Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.physics.relativity > #423637 > unrolled thread

I could not get my post !!!!!!!!

Back to article view | Back to sci.physics.relativity

Contents

  I could not get my post !!!!!!!! Omar Shabsigh <omar.shabsigh@gmail.com> - 2017-06-29 14:50 -0700
    Re: I could not get my post !!!!!!!! Dirk Van de moortel <dirkvandemoortel@hotspam.not> - 2017-06-30 00:15 +0200
      Re: I could not get my post !!!!!!!! Jim Petroff <ruuri@twjotr.eo> - 2017-06-30 11:44 +0000
    Re: I could not get my post !!!!!!!! Gary Harnagel <hitlong@yahoo.com> - 2017-06-29 17:21 -0700
      Re: I could not get my post !!!!!!!! Jim Petroff <ruuri@twjotr.eo> - 2017-06-30 11:47 +0000
        Re: I could not get my post !!!!!!!! moroney@world.std.spaamtrap.com (Michael Moroney) - 2017-06-30 16:05 +0000
          Re: I could not get my post !!!!!!!! Jim Petroff <ruuri@twjotr.eo> - 2017-07-01 08:32 +0000
      Re: I could not get my post !!!!!!!! Nicolaas Vroom <nicolaas.vroom@pandora.be> - 2017-07-01 03:15 -0700
        Re: I could not get my post !!!!!!!! Gary Harnagel <hitlong@yahoo.com> - 2017-07-01 06:23 -0700
          Re: I could not get my post !!!!!!!! Buck Millard <uiidbm@apsuw.dl> - 2017-07-01 21:02 +0000
          Re: I could not get my post !!!!!!!! Nicolaas Vroom <nicolaas.vroom@pandora.be> - 2017-07-06 01:21 -0700
            Re: I could not get my post !!!!!!!! Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-06 10:32 -0500
              Re: I could not get my post !!!!!!!! Nicolaas Vroom <nicolaas.vroom@pandora.be> - 2017-07-08 05:37 -0700
                Re: I could not get my post !!!!!!!! Gary Harnagel <hitlong@yahoo.com> - 2017-07-08 06:41 -0700
                  Re: I could not get my post !!!!!!!! Nicolaas Vroom <nicolaas.vroom@pandora.be> - 2017-07-08 08:17 -0700
                    Re: I could not get my post !!!!!!!! Poutnik <Poutnik4nntp@gmail.com> - 2017-07-08 17:43 +0200
                      Re: I could not get my post !!!!!!!! Ocho Hoshouwa <yeoh@eohotwa.ey> - 2017-07-08 16:39 +0000
                    Re: I could not get my post !!!!!!!! Gary Harnagel <hitlong@yahoo.com> - 2017-07-08 17:36 -0700
                      Re: I could not get my post !!!!!!!! Nicolaas Vroom <nicolaas.vroom@pandora.be> - 2017-07-09 06:17 -0700
                        Re: I could not get my post !!!!!!!! Gary Harnagel <hitlong@yahoo.com> - 2017-07-09 06:52 -0700
                Re: I could not get my post !!!!!!!! Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-11 10:22 -0500
                  Re: I could not get my post !!!!!!!! Nicolaas Vroom <nicolaas.vroom@pandora.be> - 2017-07-14 05:24 -0700
                    Re: I could not get my post !!!!!!!! Poutnik <poutnik4nntp@gmail.com> - 2017-07-14 15:21 +0200
                      Re: I could not get my post !!!!!!!! Garfield Dieter <igdle@rdlge.rf> - 2017-07-14 16:26 +0000
                        Re: I could not get my post !!!!!!!! Poutnik <poutnik4nntp@gmail.com> - 2017-07-14 18:57 +0200
                    Re: I could not get my post !!!!!!!! Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-14 15:42 -0500
            Re: I could not get my post !!!!!!!! Gary Harnagel <hitlong@yahoo.com> - 2017-07-06 09:54 -0700
    Re: I could not get my post !!!!!!!! "HGW..." <hgw@....> - 2017-06-30 11:18 +1000
      Re: I could not get my post !!!!!!!! Gary Harnagel <hitlong@yahoo.com> - 2017-06-29 19:01 -0700
      Re: I could not get my post !!!!!!!! Jim Petroff <ruuri@twjotr.eo> - 2017-06-30 08:44 +0000
      Re: I could not get my post !!!!!!!! pnalsing@gmail.com - 2017-06-30 14:47 -0700
    Re: I could not get my post !!!!!!!! mlwozniak@wp.pl - 2017-06-30 01:07 -0700
      Re: I could not get my post !!!!!!!! "HGW..." <hgw@....> - 2017-07-03 10:04 +1000
        Re: I could not get my post !!!!!!!! mlwozniak@wp.pl - 2017-07-02 23:06 -0700
          Re: I could not get my post !!!!!!!! "HGW..." <hgw@....> - 2017-07-04 08:58 +1000

Page 1 of 2  [1] 2  Next page →

#423637 — I could not get my post !!!!!!!!

Trying again to make my post posted. 

https://sites.google.com/view/realscience/

Let us discuss scientifically, colleagues. No repulsion please. You all have scientific minds, I think.

[toc] | [next] | [standalone]

#423638

Op 29-jun-2017 om 23:50 schreef Omar Shabsigh:
> Trying again to make my post posted.
>
> https://sites.google.com/view/realscience/
>
> Let us discuss scientifically, colleagues. No repulsion please. You
> all have scientific minds, I think.
>

Just about half of us, I estimate.

Dirk Vdm

[toc] | [prev] | [next] | [standalone]

#423666

Dirk Van de moortel wrote:

> Op 29-jun-2017 om 23:50 schreef Omar Shabsigh:
>> Trying again to make my post posted.
>>
>> https://sites.google.com/view/realscience/
>>
>> Let us discuss scientifically, colleagues. No repulsion please. You all
>> have scientific minds, I think.
>
> Just about half of us, I estimate. Dirk Vdm

Let me guess in which one of those you belong.

[toc] | [prev] | [next] | [standalone]

#423644

On Thursday, June 29, 2017 at 3:51:00 PM UTC-6, Omar Shabsigh wrote:
>
> Trying again to make my post posted. 
> >
> > https://sites.google.com/view/realscience/
> >
> > Let us discuss scientifically, colleagues. No repulsion please. You all
> > have scientific minds, I think.

As an EE, you are, of course, aware that c = 1/sqrt(mu0*epsilon0), right?

And you are, of course, aware that velocity is not absolute, yes?

And you are, of course, aware that the earth is moving about 30 km/sec
in its orbit around the sun, not so?

And as an EE, you know that capacitors do not change their capacitance
with the earth's orbital motion?

So you should be able to conclude that the speed of light is independent
of the motion of its source.  If this were not enough, experience with
communication with spacecraft moving at up to 50 km/sec, demonstrates
that this is so.

This should be quite sufficient for you to derive the Lorentz transform
equations which refute your many unfounded assertions, so I don't see
how you can deny actual experiments hen you claim actual experiments
are what counts.

[toc] | [prev] | [next] | [standalone]

#423667

Gary Harnagel wrote:

>> > Let us discuss scientifically, colleagues. No repulsion please. You
>> > all have scientific minds, I think.
> 
> As an EE, you are, of course, aware that c = 1/sqrt(mu0*epsilon0),
> right?

Untrue. that's a sqrt(inv(u*e)); doesn't need to be as zeros.

> And you are, of course, aware that the earth is moving about 30 km/sec in
> its orbit around the sun, not so?

No, bit rad/sec times the distance, which is huge. So huge, you may 
consider Earth as stationary.

[toc] | [prev] | [next] | [standalone]

#423681

The nymshifting troll, posting as Jim Petroff <ruuri@twjotr.eo> writes:

>Gary Harnagel wrote:

>>> > Let us discuss scientifically, colleagues. No repulsion please. You
>>> > all have scientific minds, I think.
>> 
>> As an EE, you are, of course, aware that c = 1/sqrt(mu0*epsilon0),
>> right?

>Untrue. that's a sqrt(inv(u*e)); doesn't need to be as zeros.

You don't even know what mu0 or epsilon0 are, nymshifter? And you claim
to know about being an EE without even knowing mu0 or epsilon0 are?

[toc] | [prev] | [next] | [standalone]

#423735

Michael Moroney crapped on himself and wrote:

> The nymshifting troll, posting as Jim Petroff <ruuri@twjotr.eo> writes:
> 
>>Gary Harnagel wrote:
> 
>>>> > Let us discuss scientifically, colleagues. No repulsion please. You
>>>> > all have scientific minds, I think.
>>> 
>>> As an EE, you are, of course, aware that c = 1/sqrt(mu0*epsilon0),
>>> right?
> 
>>Untrue. that's a sqrt(inv(u*e)); doesn't need to be as zeros.
> 
> You don't even know what mu0 or epsilon0 are, nymshifter? And you claim
> to know about being an EE without even knowing mu0 or epsilon0 are?

Youu stoopid piece of hald-engineer sob, what I wrote PROVES that I know, 
and you do NOT. Fuck off, jerk! You do not add to anything.

[toc] | [prev] | [next] | [standalone]

#423743

On Friday, 30 June 2017 02:21:27 UTC+2, Gary Harnagel  wrote:

> As an EE, you are, of course, aware that c = 1/sqrt(mu0*epsilon0), right?
C in this case is the speed of electro magnetic radiation in vacuum.
 
> And you are, of course, aware that velocity is not absolute, yes?
Speed/ velocity is equal to (r2-r1)/(t2-t1).
What is the meaning of the claim that velocity is not absolute? 
 
> And you are, of course, aware that the earth is moving about 30 km/sec
> in its orbit around the sun, not so?
> 
> And as an EE, you know that capacitors do not change their capacitance
> with the earth's orbital motion?
What is the meaning of this sentence?
 
> So you should be able to conclude that the speed of light is independent
> of the motion of its source.  

IMO the easiest(?) way to demonstrate this when you have two cars (one at  
at rest and one moving) which turn on their lights when they pass. 
You, in front of them at a certain distance, will observe these two events
simultaneous (I expect) which demonstrates that the speed of light (photons)
is not influenced by neither the emitter nor the receiver.
(But in no way quantifies this speed.)  

> This should be quite sufficient for you to derive the Lorentz transform
> equations which refute your many unfounded assertions, so I don't see
> how you can deny actual experiments hen you claim actual experiments
> are what counts.

The Lorentz factor by definition is mathematics.
See: https://en.wikipedia.org/wiki/Lorentz_factor
The physical issue starts when you use this factor in order to describe 
time, length and mass for a moving object.
The document https://sites.google.com/view/realscience/first-article
above paragraph 4 reads:
"When v > c, t’1  becomes an imaginary number to the outside observer." 
and:  "Here, at v = c , the vehicle length will seem to be zero to the 
outside observer which makes the vehicle invisible to the outside 
observer, but inside the vehicle all is as usual."
The problem is that from a mathematical point you can do that but not
from a physical point when you perform an actual experiment which
tries to validate one of these three equations. 

The biggest problem are the definition of the parameters v and c.
This same problem is also discussed in:
"Re: Speed of light in vacuum, what definition?" of 27 June
https://groups.google.com/forum/?fromgroups=#!topic/sci.physics.relativity/qHMbZ

eyXWmI  
The central question is does a super nova (its remnant) always stays at the center of its own photon sphere?
IMO it does not. Its position can vary and has a speed relatif to the 
center this sphere. That means from its own point of view physical the 
speed of light in both directions is not the same. 
The speed is only the same for the point at the center of this sphere.

Nicolaas Vroom.

[toc] | [prev] | [next] | [standalone]

#423752

On Saturday, July 1, 2017 at 4:16:00 AM UTC-6, Nicolaas Vroom wrote:
>
> On Friday, 30 June 2017 02:21:27 UTC+2, Gary Harnagel  wrote:
> >
> > As an EE, you are, of course, aware that c = 1/sqrt(mu0*epsilon0), right?
>
> C in this case is the speed of electro magnetic radiation in vacuum.

Of course.

> > And you are, of course, aware that velocity is not absolute, yes?
>
> Speed/ velocity is equal to (r2-r1)/(t2-t1).
> What is the meaning of the claim that velocity is not absolute? 

Velocity does NOT refer to some absolute reference point.  It is, as your
equation says, determined with respect to an arbitrary coordinate system.

> > And you are, of course, aware that the earth is moving about 30 km/sec
> > in its orbit around the sun, not so?
> > 
> > And as an EE, you know that capacitors do not change their capacitance
> > with the earth's orbital motion?
>
> What is the meaning of this sentence?

That epsilon0 is NOT changed by your motion.

> > So you should be able to conclude that the speed of light is independent
> > of the motion of its source.  
> 
> IMO the easiest(?) way to demonstrate this when you have two cars (one at  
> at rest and one moving) which turn on their lights when they pass. 
> You, in front of them at a certain distance, will observe these two events
> simultaneous (I expect) which demonstrates that the speed of light (photons)
> is not influenced by neither the emitter nor the receiver.
> (But in no way quantifies this speed.)  

Not exactly an EE experiment, but okay :-)

> > This should be quite sufficient for you to derive the Lorentz transform
> > equations which refute your many unfounded assertions, so I don't see
> > how you can deny actual experiments [w]hen you claim actual experiments
> > are what counts.
> 
> The Lorentz factor by definition is mathematics.
> See: https://en.wikipedia.org/wiki/Lorentz_factor

So is (r2 -r1)/(t2 - t1).  What's your point?  Mathematics is just logical
deduction from basic postulates.

> The physical issue starts when you use this factor in order to describe 
> time, length and mass for a moving object.

No.  The "physical issue" starts with the postulates:

1. Principle of relativity
2. Invariance of the speed of light

There is also the assumption that space and time are isotropic, homogeneous
and uniform.  What this means is that a transformation from one inertial
frame to another must be of the form:

x' = G*(x + H*t)
t' = A*(t + B*x)

Using the PoR, you can deduce that G must equal A.  Also from the PoR,
you can deduce that H = -v.

In the case of the Galilean transform, which assumes absolute time, A = 1
and B = 0.  Thus G = 1 also.  Using the second postulate, however, A is
NOT unity and B is NOT zero.

> The document https://sites.google.com/view/realscience/first-article
> above paragraph 4 reads:
> "When v > c, t’1  becomes an imaginary number to the outside observer." 
> and:  "Here, at v = c , the vehicle length will seem to be zero to the 
> outside observer which makes the vehicle invisible to the outside 
> observer, but inside the vehicle all is as usual."
> The problem is that from a mathematical point you can do that but not
> from a physical point when you perform an actual experiment which
> tries to validate one of these three equations. 
> 
> The biggest problem are the definition of the parameters v and c.
> This same problem is also discussed in:
> "Re: Speed of light in vacuum, what definition?" of 27 June
> https://groups.google.com/forum/?fromgroups=#!topic/sci.physics.relativity/qHMbZ
> 
> eyXWmI  
> The central question is does a super nova (its remnant) always stays at
> the center of its own photon sphere?

That's NOT a "central" question.  The central question is, Are the postulates
consistent with experimental evidence?  This question can, and has been,
answered ... by experiment.

> IMO it does not.

“All opinions are not equal. Some are a very great deal more robust,
sophisticated and well supported in logic and argument than others.”
 -- Douglas Adams

"You are not entitled to your opinion. You are entitled to your informed
opinion.  No one is entitled to be ignorant." — Harlan Ellison

> Its position can vary and has a speed relatif to the 
> center this sphere. That means from its own point of view physical the 
> speed of light in both directions is not the same. 
> The speed is only the same for the point at the center of this sphere.
> 
> Nicolaas Vroom.

Opinions are worthless without REAL evidence to back them up.  The REAL
evidence comes from experimental results and correct deduction from them.

If you use the Lorentz transform (which is logically deduced from the
postulates which have been verified experimentally), you can answer your
non-central question.  And the answer may surprise you (I did me when I
first considered it).

[toc] | [prev] | [next] | [standalone]

#423774

W dniu piątek, 30 czerwca 2017 10:52:05 UTC-4 użytkownik Gary Harnagel
napisał:

>> What is the meaning of this sentence?
> 
> That epsilon0 is NOT changed by your motion.

This would be an interesting topic to investigate. Permittivity and 
Permeability are both about consistency. Or is something you don't really 
know.

[toc] | [prev] | [next] | [standalone]

#424090

On Saturday, 1 July 2017 15:23:42 UTC+2, Gary Harnagel  wrote:
> On Saturday, July 1, 2017 at 4:16:00 AM UTC-6, Nicolaas Vroom wrote:
 

> > The central question is does a super nova (its remnant) always stays at
> > the center of its own photon sphere?
> 
> That's NOT a "central" question.  The central question is, Are the postulates
> consistent with experimental evidence?  This question can, and has been,
> answered ... by experiment.

Still the question remains: 
Does the neutron star stay at the center of the sphere. 
A different question is: What can we say about the moment of "collision"
of the two spheres. 
 
> > IMO it does not.

-- IMO 
> “All opinions are not equal. Some are a very great deal more robust,
> sophisticated and well supported in logic and argument than others.”
>  -- Douglas Adams

IMO 
> "You are not entitled to your opinion. You are entitled to your informed
> opinion.  No one is entitled to be ignorant." — Harlan Ellison

There is nothing wrong when someone has his or her own opinion.
The next step is to challenge this opinion by yourself and by others.
 
> > Its position can vary and has a speed relatif to the 
> > center this sphere. That means from its own point of view physical the 
> > speed of light in both directions is not the same. 
> > The speed is only the same for the point at the center of this sphere.
> > 
> > Nicolaas Vroom.
> 
> Opinions are worthless without REAL evidence to back them up.  
The same is true for people who don't agree with someone's opinion.

> The REAL evidence comes from experimental results and correct deduction 
> from them.
There are two possiblities:
You can start from a set of postulates and make predictions.
The evidence comes from experiments or observations which agree with
these predictions.
A different route is you make observations and you define the laws
which describe these observations, Next you make new predictions.
Also here: The evidence comes from experiments or observations which 
agree with these new predictions.
 
> If you use the Lorentz transform (which is logically deduced from the
> postulates which have been verified experimentally), you can answer your
> non-central question.  And the answer may surprise you (I did me when I
> first considered it).

This issue is discussed separately in the thread: 
	"Time dilation in Wikipedia"

Nicolaas Vroom

[toc] | [prev] | [next] | [standalone]

#424114

On 7/6/17 7/6/17 - 3:21 AM, Nicolaas Vroom wrote:
> Still the question remains:
> Does the neutron star stay at the center of the sphere.

If the star is moving inertially, then it remains at the center of the light 
sphere as seen in its rest frame; it does NOT remain at the center of the light 
sphere seen in any other inertial frame. If it is not moving inertially, it does 
NOT remain at the center of any inertial frame's sphere.

Note that relative to essentially all non-inertial coordinates there is no light 
sphere [#]. Note also that if there is gravitation from sources other than the 
neutron star itself, or if the neutron star is itself not spherically symmetric, 
then there are no light spheres at all (and of course no inertial frames, only 
locally-inertial frames).

	[#] Exercise for the reader: construct non-inertial coordinates
	on flat spacetime relative to which there is a light sphere from
	a single pulsed light source. Hint: consider the relationship
	between such coordinates and some inertial frame. Hint2: Consider
	the symmetry of the physical situation.

Tom Roberts

[toc] | [prev] | [next] | [standalone]

#424269

On Thursday, 6 July 2017 17:32:10 UTC+2, tjrob137  wrote:
> On 7/6/17 7/6/17 - 3:21 AM, Nicolaas Vroom wrote:
> > Still the question remains:
> > Does the neutron star stay at the center of the sphere.
> 
> If the star is moving inertially, then it remains at the center of the 
> light sphere as seen in its rest frame; it does NOT remain at the center 
> of the light sphere seen in any other inertial frame. If it is not moving 
> inertially, it does NOT remain at the center of any inertial frame's 
> sphere.

(The stars in a galaxy are not moving inertially, as such you have 
answered my original question)

This leads to the following remark:
What is the purpose of an inertial frame?
But there is more: Apperently there are light spheres and each of these 
light spheres have a center i.e. a point of origin.  
Is it not true that all these points of origin together define an inertial 
frame? (a coordinate system) 
 
> Note that relative to essentially all non-inertial coordinates there is 
> no light sphere [#]. 
  ?
> Note also that if there is gravitation from sources other than the 
> neutron star itself, or if the neutron star is itself not spherically 
> symmetric, then there are no light spheres at all. 
That is too strict. There is always something that resembles a light sphere.
The largest cause of any asymmetry is in the source. Gravitation from other
objects is also a cause of deformation.  
> (and of course no inertial frames, only locally-inertial frames).
  ?
 
> 	[#] Exercise for the reader: construct non-inertial coordinates
> 	on flat spacetime relative to which there is a light sphere from
> 	a single pulsed light source. Hint: consider the relationship
> 	between such coordinates and some inertial frame. Hint2: Consider
> 	the symmetry of the physical situation.
   Why this exercise?

Nicolaas Vroom

[toc] | [prev] | [next] | [standalone]

#424277

On Saturday, July 8, 2017 at 6:37:24 AM UTC-6, Nicolaas Vroom wrote:
>
> On Thursday, 6 July 2017 17:32:10 UTC+2, tjrob137  wrote:
> >
> > On 7/6/17 7/6/17 - 3:21 AM, Nicolaas Vroom wrote:
> > >
> > > Still the question remains:
> > > Does the neutron star stay at the center of the sphere.
> > 
> > If the star is moving inertially, then it remains at the center of the 
> > light sphere as seen in its rest frame; it does NOT remain at the center 
> > of the light sphere seen in any other inertial frame. If it is not moving 
> > inertially, it does NOT remain at the center of any inertial frame's 
> > sphere.
> 
> (The stars in a galaxy are not moving inertially, as such you have 
> answered my original question)

You delude yourself.  by "inertially" you apparently mean "in straight
line." but stars move approximately that way.  So your attempt to
belittle Tom Robert's lesson is pretence.

> This leads to the following remark:
> What is the purpose of an inertial frame?

To simplify explanation of how the universe works.

> But there is more: Apperently there are light spheres and each of these 
> light spheres have a center i.e. a point of origin.  
> Is it not true that all these points of origin together define an inertial 
> frame? (a coordinate system) 
>  
> > Note that relative to essentially all non-inertial coordinates there is 
> > no light sphere [#].
>
>   ?

That is, they aren't spheres to accelerated observers.

> > Note also that if there is gravitation from sources other than the 
> > neutron star itself, or if the neutron star is itself not spherically 
> > symmetric, then there are no light spheres at all.
>
> That is too strict. There is always something that resembles a light sphere.
> The largest cause of any asymmetry is in the source. Gravitation from other
> objects is also a cause of deformation.  

Sure, but it's not too strict if the gravitation is strong.

[toc] | [prev] | [next] | [standalone]

#424279

On Saturday, 8 July 2017 15:42:02 UTC+2, Gary Harnagel  wrote:
> On Saturday, July 8, 2017 at 6:37:24 AM UTC-6, Nicolaas Vroom wrote:
> >
> > On Thursday, 6 July 2017 17:32:10 UTC+2, tjrob137  wrote:
> > >
> > > On 7/6/17 7/6/17 - 3:21 AM, Nicolaas Vroom wrote:
> > > >
> > > > Still the question remains:
> > > > Does the neutron star stay at the center of the sphere.
> > > 
> > > If the star is moving inertially, then it remains at the center 
> > > of the light sphere as seen in its rest frame; it does NOT remain 
> > > at the center of the light sphere seen in any other inertial frame. 
> > > If it is not moving inertially, it does NOT remain at the center 
> > > of any inertial frame's sphere.
> > 
> > (The stars in a galaxy are not moving inertially, as such you have 
> > answered my original question)
> 
> You delude yourself.  by "inertially" you apparently mean "in straight
> line." 

Yes. Don't we all mean that?

> but stars move approximately that way.  

Yes. But on the long run (as in a galaxy) they move in a circle.

> So your attempt to belittle Tom Robert's lesson is pretence.

?

Nicolaas Vroom

[toc] | [prev] | [next] | [standalone]

#424280

On 07/08/2017 05:17 PM, Nicolaas Vroom wrote:
> On Saturday, 8 July 2017 15:42:02 UTC+2, Gary Harnagel  wrote:

>>>
>>> (The stars in a galaxy are not moving inertially, as such you have
>>> answered my original question)
>>
>> You delude yourself.  by "inertially" you apparently mean "in straight
>> line."
> 
> Yes. Don't we all mean that?

No. we do not.

By "inertially", it means without acting external net force.

It is straight line in context of Newtonian mechanics.
It is straight line in context of SR and negligible gravity.

In GR context, it is geodesics in non local scale, OR,
is is approximately a straight line in locally inertial frame.

> 
>> but stars move approximately that way.
> 
> Yes. But on the long run (as in a galaxy) they move in a circle.

Orbits are considered as inertial motion in GR context,
as gravity is not considered as a force.

-- 
Poutnik
Guard the words you use speaking about others,
as they speak about you.

[toc] | [prev] | [next] | [standalone]

#424282

Poutnik wrote:

> In GR context, it is geodesics in non local scale, OR,
> is is approximately a straight line in locally inertial frame.

Fine. Now define your straight line.

[toc] | [prev] | [next] | [standalone]

#424311

On Saturday, July 8, 2017 at 9:17:51 AM UTC-6, Nicolaas Vroom wrote:
>
> On Saturday, 8 July 2017 15:42:02 UTC+2, Gary Harnagel  wrote:
> >
> > On Saturday, July 8, 2017 at 6:37:24 AM UTC-6, Nicolaas Vroom wrote:
> > >
> > > On Thursday, 6 July 2017 17:32:10 UTC+2, tjrob137  wrote:
> > > >
> > > > On 7/6/17 7/6/17 - 3:21 AM, Nicolaas Vroom wrote:
> > > > >
> > > > > Still the question remains:
> > > > > Does the neutron star stay at the center of the sphere.
> > > > 
> > > > If the star is moving inertially, then it remains at the center 
> > > > of the light sphere as seen in its rest frame; it does NOT remain 
> > > > at the center of the light sphere seen in any other inertial frame. 
> > > > If it is not moving inertially, it does NOT remain at the center 
> > > > of any inertial frame's sphere.
> > > 
> > > (The stars in a galaxy are not moving inertially, as such you have 
> > > answered my original question)
> > 
> > You delude yourself.  by "inertially" you apparently mean "in straight
> > line." 
> 
> Yes. Don't we all mean that?
> 
> > but stars move approximately that way.  
> 
> Yes. But on the long run (as in a galaxy) they move in a circle.
> 
> > So your attempt to belittle Tom Robert's lesson is pretence.
> 
> ?
> 
> Nicolaas Vroom

You seem to be straining at gnats.  Do you also swallow camels?

[toc] | [prev] | [next] | [standalone]

#424364

On Sunday, 9 July 2017 02:36:21 UTC+2, Gary Harnagel  wrote:
> On Saturday, July 8, 2017 at 9:17:51 AM UTC-6, Nicolaas Vroom wrote:
> >
> > On Saturday, 8 July 2017 15:42:02 UTC+2, Gary Harnagel  wrote:
> > >
> > > On Saturday, July 8, 2017 at 6:37:24 AM UTC-6, Nicolaas Vroom wrote:
> > > >
> > > > On Thursday, 6 July 2017 17:32:10 UTC+2, tjrob137  wrote:
> > > > >
> > > > > On 7/6/17 7/6/17 - 3:21 AM, Nicolaas Vroom wrote:
> > > > > > 
> > > > > > Still the question remains:
> > > > > > Does the neutron star stay at the center of the sphere.
> > > > > 
> > > > > If the star is moving inertially, then it remains at the center 
> > > > > of the light sphere as seen in its rest frame; it does NOT  
> > > > > remain at the center of the light sphere seen in any other 
> > > > > inertial frame. If it is not moving inertially, it does 
> > > > > NOT remain at the center of any inertial frame's sphere.
> > > > 
> > > > (The stars in a galaxy are not moving inertially, as such you have 
> > > > answered my original question)
> > > 
> > > You delude yourself.  by "inertially" you apparently mean 
> > > "in straight line." 
> > 
> > Yes. Don't we all mean that?
> > 
> > > but stars move approximately that way.  
> > 
> > Yes. But on the long run (as in a galaxy) they move in a circle.
> > 
> You seem to be straining at gnats.  Do you also swallow camels?

When Tom Roberts writes: "If it is not moving inertially, it does 
NOT remain at the center of any inertial frame's sphere."
Immediate my next question is:
Are there frames (coordinate systems) in which the origin stays
at the center of such a light sphere.
 
Consider a Lightsource LS1 which moves in a certain direction.
Consider a second Lightsource LS2 which moves with a different 
speed in a different direction. 
(They are not exactly at collision course)
When they almost meet at closest distance each LS generates
an explosion which creates a light sphere.
At that moment and position you can assign for each LS an inertial 
frame which the LS as origin and the x axis in the direction
of movement. 
The question is will the LS stay at the center of the light sphere?
Outside observers will claim that when they see a flash from the first 
LS they also see a flash from the second LS i.e. light sphere.
This means the light spheres are almost one and the same.

The question is which inertial frame is at the center of this
light sphere?
Ofcourse you could claim that the inertial frame of LS1 is at the
center of the light sphere. But so can LS2. 
They can not be both, because the two inertial frames have 
different speeds and directions.
That means neither. This leaves the possibility open that there
is a different coordinate system with the origin at the center
and with stays at the center.

Nicolaas Vroom

[toc] | [prev] | [next] | [standalone]

#424368

On Sunday, July 9, 2017 at 7:17:45 AM UTC-6, Nicolaas Vroom wrote:
>
> On Sunday, 9 July 2017 02:36:21 UTC+2, Gary Harnagel  wrote:
> >
> > On Saturday, July 8, 2017 at 9:17:51 AM UTC-6, Nicolaas Vroom wrote:
> > >
> > > Yes. But on the long run (as in a galaxy) they move in a circle.
> > > 
> > You seem to be straining at gnats.  Do you also swallow camels?
> 
> When Tom Roberts writes: "If it is not moving inertially, it does 
> NOT remain at the center of any inertial frame's sphere."
> Immediate my next question is:
> Are there frames (coordinate systems) in which the origin stays
> at the center of such a light sphere.

He answered that:  in the frame where the source is stationary.

That should answer ALL your questions.

[toc] | [prev] | [next] | [standalone]

Page 1 of 2  [1] 2  Next page →

Back to top | Article view | sci.physics.relativity

csiph-web