Re: TIME, you old gipsy man

From: Van (Beethoven.Van_at_gmail.com)
Date: 02/11/05 

Date: 11 Feb 2005 07:59:54 -0800

PD wrote:
> Van wrote:
> > PD wrote:
> > > Van wrote:
> > > > Alex wrote:
> > > > > The theory is quite clear that the seconds are not the same
> > length
> > > on
> > > > > the two clocks.
> > > >
> > > > Exactly this is what I am trying to point out. If the seconds
are
> > of
> > > > the same length on the two clocks then it is absolutely absurd
to
> > > prove
> > > > time dilation of SR.
> > >
> > > And again you are missing the point. If you have two meter sticks
> > > moving relatively with respect to each other, the centimeter
> markings
> > > on each ruler are physically identical, yet the length of each
> stick
> > > will be shorter when measured by an observer riding on the other
> > stick.
> >
> > Well, clearly I do not get it pal. If the lenght of each stick will
> be
> > shorter measured by the observer riding on the other stick then of
> > course the centimetre markings on each ruler cannot be physically
> > identical to that observer.
>
>
> Not so, and here's a nutshell reason.
>
> Length is not a property of an object, it is the result of a
procedure.
> One sensible procedure to measure an object's (call it A) length is
to
> mark the location of one end of A against a ruler (R) held by the
> observer, and the location of the other end of A against the ruler R,
> and subtract the values of the marks on R. Because A might be moving
at
> the time, it's essential to stipulate that the marking of the two
> locations on R be done at the same time.
>
> And here is where the rub is. What is "at the same time" for this
> observer will not be at the same time for any other inertial
observer.

In that case how is the length contraction confirmed? Because we can
never ascertain two events at two different internal frame of reference
as simultaneous.

>
> Furthermore, there is no way to define length to avoid this or
similar
> ambiguities. Therefore, length is not an intrinsic property of A.
> Though nothing happens physically to A by measuring it in a different
> inertial frame, the length BY DEFINITION changes.

The length "by definition" changes? I am not able to understand this.

>
> PD
>
>
>
> >
> >
> > > If you can't understand that either, then you don't understand
what
> > it
> > > means to measure length.
> >
> > May be.
> > Come mothers and fathers
> > Throughout the land
> > And don't criticize
> > What you can't understand
> > SR and GR
> > Are beyond your command
> > Your old road is
> > Rapidly agin'.
> > Please get out of the new one
> > If you can't lend your hand
> > For the times they are a-changin'.
> >
> > >If you do understand and accept length
> > > contraction, then I would ask why you have a problem with time
> > > dilation.
> >
> > I do not have a problem with time dilation. I just want to know how
> it
> > happens.
> >
> > >
> > > PD
> > >
> > > >
> > > > >Time is gained or lost in similar way to how length on
> > > > > a 2D plane is lost if you rotate a rod out of the plane. Only
> > > > 'similar'
> > > > > however, because as Weyl put it, time is thought to be a
> negative
> > > > > dimension.
> > > > >
> > > > >
> > > > > for a summary of why see:
> > > > > http://www.users.globalnet.co.uk/~lka/conz2b.htm
> > > > >
> > > > > Best Wishes
> > > > >
> > > > > Alex Green
> > > >
> > > > Thanks,
> > > >
> > > > Van.
> >
> >
> > Thanks,
> > Van.

Thanks,
Van.

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