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Physics are there to describe observations of things' behaviours to recreate them or basically use nature for your goals. Which is not enough. Why do physicists not try to explain, why things are the way they are?

In other words:

Why does it work?

instead of

How does it work?

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Physics largely does attempt to explain complicated phenomena in terms of simple principles, but the final "Why?" is beyond explanation unless you are willing to admit the anthropic principle. This is simple a matter or infinite regress. Assume an explanation of "Why did the Big Bang bang?" and you are left with "Why did the preconditions for the Big Bang exist?". – dmckee Aug 8 '12 at 3:36
Why do you say that it's not enough for physics to describe phenomena? In what way is it necessary for physics to explain phenomena? You may get more useful answers if you edit your question to answer those. – Colin McFaul Aug 8 '12 at 3:41
Hi Richart, and welcome to Physics Stack Exchange! I'm actually not so sure whether this question fits here; it's close to being metaphysics/philosophy. The fact that this only has the soft-question tag is also a big red flag (so to speak) indicating that it's probably not appropriate for this site. I'll wait a little while to see if others would like to make an argument one way or another. (Finding another appropriate tag may lend some support to the case for keeping it.) – David Z Aug 8 '12 at 8:41
As there is no metaphysics stackexchange, I'm personally not against allowing the occasional question such as this, especially when it's properly tagged. As for this particular question, a single post to a forum such as this will probably not be satisfactory for such an open topic. I will add that my education in the history of science has taught me that over time physics has shifted in terms of which question it has been more concerned with. – Chris White Aug 8 '12 at 9:43

In some sense, physics does explain why things are the way they are. For most phenomena, physics will have an explanation of why that phenomenon happens the way it happens, or even happens at all. Ultimately, though, there are a few base phenomena that physics as it currently stands just has to take as given. Physicists do try to explain those phenomena as well, but we're always going to be stuck with some things that just are. As @dmckee pointed out in his comment, there is an infinite regress.

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In this video Feynman essentially says that a good How answer only refers to the phenomenon at hand, while a Why answer tends to compare/explain one phenomenon in terms of another phenomenon, which in turn either leads to an open-ended chain of new Why questions, or to circular logic.

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The work of physicists is to construct mathematical models that describe the world around them. This sounds complicated, but a mathematical model is just a set of equations. For example Newton's laws, as learned by generations of schoolchildren, are a mathematical model to describe motion.

Maybe this is getting excessively philosophical but the key point of a mathematical model is that it's a description of reality. No-one is claiming the model is really what happens (whatever "real" means) - it's just a description. You also need to bear in mind that all mathematical models are approximations to reality, because they make simplifying assumptions, and they have a limited scope i.e. there will be limits beyond which the model no longer applies.

A good mathematical model will usually answer lots of "why" questions. For example you might ask why a neutron decays. Well you can use the mathematical model called the Standard Model and this will tell you why the neutron decays. In fact it will answer lots and lots of why questions. But suppose you ask why is the electron mass 0.51MeV and the Standard Model can't answer this because it's put in as an assumption when constructing the Standard Model. If you ask a question about the electron mass you've reached the limits of the mathematical model and you need an improved one.

For an improved mathematical model we might take String Theory, which (hopefully) extends the Standard model to answer lots more questions. When we understand String Theory fully we can hopefully tell you why the electron mass is 0.51MeV. But there will be other deeper why questions that even String Theory can't answer, and for those we'll need an even better model.

So your distinction between how and why questions is a bit artifical. Physicists are interested in why questions, but only if they can construct a mathematical model that can address them. Whether there are why questions that cannot be answered is an open question. Einstein famously hoped general relativity would prove the universe had to be the way it is because it had no alternative. In this he was disappointed. We'd all love to have a theory of everything that would answer every why question but at present we are far from this.

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+1, clearest answer here, I think there is not much more to say. (Apart from that there are also schoolgirls and I don't think there is any valid sentence starting with "We'd all love...". Suddenly having an answer to all questions seems quite undesirable.) – NikolajK Aug 8 '12 at 12:32

Physics certainly endeavors to answer "why" and that frequently happens when the details of a phenomenon are deeply understood, such as in thermodynamics or electromagnetism. But often the mechanisms behind physical laws are a mystery and the best we can do is to describe what happens. In these cases, there frequently are many unproven theories about the underlying structure, but the description of what happens is the only objective fact.

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