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Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ?

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  Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Keith Stein <keithstein111@gmail.com> - 2018-06-12 19:09 +0100
    Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Odd Bodkin <bodkinodd@gmail.com> - 2018-06-12 18:41 +0000
      Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Keith Stein <keithstein111@gmail.com> - 2018-06-12 20:38 +0100
        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Edward Prochak <edprochak@gmail.com> - 2018-06-14 07:28 -0700
          Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Odd Bodkin <bodkinodd@gmail.com> - 2018-06-14 16:26 +0000
            Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Keith Stein <keithstein111@gmail.com> - 2018-06-15 01:31 +0100
              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Volney <volney@volney.invalid> - 2018-06-14 23:27 -0400
              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Odd Bodkin <bodkinodd@gmail.com> - 2018-06-15 14:35 +0000
              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Edward Prochak <edprochak@gmail.com> - 2018-06-15 09:17 -0700
          Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-15 06:40 +0200
            Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Edward Prochak <edprochak@gmail.com> - 2018-06-15 09:28 -0700
              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? dlzc <dlzc1@cox.net> - 2018-06-15 10:22 -0700
              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-16 12:14 +0200
                Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Edward Prochak <edprochak@gmail.com> - 2018-06-17 17:32 -0700
    Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? dlzc <dlzc1@cox.net> - 2018-06-12 12:20 -0700
      Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Keith Stein <keithstein111@gmail.com> - 2018-06-12 21:03 +0100
        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? dlzc <dlzc1@cox.net> - 2018-06-12 13:37 -0700
        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Sylvia Else <sylvia@not.at.this.address> - 2018-06-13 11:34 +1000
          Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Keith Stein <keithstein111@gmail.com> - 2018-06-15 01:59 +0100
            Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Sylvia Else <sylvia@not.at.this.address> - 2018-06-15 11:17 +1000
              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Volney <volney@volney.invalid> - 2018-06-14 23:40 -0400
            Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Volney <volney@volney.invalid> - 2018-06-14 23:33 -0400
        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Sylvia Else <sylvia@not.at.this.address> - 2018-06-13 11:40 +1000
          Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2018-06-15 16:17 -0700
            Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Sylvia Else <sylvia@not.at.this.address> - 2018-06-16 20:27 +1000
              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2018-06-16 05:40 -0700
        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? "Dono," <sa_ge@comcast.net> - 2018-06-12 19:43 -0700
        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? mitchrae3323@gmail.com - 2018-06-13 12:06 -0700
          Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Keith Stein <keithstein111@gmail.com> - 2018-06-13 21:47 +0100
            Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC  SPACE ? The Starmaker <starmaker@ix.netcom.com> - 2018-06-13 21:55 -0700
              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC  SPACE ? dlzc <dlzc1@cox.net> - 2018-06-14 07:10 -0700
                Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC  SPACE ? Werner Ballard <db@ocowak.br> - 2018-06-14 15:54 +0000
                  Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC  SPACE ? dlzc <dlzc1@cox.net> - 2018-06-14 09:25 -0700
                    Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Keith Stein <keithstein111@gmail.com> - 2018-06-15 02:25 +0100
                      Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Werner Ballard <db@ocoak.bn> - 2018-06-16 14:02 +0000
                  Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-15 00:17 +0200
                    Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? dlzc <dlzc1@cox.net> - 2018-06-14 15:34 -0700
                      Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-15 01:13 +0200
                        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? dlzc <dlzc1@cox.net> - 2018-06-14 17:53 -0700
                          Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-15 06:22 +0200
                            Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? dlzc <dlzc1@cox.net> - 2018-06-15 06:44 -0700
                              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Werner Ballard <db@ocoak.bn> - 2018-06-15 14:32 +0000
                              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-16 10:00 +0200
                                Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? dlzc <dlzc1@cox.net> - 2018-06-16 08:13 -0700
                                  Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Werner Ballard <db@ocoak.bn> - 2018-06-16 15:24 +0000
                                  Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-18 14:06 +0200
                Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC   SPACE ? The Starmaker <starmaker@ix.netcom.com> - 2018-06-14 10:30 -0700
                  Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC   SPACE ? dlzc <dlzc1@cox.net> - 2018-06-14 11:52 -0700
                    Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Volney <volney@volney.invalid> - 2018-06-14 15:08 -0400
                      Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC  SPACE ? The Starmaker <starmaker@ix.netcom.com> - 2018-06-14 13:00 -0700
                        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Volney <volney@volney.invalid> - 2018-06-14 16:13 -0400
                          Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC  SPACE ? The Starmaker <starmaker@ix.netcom.com> - 2018-06-14 13:55 -0700
                            Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Volney <volney@volney.invalid> - 2018-06-14 17:22 -0400
                              Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC  SPACE ? The Starmaker <starmaker@ix.netcom.com> - 2018-06-14 15:25 -0700
                                Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Volney <volney@volney.invalid> - 2018-06-14 23:21 -0400
                                  Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC  SPACE ? The Starmaker <starmaker@ix.netcom.com> - 2018-06-15 12:25 -0700
                                    Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Volney <volney@volney.invalid> - 2018-06-15 18:06 -0400
                                      Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC  SPACE ? The Starmaker <starmaker@ix.netcom.com> - 2018-06-15 15:22 -0700
                                        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Volney <volney@volney.invalid> - 2018-06-15 18:44 -0400
                                        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC   SPACE ? The Starmaker <starmaker@ix.netcom.com> - 2018-06-15 15:54 -0700
    Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? The Starmaker <starmaker@ix.netcom.com> - 2018-06-12 16:26 -0700
    Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? "Dono," <sa_ge@comcast.net> - 2018-06-12 18:07 -0700
      Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Zandra Sobczak <acako@raswa.bo> - 2018-06-13 12:24 +0000
        Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Paparios <mrios@ing.puc.cl> - 2018-06-13 05:59 -0700
          Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Zandra Sobczak <acako@raswa.bo> - 2018-06-13 13:37 +0000
    Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? SolomonW <SolomonW@citi.com> - 2018-06-14 01:37 +1000
      Re: Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? Keith Stein <keithstein111@gmail.com> - 2018-06-13 21:31 +0100
    Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2018-06-13 16:13 -0700
      Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2018-06-13 16:20 -0700
        Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ? "David (Kronos Prime) Fuller" <fuller.david@hotmail.com> - 2018-06-13 16:22 -0700

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#461064 — Is it possible to MEASURE the speed of light,iN INTERGALACTIC SPACE ?

I understand of course how it can be extrapolated
from measurements in laboratories on Earth, but is
it possible, even in theory, to MEASURE the speed
at which light travels through intergalactic space ?

keith stein

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#461067

Keith Stein <keithstein111@gmail.com> wrote:
> 
> I understand of course how it can be extrapolated
> from measurements in laboratories on Earth, but is
> it possible, even in theory, to MEASURE the speed
> at which light travels through intergalactic space ?
> 
> keith stein
> 

Yes. See Roemer. 

-- 
Odd Bodkin — Maker of fine toys, tools, tables

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#461075

On 12/06/2018 19:41, Odd Bodkin wrote:
> Keith Stein <keithstein111@gmail.com> wrote:
>>
>> I understand of course how it can be extrapolated
>> from measurements in laboratories on Earth, but is
>> it possible, even in theory, to MEASURE the speed
>> at which light travels through intergalactic space ?
>>
>> keith stein
>>
> 
> Yes. See Roemer.

That's fine for interplanetary space, but that's
a long way short of the intergalactic space i was
asking about, Old Bodkin, but thanks response.

keith stein

> 

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#461225

On Tuesday, June 12, 2018 at 3:38:02 PM UTC-4, Keith Stein wrote:
> On 12/06/2018 19:41, Odd Bodkin wrote:
> > Keith Stein <keithstein111@gmail.com> wrote:
> >>
> >> I understand of course how it can be extrapolated
> >> from measurements in laboratories on Earth, but is
> >> it possible, even in theory, to MEASURE the speed
> >> at which light travels through intergalactic space ?
> >>
> >> keith stein
> >>
> > 
> > Yes. See Roemer.
> 
> That's fine for interplanetary space, but that's
> a long way short of the intergalactic space i was
> asking about, Old Bodkin, but thanks response.
> 
> keith stein
> 
> >

I wonder, has Roemer's method been used with exoplanets?

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#461235

Edward Prochak <edprochak@gmail.com> wrote:
> On Tuesday, June 12, 2018 at 3:38:02 PM UTC-4, Keith Stein wrote:
>> On 12/06/2018 19:41, Odd Bodkin wrote:
>>> Keith Stein <keithstein111@gmail.com> wrote:
>>>> 
>>>> I understand of course how it can be extrapolated
>>>> from measurements in laboratories on Earth, but is
>>>> it possible, even in theory, to MEASURE the speed
>>>> at which light travels through intergalactic space ?
>>>> 
>>>> keith stein
>>>> 
>>> 
>>> Yes. See Roemer.
>> 
>> That's fine for interplanetary space, but that's
>> a long way short of the intergalactic space i was
>> asking about, Old Bodkin, but thanks response.
>> 
>> keith stein
>> 
>>> 
> 
> I wonder, has Roemer's method been used with exoplanets?
> 
> 

I would think this method would apply to any predictable orbit outside the
solar system. Roemer’s method was to simply look for the variation in the
time that a highly regular event based on how far the earth is from that
event. In Roemer’s case the regular event is the eclipsing of Io, and the
variation of distance is caused by Earth being close to, or far away from,
Jupiter. 

But simply swap eclipsing of Io for pulsar beats or the luminosity of
eclipsing binaries in the galaxies, and still use the semi-annual orbit of
the earth, which has a throw of 16.6 light minutes, to do a comparable
measurement within the galaxy. 

-- 
Odd Bodkin — Maker of fine toys, tools, tables

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#461289

On 14/06/2018 17:26, Odd Bodkin wrote:
> Edward Prochak <edprochak@gmail.com> wrote:
>> On Tuesday, June 12, 2018 at 3:38:02 PM UTC-4, Keith Stein wrote:
>>> On 12/06/2018 19:41, Odd Bodkin wrote:
>>>> Keith Stein <keithstein111@gmail.com> wrote:
>>>>>
>>>>> I understand of course how it can be extrapolated
>>>>> from measurements in laboratories on Earth, but is
>>>>> it possible, even in theory, to MEASURE the speed
>>>>> at which light travels through intergalactic space ?
>>>>>
>>>>> keith stein
>>>>>
>>>>
>>>> Yes. See Roemer.
>>>
>>> That's fine for interplanetary space, but that's
>>> a long way short of the intergalactic space i was
>>> asking about, Old Bodkin, but thanks response.
>>>
>>> keith stein
>>>
>>>>
>>
>> I wonder, has Roemer's method been used with exoplanets?
>>
>>
> 
> I would think this method would apply to any predictable orbit outside the
> solar system. Roemer’s method was to simply look for the variation in the
> time that a highly regular event based on how far the earth is from that
> event. In Roemer’s case the regular event is the eclipsing of Io, and the
> variation of distance is caused by Earth being close to, or far away from,
> Jupiter.
> 
> But simply swap eclipsing of Io for pulsar beats or the luminosity of
> eclipsing binaries in the galaxies, and still use the semi-annual orbit of
> the earth, which has a throw of 16.6 light minutes, to do a comparable
> measurement within the galaxy.

The distance the light travels through INTERGALACTIC SPACE is clearly in
no way effected by where the Earth is in its orbit around the sun. So
Roemer's method has no chance of measuring the speed of light in inter-
galactic space, even if the source is on another galaxy, i think.

keith stein
> 

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#461306

On 6/14/2018 8:31 PM, Keith Stein wrote:
> On 14/06/2018 17:26, Odd Bodkin wrote:
>> But simply swap eclipsing of Io for pulsar beats or the luminosity of
>> eclipsing binaries in the galaxies, and still use the semi-annual 
>> orbit of
>> the earth, which has a throw of 16.6 light minutes, to do a comparable
>> measurement within the galaxy.
> 
> The distance the light travels through INTERGALACTIC SPACE is clearly in
> no way effected by where the Earth is in its orbit around the sun.

It most certainly is, for a source near the ecliptic. If the earth is in 
between the source and the sun the distance is shorter than when the 
earth is on the far side of the sun.

> So Roemer's method has no chance of measuring the speed of light in inter-
> galactic space, even if the source is on another galaxy, i think.

Nope.

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#461342

Keith Stein <keithstein111@gmail.com> wrote:
> On 14/06/2018 17:26, Odd Bodkin wrote:
>> Edward Prochak <edprochak@gmail.com> wrote:
>>> On Tuesday, June 12, 2018 at 3:38:02 PM UTC-4, Keith Stein wrote:
>>>> On 12/06/2018 19:41, Odd Bodkin wrote:
>>>>> Keith Stein <keithstein111@gmail.com> wrote:
>>>>>> 
>>>>>> I understand of course how it can be extrapolated
>>>>>> from measurements in laboratories on Earth, but is
>>>>>> it possible, even in theory, to MEASURE the speed
>>>>>> at which light travels through intergalactic space ?
>>>>>> 
>>>>>> keith stein
>>>>>> 
>>>>> 
>>>>> Yes. See Roemer.
>>>> 
>>>> That's fine for interplanetary space, but that's
>>>> a long way short of the intergalactic space i was
>>>> asking about, Old Bodkin, but thanks response.
>>>> 
>>>> keith stein
>>>> 
>>>>> 
>>> 
>>> I wonder, has Roemer's method been used with exoplanets?
>>> 
>>> 
>> 
>> I would think this method would apply to any predictable orbit outside the
>> solar system. Roemer’s method was to simply look for the variation in the
>> time that a highly regular event based on how far the earth is from that
>> event. In Roemer’s case the regular event is the eclipsing of Io, and the
>> variation of distance is caused by Earth being close to, or far away from,
>> Jupiter.
>> 
>> But simply swap eclipsing of Io for pulsar beats or the luminosity of
>> eclipsing binaries in the galaxies, and still use the semi-annual orbit of
>> the earth, which has a throw of 16.6 light minutes, to do a comparable
>> measurement within the galaxy.
> 
> The distance the light travels through INTERGALACTIC SPACE is clearly in
> no way effected by where the Earth is in its orbit around the sun. So
> Roemer's method has no chance of measuring the speed of light in inter-
> galactic space, even if the source is on another galaxy, i think.
> 
> keith stein
>> 
> 
> 

I’m curious why you think the space between galaxies is fundamentally
different than the space between stars in our galaxy, and different than
the space between planets in the vicinity of our one star. 

-- 
Odd Bodkin — Maker of fine toys, tools, tables

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#461361

On Thursday, June 14, 2018 at 8:31:52 PM UTC-4, Keith Stein wrote:
> On 14/06/2018 17:26, Odd Bodkin wrote:
> > Edward Prochak <edprochak@gmail.com> wrote:
> >> On Tuesday, June 12, 2018 at 3:38:02 PM UTC-4, Keith Stein wrote:
> >>> On 12/06/2018 19:41, Odd Bodkin wrote:
> >>>> Keith Stein <keithstein111@gmail.com> wrote:
> >>>>>
> >>>>> I understand of course how it can be extrapolated
> >>>>> from measurements in laboratories on Earth, but is
> >>>>> it possible, even in theory, to MEASURE the speed
> >>>>> at which light travels through intergalactic space ?
> >>>>>
> >>>>> keith stein
> >>>>>
> >>>>
> >>>> Yes. See Roemer.
> >>>
> >>> That's fine for interplanetary space, but that's
> >>> a long way short of the intergalactic space i was
> >>> asking about, Old Bodkin, but thanks response.
> >>>
> >>> keith stein
> >>>
> >>>>
> >>
> >> I wonder, has Roemer's method been used with exoplanets?
> >>
> >>
> > 
> > I would think this method would apply to any predictable orbit outside the
> > solar system. Roemer’s method was to simply look for the variation in the
> > time that a highly regular event based on how far the earth is from that
> > event. In Roemer’s case the regular event is the eclipsing of Io, and the
> > variation of distance is caused by Earth being close to, or far away from,
> > Jupiter.
> > 
> > But simply swap eclipsing of Io for pulsar beats or the luminosity of
> > eclipsing binaries in the galaxies, and still use the semi-annual orbit of
> > the earth, which has a throw of 16.6 light minutes, to do a comparable
> > measurement within the galaxy.
> 
> The distance the light travels through INTERGALACTIC SPACE is clearly in
> no way effected by where the Earth is in its orbit around the sun. So

Really? why would the effect be different for intergalactic light
than for interplanetary light? You seem to be postulating that
the laws of physics vary in different locations in the universe.

> Roemer's method has no chance of measuring the speed of light in inter-
> galactic space, even if the source is on another galaxy, i think.
> 
Well I am not sure but I thought all the exoplanets found so far
are within our galaxy. It was just a curious question.
You don't seem to know if it has been used or not.
maybe if that is the case, please don't bother to reply.

Ed

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#461313

Edward Prochak wrote:
> On Tuesday, June 12, 2018 at 3:38:02 PM UTC-4, Keith Stein wrote:
>> On 12/06/2018 19:41, Odd Bodkin wrote:
>>> Keith Stein <keithstein111@gmail.com> wrote:
>>>> I understand of course how it can be extrapolated
>>>> from measurements in laboratories on Earth, but is
>>>> it possible, even in theory, to MEASURE the speed
>>>> at which light travels through intergalactic space ?
>>> Yes. See Roemer.
>> That's fine for interplanetary space, but that's
>> a long way short of the intergalactic space i was
>> asking about, Old Bodkin, but thanks response.
> 
> I wonder, has Roemer's method been used with exoplanets?

Unlikely, given that we have not observed exoplanets directly yet, and that
the ratio of the distance to an exoplanet and the diameter of Terra’s orbit
grows the farther away the exoplanet is.

Also, exoplanets have not yet been observed in any way in other galaxies and
likely never will be.

(You seem to be ignorant of what “Rømer’s method” was, what an exoplanet is,
and what “intergalactic” means.)

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#461364

On Friday, June 15, 2018 at 12:40:34 AM UTC-4, Thomas 'PointedEars' Lahn wrote:
> Edward Prochak wrote:
> > On Tuesday, June 12, 2018 at 3:38:02 PM UTC-4, Keith Stein wrote:
> >> On 12/06/2018 19:41, Odd Bodkin wrote:
> >>> Keith Stein <keithstein111@gmail.com> wrote:
> >>>> I understand of course how it can be extrapolated
> >>>> from measurements in laboratories on Earth, but is
> >>>> it possible, even in theory, to MEASURE the speed
> >>>> at which light travels through intergalactic space ?
> >>> Yes. See Roemer.
> >> That's fine for interplanetary space, but that's
> >> a long way short of the intergalactic space i was
> >> asking about, Old Bodkin, but thanks response.
> > 
> > I wonder, has Roemer's method been used with exoplanets?
> 
> Unlikely, given that we have not observed exoplanets directly yet, and that
> the ratio of the distance to an exoplanet and the diameter of Terra’s orbit
> grows the farther away the exoplanet is.
> 
> Also, exoplanets have not yet been observed in any way in other galaxies and
> likely never will be.
> 
> (You seem to be ignorant of what “Rømer’s method” was, what an exoplanet is,
> and what “intergalactic” means.)
> 
> -- 
> PointedEars
> 
> Twitter: @PointedEars2
> Please do not cc me. / Bitte keine Kopien per E-Mail.

Only Keith is fixated on the intergalactic.

I was idly wondering if Roemer's method was tried
on exoplanets, all of which discovered so far are within
our galaxy (I think). But pondering it a bit, it would be
impossible since the method requires observing the eclipse
of the planet. since it orbits a star, it will never be
in shadow! So yes I was a bit of a dummy.  8^)

ed

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#461375

Dear Edward Prochak:

On Friday, June 15, 2018 at 9:28:29 AM UTC-7, Edward Prochak wrote:
...
> I was idly wondering if Roemer's method was tried
> on exoplanets, all of which discovered so far are within
> our galaxy (I think). But pondering it a bit, it would be
> impossible since the method requires observing the eclipse
> of the planet. since it orbits a star, it will never be
> in shadow! So yes I was a bit of a dummy.  8^)

No you were not, or not entirely.  SOME planetary detections look for the dimming of the primary, which is suitable when that ecliptic plane is close to including Earth.  In those cases, this would work.  Earth is "in shadow", which is good enough.

Don't be so hard on yourself.

David A. Smith

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#461450

Edward Prochak wrote:

> I was idly wondering if Roemer's method was tried
> on exoplanets, all of which discovered so far are within
> our galaxy (I think).

Yes, AISB.

> But pondering it a bit, it would be impossible since the method requires
> observing the eclipse of the planet. since it orbits a star, it will
> never be in shadow!

The problem runs much deeper than that.

It is commonly believed, even by physicists, and was by me until now, that
Ole Rømer calculated the speed of light based on his observations of Io.
However, especially to my own surprise, that is historically *incorrect*:

<https://en.wikipedia.org/wiki/Ole_R%C3%B8mer#Rømer_and_the_speed_of_light>
pp.,

and especially

Saito, Yoshio (June 2005). "A Discussion of Roemer's Discovery concerning
the Speed of Light". AAPPS Bulletin. 15 (3): 9–17.
<http://aappsbulletin.org/myboard/down.php?Board=webzine&filename=Vol.15-3.pdf&id=147&fidx=2>
(PDF)

Bottom line:

Rømer used and improved Giovanni Domenico *Cassini*’s observations (the same
after which the ”*Cassini*–*Huygens*” 1997–2017 Saturn probe was named) of
eclipses of the Galilean moons by Jupiter.

It was Cassini who had assumed at first that, because of his observations,
light would have a finite speed.  However, Cassini (or, reportedly, “the
Cassini family”) for an unknown reason apparently did not seek to
substantiate that hypothesis; Rømer *reportedly* did.

Rømer *reportedly* presented his findings to the French Academy of Sciences,
but never published them; apparently the original presentation has been lost
and we have only the questionable «Démonstration touchant le mouvement de la
lumière trouvé par M. Roemer de l'Académie des sciences» *by an anonymous
layman/crackpot reporter* as evidence of Rømer’s assumption of a finite
speed of light.  At best, Rømer discussed the *retardation* (delay) of light
for the ephemeris of Io.

It were other scientists, beginning with Christaan *Huygens* (see above),
who interpreted Rømer’s data (as we know now, correctly) to calculate a
value for the speed of light.


The method that we are talking about is actually based on different
light-travel times at different times in Terra’s (Earth’s) orbit.

So, in theory, we could use that method with an exoplanet, even though it is
not eclipsed by its star, if we could observe that planet directly: We could
measure the time that it takes to appear on the other side of its star or
orbit at different times of the terrestrial year.  Unfortunately, we unable
to see the exoplanet: the star is much brighter than the planet, and the
exoplanet is obviously closer to its star than to us.

We could also use that method even though we cannot see the exoplanet
directly: We could use the dips in the star’s light curve by which the
exoplanet was discovered in the first place.  The dips would be ahead of
and behind schedule the same as the eclipse of Io by Jupiter.

To me, the main problem here is that exoplanets are very far away: they
are planets moving *around another star* (in our galaxy).

The distance to them compared to the diameter of Terra’s orbit is *huge*:
the closest star (to Terra), Proxima Centauri (α Cen C) is ca. 4.25
light-years away; that is already 268'800 times the distance from Terra to
Sol (the Sun) [1] (and it has a planet, Proxima b, discovered in 2016 [2]).
So it will be increasingly difficult to measure differences in light-travel
time, the farther out the exoplanet is.

Also, because of an exoplanet’s distant location, there is the interstellar
medium and considerably enough curved spacetime (by other stars, and
interstellar clouds) in-between the observer and the star/planet which both
could interfere even if there is a clear line-of-sight.


HTH

PointedEars
___________
[1] <http://www.wolframalpha.com/input/?i=4.25+ly+in+AU&dataset=>
[2] <https://en.wikipedia.org/wiki/Proxima_Centauri>
-- 
Q: What did the nuclear physicist order for lunch?
A: Fission chips.

(from: WolframAlpha)

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#461568

On Saturday, June 16, 2018 at 6:14:38 AM UTC-4, Thomas 'PointedEars' Lahn wrote:
> Edward Prochak wrote:
> 
> > I was idly wondering if Roemer's method was tried
> > on exoplanets, all of which discovered so far are within
> > our galaxy (I think).
> 
> Yes, AISB.
> 
> > But pondering it a bit, it would be impossible since the method requires
> > observing the eclipse of the planet. since it orbits a star, it will
> > never be in shadow!
> 
> The problem runs much deeper than that.
> 
> It is commonly believed, even by physicists, and was by me until now, that
> Ole Rømer calculated the speed of light based on his observations of Io.
> However, especially to my own surprise, that is historically *incorrect*:
> 
> <https://en.wikipedia.org/wiki/Ole_R%C3%B8mer#Rømer_and_the_speed_of_light>
> pp.,
> 
> and especially
> 
> Saito, Yoshio (June 2005). "A Discussion of Roemer's Discovery concerning
> the Speed of Light". AAPPS Bulletin. 15 (3): 9–17.
> <http://aappsbulletin.org/myboard/down.php?Board=webzine&filename=Vol.15-3.pdf&id=147&fidx=2>
> (PDF)
> 
> Bottom line:
> 
> Rømer used and improved Giovanni Domenico *Cassini*’s observations (the same
> after which the ”*Cassini*–*Huygens*” 1997–2017 Saturn probe was named) of
> eclipses of the Galilean moons by Jupiter.
> 
> It was Cassini who had assumed at first that, because of his observations,
> light would have a finite speed.  However, Cassini (or, reportedly, “the
> Cassini family”) for an unknown reason apparently did not seek to
> substantiate that hypothesis; Rømer *reportedly* did.
> 
> Rømer *reportedly* presented his findings to the French Academy of Sciences,
> but never published them; apparently the original presentation has been lost
> and we have only the questionable «Démonstration touchant le mouvement de la
> lumière trouvé par M. Roemer de l'Académie des sciences» *by an anonymous
> layman/crackpot reporter* as evidence of Rømer’s assumption of a finite
> speed of light.  At best, Rømer discussed the *retardation* (delay) of light
> for the ephemeris of Io.
> 
> It were other scientists, beginning with Christaan *Huygens* (see above),
> who interpreted Rømer’s data (as we know now, correctly) to calculate a
> value for the speed of light.
> 
> 
> The method that we are talking about is actually based on different
> light-travel times at different times in Terra’s (Earth’s) orbit.
> 
> So, in theory, we could use that method with an exoplanet, even though it is
> not eclipsed by its star, if we could observe that planet directly: We could
> measure the time that it takes to appear on the other side of its star or
> orbit at different times of the terrestrial year.  Unfortunately, we unable
> to see the exoplanet: the star is much brighter than the planet, and the
> exoplanet is obviously closer to its star than to us.
> 
> We could also use that method even though we cannot see the exoplanet
> directly: We could use the dips in the star’s light curve by which the
> exoplanet was discovered in the first place.  The dips would be ahead of
> and behind schedule the same as the eclipse of Io by Jupiter.
> 
> To me, the main problem here is that exoplanets are very far away: they
> are planets moving *around another star* (in our galaxy).
> 
> The distance to them compared to the diameter of Terra’s orbit is *huge*:
> the closest star (to Terra), Proxima Centauri (α Cen C) is ca. 4.25
> light-years away; that is already 268'800 times the distance from Terra to
> Sol (the Sun) [1] (and it has a planet, Proxima b, discovered in 2016 [2]).
> So it will be increasingly difficult to measure differences in light-travel
> time, the farther out the exoplanet is.
> 
> Also, because of an exoplanet’s distant location, there is the interstellar
> medium and considerably enough curved spacetime (by other stars, and
> interstellar clouds) in-between the observer and the star/planet which both
> could interfere even if there is a clear line-of-sight.
> 
> 
> HTH
> 
> PointedEars
> ___________
> [1] <http://www.wolframalpha.com/input/?i=4.25+ly+in+AU&dataset=>
> [2] <https://en.wikipedia.org/wiki/Proxima_Centauri>
> -- 
> Q: What did the nuclear physicist order for lunch?
> A: Fission chips.
> 
> (from: WolframAlpha)

Nice presentation. Thanks.
Ed

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#461072

Dear Keith Stein:

On Tuesday, June 12, 2018 at 11:09:39 AM UTC-7, Keith Stein wrote:
> I understand of course how it can be extrapolated
> from measurements in laboratories on Earth, but is
> it possible, even in theory, to MEASURE the speed
> at which light travels through intergalactic space ?

Well, they do infer "instantaneous" expansion rates, using Einstein crosses, where the different images are different distances from the gravity center.  So this "assumes" a constant speed of light over that entire path, regardless of duration.

So if you had something in mind, there'd be the precise timing necessary to validate or invalidate "some value' for a speed of light.

David A. Smith

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#461077

On 12/06/2018 20:20, dlzc wrote:
> Dear Keith Stein:
> 
> On Tuesday, June 12, 2018 at 11:09:39 AM UTC-7, Keith Stein wrote:
>> I understand of course how it can be extrapolated
>> from measurements in laboratories on Earth, but is
>> it possible, even in theory, to MEASURE the speed
>> at which light travels through intergalactic space ?
> 
> Well, they do infer "instantaneous" expansion rates, using Einstein crosses, where the different images are different distances from the gravity center.  So this "assumes" a constant speed of light over that entire path, regardless of duration.
> 
> So if you had something in mind, there'd be the precise timing necessary to validate or invalidate "some value' for a speed of light.
> 
> David A. Smith
> 
Thanks for the response David.

I rather think Einstein DEFINED the speed of light to be constant.
One problem with that approach is that if the speed of light in
intergalactic space is actually slowing down, then you are going
to think the universe is expanding, when in fact it isn't.

keith stein

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#461082

Dear Keith Stein:

On Tuesday, June 12, 2018 at 1:03:38 PM UTC-7, Keith Stein wrote:
...
> One problem with that approach is that if the speed of light in
> intergalactic space is actually slowing down, then you are going
> to think the universe is expanding, when in fact it isn't.

False assumption.  Two set of "rays", each spending a different amount of time between source, and us.  A "signatory event" is written in the "data streams", so that we can sync what happened at the source and arrival here over two paths.

Its data.  Consider it from your obsession's point of view.  Two drastically different length light paths...  It is extragalactic, and precise timing has been applied.  It is up to you to show that the "geometric" path is anomalously affected by a varying c, and why the diverence angle is not larger (as required by slowing c).

David A. Smith

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#461112

On 13/06/2018 6:03 AM, Keith Stein wrote:
> I rather think Einstein DEFINED the speed of light to be constant.
> One problem with that approach is that if the speed of light in
> intergalactic space is actually slowing down, then you are going
> to think the universe is expanding, when in fact it isn't.

This is a misstatement. In his special theory of relativity, Einstein 
takes as a postulate that the laws of physics are dependent only on 
relative velocities. One consequence of that is that the speed of light 
in a vacuum must be constant.

But all that means is that the theory would be falsified if it were 
later determined by experiment that the speed of light in a vacuum is 
not constant. No such falsification has occurred.

Sylvia.

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#461294

On 13/06/2018 02:34, Sylvia Else wrote:
> On 13/06/2018 6:03 AM, Keith Stein wrote:
>> I rather think Einstein DEFINED the speed of light to be constant.
>> One problem with that approach is that if the speed of light in
>> intergalactic space is actually slowing down, then you are going
>> to think the universe is expanding, when in fact it isn't.
> 
> This is a misstatement. In his special theory of relativity, Einstein 
> takes as a postulate that the laws of physics are dependent only on 
> relative velocities. One consequence of that is that the speed of light 
> in a vacuum must be constant.
> 
> But all that means is that the theory would be falsified if it were 
> later determined by experiment that the speed of light in a vacuum is 
> not constant. No such falsification has occurred

  Sylvia, there never has been, and never will be, an experimental
determination of the speed of light in vacuum.  Intergalactic space
is not a vacuum (although it is much closer to it than anything
obtainable on Earth). The intergalactic medium is known to be mostly,
but not entirely, Hydrogen. As the Universe evolves the intergalactic
medium will no doubt evolve with it, so it is entirely feasible that
the speed of light in intergalactic space is slowing down, and my
guess is that it is. (by about 1 part in 14 billion per year)

keith stein

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#461296

On 15/06/2018 10:59 AM, Keith Stein wrote:
> On 13/06/2018 02:34, Sylvia Else wrote:
>> On 13/06/2018 6:03 AM, Keith Stein wrote:
>>> I rather think Einstein DEFINED the speed of light to be constant.
>>> One problem with that approach is that if the speed of light in
>>> intergalactic space is actually slowing down, then you are going
>>> to think the universe is expanding, when in fact it isn't.
>>
>> This is a misstatement. In his special theory of relativity, Einstein 
>> takes as a postulate that the laws of physics are dependent only on 
>> relative velocities. One consequence of that is that the speed of 
>> light in a vacuum must be constant.
>>
>> But all that means is that the theory would be falsified if it were 
>> later determined by experiment that the speed of light in a vacuum is 
>> not constant. No such falsification has occurred
> 
>   Sylvia, there never has been, and never will be, an experimental
> determination of the speed of light in vacuum.  Intergalactic space
> is not a vacuum (although it is much closer to it than anything
> obtainable on Earth). The intergalactic medium is known to be mostly,
> but not entirely, Hydrogen. As the Universe evolves the intergalactic
> medium will no doubt evolve with it, so it is entirely feasible that
> the speed of light in intergalactic space is slowing down, and my
> guess is that it is. (by about 1 part in 14 billion per year)
> 
> keith stein
> 
> 
> 
It is not remotely reasonable to suppose that light behaves in a 
fundamentally different way just because there are a few atoms per cubic 
metre in the space traversed by the light.

Sylvia.

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