Re: The Cost of Relativity

From: Myxococcus xanthus (mold-guardian_at_comcast.net)
Date: 07/27/04 

Date: 26 Jul 2004 23:39:01 -0700

"Marv Raybin" <raymarv@sbcglobal.net> wrote in message news:<BpXMc.97128$aN6.44901@newssvr29.news.prodigy.com>...
> Tom Potter wrote:
> > > Also, could you list some specific areas where General
> > > Relativity is profitably used as an engineering tool?
> > >
> http://www.physlink.com/Education/AskExperts/ae161.cfm
>
> "Experiments with subatomic particles, however, confirm Relativity's
> prediction of increasing mass at speeds near c. Devices from particle
> accelerators to TV PICTURE TUBES MUST ACCOUNT FOR MASS INCREASE IN ORDER TO
> WORK PROPERLY."

Hmmm...

The relativistic mass increase of electrons in a TV picture tube is on
the order of 0.5%, and the corrections needed to account for this
effect are insignificant compared with the standard tolerances of the
electronic components used in television set manufacture.

To make the claim that TV picture tubes must account for relativistic
mass increase only gives ammunition to crackpots like Tom Potter,
becase the plain fact of the matter is, 0.5% is rather an
insignificant correction, and I do not doubt his claim that he has sat
in on several engineering discussions of TV picture tubes without ever
hearing relativity being discussed.

On the other hand, electron microscopes operate at much higher
voltages than TV picture tubes, typically over 200 keV, so the
relativistic effects in electron microscopes are far more pronounced
than in TV sets. Also, the allowable tolerances in the magnetic and
electrostatic lenses used in electron microscopes are far tighter than
those of TV tube focusers.

I have had considerable experience in transmission electron microscopy
(mostly thin films of DNA spreads, but also a lot of sectioning
experience), and a modest amount of experience in scanning electron
microscopy (surface studies of my namesake bacterium). I will state
without reservation, that EVERY serious paper in EM lens design that I
have ever read discusses relativity. One simply CANNOT design a high
performance EM lens without taking SR into account. Relativity is
essential for ray tracing and the computation of EM lens abberations.

Myxococcus xanthus

Relevant Pages

  • Re: The Cost of Relativity
    ... > accelerators to TV PICTURE TUBES MUST ACCOUNT FOR MASS INCREASE IN ORDER TO ... electron microscopes operate at much higher ... have ever read discusses relativity. ...
    (sci.physics.relativity)
  • Re: The Cost of Relativity
    ... >> accelerators to TV PICTURE TUBES MUST ACCOUNT FOR MASS INCREASE IN ORDER ... > relativistic effects in electron microscopes are far more pronounced ... > have ever read discusses relativity. ...
    (sci.physics)
  • Re: The Cost of Relativity
    ... >> accelerators to TV PICTURE TUBES MUST ACCOUNT FOR MASS INCREASE IN ORDER ... > relativistic effects in electron microscopes are far more pronounced ... > have ever read discusses relativity. ...
    (sci.physics.relativity)