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382) Data, facts, laws and theories

Ludwik Kowalski

Montclair State University, New Jersey, USA
October 17, 2009


The abbreviated version of the text below was posted on the CMNS list yesterday.

What follows was prompted by Nicholas Wade’s New York Times Book Review (October 11, 2009). My comment is about scientific DATA, FACTS, LAWS and THEORIES.

Cognitive Structure of Science

a) Any recorded piece of information, about a natural phenomenon, is DATA. It can be the result of an observation or an experiment; it can be qualitative or quantitative.

b) A piece of data recognized as valid, by most practitioners in a given field, becomes a FACT. Laboratory facts are confirmed data; any scientist using the same protocol is expected to obtain the same data; at a specified level of reproducibility. Science is not mathematics; that is why the level of reproducibility, for example 90%, should be reported.

c) A LAW is a generalization of facts. I am thinking about Kepler’s Laws (how planets move), about Mendeleyev’s Law (how elements are ordered in a chart), Faraday‘s Law (how changing currents can be induced), etc.

d) A THEORY is an explanation of a law. I am thinking about Newton’s gravitational theory, about Maxwell’s equations, about quantum mechanics, about Heizenberg’s principle, etc. Distinctions between laws and theories (and between facts and theories) are worth recognizing. Unfortunately, this is not always done.

e) Theories are based on assumptions which may or may not be valid. Assumptions can be based on facts, on laws, or on intuition.

f) Scientific theories are validated not only on the basis of their logical (mathematical) correctness but also on the basis of their ability to guide to discoveries of unknown facts. Scientific theories evolve; some theories are more powerful, more general, more useful and more elegant, than others. A theory is not acceptable to scientists unless it is susceptible to refutation. In other words, a scientific theory must be falsifiable.

g) The concept of ‘absolute truth,’ often used by mathematicians and theologians, does not belong to science. Wade wrote: “A theory, however strongly you believe it, inherently holds a small question mark. The minute you erase the question mark, you’ve got yourself a dogma.”

h) An hypothesis is a tentative idea to be confirmed. It is a common instrument of human thinking. Hypothesizing is used by all those who collect data, who turn data into facts, who generalize from individual facts, and by those who explain facts of nature. Tentative assumptions are made by all thinking people, not only by physical scientists.

i) To avoid confusion, scientists try to define their terminology. The term ‘theory,’ for example, does not mean the same thing as the term ‘hypothesis.’ But non-scientists often confuse these two terms. In common language the words ‘theory’ and ‘speculation’ are often used as if they were synonyms.

j) ‘Force,’ ‘energy,’ and ‘power’ are commonly used interchangeably by non-scientists. Novice physics students often find this confusing.

Several researchers commented at once; the above text contains additions made to accommodate comments. The entire text shown above was posted this morning on the Phys-L list for physics teachers. This generated three interesting replies, as shown below in blue.

Teacher 1:
I also read Wade's article.

I disagree; I don't think a meaningful distinction can be drawn between fact, theory and law. For starters, Newton's laws are wrong but Einstein's theory is correct. Kepler's laws are only approximate. So we don't use these terms consistently (perhaps we should but it is too late, we don't).

Second, facts are contingent on theory in at least two ways. The fact that we observe current flow is contingent on our theories of how ammeters and voltmeters work. There are few observations made today that don't depend on starting with some assumed (theoretical) knowledge. This is ok, we can't test everything at once so we assume some things are true while we test other things. Theories also tell us where to look for facts. We don't just go out and start measuring stuff to see if there is some correlation somewhere. For example the data supporting black holes only makes sense because we have a theory of black holes. We have to know to look for gravitational lensing before we can discover the fact that black holes exist. It doesn't make sense to try to separate facts from theory.

I think Wade in the NYT book review was trying to get at how science can be right at the same time that it can change over time. Here is a better way to think about it. We are perfectly rational to believe (and I mean really believe) that something is true if all the data supports it and, upon trying to find counter evidence we find none (this is important- finding data in support is often easier but one good counter example destroys the theory). It is equally rational to change your mind if you get better information. I really believe my breakfast cereal is nutritious. Then I read in the news about a contamination problem and change my mind. I am not being silly or irrational, rather I am being very rational.

Now, any good scientific concept is fruitful- it suggests new ideas to try. So sure, the testing process is never done but just because you can think of some new test doesn't mean you should abandon the concept. In the history of science we almost never abandon a theory or law until we have something better to replace it. This also is rational; a well established theory is worth keeping, even if it might suggest new ways to test it.

We should believe (I mean really believe it is true) in evolution as the best truth that is available. Until we have evidence to the contrary. And it also makes sense to keep testing it, even while believing it is true.

Oh and hypothesis are a nice idea but I don't think very many scientists actually operate that way. We start with something that looks interesting or puzzling and start playing around with it; our intuition outruns our rational mind at first. Usually after the fact we can come up with a hypothesis but more often we start with a hunch or a dream or an idea. The guy who discovered the benzene ring didn't have a hypothesis initially- he dreamed of a snake rolling down a hill by biting its tail and forming a hoop. But it doesn't matter where we get ideas from (hypothesis or dreams). What matters is if we can back them up with physical data and, after trying hard to knock them down, they are still standing. I have noticed that biology papers tend to state a formal hypothesis but I don't see this done in many physics papers.

Teacher 2
I disagree with almost all of Wade's list and agree with Teacher 1's criticisms.

One more point:  According to my understanding of the term, a hypothesis may be made without regard to whether it is true or not. Sometimes a hypothesis is assumed, expected, or hoped to be true but sometimes not. In particular, at the start of a proof by contradiction, we make a hypothesis that we expect to be entirely false.

To repeat: offering a hypothetical statement says *nothing* about the truth, falsity, probability, improbability, etc. of the statement. For more on this, see

 http://www.av8n.com/physics/hypothesis.htm

There are other words we can use, such as conjecture or supposition, when we wish to suggest some marginal or provisional belief in a statement. Of course at this point we are dealing in shades of gray, since all scientific laws are to some extent provisional.

Here's my take on truth, belief, and knowledge:  

http://www.av8n.com/physics/truth.htm


I agree with KF that real-world day-to-day scientific activity is _not_ well described in terms of hypothesis testing.  It is often the case that scientific results can _retrospectively_ be analyzed in terms of hypotheses supported and hypotheses rejected ... but this is usually not necessary or even helpful at the beginning or middle of a project.

It just cracks me up when people who have not ever done science, nor even seen it done, insist that "THE scientific method" equates to hypothesis testing.  I wish non-scientists would refrain from telling scientists how to do science.

Teacher 3
Hi all- I've NOT read the NY Times article, but have read the postings. It's my undestanding that the accepted, currently-used term is "model". The take is, that it is too presumptuous to claim that we are seeking truth, as physicists our job is to predict the results of experiments. We do this by formulating models which, if successful, become "standard models."  Thus one occasionally hears reviewers say "the standard model appears to be working embarrassingly well" - meaning that we expect that there is "physics beyond the standard model" that should reveal itself in precision tests of the standard model.

We know, of course, that there are observations that don't seem to fit within the framework of our standard models - we characterize these as "unexplained".

Currently, where the support dollars are going, the following are objects of attention:

*) Dark matter - what is it?  Supersymmetry is a popular guess.
*) Dark energy - is it just Einstein's constant? Is there a Higgs that can be identified with a mechanism for giving particles mass (I claim that a well-defined particle is not needed for the Higgs mechanism)
*) What are the neutrino mixing parameters?
*) Does supersymmetry exist?
*) Do the weak interactions become strong at high energies?
*) Can accelerator designors find acceleration schemes that will permit the construction of small high-energy colliders.

There are also some questions left over from the 'sixties, but these are no longer popular.

Ludwik's Reply:
I hope that there will be more contributions to this interesting thread. I do not disagree with the above comments. Let me make one thing clear; I did not try to write an essay on the so-called scientific method. It is impossible to write such essay without omitting some aspects of scientific methodology. Furthermore, what one writes depends on the audience. In the CMNS field, which used to called “Cold Fusion,” a distinction between data and facts, as I defined these words, is very important; the amount of data is very impressive we are still waiting for recognized facts. In my opinion, the most promising data should be identified and all efforts should be concentrated on turning these data into facts. Agreeing on the meaning of essential words is an important preliminary step for discussing scientific methodology of validation.

I hope that my description of four essential concepts, DATA, FACT, LAW and THEORY is clear. But I am not sure that the above four words are the best for the corresponding concepts. Which words would be more appropriate (leading to a minimum number of possible confusions)? .

I also like the term “model;” it is a synonym for “theory.” But I always add the adjective “theoretical,” to avoid confusion with a physical model, for example, of a building, a bridge, or airplane. The term hypothesis is part of common language and scientists are not forbidden to use it. A hypothesis is an assumption that something is either true or not true. Tracing the origin of assumptions might be interesting; but that is a different topic. Validations of scientific assumptions should not be based on their origins.

P.S. (10/18/2009)

M.B. who I encountered on another forum, asked a question about the so-called “sociological science.” I think she is a not-a-very-young journalist. She wrote: “I personally wondered what science is in poli sci.” Then she specified:

I have a Bachelors (1944) and already was skeptical of the "science" aspect. My motive to study such was more for the philosophy of international politics. Regardless, how does one measure? There are hints such as candidate polling (and George Gallup had U of Iowa connections.) Like nowadays, we studied wars and new peace pacts. Hardly a topic to quantify. As I watch what modern students study, it seems they take the courses to engage in jobs with government or the media. There is merit, but I question the science.

Something different might be said for economics. Of all the social sciences, here we have measurable data and I forgive those who call it science--the "dismal science" they say.

Sociology falls in an iffy category for me. It seems that studies on prison recidivism, for example, may use quantifying (therefore conclusion) methods.

I believe social sciences, balanced against physical sciences, have relevance. However, deep study requires more than a few studies which pit two human conditions against each other. Most issues relating to international affairs--war and peace, for example--relate mostly to economics. I guess that's why I was called an economic determinist, even before I was old enough to vote.

This is an interestiing topic. Sociologists, political analysts, historians, psychologists, economists, mathematicians , philosophers, etc. do often call themselves scientists. Many people thing that scientists are all those who use numbers. I am not sure that this is correct; the methodology of validation is probably a better yardstick, to distinguish scientists (as a group) from nonscientists. That topic, by the way, is likely be of great interest to most students.

Teacher 4:
I would assume the article in question is "Evolution All Around" criticizing the book " THE GREATEST SHOW ON EARTH The Evidence for Evolution" By Richard
Dawkins.

1) The review is quite reasonable and actually only differentiates between theories and facts.  It says that Dawkins strays into saying evolution is a fact and not a theory or model.  This looks like a very reasonable criticism of Dawkins.  As far as I can see it makes no general definitions of the other words.

2) As to a law being a generalization of facts, that is not exactly how the term is used.  Virtually all laws are equations or relationships which may be either general or specific.  If you look at all of the laws they are generally equations such as Boyle's law, Newton's laws...  Sometimes the equation is merely implied as a statement of a principle.

3) A theory is a consistent framework for relating various laws and facts so that one can make predictions about unknown situations.  Sometimes you can also call a theory a model.  But in no sense is it an explanation.  The theory itself can often not be explained, but it can be used to generate predictions.  If it can be explained that would be in terms of another theory and eventually you get to postulates or assumptions which have no explanations, and are sometimes do not even look reasonable, but they work.

4)


I numbered the paragraphs and eliminated the last one; it has nothing to do with the topic of our thread. The above message is a good illustration of disagreements resulting from imprecise terminology. My terminology of the four basic terms (data, facts, laws and explanations) has been introduced.; let me stick to it.

1) Evolution is a theory explaining many facts recognized by biologists. Dawkins, on the other hand, according to the above, states that evolution is a fact. Yes, I know that the term ‘fact’ can refer to different things in common language. That is why scientists must first agree on definitions of basic terms. 

2) This paragraph is another illustration of the same thing. I suggest that the term “fact” should refer to validated data  (accepted by most practitioners), not to anything else. Likewise, I suggest that the term  “law” refers to nothing else than a generalizations of facts. 

What is wrong with this approach? How else can we deal with imprecise terminology of common language? As I already mentioned, some people use the words “force,” “energy,” and “power” interchangeably. As physicists we introduced precise definitions of these terms to students, and we try to stick to these definitions. What is wrong with assigning precise meaning to the four concepts needed to discuss scientific validations? Three questions should probably be answered:

a) Do we need precise definitions of basic words used to discuss scientific validations? 

b) Are the four concepts I identified (by assigning specific four words to them) indeed essential, as far as scientific validation is concerned?

c) Are the words assigned to these concepts appropriate? If not then what are better words?


P.S.
Note what I am referring specifically to scientific validations. This term does not cover as many topics as the often-rejected term “scientific method.” I am not proccupied with generalizations about how discoveries are made (what comes first, etc.).

I believe that the four concepts I defined are essential, as far as scientific validation is concerned. But I suspect that better words can be chosen to name these concepts.

Teacher 5
I will admit that I cringed a bit when I saw a video in which Dawkins used that phrase, but if one looks at "evolution" as a term simply meaning "change over time," then it seems much more reasonable to assert that evolution is a fact. The observed fossil record is clear--by whatever method one can imagine the fact is that species have changed over time. Now when one extends the idea to "evolution by natural selection," then we have moved into the realm of theory (beyond hypothesis, since evolution by natural selection is a synthesis of an overwhelming body of evidence) or model by which we explain how the "fact" of evolution came about.

It isn't clear from Dawkins' comments if he does mean evolution in its more simple sense, or in its more complete and common meaning. I'm sure however, that if questioned about it, he would either modify his comment or clarify his definition of evolution to conform to the standards we are discussing here.

His insistence on using the word "fact" is, I believe, more of a rhetorical device than a logical one. He is trying to emphasize that, based on the overwhelming evidence and the interlocking methods by which evolution is taken to occur, evolution by natural selection is as close to a "fact" as almost anything scientific can be. The idea is over 150 years old, and all of the evidence so far developed supports it fully. This is a rather long lifetime for a theory to stand in the modern world, where challenging a prevalent idea is a widely accepted scientific activity. After all, few scientists are going to go down in history for confirming Darwin's work, it is the ones who successfully upset that apple cart who will be remembered.

Teacher 4 again:
While the definition proposed for a fact aligns with common usage in science, the proposed usage of law does not.  Just look at all of things called laws and in general they are relationships between variables. Everyone may propose a definition, but to be used it must be accepted by the community that uses it.

Historically the definition of a law has been taught as something at variance with the way in which it is actually used.  The old definition of law as a verified theory still appears in many texts, but it is going away as it is completely out of alignment with actual usage.  Come up with a list of laws, so we can find out how often it is not a relationship between variables.  If there are no counter examples or they are few, then the definition that I have proposed is the common usage and should stand.

Language is not definable by logical rules, but relies on common agreed on definitions.  Many arguments about "what is" are often just people insisting their definition is correct and the other person is using it wrong. Dictionaries now recognize that and are no longer purely prescriptive.

As to imprecise terminology there is no use telling students definitions that are at odds with how people in the field of study actually use the terms.  What about the historians of science?  How do they define the terms in question, or what definitions have they found tend to be prevalent now?

Ludwik’s reply:
1) Each Kepler's law is an example in which the term "law'" means "a generalization based on facts."

2) What would be a better term for "a generalization based on facts." Should we say "Kepler's generalizations?"

3) Newton's law of gravitation, on the other hand, is not "a generalization based on facts." That is why I think it is better to say "Newton's theory of gravitation." It explains Kepler's Laws in terms of postulated F=G*M*m/r^2 .

4) Yes, what I am trying to do is full of traps. But is it worth trying? Please help me to choose better words, to make definitions more acceptable. I believe the four selected concepts are essential, as far as scientific validations are concerned. What names are better than DATA, FACT, LAW, and THEORY?

Teacher 6:

Not to take away from Teacher 5’s point, which I agree with, but I wince a little bit whenever I hear appeals to the amount of "supporting evidence" for a theory without an accompanying assessment of the degree to which the theory may be *vulnerable* to evidence.  After all, proponents of intelligent design can also point to overwhelming
supporting evidence.  The difference is that it is entirely inconceivable that any evidence could ever be found that is inconsistent with ID.

Teacher 5 again:
Valid point. I was thinking about the possibility of evidence against evolution that could be conclusive (e.g., finding fossils from widely different time periods co-located in the same rock layer), but decided to leave it out to keep my response short. It is certainly true that, even as a "fact" evolution is still subject to refutation by evidence, although, so far, all the evidence found supports the evolutionary model we presently have constructed. ID [Intelligent Design], on the other hand, as John points out, is not susceptible to refutation and therefore cannot be considered a scientific theory in any sense. And furthermore, not only can it not be refuted in principle, it can also make no useful predictions about what we should expect to find, while the evolution model makes many of them.

Ludwik’s comment:
According to point (f) in:

 http://csam.montclair.edu/~kowalski/cf/382terms.html

“Scientific theories are validated not only on the basis of their logical (mathematical) correctness but also on the basis of their ability to guide to discoveries of unknown facts. Scientific theories evolve; some theories are more powerful, more general, more useful and more elegant, than others.”

I will add another sentence “A theory is not acceptable to scientists unless it is susceptible to refutation. In other words, a scientific theory must be falsifiable.

The attribute of usefulness was suggested by someone who is not on our list. I am open to constructive suggestions.

Teacher 4 again :
Boyles law, Newton's laws, Kepler's laws, Hooke's law, The law of conservation of energy... have very little in common except for the fact that they are called laws and that they are relationships between variables.

One might call conservation of energy a universal law meaning that there are no known exceptions, while Hooke's law is an empirical law which certainly has exceptions.  Why not have E=mc^2 as a law?  But for some historical reason it is not.  The term law would seem to imply that it is absolute, while many laws are only obeyed under certain conditions.

Hooke's law can be easily discovered by a student in a short lab, while Kepler's laws took years and much struggle to create.  The term law seems to be applied to various equations almost by accident.  I could just publish an experiment and generalize it and call it a law according to your definition. Is Hooke's law general?  Is F=mg also a law?  Or how about Ff=mu Fn? Sometimes they may be considered laws, but sometimes not.

I object to the word explanation because ultimately one comes up against the< fact that your explanation is just a statement "that is the way it is". Theories are in a sense complete reasonably consistent models which cover a whole range of phenomena.  As such they are merely what we use to make predictions.  They explain thing in terms of other things, but ultimately they are not complete explanations.  The term explanation leads students and the public to think that they are final complete explanations rather than tentative models.

Part of the problem in the past has been the rigid definitions of these things promoted by textbook authors.  These are not strictly scientific terms, but partially social and historical.  Making rigid narrow definitions will be confusing because each scientist has a slightly or greatly different view of these terms.  So I propose that law is a historical term applied to a relationship between variables.  It is very difficult to say much beyond that.  It is easier to say why one is Sir Soandso than to say why something is called a law.  He was knighted by the queen or king, but laws are decided by convoluted accidents of history.

Teacher 7 :
One of the main problems involved in discussing whether evolution is a fact or theory is the context.  There are two which tend to be commingle.

One issue is the evolution of life forms.  There are many robust lines of evidence that life forms have evolved from common ancestors. Unfortunately, some have shortened the idea of the evolution of life forms to the single word, evolution. So in this context, evolution is a fact.

The other issue is the means by which evolution has occurred.  Darwin's theory is that of evolution by natural selection. Unfortunately, some have shortened the theory of evolution by natural selection to the single word, evolution.  So in this context, evolution is a theory.

This was most eloquently stated by Stephen Jay Gould who wrote: "Well, 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 apelike ancestors whether they did so by Darwin's proposed mechanism or by some other, yet to be discovered." [Stephen Jay Gould, "Evolution as Fact and Theory," May 1981; from Hen's Teeth and Horse's Toes, New York: W. W. Norton & Company, 1994, pp. 253-262.]

Teacher 8 :
Teacher 4 wrote: “Boyles law, Newton's laws, Kepler's laws, Hooke's law, The law of conservation of energy... have very little in common except for the fact that they are called laws and that they are relationships between variables.” And that they are all generalizations of facts.  In physics, we tend to generalize by making equations with variables.

“However, given that the genesis of this discussion was evolution, one might like to choose definitions that apply in biology.  How do biologists use the term law?  A little googling reveals that although there is some disagreement about whether biology can have laws (see

<http://www.springerlink.com/content/g0gj47u3q5716250/>),

the term is used for generalizations that cannot be expressed in terms of variables
(see

<http://en.wikipedia.org/wiki/Dollo%27s_law>).

Teacher 4 also wrote: “Why not have E=mc^2 as a law?  But for some historical reason it is not. ...I could just publish an experiment and generalize it and call it a law according to your definition. Is Hooke's law general?  Is F=mg also a law?  Or how about Ff=mu Fn? “ I think it is clear that Ludwik is using 'generalize' in the sense of 'summarize,' not in the sense of 'extrapolate.'  Perhaps there is a wording that is less open to misinterpretation.

Nevertheless, I would have no trouble calling E=mc^2 and F_f= mu F_N 'laws.'  They are not traditionally associated with someone's name, but I can easily imagine using the word 'law' while describing them to a student.

Teacher 4 also wrote: “Sometimes they may be considered laws, but sometimes not.” Taking this in context, I believe what is intended by this sentence is "Sometimes they may be considered accurate, but sometimes not."  The usage of "law" here would then be consistent with “The term law would seem to imply that it is absolute, “ But of course Hooke's law famously demonstrates that this is not consistent with normal usage -- as John explicitly states.  Whether some generalization is 'sufficiently accurate' in any _specific_ situation is not pertinent to whether it can appropriately be called a law.

Ludwik’s new suggestion”
Thank you for these illustrations and observations, John and James.

1) I wrote:

DATA = what is reported
FACTS = validated data
LAWS = generalized facts
THEORIES = explanations of laws and facts

I am glad that we are not arguing about the concepts appearing on the right of the equations. They are essential and obvious. I am certainly not the first to identify them. We are arguing about the words appearing on the left.

2) And yes, we have to deal with "social and historical" factors. Different people assign different meaning to words. This does create confusion. How can the situation be improved? One possibility is to invent totally new words, such as:

AADO=what is reported
BADO=validated AADO
CADO=generalized BADO
DADO=explanations of BADO and CADO

Yes, this is terribly artificial and probably impossible to impose.

3). Another approach would be to use existing words which are not likely to generate confusion. Here is one such possibility.

FIND=what is found and reported
CONFIRMATION=validated FIND
GENERALIZATION=generalized CONFIRMATIONS
MODEL=explanations of GENERALIZATIONS and CONFIRMATIONS

For example:

John’s find and Mary’s confirmation.
Kepler’s generalizations and Newton’s model.

That is probably better than artificial words. Perhaps someone will suggest better words; I am not a native English speaker. The third option is to accept the existing chaos and suffer the consequences.

Teacher 4 again :
No matter what we decide to do, there is no way to impose a specific set of terminology on physicists, let alone chemists and biologists.  The only thing we can do is to try to communicate to students a fairly rational view. We don't have a prescriptive language academy as the French do.  Despite that the French still do not follow the orders from above.

So there is no sense getting upset about some variant terminology as long as it is not too far from the mark.  It is fun to argue about it!  And our discussions have very little effect on the larger community who is oblivious
of them.

However, it would be good to get the outrageous mistakes out of the textbooks in regards to this terminology.  While the texts are very poor at teaching students, they are used as a resource by teachers and the teachers often slavishly follow them.  When the latter is done science ends up being a hash.

It is sort of like dancing.  One can accept some mistakes as long as the person does not go in a totally wrong direction and mess up everyone.  So whether they do a proper hay, or just a circle is not disastrous.

Teacher 7 :
The Clausius statement of the 2nd Law of Thermodynamics? Or the Kelvin-Planck statement?

Teacher 4 again :
I did say that a law can be an equation, and the 2nd law of thermo can be an inequality equation.  But laws are sometimes stated in such a way as to obscure the equation such as NTN1 or NTN3.  One can play the game all day with looking for exceptions, but can anyone make a fairly good list of the known things that are all called laws and see if there are any rules that govern the preponderance of them.  Then a better definition might be found. We don't make the rules for what is called a law, common usage is the true deciding factor, and there are always exceptions.  It the alternately proposed definition of a law seems more reasonable where do laws stop and theories begin?  Another thing one can say about laws is that they are very specific, and that a theory often encompasses a number of laws.  But we are dealing with classification which is somewhat alien to physicists, but not to biologists.

So can someone come up with a comprehensive list?  The majority of examples
prove the rule, not the exceptions because the definition of a law is not a
physics definition.

Teacher 8 :
How are the Law of Conservation of Momentum or the Law of Conservation of Energy a relationship between two variables?  The two take very different forms depending on what types of energy are being converted or what type of collision is being discussed.  Newton's First Law of Motion?  Newton's Third Law of Motion?  Lenz's Law?

Wow, speaking of Lenz's Law, I came across this very cool video:
http://www.youtube.com/watch?v=fxC-AEC0ROk

Teacher 9 :
I think I know what "Data" is.  And I'll even accept "Confirmed Data" I suppose as a comment that the experimental results are reproducible.

I don't know what "generalized data" is.

I don't know the difference between a theory, a law, a model, a framework, a [insert name].  How does this affect the way I teach or learn physics?  It just seems to me that it is an accident of the historical development as to which term is associated with which development in physics -- maybe a measure of the term in vogue at the time of the development.  Is the standard model of particle physics a theory?  A model?  Is there some semantic arithmetic law:  2 theories + 1 law = 1 model?  (And if that's true and no one has claimed it, can it be Keller's Law?  No wait, Keller's Theory?  No wait, arg!)

No one who does physics or who teaches physics should be up at night worrying about these distinctions.  So I wonder about the biologists.  Is evolution a theory, a law, a model?  I question the motivation of those who would have us ponder this, with a line from the movie 1776:  "Whatever it is, I'm against it!"

Teacher 10 :
I was taught to use "The Energy Principal"  by Peter Redmond whenever possible, as it is easier.  This was some time ago -- have laws been substituted for principles?

I instinctively used law for the relationship of extension and force in my hardening magnetic repulsion oscillator. Not a generalization; is this wrong?

Ludwik Kowalski:
1) In a private message B.K. wrote:
Jules Henri Poincare (1854-1912) observed that “Science is built with facts as a house is with stones, but a collection of facts is no more a science than a heap of stones is a house.”

2) Let me paraphrase this : Laws of physics are relation between variables, but a relation between variables is not necessarily a law of physics.

3) And here is something similar. Each medieval stonecutter, working on a cathedral,  was asked "what are you doing?"  The first said: "I am chipping stones," the second said: "I am supporting my family;" and the third said:  "I am glorifying God."

Teacher 11:
. . . The word "believe" often has a semi-religious overtone. To many people "believe" is equivalent to "faith in something that will never change" or even "my strongly held opinion that I have no intention of changing no matter what".

But most often scientists have something slightly different in mind. If I say I believe in something, for example evolution or the theory of relativity, what I really mean is that I think there is good evidence supporting it and no credible evidence against it. So it is reasonable to believe in it, at least until there was credible evidence to the contrary.

The idea that we can (and ought to) change our beliefs when we get new, better evidence seems to be a foreign idea to most people. Yet most people do this all the time, at least for beliefs that aren't so central. We believe our neighbor is honest and then we find his name in the paper as a crook so we change our belief.

I have no problem if someone uses the word believe in the above sense, either for belief in god or belief in evolution or even belief that evolution doesn't occur. Once we understand "belief" as something open to change based on evidence we can start talking about evidence.


Ludwik:
The word ‘believe’ does belong to common language. But it is not used in scientific validations of facts and theories.

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