Re: Fun with C

["Elias Salomão Helou Neto" <eshneto@gmail.com>]

On Apr 24, 6:20 pm, "Nasser M. Abbasi" <n...@12000.org> wrote:
> >> Do then you start teaching students nonlinear systems before
> >> linear systems?
>
> > If you are going to teach them pendulum, would it make much sense to
> > pretend it linear? x is a pretty good approximation of sin(x) near 0.
>
> It is not pretending, it is approximation. A good one, if the angle is
> small.  Buildings, rockets, trains, advanced control systems are
> designed based on linear system theory, and somehow they seem to
> work just fine. My teacher kept telling us this all the time. He should
> know :)

Dmitry seems to deny the value of proper approximations, he is clearly
not a physicist :-) Neither am I, but as an Applied Mathematician I do
value them.

> > BTW, there is an important difference between empirical and fundamental
> > laws of nature.
>
> And what makes you think GR is fundamental and classical mechanics
> is not?  We do not know what the fundamental laws of nature are, if
> we did, we would have a unified field theory, which we do not. GR works
> well in large scale, but not too well at at the nano-scale, so it
> can't be a fundamental law of nature.

What are fundamental laws of nature? We will never be able to tell. In
fact, all we have are empirical laws, but some seem to don't
understand it.

>
> Everything we learn can be viewed as approximation to how nature work.

Yep!

> >> Your point that we should start learning general relativity
> >> before classical mechanics makes no sense to me.
>
> > My point is that historic views need not to be taught.
>
> My view is the opposite. I learn a subject better by learning how
> it came about. I like to read old papers and books more than new ones,
> because it gives me more insight into the subject. Even if the
> old views are no longer the most accurate ones on the subject.

Dmitry's viewpoint scared me at first, but I guess he meant that not
everything should be taught in physics school. No one could deny the
value of history, not even such a controversial guy :-)

> > Anyway, importance
> > of classic mechanics looks overestimated. You cannot see planets when
> > living in a large city, but do can the computer on your desk. Explain why
> > it works using Newtonian mechanics.
>
> Do not understand.

Nobody could. He is confusing things because the presence of
"mechanics" in "quantum mechanics".

>
> >> Then why not start with string theory first before general
> >> relativity?
>
> > String theory is not yet generally accepted.
>
> It is tought at many schools allready. Any way, the point
> is that, there are many models of nature, some are
> more complicated than others. If a model works well for
> what one wants to do, and the model is simpler, use that
> mathematical model.
>
> Telling a civil engineer they need to learn GR first in order
> to design a building do not make any sense.

Does it?

Elias