Caption: "Statue personifying "Science" in front of the Boston Public Library on Copley Square of the Back Bay of Boston. January 2009 photo by John Stephen Dwyer."
Credit: User:Boston, AKA John Stephen Dwyer.
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Sections
We then look a units because they are topic that has to be stuck in at the begining of a course in conceptual physics.
Then we look at some example cases where theory and observation combine to give scientific knowledge.
So like a lot of other important areas of human culture, there can be no adequate one-sentence or one-paragraph definition.
One should try, of course, to find short definitions that are useful.
But I'm not going to do that, but instead just try a list of ingredients that make up science.
This is my own conction, but I don't think there is anything too idiosyncratic or eccentric. But everyone probably has different emphases and nuances
However, a general aim of science is to find that theories that explain large realms of reality---very general theories.
In fact, most people would say finding such general theories is the main aim of science.
There are many theories and probably many more to find.
Fortunately, one does not have to understand everything to understand something.
All theories are actually of limited scope. But each insofar as they are true allow some part of reality to be understood.
In pure math, the set of axioms should be complete for the realm the theory is good for. Everything in that realm can be derived from the axioms.
In other sciences---and we'll get to plurality of sciences in a moment---the axioms of theory often have to be supplemented by micro-axioms introduced as one goes a long deducing behaviors. But the axioms are the main part of a theory.
The statuses of theories have a large range: e.g., definitively true, true insofar as we know (and maybe truly true), approximately true, partially true, mainly false (but with with some truthiness), false but suggestive, and stupid false.
An true theory as far as we know would be one that we have no reason to doubt. Newtonian physics falls into that category I think.
Described as the theory of motion in the LIMIT of motion that is well above atomic in size scale, much slower than the vacuum light speed, much smaller than the cosmological scale, and with gravity much weaker than that of black holes then Newtonian physics is exact.
The key word is LIMIT: it is exact in a particular limit.
If you think of motion in general, Newtonian physics is only an approximate theory near its realm of validity and a wrong theory well out of that realm.
There are theories which are always approximate. They may or may not be useful in understanding reality. Often such theories are too lowly to be called ``theories'' and are called models. A system may simply be too complex and too particular to have an exact theory, and so a simple model of it is created that captures to some degree it's behavior. For example, all stars even of a certain class are not identical and their structures are complex. So to understand them one creates a simple model that explains their most important features. For example, no star is exactly spherically symmetric, but spherically symmetric models explain much of their behavior. If you want to understand non-spherical behavior, you need a more complex model.
There are partially true theories or mostly false theories. They can be useful in leading to better theories.
A stupid false theory would be pretty useless.
But most scientists would I think disagree.
A theory makes predictions about things which have never been observed.
Those predictions may be true or false, but they come from the theory not observations.
I also think---just following a particular herd---that absolutely true theories could be regarded as the bedrock of reality---laws ordained somehow by the nature of reality.
If one likes, one could also say that true theories (and there a many that are true as far as we know) are part of reality itself.
The particular objects are also part of reality.
As time passes you learn more about particular systems and you improve your theories.
Improved theories are ones that are more exact and/or more general (i.e., explaining more).
Schematically, the scientific method is a cycle of experimentation/observation and theorizing/model-building.
But the cycle is evolving: improved theories suggest improved experiments and vice versa.
A schematic diagram of the
scientific method.
Well philosopher Karl Popper (1902--1994) argued that a scientific theory should be falsifiable.
Caption: "Karl Popper (1902--1994) in 1990."
Popper is an important modern philosopher known for emphasizing the concept of the falsifiability of scientific theories and his book The Open Society and Its Enemies (Popper, K. 1945).
Credit: Unknown photographer.
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Falsifiable means that a theory should make predictions that can be proven wrong and therefore prove the theory wrong.
I think that outside of pure math most people would agree that scientific theories should be falsifiable usually.
But most scientists I think would not want to make falsifiability the main desideratum of theorizing.
Such a theory would naturally be falsifiable since it has generality.
A theorist just aiming at easily falsified theories might end up with a lot of false theories or theories of such limited scope that they would be of little value.
Some would argue that the theory of parallel universes is not scientific since it is not falsifiable.
The upshot of tricky cases is that I---just following a particular herd---think it is wrong to be too dogmatic about whether or not a theory is falsifiable.
In fact, one can talk about degrees of falsifiability with ``not falsifiable in principle'' being the extreme limit.
Falsification is a useful test of the scientific value of a theory or a consequence of theory, but not an absolute yes-no decider on its scientifc value.
One also has to say that it's often hard to do falsification. Experiments at the frontier of scientific research are often hard to do and often give wrong results. No one should give up on a promising theory just because a few doubtful experiments disagree with its predictions.
And yet another thing. Wrong theories can make right predictions. So a few right predictions does not prove a theory.
Science is one---but there are plurality of fields that are sciences using the term science in a different way.
Actually, there is a sort of hierarchy of sciences---using the word hierarchy loosely.
Fundamental physics is at the bottom---the science of the most elementary particles and forces.
Elementary particles are the elements of matter and elementary forces determine the elementary motions.
``Fundamental'' in physics means just-so---no further explanation is possible.
The term ``fundamental physics'' can be used in three ways:
Context must decide between the meanings as usual.
Then going upward, vaguely speaking, chemistry, biology, psychology, the social sciences, (e.g., economics)---and on and on.
It's fair to call fundamental physics the most ``basic science''---but I don't think that implies most important.
When I was a young boy physicist, I did think so: everything can be derived from fundamental physics, and so it was the true existential science.
But no more.
The concept of emergence has shown me the error of my ways.
---no sharp boundaries, the individual names label key centers of realms of reality as we percieve them.
They could be expanded and improved---and contracted and improved.
But any discussion of definitions eventually ends in exhaustion---and sometimes hemlock.