Re: The true crackpots


mluttgens@xxxxxxxxxx wrote:
> PD wrote:
> > Dirk Van de moortel wrote:
> > > "PD" <TheDraperFamily@xxxxxxxxx> wrote in message news:1128450923.897784.41920@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> <...>
>
> > What Luttgens and Seto don't recognize is that experimenters sometimes
> > have to be clever instead of direct, because (a) the direct measurement
> > is difficult to do with the precision desired to learn anything; (b)
> > the direct measurement is often fraught with sources of experimental
> > uncertainty that a more clever design will rule out; (c) a more clever
> > design will allow you to learn more than a direct approach.
>
> What you wrote are generalities.

I pointed to the correct place to do the library work. Now when I do
that to TomGee, he splutters that I'm asking him to read the entire
library (when in fact I've done no such thing) and complains that I
won't write everything that he needs to see in a post.

>
> > This comes
> > with the frustration for Luttgens and Seto that it makes the setup of
> > the experiment harder to understand, to the point where they are likely
> > to give up and ask why nobody has done the easier-to-understand thing.
>
> You are implying that Luttgens and Seto are stupid, whereas I, PD, am
> sooo bright!

I did not mean to imply that at all, though in rereading my words, I
see I could have been more careful in my choice of them. I suspect you
are amply bright. Now the question is whether you're willing to do the
hard work.

>
> >
> > As an example of this, it is very hard to measure a length difference
> > between two rods to a precision of a tenth of a micrometer over a meter
> > or so. However, using a rod marked not with notches every micrometer
> > but with optical wavelengths instead, then the interference between two
> > light beams becomes an extremely sensitive measure of length
> > difference, as anyone who has stared at a rainbow-colored (and very
> > thin) film of oil in the supermarket parking lot can tell you. It's
> > precisely this kind of cleverness that's required to make a sensitive
> > measurement.
> > This does not negate the fact that the clever methods are measuring the
> > *same* thing as the more brute-force technique, albeit with less error
> > and greater precision.
>
> Other generalities.
>
> > For rapidity, mentioned to Luttgens, the trick is simple. Rather than
> > measure a single rod, we'll measure several hundred at a time by laying
> > out the rods to make a barrel-shaped grid, formed by the rods, wrapped
> > around a source that emits particles uniformly in all directions. In a
> > reference frame where the source is stationary (wrt that reference
> > frame), then the signature of the physics is that the number of
> > particles that pass through each grid-box will be the same, on average.
> > A particle detector in each grid-box will do the trick. Now, if I
> > repeat the experiment but in a different reference frame where the
> > source is now moving, special relativity makes a very specific
> > prediction about how the lengths of those rods and the shapes of those
> > grid-boxes will be contracted as measured in this frame. Of course, the
> > physics is the same, and so I should *still* measure the same number of
> > particles through each grid box. Nothing physical has changed, after
> > all, excect the reference frame with which I view the same process.
> > Now, since the rate through each grid-box is the same as before, if I
> > take a snapshot -- a narrow slice in time, I should still get an even
> > distribution of particles through the grid-boxes. If I average over a
> > bunch of these snapshots, then I will iron out the statistical
> > fluctuations that come from taking a narrow slice in time. But as long
> > as I'm taking a snapshot, then I can capture the same information with
> > a *new* grid that is stationary wrt me (and of course the source is
> > flying through this new grid). And I would expect to get a uniform
> > distribution in this new grid *if and only if* it has the same
> > configuration of rods as the *contracted* ones of the moving grid.
> > Since SR provides a handy prescription for the contraction of each and
> > every one of the moving rods, then it is easy for me to make a grid
> > that looks just like the moving one for that eyeblink. Then all I have
> > to do is count the particles through each grid-box in this snapshot
> > camera. If SR is right, then I will come up with the same, uniform
> > distribution of particles through each grid-box, even though the
> > grid-boxes are oddly distorted due to the contraction of their sides.
> > If SR is wrong, then I will see a skewed and nonuniform distribution of
> > particles from the moving source, because I will have built my grid
> > rods wrong. But lo-and-behold, the distribution of particles from the
> > moving source into the new grid, built according to the prescriptions
> > of SR, is *exactly* the same as what it was originally. I have thus
> > verified that the length contraction really does happen the way that SR
> > says it does, not for a single rod, but for hundreds of rods, verified
> > for each and every grid box.
> > This is an example of an elegant and creative experimental design that
> > not only measures what you set out to measure, but does better.
> >
> > And yes, Lorentz contraction of a rod is *experimentally verified.
>
> Publish your results, you could get a Nobel prize!

Indeed, my name is on a paper or two about this topic, but I don't
think they're going to garner a Nobel prize. That's a pity, of course.
I suspect the reason is that it isn't astounding news, and that the
experimental confirmation has been this way dozens of times, as well as
in other ways dozens of times. It is now so routine that it is recorded
in a manual: http://pdg.lbl.gov.

Your surprise that special relativity makes specific, direct,
observational predictions which have been observationally confirmed,
however, is something that needs to happen only once. Now that you're
aware of some experimental history, you don't have to repeat the same
mistake again. That having been accomplished, what do you think your
next task in understanding special relativity should be?

PD

.

Relevant Pages

  • Re: The true crackpots
    ... between two rods to a precision of a tenth of a micrometer over a meter ... particles that pass through each grid-box will be the same, ... A particle detector in each grid-box will do the trick. ... particles through each grid box. ...
    (sci.physics.relativity)
  • Re: The true crackpots
    ... > have to be clever instead of direct, ... > between two rods to a precision of a tenth of a micrometer over a meter ... > particles that pass through each grid-box will be the same, ... > particles through each grid box. ...
    (sci.physics.relativity)
  • Re: The true crackpots
    ... there is no proof of lenght contraction. ... > between two rods to a precision of a tenth of a micrometer over a meter ... > particles that pass through each grid-box will be the same, ... > particles through each grid box. ...
    (sci.physics.relativity)
  • Re: The true crackpots
    ... >> moving meter rod. ... >> for Luttgens, there is no proof of lenght contraction. ... > between two rods to a precision of a tenth of a micrometer over a meter ... > particles through each grid box. ...
    (sci.physics.relativity)