.

If you have constructed your model carefully it can be used to falsify any theory you subsequently form using it as a basis.

If that doesn't reveal any flaws you further test your theory by extrapolating outside your model into real world applications.

If it survives that process, plus the rational criticism of other interested parties, the theory is accepted as Truth, subject to new data. A theory is precise and must be true in all cases to be accepted.

The model is literally what it says on the can, a small scale, simplified version of the relevant issues, to clarify thinking and must accurately represent the real world in the dimensions you are investigating.

 

[Bomb#20]

I should have put this in the dumb questions thread. Thanks, Bomb but I'm still not comprehending.

Sorry. What I was getting at is that a math formula that matches the observations and lets you make predictions in some limited domain is all you need in order to have a model. For a theory, you also need to have some idea of what's going on, some explanation for why the formula is what it is. Ideally it should let you predict the boundaries of the domain where the formula applies, and/or connect that domain to other prima facie unrelated observations. Newton's actions and reactions not only explain why planets move in Kepler's ellipses and why they move at the speeds Kepler specified, but also tell us those rules are only accurate in the limit where the planets are small enough and far enough apart that you only have to take into account the sun's effect on them and you can ignore their effects on one another; the icing on the cake is Newton's hypothesis also accounts for apples falling off trees.

Similarly, Planck worked out a formula for the amount of light at each wavelength that comes off a hot object, a formula that matched measurements. Einstein proposed that light is made up of individual photons and showed how that being the case would result in the light from hot objects having a spectrum that matches Planck's equation; the icing on the cake is that photons also neatly account for the photoelectric effect.

 

[none]

Title says it all.

I dunno I'd need an example of a theory of a theory before I could say for sure.
I can realize a model of a model, but theory of a theory I don't realize right now...

 

[Clivedurdle]

Isn't it all a mistake tracking back to Plato? Essentialism - a perfect theory out there.

Should not it always be both together - maybe we need a new term? So theories by themselves and models by themselves are both incomplete, we need stuff to be brought together - grounded.

And then maybe we may politicise both theory and models - art, commonwealth?

Theories are scaffolding. Models are sculptures. Reality is interesting and complex!

 

[spikepipsqueak]

Feedback. Successive approximation on a complex level until the theory explains everything and the model is demonstrably accurate.

When the theory doesn't fall into place as you expected, you check the model for missing elements, terms, before junking the whole thing.

Using your theory in the real world further refines your model.

 

[untermensche]

Models are tools to reduce a situation to something a human can make use of.

In that they are reductions of the real world they are abstractions of the real world.

Many times they are simply equations that humans can plug in values and make predictions when the underlying explanation of variables is known.

But it must always be understood that models and the real world are two distinct things. The real world doesn't operate by following an equation.

Theories are attempts at complete explanations for physical phenomena.

So the Theory of Evolution is an attempt to fully explain how evolution occurs.

Theories make use of models, that is their only connection.

 

[Clivedurdle]

Isn't a theory a more formalised model then?

 

[untermensche]

Isn't a theory a more formalised model then?

A model is complete. It is finished. It works to make predictions of behavior.

We have models of the way the weather changes that help make predictions.

The predictions break down after a while so that means the models aren't perfect. This means new models have to be devised. But those models will be complete as well.

Theories are not complete.

Theories are kind of like saying, this is as much as we presently know about subject X. They can be changed and added to and taken from. They are not complete.

 

[boneyard bill]

A scientific theory is a collection of laws or other well-established facts. It differs from an ordinary theory which can include suppositions or non-empirical data. Thus Newton's theory of gravity combined the law of planetary motion with the law of falling bodies to produce an understanding of gravity as something that operated within both laws and unified them.

A model does not have to be based on well-established observable fact. I can make a model of just about anything and for any purpose. Bohr's "model" of the atom, for example, allows us to visualize something that cannot actually be visualized, but virtually all scientists agree that the model is not, in fact, an accurate representation of the atom.

A scientific theory is a model, but not all models are scientific theories.

 

[skepticalbip]

A scientific theory is a collection of laws or other well-established facts. It differs from an ordinary theory which can include suppositions or non-empirical data. Thus Newton's theory of gravity combined the law of planetary motion with the law of falling bodies to produce an understanding of gravity as something that operated within both laws and unified them.

A model does not have to be based on well-established observable fact. I can make a model of just about anything and for any purpose. Bohr's "model" of the atom, for example, allows us to visualize something that cannot actually be visualized, but virtually all scientists agree that the model is not, in fact, an accurate representation of the atom.

A scientific theory is a model, but not all models are scientific theories.

Exactly.

A model is a useful way of visualization that is useful but that can be and often is contrary to what we do know. e.g. The Earth is modeled as being at the center of the universe for celestial navigation and in astronomy for aiming telescopes and, as you mentioned, the Bohr atomic model. Models, however, can also be attempts to understand reality.

Theories are mathematical descriptions that apply our known physical laws to understand some facet of reality.

 

[fromderinside]

A scientific theory is a collection of laws or other well-established facts. It differs from an ordinary theory which can include suppositions or non-empirical data. Thus Newton's theory of gravity combined the law of planetary motion with the law of falling bodies to produce an understanding of gravity as something that operated within both laws and unified them.

A model does not have to be based on well-established observable fact. I can make a model of just about anything and for any purpose. Bohr's "model" of the atom, for example, allows us to visualize something that cannot actually be visualized, but virtually all scientists agree that the model is not, in fact, an accurate representation of the atom.

A scientific theory is a model, but not all models are scientific theories.

Exactly.

A model is a useful way of visualization that is useful but that can be and often is contrary to what we do know. e.g. The Earth is modeled as being at the center of the universe for celestial navigation and in astronomy for aiming telescopes and, as you mentioned, the Bohr atomic model. Models, however, can also be attempts to understand reality.

Theories are mathematical descriptions that apply our known physical laws to understand some facet of reality.

I'm thinking that if there aren't variables it can still be a model. Kepler used argument to support the model he developed of heliocentric planetary motion. He also used Occam's razor to eliminate the other models. It was a rational argument of one solution of three based on the same set of observations. Newton found relations in physical motion through experiment which expanded from what Galileo had done before him. He used these relations to develop a theory of motion which covered not only planetary motion but the dropping of an apple from a tree, and the relationship between applied energy and motion and energy consequent.

Rational argument is nice, but it appeals only to logic for presentation of facts. Theory requires descriptions and relations of variables to be developed through the operations necessary to create and use them. Its in the operations, the empirical machine, that makes the difference between scientific models and theories.*

*^{_{I have to discriminate between scientific and other theory and model since science is the only one that requires material operations where clear differences between models and theories can be discriminated.}}

 

[ryan]

A scientific theory is a collection of laws or other well-established facts. It differs from an ordinary theory which can include suppositions or non-empirical data. Thus Newton's theory of gravity combined the law of planetary motion with the law of falling bodies to produce an understanding of gravity as something that operated within both laws and unified them.

A model does not have to be based on well-established observable fact. I can make a model of just about anything and for any purpose. Bohr's "model" of the atom, for example, allows us to visualize something that cannot actually be visualized, but virtually all scientists agree that the model is not, in fact, an accurate representation of the atom.

A scientific theory is a model, but not all models are scientific theories.

Exactly.

A model is a useful way of visualization that is useful but that can be and often is contrary to what we do know. e.g. The Earth is modeled as being at the center of the universe for celestial navigation and in astronomy for aiming telescopes and, as you mentioned, the Bohr atomic model. Models, however, can also be attempts to understand reality.

Theories are mathematical descriptions that apply our known physical laws to understand some facet of reality.

I was looking through my textbooks, and I noticed something very interesting that I didn't think was all that interesting before we started talking about models in the other thread.

It's not just math like Maxwell's equations that can predict and explain nature. The periodic table and the pattern of particles in the eightfold way also seem to be intrinsically true. There is something incredibly interesting to me about the fact that the eightfold way and the periodic table were able to make predictions about what particles and elements should fill the gaps when these models were not as complete as they are now, http://en.wikipedia.org/wiki/Eightfold_Way_(physics) .

How can we be right about something without knowing it first, amazing!

Addition:

I read what you said about math again, and I think I misunderstood what you were going for. You probably meant math in general and not specific equations like Maxwell's.

If that's what you meant, then I agree. Mathematical descriptions of the models seems to be the primary reason why there is this regularity of the models that I mentioned above. The math is what shows the order of the particles and the elements.

 

[Loren Pechtel]

A theory is a model that has stood up to challenges.