Scientific law vs. theory, Newton vs. Einstein

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Main Question or Discussion Point

My son is taking a chemistry class in high school, and he was telling me this morning that their teacher had taught them there was some kind of fundamental distinction between scientific laws and theories. He said the teacher had told them that laws are just fundamental regularities observed in nature, whereas theories are attempts at explanation of the phenomena.

This puzzled me a little bit. I asked him, for example, why he thought Newton's "laws" describing mechaics were considered laws, but Einstein's relativity describing mechanics was a theory. Because, he replied, Newton just stated a regularity that is observed without exception (he has not yet formally studied quantum mechanics or relativity), whereas Einstein provided a detailed explanation of WHY those things were happening.

But that can't be right. Einstein didn't know WHY the speed of light has to be a limit of how fast anything can go, or WHY it is the particular speed that it is, or WHY gravity bends space and time the way it does. He just was using certain observations like the Michelson Morley experiment to come up with a new mathematical model, very much like Newton.

I had heard another explanation from a historian of science that I liked better: In Newton's time, science was still young and ambitious enough that they were sure that equations with such striking regularity were "reading the mind of God"- reflections of ultimate reality and truth. But later, as we learned more (for example that even Newton's "Laws" really are just approximations and can be violated), science became more humble, and now they never use the word "law" anymore for their latest models. They call them "models" or "theory", no matter how many mountains of evidence they have for them. They know the paradigm, no matter how apparently good, can always shift with further possible observations or better ideas. So this is more of a historical distinction in the use of the words than a fundamental distinction in these different scientific ideas. There really is nothing fundamentally different between Newton's "Laws" or Einstein's "theories" in what they were attempting to do or what they were from a purely scientific standpoint. We just call them different things for historical reasons, and a shift in our philosophy of science and what we think it's really doing.

So what do you guys think?
 
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Answers and Replies

  • #2
Thuring
I imagine it's a theory until proven, then it's a law. Laws don't always last forever. People will be calling Einstein's work a "theory" out of habit. There is an article in Wikipedia.
 
  • #4
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I imagine it's a theory until proven, then it's a law. Laws don't always last forever. People will be calling Einstein's work a "theory" out of habit. There is an article in Wikipedia.
I don't think that's quite right. Evolutionary biology, relativity, quantum mechanics, are all "theories", but they have all been pretty much proven to all the experts' satisfaction. It's not like there is any more uncertainty to them. They are about as certain as "Newton's laws".
 
  • #5
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I read the article. Here are some quotes that I find a little questionable:

""Laws are descriptions — often mathematical descriptions — of natural phenomenon; for example, Newton's Law of Gravity or Mendel's Law of Independent Assortment. These laws simply describe the observation. Not how or why they work"

Come on, really? Quantum field theory tells us how or why quantum fields work? We have no idea how or why they work. They are just a mathematical model. And Einstein's general relativity? "Spooky action at a distance" is some kind of "how or why it works"?

Here is another quote:
"In science, laws are a starting place," said Peter Coppinger, an associate professor of biology and biomedical engineering at the Rose-Hulman Institute of Technology. "From there, scientists can then ask the questions, 'Why and how?'" "

Again, Einstein's general relativity is just a mathematical model. It's just a mathematical model that describes things, perhaps a little more accurately than Newton's laws. But is there some fundamental difference? They both leave tons of questions unanswered. Why does gravity behave the way it does in Einstein's theory? Is it gravitons? Or Quantum loop gravity? Does string theory have something to do with it? Einstein didn't know anymore than Newton. He just made some adjustments to Newton's equations. So why is one a law and the other a theory?
 
  • #6
Thuring
Yes, I was wrong (though I still like my answer better lol)

From Wikipedia:
Laws differ from scientific theories in that they do not posit a mechanism or explanation of phenomena: they are merely distillations of the results of repeated observation. As such, a law is limited in applicability to circumstances resembling those already observed, and may be found false when extrapolated. Ohm's law only applies to linear networks, Newton's law of universal gravitation only applies in weak gravitational fields, the early laws of aerodynamics such as Bernoulli's principle do not apply in case of compressible flow such as occurs in transonic and supersonic flight, Hooke's law only applies to strain below the elastic limit, etc. These laws remain useful, but only under the conditions where they apply.
 
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  • #7
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This phrasing might clarify WRT to Einstein:

"In 1905, Albert Einstein determined that the laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of all observers. This was the theory of special relativity. It introduced a new framework for all of physics and proposed new concepts of space and time."

https://www.space.com/17661-theory-general-relativity.html
 
  • #8
Thuring
Scottdave provided a good article ...
 
  • #10
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One of the things said in one of the discussions was:

"The term "law" in physics has gone out of style. Physicists still use the term for older concepts that were labeled as laws."

Does everyone agree with that? Because then it seems that the historical explanation for the difference of terms is more appropriate, and this stuff the chemistry teacher has been saying may not be as accurate.
 
  • #11
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Yes, I was wrong (though I still like my answer better lol)

From Wikipedia:
Laws differ from scientific theories in that they do not posit a mechanism or explanation of phenomena: they are merely distillations of the results of repeated observation.
So how is that definition of law not what quantum theory is all about? So should we be calling it "quantum law"? Neither Heisenberg's matrix mechanics, nor the Schrodinger's equation, nor Dirac's equation, are anything other than "do not posit a mechanism or explanation of phenomena: they are merely distillations of the results of repeated observation."

As such, a law is limited in applicability to circumstances resembling those already observed, and may be found false when extrapolated.
So how do we know that relativity or quantum mechanics are not limited applications resembling those already observed, and not of some bigger scientific model?
 
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  • #12
George Jones
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I like what Robert Geroch, a top mathematical physicist, wrote in one of his books:

Robert Geroch said:
It seems to me that "theories of physics" have, in the main, gotten a terrible press. The view has somehow come to be rampant that such theories are precise, highly logical, ultimately "proved". In my opinion, at least, this is simply not the case - not the case for general relativity and not the case for any other theory in physics. First, theories, in my view, consist of an enormous number of ideas, arguments, hunches, vague feelings, value judgements, and so on, all arranged in a maze. These various ingredients are connected in a complicated way. It is this entire body of material that is "the theory". One's mental picture of the theory is this nebulous mass taken as a whole. In presenting the theory, however, one can hardly attempt to present a "nebulous mass taken as a whole". One is thus forced to rearrange it so that it is linear, consisting of one point after another, each connected in some more or less direct way with its predecessor. What is supposed to happen is that one who learns the theory, presented in this linear way, then proceeds to form his own "nebulous mass taken as a whole". The points are all rearranged, numerous new connections between these points are introduced, hunches and vague feelings come into play, and so on. In one's own approach to the theory, one normally makes no attempt to isolate a few of these points to be called "postulates". One makes no attempt to derive the rest of the theory from postulates. (What, indeed, could it mean to "derive" something about the physical world?) One makes no attempt to "prove" the theory, or any part of it. (I don't even know what a "proof" could mean in this context. I wouldn't recognize a "proof" of a physical theory if I saw one.)
I like also what Nobel-laureate Steven Weinberg wrote in one of his books:

Steven Weinberg said:
... scientific research is more honestly reported as a tangle of deduction, induction, and guesswork
 
  • #13
scottdave
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One of the things said in one of the discussions was:

"The term "law" in physics has gone out of style. Physicists still use the term for older concepts that were labeled as laws."

Does everyone agree with that? Because then it seems that the historical explanation for the difference of terms is more appropriate, and this stuff the chemistry teacher has been saying may not be as accurate.
As a parent, I have noticed that sometimes the information given by the teacher, doesn't always convey to the same understanding by the student. I have had my daughter tell me things the teacher "taught", which caused me to email the teacher to find out what was going on. Some of the times, it was that the student (my daughter) didn't understand, or didn't write it down correctly. Sometimes she would say "they don't teach anything, they just want us to read the book...."
 
  • #14
Thuring
Sometimes you do have to read the book ...
 
  • #15
f95toli
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One of the things said in one of the discussions was:

"The term "law" in physics has gone out of style. Physicists still use the term for older concepts that were labeled as laws."

Does everyone agree with that? Because then it seems that the historical explanation for the difference of terms is more appropriate, and this stuff the chemistry teacher has been saying may not be as accurate.
Pretty much. There is certainly no clear distinction between "law" and "theory" in science and these days we tend to avoid using the word "law" for new discoveries/theories. Sometimes you do see people trying to define what constitutes a "law" (usually to say that it is some sort of simple relationship such as F=-kx), but there are so many exceptions that this pointless in my view.
Ultimately it is just a name for something and it doesn't really matter if we call it a "law", "theory" or even "principle" as long as we know what we are referring to.
 
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  • #16
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Pretty much. There is certainly no clear distinction between "law" and "theory" in science and these days we tend to avoid using the word "law" for new discoveries/theories. Sometimes you do see people trying to define what constitutes a "law" (usually to say that it is some sort of simple relationship such as F=-kx), but there are so many exceptions that this pointless in my view.
Ultimately it is just a name for something and it doesn't really matter if we call it a "law", "theory" or even "principle" as long as we know what we are referring to.
There appears to be a lot of 'rules' and 'laws' in biology, and if anything they are less rigorous than theories and hypotheses and just describe trends and relationships: https://en.wikipedia.org/wiki/Biological_rules
 
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I think it is a duty of science to clarify such terms because to the general public “theory” means Day dream guesswork. How does one express the distinction between a highly successful theory such as relativity or quantum with speculative or less successful theories.
 
  • #18
BillTre
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There appears to be a lot of 'rules' and 'laws' in biology, and if anything they are less rigorous than theories and hypotheses and just describe trends and relationships: https://en.wikipedia.org/wiki/Biological_rules
Biology is funny in this way.
The theory of evolution (by natural selection (and other stuff)) is one of the better supported biological concepts, yet it is kind of unclear in the details of how it applies to things which have to get fleshed out fror particular cases. Different interpretations of this approach have to be balanced against each other to come to a conclusion in different particular cases.
What level is selection or adaptation being discussed? Levels being organismic (the organisms), molecular, population.
Which approach provides the more accurate analysis?
How should they (can they) be used in a combined analysis?

In addition to rules and laws there are other paradigmatic concepts (like the"Central Dogma" (or more generally, just how the flow of biological information is understood (which to my knowledge is un-named))) important to understanding that are not called theories, laws, or rules.

Theories, rules, laws, etc have 2 disadvantages going for them WRT common understanding:
1) the words are used differently in scientific jargon from how they are used in common language.
2) the meanings underlying how the words have been applied has varied over the years, however once applied to something, that labeling can outlast the meaning for its application, even in scientific communication.
 
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  • #19
Tpotts09
I think it is a duty of science to clarify such terms because to the general public “theory” means Day dream guesswork. How does one express the distinction between a highly successful theory such as relativity or quantum with speculative or less successful theories.
I definitely agree with this. There needs to be clearly defined guidelines and a hierarchy for scientific theories based evidence and ranked based on probability of the theories being true. For example, I would call natural selection the "alpha theory" since it has the most supporting evidence and is most probable correct answer based on research. Some theories will always remain theories due to either the physical limits of testing and experiments or due to the limits of our technology which is why once a theory has been tested to the full extent to which we are able without any evidence to disprove the theory, it is then treated as a "generally excepted scientific fact" (Such as natural selection or relativity).

Also being accurate in terminology helps. I keep hearing the phrase "Theory of evolution" on a daily basis. Evolution has been observed and tested, it is no longer a theory. What they should be saying is the "theory of natural selection" in my opinion.
 

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