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

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From: Inertial on 11 Mar 2010 16:05

"G. L. Bradford" <glbrad01(a)insightbb.com> wrote in message
news:qJSdnZRY8MdDvgTWnZ2dnUVZ_iydnZ2d(a)insightbb.com...
>
> "Inertial" <relatively(a)rest.com> wrote in message
> news:4b98c72d$0$8803$c3e8da3(a)news.astraweb.com...
>>
>> "G. L. Bradford" <glbrad01(a)insightbb.com> wrote in message
>> news:WaidncSioueeWwXWnZ2dnUVZ_sudnZ2d(a)insightbb.com...
>>> Planet A and planet B are similar planets one light year apart. A ship
>>> leaves planet A for planet B and the length of the voyage is set for one
>>> year, usual for this commuter ship. The month of departure planet A is
>>> Mar 2010. The month of scheduled arrival planet B is Mar 2011. The ship
>>> leaves planet A on time (Mar 2010) and arrives planet B on time (Mar
>>> 2011).
>>
>> So you have a spaceship travelling at the speed of light. Just a tad
>> unrealistic.
>>
>>> If an observer from planet A could observe the ship's arrival at planet
>>> B, what date would the observation of arrival planet B, Mar 2011, take
>>> place? As far as planet A is concerned, as far as the observer observes
>>> and clocks the arrival, the arrival at planet B takes place, Mar 2012,
>>> two years from the date of the ship's departure....and thus, observed
>>> from planet A, two years from the date of departure of his twin brother.
>>>
>>> The ship goes, and light comes (c). The ship goes farther out, and
>>> light comes from farther out (c). The ship goes even farther out, and
>>> light comes from even farther out (c). The ship goes one light year out
>>> in one year and it takes light one year from the instant of arrival to
>>> communicate the arrival of the ship and brother to the observer
>>> (c).....who notices from the light speed communication that his brother
>>> appears to have aged only one year between Mar 2010 (when he departed
>>> planet A) and Mar 2012 (when he arrived planet B [[per the observation
>>> of that arrival at planet A!]]). His brother APPARENTLY ages only one
>>> year while he definitely ages two during the time period, Mar 2010-Mar
>>> 2012.
>>>
>>> Of course he is smart enough to realize that his brother's apparent
>>> stretching out in space-time observed during the voyage out was nothing
>>> more than an illusion. Particularly when he arrives home apparently in
>>> precisely the same month (Mar 2012) he is observed to have left planet B
>>> (planet B observed, Mar 2011, from planet A, Mar 2012). He is smart
>>> enough to realize that the planet B observed from planet A is the one
>>> that is one year behind the times of the real-time planets A and B, and
>>> that any arrival, and any departure, observed to be happening there from
>>> planet A happened one year ago, making his age one year ago, and his
>>> brother's unobserved age one year ago upon his actual arrival and
>>> departure planet B, the same age.
>>>
>>> The twin brother gets to planet B a year before he is observed to get
>>> to planet B from planet A. The observation of the duration of the voyage
>>> from planet A is a year longer than the actual voyage takes. Yet it is
>>> the actual length of the outbound space voyage, one year, that is
>>> communicated to the observer on planet A in a two year long span of time
>>> where everything concerning the ship, and thus the brother, seems to
>>> slow down (seems to stretch) in the observer's view. The ship, the
>>> brother, and the ship's clock, outran by a full year the ship, the
>>> brother, and the ship's clock, the observer observed.
>>>
>>> Now someone will say that the time observed from planet A, and thus the
>>> stretching that is observed, is the literal physical reality of the
>>> traveler. They have no concept that the traveler's space-time reality on
>>> the spot might be one thing and his space-time relativity to an ever
>>> more distant observer quite another.
>>
>> Of course, you've ignored relativistic effects completely in that (apart
>> from having a spaceship travel at the speed of light) .. so I'm not sure
>> what the point of your post was.
>>
>>
>
> ==========================
>
> The ship didn't travel at the speed of light in its own frame.

Nothing with mass can travel at c in EVERY inertial frame. It travelled one
light year in a year .. that is the speed of light. Also anything
travelling at c travels at c in EVERY inertial frame.

How's about you slow your ship down to something that is at least
conceivable.

> Not by 300,000 kps did it travel at c.

Eh? What do you think c is?

> Which just goes to show that you've paid not a bit of attention and
> understood nothing.

Paying attention to what in particular?

So you still haven't said what the point of this post was? What point are
you trying to make?

From: Inertial on 11 Mar 2010 16:06

"G. L. Bradford" <glbrad01(a)insightbb.com> wrote in message
news:9YCdnRhgj8yIuQTWnZ2dnUVZ_rGdnZ2d(a)insightbb.com...
>
> "Peter Webb" <webbfamily(a)DIESPAMDIEoptusnet.com.au> wrote in message
> news:4b98cae0$0$11705$afc38c87(a)news.optusnet.com.au...
>>
>> "Inertial" <relatively(a)rest.com> wrote in message
>> news:4b98c72d$0$8803$c3e8da3(a)news.astraweb.com...
>>>
>>> "G. L. Bradford" <glbrad01(a)insightbb.com> wrote in message
>>> news:WaidncSioueeWwXWnZ2dnUVZ_sudnZ2d(a)insightbb.com...
>>>> Planet A and planet B are similar planets one light year apart. A ship
>>>> leaves planet A for planet B and the length of the voyage is set for
>>>> one year, usual for this commuter ship. The month of departure planet A
>>>> is Mar 2010. The month of scheduled arrival planet B is Mar 2011. The
>>>> ship leaves planet A on time (Mar 2010) and arrives planet B on time
>>>> (Mar 2011).
>>>
>>> So you have a spaceship travelling at the speed of light. Just a tad
>>> unrealistic.
>>>
>>
>> I think you should lighten up a bit. Photons travel at c, and this is
>> really just a special case of a more general question.
>>
>> The real problem is that looking at what happens at exactly c doesn't
>> really show the general principle, which is why real world hypothetical
>> spacecraft travel at 0.99c. But Mr Bradford maybe doesn't know that.
>>
>> I do agree however that his post seemed pointless.
>>
>> BTW, is you alias Inertial because of SR ?
>>
>>
>
> ======================
>
> The same goes for you as "Inertial"
>
> GLB

Why so hostile .. just want to know what point you are trying to make.

From: Inertial on 11 Mar 2010 16:26

"Ste" <ste_rose0(a)hotmail.com> wrote in message
news:62596b56-2c09-420b-9c2b-605258fba688(a)y17g2000yqd.googlegroups.com...
> On 11 Mar, 01:31, "Inertial" <relativ...(a)rest.com> wrote:
>> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>>
>> news:7df1fc51-d0aa-461b-8c57-cbd52d6c9438(a)b7g2000yqd.googlegroups.com...
>>
>>
>>
>>
>>
>> > On 9 Mar, 23:41, "Inertial" <relativ...(a)rest.com> wrote:
>> >> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>>
>> >>news:e37617e7-52f9-4fbd-a740-bac32eb220dd(a)o3g2000yqb.googlegroups.com...
>>
>> >> > On 9 Mar, 05:34, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
>> >> > wrote:
>> >> >> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>>
>> >> >> Did you look at the diagrams on the Wikipedia page on the twins
>> >> >> paradox
>> >> >> as I
>> >> >> suggested?
>>
>> >> >> This shows *exactly* what the moving and stationary clocks see as
>> >> >> happening
>> >> >> at all stages of the thought experiment.
>>
>> >> > This isn't the twins paradox,
>>
>> >>http://en.wikipedia.org/wiki/Twin_paradox
>>
>> >> Of course it is the twins paradox. Do you even know what the twins
>> >> paradox
>> >> is ? Lets see what the web page says
>>
>> >> "In physics, the twin paradox is a thought experiment in special
>> >> relativity,
>> >> in which a twin makes a journey into space in a high-speed rocket and
>> >> returns home to find he has aged less than his identical twin who
>> >> stayed
>> >> on
>> >> Earth. This result appears puzzling because each twin sees the other
>> >> twin
>> >> as
>> >> traveling, and so, according to the theory of special relativity,
>> >> paradoxically each should find the other to have aged more slowly. How
>> >> the
>> >> seeming contradiction is resolved, and how the absolute effect (one
>> >> twin
>> >> really aging less) can result from a relative motion, can be explained
>> >> within the standard framework of special relativity. The effect has
>> >> been
>> >> verified experimentally using precise measurements of clocks flown in
>> >> airplanes.[1][2]"
>>
>> > I repeat myself again, the scenario we have here is *not* the twins
>> > paradox.
>>
>> Then what are you talking about now?
>>
>> >> > so it would be strange to find the
>> >> > answer to my question there. Also, I've read that page in the past,
>> >> > and I don't recall it having relevant detail.
>>
>> >> Clearly you are either lying about reading it, or you didn't
>> >> understand
>> >> it.
>>
>> > 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.
>>
>> Then what are you talking about now?
>
> Perhaps you should review the previous postings, but as a quick
> summary, this scenario essentially involves *both* twins leaving
> Earth, in diametrically opposite directions. Hence when the twins
> return to Earth, they are the same age as each other (although both
> younger than a third sibling who remained on Earth).

So the same twins scenarion .. Just doing it twice at the same time.

You can have as many 'twins' leaving earth in as many directions as you
like. it doesn't change that for each of them the same explanation of the
twins paradox applies.

So the posts referring to the wikipedia pages on the twins paradox is
perfectly applicable .. twice.

From: Inertial on 11 Mar 2010 16:29

"Dono." <sa_ge(a)comcast.net> wrote in message
news:be6a93ae-f508-4359-bf14-175e48bfcef3(a)l24g2000prh.googlegroups.com...
> On Mar 11, 12:12 am, "Inertial" <relativ...(a)rest.com> wrote:
>>
>> > You are using the speed composition .
>>
>> Of course .. that is the correct formula to use to convert a measured
>> speed
>> in one frame to a measured speed in another in LET
>>
>
> In doing so, you are using the CONCLUION (what you were asked to
> prove) in the demonstration.

Nope

> So, you produced a fake "proof". Congratulations, idiot.

You are the idiot who knows the math, but doesn't understand the physics
behind it.

Go back to school, little Dono. You may get some understanding on top of
your knowledge.

From: Peter Webb on 11 Mar 2010 16:57

"PD" <thedraperfamily(a)gmail.com> wrote in message
news:2e16df28-8aaa-4a83-b215-9dae14eb075f(a)g28g2000yqh.googlegroups.com...
On Mar 11, 7:37 am, "Peter Webb"
<webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> news:860a5e85-6231-4eeb-a3a8-f2b25ced173b(a)x12g2000yqx.googlegroups.com...
>
>
>
> > On 11 Mar, 01:58, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> > wrote:
> >> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> >> > except for the fairly
> >> > obvious explanation that it is the reference clock which is
> >> > undergoing
> >> > a "real" slowdown.
>
> >> Or, that you have no idea of what SR predicts, and have completely and
> >> falsely assumed that observers see clocks jump ahead when turnaround
> >> occurs.
>
> > I'm merely going off what "experts" here say happens. I didn't say
> > there is a "leap ahead". Paul Draper (if I remember correctly) said
> > there is a "leap ahead". Now perhaps I misunderstood, but that is what
> > was said.
>
> Perhaps that was what he said.
>
> But now you know.
>
> No leap ahead.

http://scope.joemirando.net/faqs/Relativity/SR/TwinParadox/twin_gap.html

This and the supporting links give some of the context here.

____________________________________
Including the same sort of diagram as on the wiki page, which answers Ste's
question, if he could be bothered to look and read.