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From: Peter Webb on 3 Mar 2010 09:01

By analogy: One does not design a skyscraper using Euclid's
Elements, and one does not get to General Relativity through
either Einstein's original or Milne's "inverted" axiomatic
development of relativity. It's just too cumbersome a way to
get there.

Proceeding forward means presenting Minkowski spacetime. The
Minkowski spacetime approach to relativity in essence replaces
the two postulates with a single assertion: "The geometry of the
universe is accurately described (in low gravity fields) by a
four dimensional manifold with properties as follows..."

____________________
Its still a very, very long way from Minkowski to GR, and very few people go
the whole way.

I guess the problem with Minkowski is that its very simple if you understand
some quite abstract concepts, specifically matrices, vectors and imaginary
numbers (a term I have not used so far in this newsgroup, lest some crackpot
size upon it. "Complex numbers" scarcely seems better). If you don't know
these concepts reasonably well, you are stuffed, and learning them takes as
long as does learning SR itself some other way. Whereas the other approaches
are purely algebraic; they are not as self explanatory, but don't involve
any even slightly sophisticated maths.

And, again, as I think you have pointed out and certainly many others have,
that is one of the delights of relativity, that you can derive the same
theory and equivalent formulations in so many completely different ways.

From: bert on 3 Mar 2010 09:29
On Mar 2, 9:56 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
> On Mar 2, 8:33 pm, Jerry <Cephalobus_alie...(a)comcast.net> wrote:
>
>
>
>
>
> > On Mar 2, 7:06 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > On Mar 2, 5:34 am, Jerry <Cephalobus_alie...(a)comcast.net> wrote:
> > > > Special relativity has been established as true within its
> > > > domain of applicability. Period.
>
> > > Your appeal to athority is noted.  Some of us don't accept things just
> > > because everyone else believes it, particularly when it leads to
> > > unexpected results.  You would have fit in well with the flat earth
> > > society.
>
> > Not an appeal to authority. Rather, a modest amateur familiarity
> > with the literature.
>
> > I have in my file folders nearly one hundred papers dating from
> > the late 1800's to the present dealing with the experimental
> > basis of relativity. I have read many more papers than those that
> > I own.
>
> > This is, of course, a very small number compared with the many
> > hundreds of papers and subscription journal volumes that I own
> > and have read which concern my actual field of work. I know my
> > priorities. I am most definitely not a physicist in real life,
> > and make no claims to any special expertise.
>
> > Nevertheless, I imagine that I am probably somewhat more familiar
> > with the experimental literature than you.
>
> > True or false?
>
> > Jerry
>
> Seems you have that appeal to athority thing down to a science ;-)
>
> Bruce- Hide quoted text -
>
> - Show quoted text -

If a photon ever changed its speed it would no longer be a photon
TreBert
From: PD on 3 Mar 2010 11:21
On Mar 2, 8:12 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:

>
> > It is not a function of finite propagation speeds, this we know,
> > because we took into account the finite propagation speeds in our
> > procedure for determining simultaneity/nonsimultaneity. Do you not
> > remember that?
>
> I beg to differ.  It is not a "mere" or "simple" function of finite
> propagation speed, but it *is* a function of it IMO.  RoS only took it
> into account by allowing us to use different time coordinates in each
> frame.  If the speed of light was infinite there would be no RoS.
>

I disagree. All that is needed in relativity of simultaneity is a
signal speed that can be VERIFIED to be the same from both events by
either observer. Since the distance from the events to the observer is
equal, as verifiable at any time by each observer, we learn from this
that each observer KNOWS the propagation delays from each event to the
observer are equal. This acknowledges the propagation delays
completely, but simply allows for verification that they are the same.
Then the determination of simultaneity or nonsimultaneity of the
original events is completely unambiguous: If the observer receives
both signals at the same time, then (because the propagation delays
are the same) the original events were simultaneous; if the observer
receives both signals at different times, then (because the
propagation delays are the same) the original events were
nonsimultaneous.

Then the frame-dependence of simultaneity follows directly from the
experimental *observation* that for the same pair of events, one
observer correctly and unambiguously concludes the events were
simultaneous, and the other observer correctly and unambiguously
concludes the events were nonsimultaneous.

You've mentioned in the past that you found your disbelief in
relativity stems from being unable to find a good, understandable
explanation of it. I invite you to read back on this thread where I
was trying to explain to Ste (who has a similar complaint) how this
comes about.
From: PD on 3 Mar 2010 11:43
On Mar 3, 3:05 am, Ste <ste_ro...(a)hotmail.com> wrote:
> On 2 Mar, 18:37, PD <thedraperfam...(a)gmail.com> wrote:
>
> > On Mar 2, 11:23 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > The point about emphasising the similarities between science and
> > > religion is to combat some of the more absolute assertions about the
> > > nature and value of science. In reality, what you really have is two
> > > religions at war, where 99% can be the same and yet both insist that
> > > the remaining 1% difference is a fundamental difference.
>
> > Gee, I happen to think that the scientific method on one side, and the
> > belief in a supernatural entity on the other, are more than "1%"
> > insignificant differences.
>
> Religious believers always do insist this. Many of the major religions
> of the world share in common a God, much of their scripture, and most
> of their prophets, and yet all insist that the remaining differences
> are fundamental. Indeed, if you go to somewhere like Afghanistan, to
> the outside eye the people apparently share a common religion, and yet
> the mere difference of emphasis on some small aspects of scripture are
> enough for the proponents of differing interpretations to consider
> their differences fundamental.

I don't understand what you're trying to argue. I've told you that I
believe that the difference between science and religion is not a 1%
and insignificant difference. You tell me something about what
religious folks believe about their religions, as though that has any
bearing on what I told you about the significance of the difference
between science and religion. Are you trying to tell me that because
what you consider a 1% difference between religions is not considered
a 1% difference by religious folks, that this somehow maps to what you
consider to be a 1% difference between science and religion? What
about the 1% difference between mammals and reptiles?

>
> > > And certainly, one can discuss the differences between science and
> > > religion, and its significance, but the debate certainly *cannot* be
> > > conducted in terms of sayng that science invariably produces more
> > > truth, or is more functional, or is more objective, or involves less
> > > faith at its core.
>
> > Who said that science invariably produces more truth, or is more
> > functional, or is more objective? I certainly have never told you
> > that.
>
> You have certainly said that it is more functional - perhaps in a
> slightly different way of saying it's "useful".

I certainly did not say that science is more functional or useful than
religion.

> And of course, I'm not
> just addressing the specific things that you've said, but instead
> setting out my case in a more general way. Science is, after all, not
> just you.

Nevertheless, you are tossing up strawmen as though I've maintained
that they are true, and I've never told you they are.

>
> > > > > I personally think it's more convenient to compare and contrast,
> > > > > rather than trying to establish a definition for either religion or
> > > > > science. Indeed, attempts to establish a consistent definition of
> > > > > science, by men better than me, have time and again died a thousand
> > > > > deaths.
>
> > > > By that approach, one could easily be convinced that cows are
> > > > reptiles, no?
>
> > > Indeed. But if people are determined to focus on the differences, the
> > > question is why.
>
> > To decide if a cow is a reptile, which I believe was the question at
> > hand. No, I'm sorry, it was to decide if science is a religion. Same
> > thing, more or less.
>
> I think I missed your point.
>
> > > If you want cow's milk to drink, then it's convenient
> > > to distinguish between cows and reptiles. But people are less clear
> > > about why they want science and not traditional religion.
>
> > Who said people want science and not traditional religion?
>
> I said that.

Then say "I am less clear why I want science and not traditional
religion." I don't believe the generalization you made applies, and it
certainly does not apply to me.

From: PD on 3 Mar 2010 11:50
On Mar 3, 3:22 am, Ste <ste_ro...(a)hotmail.com> wrote:
> On 2 Mar, 18:38, PD <thedraperfam...(a)gmail.com> wrote:
>
>
>
> > On Mar 2, 11:36 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > > > And if science is not likely to deliver the goods, then it's useful to
> > > > > know ahead of time.
>
> > > > I would judge that on performance. If someone is the world record
> > > > holder in the 100 m dash, and you ask the question how it is that the
> > > > record holder trained to be the fastest, and you were not convinced
> > > > that those methodologies were sound or were guaranteed to produce a
> > > > world-class sprinter, there is still the fact that he is the world-
> > > > record holder.
>
> > > Yes, but it is relevant to determine whether he is the record-holder
> > > because of his naturally strong physique, or whether it is the
> > > training regime, or indeed whether it is the various expensive snake-
> > > oil supplements and drugs that he has been given.
>
> > Good. Then you tell ME why science has a track record of studying the
> > aspects of nature that it does in a successful way.
>
> Well that is what we're discussing.
>
> I think science is so successful because it has naturalistic axioms.
> It is a naturalistic faith. The defining characteristic of science is
> not verificationism, or falsificationism, or any of what is
> traditionally considered to demarcate science, but the fact that it
> holds axiomatically that (which is to say, its followers have faith
> that) the world is wholly orderly, consistent, and basically
> mechanistic, and that the principles by which the world operates can
> be discovered by humans.

And this is not an accurate statement of fact, as evidenced by the
fact that something that IS classified as a science (physics) has
followers that DO NOT have faith that the world is basically
mechanistic and deterministic, nor do the followers hold that ALL that
in nature is understandable in this fashion. What is a more accurate
statement about its followers is that they believe that a certain
class of reliably replicable phenomena in nature can be understood by
rules that are discoverable by humans, though those rules may not be
deterministic or basically mechanistic. Those followers also believe
in the demonstrated practical efficacy of a particular methodology of
investigation, though it need not be assumed that it is a priori the
best methodology either in general or in specific.

>
> This is what fundamentally sets apart things like creationism from
> science. Whatever other hoops creationism manages to jump through, it
> will never jump through the hoop of naturalism, and that is what
> *fundamentally* sets it apart from science.

And also FUNDAMENTALLY distinguishes science from religion. Thanks.

> And a naturalistic
> approach is, in fact, the only common thread that links together all
> of what is, and has been, considered science.

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