So there was a discussion about evolution on another board and the whole “law versus theory” topic came up. I noticed that various sites seemed to have different opinions about what is a law versus what is a theory, so come to you all to sort out the mess.
So I am confused. Can a theory be made into a law?
Finally, what is the difference between the law of gravity and the theory of gravity? Is there one?
I have this feeling that I am just being completely dense and missing something that should be perfectly clear to me. It’s been decades since I have had a science class, so I would appreciate it if you explain things so they are easy to understand.
No. A theory and a law are two totally different things. A law is a description of what is observed. A theory is a description of how that law works.
The law of gravity simply states the observable relationship between mass, distance, and gravitational force. The theory of gravity attempts to explain how the law of gravity actually works.
If reference to the original topic, there is a sort of law of evolution. The problem is, it’s usually referred to simply as “evolution”, or sometimes the “fact of evolution”. Evolution happens, and has been observed in limited cases. It can also be easilly extrapolated from available evidence for larger cases.
The theory of evolution attempts to explain how evolution actually works.
a law is a rule that matter or whatever seems to obey regardless of the explanation. In other words the laws of gravity dictate that what goes up must come down. The “theory” of gravity attempts to explain WHY such a thing occurs.
Theory can only become law when it can be proven correct. For instance we can theorize that mars has water on it and we can give all kinds of evidence to defend our views. It will stay a theory though until such time as water can be proven.
Now we know that with gravity what goes up must come down. That is essentially a “law” that is observable and provable.
Now the theory is that all mass attracts other mass and that gravity represents a “warping” of space. We can not see this warping nor can we really prove there is such a thing as gravity we can only observe the laws in action and theorize the cause.
Theories explain laws. Theories never, ever become laws.
Sience never proves anything. Only math has proofs.
Another common misconception. That’s called a hypothesis, not a theory. The definition of “theory” that is used by people in everyday conversation is much different than how the word is used in science.
“Must” is a little too strong. Just exceed escape velocity, and it ain’t comin’ back down.
No, the law is that all mass attracts other mass. The “warping of space” is the theory that attempts to explain the law.
I agree with Joe, who said the difference between a law and theory a little more…coherently than I did :D.
PhuQan G Nyus-as Joe said laws never become theories, in fact that’s one of the sticking points for creationists that I’ve found. The idea is that since theory is (in the popular vernacular), is basically a ‘guess’ then it shouldn’t be regarded as correct. This is actually not the case. A scientific theory is a lot more then a guess, as is a hypothesis (which is an educated guess).
All it really means is that scientists began to lose some of their hubris.
All of the “Laws” of science are pre-1900. After that, I don’t believe that any new “Laws” have been stated. (The last ones were probably Maxwell’s Laws of Electromagnetism.) The first statement we call a "Theory"entered the public consciousness after 1859 when Darwin’s work began being referred to as the Theory of Evolution . Since that time we’ve also had the Theory of Relativity and Quantum Mechanical Theory.
The changeover is as much sociological as anything else. Scientists had a different conception of their place in society and looked at their work as descriptions of the way the world worked rather than as final explanations of it.
Even so, there just aren’t that many capital “T” Theories, and there were only a few capital “L” Laws. I’m not even sure that any of the individual discovers of the Laws and Theories were the ones responsble for labeling them Laws and Theories. Others in their cultures took these and used them as they saw appropriate in their day.
However, there is still some use of the older term, in that physics is considered to consist of universal laws that apply to any place and time (outside singularities). But these are small “l” laws rather than capital "L’ Laws.
Consider this. Gravity follows an inverse square law. It does not follow an inverse cube law. But we don’t say that newton’s Theory of Universal Gravitation is a law and that inverse-cube gravity is ‘only a theory’.
“Law” has been used several different ways in science over the years. When Malthus wrote that population rises according to a geometrical law he meant that (as we would put it now) that it tends to rise as an exponential function of time, nothing more. Lots of ‘laws’ in science and maths, especially older ones are what we would call ‘functions’ now. Some others are verbal formulations in a more general sense, such as the ‘Laws’ of Thermodynamics. The Laws of the Thermodynamics now have the status of having been well-tested and almost universally accepted–but they were called ‘laws’ before that was true.
Meanwhile, a theory is a different class of thing. A theory, like the Theory of Universal Gravitation, Atomic Theory, the Molecular Theory of Gases, Number Theory, Quantum Theory, the Theory of Special Relativity, the Theory of General Relativity, Galois Theory, the Germ Theory of Disease, etc, etc, is a coherent body of axioms and reasoning, especially one that provides a unified explanation for diverse phenomena. On occasions, rival theories have attempted to explain the same phenomena–for example the Theory of the Humours and the Germ Theory of Disease, or the Wave Theory of Light and the Corpuscular Theory of Light. In some such cases one of the rivals makes a testable prediction that is not borne out by experiment, or fails to predict something that the other predicts and that is observed. But it is not the tentative nature of the body explanations that makes it a theory: all propositions in science are, formally speaking, tentative. Rather, it is the coherence and ability to generate predictions and explanations that makes a theory.
Agback, no offense intended whatsoever, but I wouldn’t drag mathematics into this discussion. The foundation of the physical sciences is experimental observation, a key part of the scientific method. All physical laws and theories must agree with what is actually observed and measured.
In math, on the other hand, the foundation is a set of assumptions (postulates?) which leads to everything else (or so I am lead to believe, but IANAM*). Physical observation never comes into it. For example, Euclidean geometry is based on Euclid’s five postulates presented in his Elements–physical observations of the universe are irrelevant.
These two very different foundations lead to differing views of laws and theories. For one thing, mathematicians prove things. Physical scientists do not.
I have a question about some “Laws” that have been “disproven” or at least found to only apply in limited situations.
I’m thinking of, for instance, Newton’s Laws of Motion. They’re accurate for commonly observable physical interactions here on Earth, but when we get into relativistic speeds, for example, they become inaccurate. Put another way, the Theory of Relativity has disproven Newton’s Laws.
Taken to the extreme, we can calculate the relativistic component of a slow-speed collision between two marbles, even though that component would be well below the threshhold of what we can measure about the collision.
Although linguistic inertia will probably mean that Newton’s Laws will remain described as “Laws,” what how would we describe them today if we were naming them for the first time?
as she likes psychics, ghosts, etc.