A constant speed of light in all reference frames? Surely you can't be serious. [Physics]

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From: Inertial on 12 Mar 2010 01:42

"Dono." <sa_ge(a)comcast.net> wrote in message
news:b2c70538-0b53-4293-9c7e-b44461f47e30(a)q2g2000pre.googlegroups.com...
> On Mar 11, 2:28 pm, "Inertial" <relativ...(a)rest.com> wrote:
>>
>> Yes .. there are. The underlying 'reality' in LET is a simple 3D space
>> with
>> Galilean transforms.
>
> Insane dumbfuck, what hallucinogenics are you on?

None .. I understand physics. You should try learning it sometime, so you
can discuss rationally with those of us here who have. ATM you're just
another crackpot like Ken.

From: Peter Webb on 12 Mar 2010 02:24

"Inertial" <relatively(a)rest.com> wrote in message
news:4b99e24c$0$27810$c3e8da3(a)news.astraweb.com...
>
> "Dono." <sa_ge(a)comcast.net> wrote in message
> news:b2c70538-0b53-4293-9c7e-b44461f47e30(a)q2g2000pre.googlegroups.com...
>> On Mar 11, 2:28 pm, "Inertial" <relativ...(a)rest.com> wrote:
>>>
>>> Yes .. there are. The underlying 'reality' in LET is a simple 3D space
>>> with
>>> Galilean transforms.
>>
>> Insane dumbfuck, what hallucinogenics are you on?
>
> None .. I understand physics. You should try learning it sometime, so you
> can discuss rationally with those of us here who have. ATM you're just
> another crackpot like Ken.
>
>

I think that if he knew any physics, he would be posting stuff about
physics. As it is, he just seems to want to have a fight with somebody about
something. He doesn't care with whom or about what.

Takes two to tango, Inertial. And you can pick your dance partner.

From: G. L. Bradford on 12 Mar 2010 04:34

"PD" <thedraperfamily(a)gmail.com> wrote in message
news:160d014f-cb0a-4f4a-908c-2a99f691d54f(a)q16g2000yqq.googlegroups.com...
On Mar 11, 2:15 pm, Ste <ste_ro...(a)hotmail.com> wrote:
> On 11 Mar, 15:12, PD <thedraperfam...(a)gmail.com> wrote:
>
>
>
> > On Mar 11, 6:43 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > On 11 Mar, 01:51, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> > > wrote:
>
> > > > No, perhaps you didn't understand. As I say, this is *not* the twins
> > > > paradox, because in the twins paradox only *one* twin leaves Earth.
>
> > > > ________________________
> > > > Its functionally the same. It is exactly the twins paradox, but with
> > > > two
> > > > twins apparently doing exactly the same thing.
>
> > > > Even if you cannot see that, the explanation on the Wikipedia page
> > > > of the
> > > > Twins Paradox is trivially adapted for two twins.
>
> > > > I assume that you do not understand the Wikipedia twins paradox
> > > > page, or
> > > > else you would know the answers to your questions already. Which
> > > > parts don't
> > > > you understand?
>
> > > Let's just go through it step by step Peter, as we have been doing.
> > > It's pointless spending 10 more postings arguing about how the
> > > Wikipedia page does or does not answer the question, or how it is or
> > > is not relevant. As I've just said in a post to Inertial, the only
> > > analogy between my scenario and the twins paradox is that, in my
> > > scenario, both twins leave Earth, and both return the same age as each
> > > other - hence no paradox, and hence bearing no resemblance at all to
> > > the twins paradox.
>
> > First of all, let's establish what you think is paradoxical at all
> > about the description of the twins in the twin puzzle. Then let's see
> > whether this paradox is present in the case you mention.
>
> As I understand it, the supposed "paradox" in the twins paradox was
> that one returned younger than the other. It was, of course, not a
> paradox at all, but that's besides the point.

No, then you do not understand the paradox, because there is nothing
contradictory in that statement at all. It may be surprising, but it's
not contradictory, not paradoxical. Disagreement of clocks is not a
paradox.

The paradox, which is what is perceived (normally) by freshmen when
first introduced to this statement, is embodied in their immediate
classroom question: "But in the frame of the traveling twin, it is the
earth twin that is moving away and returning. Since this is symmetric
to the case of the traveling twin moving away and returning, then
shouldn't the traveling twin expect the earth twin to be younger when
they meet again?" Now perhaps the paradox is more apparent to you.

However, the puzzle is specifically designed to emphasize the danger
of oversimplifying. In fact, the two twins are NOT symmetric, because
one unambiguously experiences acceleration and the other unambiguously
experiences no acceleration. This then leads to a discussion of what
produces the asymmetry in the time.

Perhaps if you had started out by asking, "Since I don't see any
obvious paradox here at all, perhaps someone could illuminate me as to
why this is called the twin paradox?" Then at least you would have
been on square one.

> In our scenario however, we have already agreed that both clocks
> return to the origin displaying the same time, hence there is no
> correspondence at all with the twins paradox.

=========================

It's not a 4-d || 4-d scenario....to a 4-d result! It's strictly a 1-d ||
1-d scenario, so naturally the result comes out strictly 1-d.

GLB

========================

From: harald on 12 Mar 2010 05:50

On Mar 12, 4:54 am, "Inertial" <relativ...(a)rest.com> wrote:
> "Paul Stowe" <theaether...(a)gmail.com> wrote in message
>
> news:722fe1d3-ba1d-4439-bffe-eda2ca668f82(a)p3g2000pra.googlegroups.com...
>
>
>
> > On Mar 10, 8:57 am, PD <thedraperfam...(a)gmail.com> wrote:
> >> On Mar 9, 9:41 pm, PaulStowe<theaether...(a)gmail.com> wrote:
>
> >> > On Mar 8, 8:05 pm, "Inertial" <relativ...(a)rest.com> wrote:
>
> >> > > "PaulStowe" <theaether...(a)gmail.com> wrote in message
>
> >> > >news:1132a230-92d9-484a-b0c1-d3a97532cad9(a)z10g2000prh.googlegroups.com...
>
> >> > > >> >> SR explains it as having to be c due to the geometry of
> >> > > >> >> spacetime
>
> >> > > >> > That's simply a silly idea...
>
> >> > > >> That you think it is silly is your problem, not that of SR
>
> >> > > > Something physical may be represented by a geometric description..
>
> >> > > And our universe is represented by Minkowski geometry.
>
> >> > Yes, you can descibe localized behavior with that format. BUT! to do
> >> > so you must depend on finite light speed and its physical
> >> > independence. Geometry neither predicts. explains, or has a basis for
> >> > that.
>
> >> That's incorrect, Paul. The geometric structure of spacetime imposes
> >> both a finite speed of light AND makes it frame-independent.
>
> >> The geometric structure of spacetime *necessarily* divides pairs of
> >> events into three categories: spacelike-separated, timelike-separated,
> >> and nullcone-separated. This structure also immediately leads to the
> >> result that any wordline that could be traversed by something between
> >> timelike-separated events will, in any other inertial reference frame,
> >> still be between timelike-separated events. What this means explicitly
> >> is that this object can never span two spacelike-separated events.
> >> Thus, the universe of events is strictly divided into two completely
> >> separated causal domains. The boundary of these domains is the null
> >> cone. Since the null cone has a definite slope of space vs time, this
> >> imposes a causal speed limit. (This limit does not exist in Euclidean
> >> 3D+1D space -- it is a unique feature of the 4D space and its
> >> geometry.)
>
> >> Furthermore, while transformations between inertial frames will shift
> >> the slopes between pairs of timelike events (that is, the speed of an
> >> object traveling between the two events), the same transformation
> >> between pairs of events on the null cone do not change slope. What
> >> this means is that any object that can travel between two events on
> >> null cone will have the same speed regardless of inertial reference
> >> frame.
>
> >> So you see, the geometric structure DOES imply both a causal speed
> >> limit and the invariance of that causal speed limit with choice of
> >> inertial reference frame. It just so happens that light appears to be
> >> one of the candidate objects that can travel between nullcone-
> >> separated events.
>
> >> If you need to see how the structure does impose those limits
> >> formally, I could point you to a reference book or two that derives
> >> this unambiguously.
>
> >> At the time that Einstein proposed special relativity, he did not
> >> understand how such a geometric structure could produce those two
> >> conclusions as necessary consequences. And so he just posited the
> >> invariance of the speed of light as a postulate (or equivalently,
> >> demanded that Maxwell's equations obey the principle of relativity).
> >> It was only later that the geometric structure was uncovered and it
> >> was understood how the light postulate follows directly from this
> >> structure.
>
> >> PD
>
> > I wasn't going to bother with a reply since we have gone round & round
> > on this very point. I find your argument without merit and I'm
> > certain that you mind is made up. Why act like kid and continuously
> > and say no it ain't, yes it is???
>
> > In minkowski math c can be any finite value.
>
> Indeed it can. But we observe it to have a particular value in our
> universe.
>
> > As Tom Roberts would
> > argue the are nearly a infinite number of variations which fit this
> > form.
>
> All equivalent as long as c is finite
>
> > Thus it's dependent upon c being a 'physical' constant.
>
> Yes .. it just doesn't really matter that much what particular value it has.
> But it does have a particular value in our universe
>
> > And,
> > as GR shows, it not even global. Now why might that be??? The logic
> > (actually lack thereof) and thought process is 'in my opinion' silly
> > and no one, not in print nor herein has provided any argument that is
> > convincing that the math and geometry is NOT! a resultant of physical
> > processes rather some magical geometry...
>
> The geometry models what we find happens physically. Why you insist there
> be some physical cause for why space and time is as modeled by Minkowski
> geometry, but do not similarly require a physical cause for why it would be
> modeled by Euclidean geometry (especially when experimental evidence points
> to it NOT being so modeled) sounds rather hypocritical to me.

There is obviously a physical cause for the way different types of
maps can be used for describing the surface of the Earth, and
similarly there is a physical cause for the different geometries that
we can conveniently use for describing physical processes.
Note that no experimental evidence points to my personal preference of
geometry I use to describe it, just as you cannot know from the
physics of the Earth what projection the captain of a ship prefers.

Harald

From: Peter Webb on 12 Mar 2010 06:17

>
> The geometry models what we find happens physically. Why you insist there
> be some physical cause for why space and time is as modeled by Minkowski
> geometry, but do not similarly require a physical cause for why it would
> be
> modeled by Euclidean geometry (especially when experimental evidence
> points
> to it NOT being so modeled) sounds rather hypocritical to me.

There is obviously a physical cause for the way different types of
maps can be used for describing the surface of the Earth, and
similarly there is a physical cause for the different geometries that
we can conveniently use for describing physical processes.
Note that no experimental evidence points to my personal preference of
geometry I use to describe it, just as you cannot know from the
physics of the Earth what projection the captain of a ship prefers.

_____________________________
No. We are not talking about a map of the structure, we are talking about
its underlying properties.

Whilst we can model the earth in 2D, in reality it is a sphere. Your choice
of projections doesn't change that.
You don't need spherical geometry to navigate 10 kms by boat, Euclidean will
do fine, but nobody denies the surface of the earth is spherical. And you
don't need Minkowski geometry to model objects travelling at 100 kms/hr,
Euclidean will do fine, but nobody (should) deny the Universe is
"Minkowskian".