Re: Is time dilation real?


jgreenfield@xxxxxxxxxxx wrote:
> PD wrote:
>
> > jgreenfield@xxxxxxxxxxx wrote:
> > > Wugi wrote:
> > >
> > > > PD :
> > > >
> > > > Just "fell" into this thread by chance, so I'm answering some issues along
> > > > my conversational impressions :-)
> > > >
> > > > > > > Right. I'm shooting at the idea that length contraction is only an
> > > > > > > observational artifact by removing speed of communication
> > > > > > > considerations. If a durable record of the contraction is created and
> > > > > > > there is no communication with the observer other than that static
> > > > > > > record can it be thought of as an artifact of observation?
> > > >
> > > > Length contraction (and time dilatation) is a measurement result "artifact",
> > > > not an observational one. It results from some back-calculations of
> > > > observational data (taking into account finite light speed from the various
> > > > parts of observation). But it is physically real enough all right.
> > > > If you want observational (visual) artifacts, these include:
> > > > - extra length contraction at recession,
> > > > - length *dilatation* at approach,
> > > > - maximum velocity -c/2 at recession v=-c,
> > > > - infinite speed and single moment of observation at approach v=c
> > > > - the universe as we observe it "now", with events at N light-years happened
> > > > N light-years back.
> > > >
> > > > > > Spot on, Bob.
> > > > > > Observers can be (often are wrong/mistaken)
> > > > > > Apply the paint via holes in the rims, in contact with the track- no
> > > > > > wriggle room in that!
> > > > > > DHr's can't "see" the con, even when it is right before them.
> > > > > > Attention PD, and other devotees!
> > > > > > What would the observer measure (using AEism) the shortening of a 100 m
> > > > > > rest train to be when travelling .5c if he was
> > > > > > 1) 10m from the track
> > > > > > 2) 100 m
> > > > > > 3) 10,000 m ???????????
> > > > >
> > > > > That depends. How do you plan to measure the length of the train from
> > > > > 10,000m away?
> > > >
> > > > Would that be much different from one passing nearby?
> > > >
> > > > Have a go at my QB-programmes "Relaty" (measuring 'artifacts') and "Relasee"
> > > > (visual observation 'artifacts') on
> > > > http://home.scarlet.be/~pin12499/qbasics.htm
> > > > In the latter program you can "run" interactively relativistic trains along
> > > > your platform; see the above-mentioned observational artifacts "in real
> > > > time". Other observational effects include a passing squadron, the farther
> > > > rows of which correspond to a track seen at a distance, as asked for above;
> > > > see also the effect of the frontal rows in approach and in recession...
> > > >
> > > > guido
> > >
> > > Did you "fall in" on your head, or are you as naturally thick as pd?
> > > I repeat: The light involved in the length contraction travels along
> > > the train (and not beyond it).
> > > Off train "observers" do NOT SEE ANYTHING!!!!!!!!!!!!!!!
> > > ........which is why pd is stammering about "how far away". The point
> > > being, that doesn't matter; NO trackside observer receives the light
> > > which is involved.
> > >
> >
> > I'll ask you the same question I asked before. You say "Off train
> > observers don't see anything". I ask you, you mean to tell me you can't
> > see a train while standing to one side of the tracks?
>
> Which part of "the light which is involved", do you fail to understand?
> The driver is claimed to "see" the rear coming up to meet him, while
> the photons are travelling the length of the train. Do you think that
> the trackside "observer" ALSO sees that beam (pulse)?
>

If the source radiates in all directions, I don't see why not.

PD

.

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