Re: [Phys-l] Relativistic Time Dilation and the Bernoulli Effect

[John Denker <jsd@av8n.com>]

On 03/25/2007 01:13 PM, Tibor G Molnar wrote:

> The idea occurred to me as I was reading about the Bernoulli effect, 
> notably at Mark Mitchell's website:
> http://home.earthlink.net/~mmc1919/venturi.html ;
> and while pondering Mark's "jostling demo" at:
> http://home.earthlink.net/~mmc1919/venturi_discuss_nomath.html

That site's qualitative explanation of the Bernoulli effect is
qualitatively wrong.  It bears no discernible relationship
to the true physics.

  That site also has a mathematical derivation of the Bernoulli
  effect.  I didn't check it for mathematical correctness.  But
  to the extent that the mathematical version is used to support
  the qualitative version, there's a big problem.

> I happened upon Phys-L as I was searching Scirus for extant research on the
> relationship between the Bernoulli effect and relativistic time dilation,
> in an attempt to confirm/disconfirm a recent "brainwave" of mine.  I
> haven't yet found what I was looking for, so I turn to Phys-L list members
> for a little assistance.

This is a physics list, not a metaphysics list.

> I particularly liked the idea of describing the net (anisotropic) pressure 

There is no such thing as "anisotropic" pressure.  In all situations
where pressure makes sense, including (as a subset) all situations
where the Bernoulli equation makes sense, pressure is a scalar,
having no direction in space.  This is easy to prove;  look in the
opening pages of almost any fluid-dynamics text, or just calculate
the forces on a small parcel of fluid.

> Armed with this "revelation", even a naive viewing of the "jostling demo" 
> leads directly to a visceral realisation that Bernoulli's principle is a 
> simple and direct consequence of the conservation of energy and momentum. 

Well, the Bernoulli effect can of course be understood as a consequence
of the laws of motion, including conservation of energy and momentum.
But this has nothing to do with aforementioned model of kids "jostling"
in the hallway.

> Perhaps a little too simplistically, I can imagine how matter particles 
> might be semi-permanent higher-order vortex-like structures in some or 
> other elastic, fundamentally particulate quantum 'foam'; the individual 
> Planck-sized corpuscles of which jiggle about more or less energetically in 
> some quasi-random "Brownian" motion as might be described statistically by 
> Maxwell's kinetic theory and speed distribution equations.  I can further 
> imagine that these complex, feedback-reinforced solitonic structures might 
> form local minima in the energy distribution within the quantum foam, and 
> therefore be in more or less stable, local equilibrium states.  And, 
> granted these imaginings, I can further imagine how these higher-order 
> structures might themselves move more or less randomly through this quantum 
> substrate, both propelled and impeded only by the quasi-random Brownian 
> motion of other such structures, and the various motions of the quantum 
> foam itself.  Although on the wrong scale and quite the wrong shape, this 
> is not too unlike how I imagine a tornado to move through the dynamic 
> substrate of atmospheric air molecules.

That is a travesty of physics.  That is just a bucket of buzzwords.
Calling it "a little too simplistic" does not begin to describe what's
wrong.

That is not physics, and going down that road will not lead to
physics.

Physics involves quantitative models and falsifiable predictions.

> Anyway, my thoughts then wandered even further, to General Relativity.  I 
> have recently read a little about how the apparent 

That's well said:  "apparent" being the key word.

> lengthening of the 
> lifetime of high-speed muons created in the upper atmosphere is evidence of 

Again well said:  suggestive "evidence" of, not "proof" of.

> relativistic time dilation.  And, indeed, Einstein's relativistic 
> description of the effect in terms of a Lorentzian transformation seems to 
> fit the observed data.

Again well said:  It is most definitely not the only way of
fitting or explaining the observed data.

The FitzGerald-Lorentz contraction predates relativity.  Einstein
(and virtually everyone else working in the field) gave up on it
nearly 100 years ago.  For details, see:
  http://www.av8n.com/physics/odometer.pdf

> But I note that this is just to describe the effect of time dilation, and 
> not to provide a causal mechanism for it. 

There is no need for a causal mechanism for something that
doesn't really occur.
  http://www.av8n.com/physics/spacetime-trig.pdf
  http://www.av8n.com/physics/odometer.pdf

Furthermore FWIW, since Day One of science as we know it, science
has not depended on "causal mechanisms".  Galileo is called the
father of modern science in part for insisting that it suffices
to say /what/ will happen;  we leave it to the metaphysicians to
say /why/ it happens.  For the next level of detail, see
  https://carnot.physics.buffalo.edu/archives/2006/05_2006/msg00125.html

>  And so I thought, what if the 
> apparent lengthening of the muon lifetime is not due to some or other 
> metaphysical stretching of time, but the rather more practical product of 
> some kind of Bernoulli effect?

Not a chance.