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From: Ste on 21 Feb 2010 19:42
On 21 Feb, 22:28, mpalenik <markpale...(a)gmail.com> wrote:
> On Feb 21, 4:57 pm, Ste <ste_ro...(a)hotmail.com> wrote:
>
>
>
>
>
> > On 21 Feb, 01:45, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> > wrote:
>
> > > "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> > > > On 20 Feb, 05:27, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> > > > wrote:
> > > >> If you're suggesting that it's improbable that a theory could work not
> > > >> because its premises were correct, but because it simply promoted
> > > >> correct behaviours, then wonders why religion has fared so well. In
> > > >> any event, I'm willing to accept Feynman's argument, basically that QM
> > > >> amounts to a workable mathematical model, and makes no claim to any
> > > >> truth more fundamental than that.
>
> > > >> ________________________________
> > > >> The whole of physics is like that, not just QM. Physics just gives us the
> > > >> eqns by which the universe functions. It does not make claim to any more
> > > >> truths fundamental than the eqns; the rest is just philosophy.
>
> > > >> Your problem of course is that you don't understand the eqns, so you
> > > >> don't
> > > >> understand physics.
>
> > > > On the contrary, my problem is that physics seems to have dispensed
> > > > with the physical. Yet it is the physical, as opposed to the
> > > > mathematical, that I am interested in. That is, the qualitative
> > > > physical concepts  - what I've referred to as an explanation at the
> > > > the "practical-mechanical" level - that would seem to me to
> > > > distinguish physics from maths are largely absent, and indeed seem to
> > > > be systematically deprecated and devalued.
>
> > > You should look up, and learn, Minkowski space time. This gives a
> > > practical/mechanical explanation of SR that most physicists find very easy
> > > to use and understand. However even simple explanantions do involve high
> > > school mathematics. Like I said, it can only be "dumbed-down" so far.
>
> > Peter, will you please stop treating me as an idiot, as though I
> > somehow don't understand the nature of Minkowski spacetime.
>
> You don't.  What makes it Minkowski spacetime?  How do space and time
> behave under rotation in a way that is different from a rotation in
> non-Minkowskian spacetime?  What shape is a curve made up of points
> equidistant from the origin?  Why is it different from regular,
> euclidean space?  What is it about a moving object that makes it look
> like it's rotated in a 4 dimensional, Minkowskian manifold?

I've no idea, but I know none of it has any connection with a
"practical-mechanical explanation".
From: mpalenik on 21 Feb 2010 19:47
On Feb 21, 7:42 pm, Ste <ste_ro...(a)hotmail.com> wrote:
> On 21 Feb, 22:28, mpalenik <markpale...(a)gmail.com> wrote:
>
>
>
> > On Feb 21, 4:57 pm, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > On 21 Feb, 01:45, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> > > wrote:
>
> > > > "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> > > > > On 20 Feb, 05:27, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com..au>
> > > > > wrote:
> > > > >> If you're suggesting that it's improbable that a theory could work not
> > > > >> because its premises were correct, but because it simply promoted
> > > > >> correct behaviours, then wonders why religion has fared so well. In
> > > > >> any event, I'm willing to accept Feynman's argument, basically that QM
> > > > >> amounts to a workable mathematical model, and makes no claim to any
> > > > >> truth more fundamental than that.
>
> > > > >> ________________________________
> > > > >> The whole of physics is like that, not just QM. Physics just gives us the
> > > > >> eqns by which the universe functions. It does not make claim to any more
> > > > >> truths fundamental than the eqns; the rest is just philosophy.
>
> > > > >> Your problem of course is that you don't understand the eqns, so you
> > > > >> don't
> > > > >> understand physics.
>
> > > > > On the contrary, my problem is that physics seems to have dispensed
> > > > > with the physical. Yet it is the physical, as opposed to the
> > > > > mathematical, that I am interested in. That is, the qualitative
> > > > > physical concepts  - what I've referred to as an explanation at the
> > > > > the "practical-mechanical" level - that would seem to me to
> > > > > distinguish physics from maths are largely absent, and indeed seem to
> > > > > be systematically deprecated and devalued.
>
> > > > You should look up, and learn, Minkowski space time. This gives a
> > > > practical/mechanical explanation of SR that most physicists find very easy
> > > > to use and understand. However even simple explanantions do involve high
> > > > school mathematics. Like I said, it can only be "dumbed-down" so far.
>
> > > Peter, will you please stop treating me as an idiot, as though I
> > > somehow don't understand the nature of Minkowski spacetime.
>
> > You don't.  What makes it Minkowski spacetime?  How do space and time
> > behave under rotation in a way that is different from a rotation in
> > non-Minkowskian spacetime?  What shape is a curve made up of points
> > equidistant from the origin?  Why is it different from regular,
> > euclidean space?  What is it about a moving object that makes it look
> > like it's rotated in a 4 dimensional, Minkowskian manifold?
>
> I've no idea, but I know none of it has any connection with a
> "practical-mechanical explanation".

It actually does, you simply don't accept that reality works that
way. What you want is an explanation that:
1) Physically describes what is happening
and
2) conforms to your preconcieved notions about how reality works.

1) is possible but there does not and *cannot* exist an explanation
that satisfies 2).
From: Ste on 21 Feb 2010 19:53
On 21 Feb, 22:37, mpalenik <markpale...(a)gmail.com> wrote:
> On Feb 21, 4:57 pm, Ste <ste_ro...(a)hotmail.com> wrote:
>
>
>
> > and the authority of this group is
> > implicitly invoked on yet another occasion.
>
> This group has no "authority" on anything whatsoever.

The "group" to which I was referring, and you snipped the qualifying
clause, was "physicists as a group of people", not "this newsgroup".



> I have no idea why most of the people who post here do so.

Indeed. I've asked myself the question why I post here. ;)



> I even
> asked PD about this a while back.  For me, it's kind of theraputic,
> after grading dozens of papers where freshman students have written
> "no polarization" and then drawn a picture of polarized atoms, or
> listed "the force the boy exherts on the mother is smaller than the
> force the mother exherts on the boy" as a reason for why a mother who
> pushes a boy on ice-skates doesn't move, while the boy does.

I dare say the answer to that question (although I know you weren't
asking the question) is that the movement of each depends
predominantly on their relative mass and the friction with the ground.
I certainly hope these students to which you refer were high-school
students, not university students.



> You can't call them stupid, although here, there is no such rule when
> someone says something so mind-bogglingly sputid.  On the other hand,
> at least, freshman physics students are capable of learning, whereas
> for some miraculous reason, 90% of the people here seem to be stuck in
> perpetual, unwavering ignorance.

Perhaps part of the reason is that students in a formal setting are
pre-weeded for susceptibility to your teaching?
From: Ste on 21 Feb 2010 20:01
On 21 Feb, 23:10, mpalenik <markpale...(a)gmail.com> wrote:
> On Feb 21, 4:57 pm, Ste <ste_ro...(a)hotmail.com> wrote:
>
>
>
> > If we were to extrapolate a trend from history, then physics has not
> > yet given us a single equation which describes how the universe
> > functions. It has given us some rules of thumb and some cumbersome
> > approximations.
>
> This just further illustrates that you don't understand how physics
> actually works.  The history of physics isn't a series of blunders
> that we've thrown out as we get better and better equations, hampered
> by our belief in the old equations.  Rather, physics at just about
> every point in time since the renaissance has been a journey from very
> specific to more general rules--criteria by which any new physics must
> be constrained.

Rubbish.



> For example, Kepler, while not really a physicist per-se, devised
> descriptions of the elliptical orbits that planets must follow.

A description which in fact they don't follow, hence the need for GR.



> Newton, then, discovered that this is a special case of the
> conservation of angular momentum, which is a much more general
> principle--however, conservation of angular momentum MUST be able to
> reproduce the elliptical orbits of planets, or else it is wrong.
> Kepler's rules constrained Newton's theories.
>
> Special relativity then changed Newton's laws, a bit.  The basic
> principles, like F = dp/dt remained, but Special relativity says that
> space and time must transform differently than they do in Newtonian
> mechanics.  However, Newtonian mechanics is still a special case of
> special relativity--as the speed of an object approaches zero, the
> laws begin to reproduce Newton's laws.

In other words "Newtonian mechanics are valid, as long as nothing is
moving". Which somewhat defeats the purpose of mechanics, which is to
describe movement, no? I think you're rewriting history Mark.



> Newton's laws, in this way,
> constrain Special Relativity.  Because if it did *NOT* reproduce
> Newton's laws at low speeds, it would be wrong.
>
> General relativity came along and it turns out that special relativity
> only works as a limiting case of general relativity, specifically,
> when there is no mass or energy present.  As the amount of mass and
> energy present goes to zero, general relativity reproduces special
> relativity.  If it could not do this, it would be wrong.

In other words, SR is correct until it is applied to anything real.
Again, given that science is supposed to describe reality...



> Any new physics must be able to reproduce the old physics in the
> regimes in which it has been tested.  Any new theory that cannot do so
> is necessarily wrong because it has already been ruled out by
> experiment.
>
> There's no way to know whether at some higher energy or smaller
> distance than we've observed the laws of physics actually are
> different than what we believe.  But even so, these new laws must
> reduce to the old ones at lower energies and larger distances.

I don't think there is any necessity that new laws encompass the old,
so long as the new law is consistent with data.
From: mpalenik on 21 Feb 2010 20:04
On Feb 21, 7:53 pm, Ste <ste_ro...(a)hotmail.com> wrote:
> On 21 Feb, 22:37, mpalenik <markpale...(a)gmail.com> wrote:
>
> > On Feb 21, 4:57 pm, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > and the authority of this group is
> > > implicitly invoked on yet another occasion.
>
> > This group has no "authority" on anything whatsoever.
>
> The "group" to which I was referring, and you snipped the qualifying
> clause, was "physicists as a group of people", not "this newsgroup".

Physicists have the authority to interpret their own equations because
1) they came up with them, so they know the principles that the
equations are derived from (whereas you have repeatedly said that
relativity is a form of correction for propagation delays which was,
first of all, not how it was derived, and second of all gives very
different predictions from what you get when you actually account for
propagation delays. The two give different predictions, therefore
they cannot be the same thing).
2) Have demonstrated that their models predict actual, measured
phenomena
3) Have spend more than a month thinking about the issues that you are
asking about

>
> > I have no idea why most of the people who post here do so.
>
> Indeed. I've asked myself the question why I post here. ;)
>
> > I even
> > asked PD about this a while back.  For me, it's kind of theraputic,
> > after grading dozens of papers where freshman students have written
> > "no polarization" and then drawn a picture of polarized atoms, or
> > listed "the force the boy exherts on the mother is smaller than the
> > force the mother exherts on the boy" as a reason for why a mother who
> > pushes a boy on ice-skates doesn't move, while the boy does.
>
> I dare say the answer to that question (although I know you weren't
> asking the question) is that the movement of each depends
> predominantly on their relative mass and the friction with the ground.
> I certainly hope these students to which you refer were high-school
> students, not university students.

Nope, first year college freshmen. Several students, on the last test
that I graded, said that the force the mother exerts on the boy is
much greater than the force that he exerts on her. Most of them
didn't, but several did.

>
> > You can't call them stupid, although here, there is no such rule when
> > someone says something so mind-bogglingly sputid.  On the other hand,
> > at least, freshman physics students are capable of learning, whereas
> > for some miraculous reason, 90% of the people here seem to be stuck in
> > perpetual, unwavering ignorance.
>
> Perhaps part of the reason is that students in a formal setting are
> pre-weeded for susceptibility to your teaching?

The people taking physics 172 are from physics, chemistry (sometimes),
and engineering classes. The people taking physics 220 (physics
without calculus) are from life science courses and other non-hard-
science fields. They even have a physics without "math" for
elementary education majors. All of these people seem to be able to
learn something to varying degrees. All of them become unconfused
about at least part of the course material faster than the people in
this group.

Do most of the people here seem to you like a random selection of
sane, well adjusted, normal people? mpc755? BURT? Androcles?
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Prev: Quantum Gravity 357.91: Croatia Shows That Probability of Vacuum Energy Density is More Important than its Vacuum Expectation Value (VEV) of the Hamiltonian Density, in line with Probable Causation/Influence (PI)
Next: Hubble Views Saturn's Northern/Southern Lights