L'affaire "STAR TREK," ONLY SMALLER

It.scienza 1 Luglio 2000

Nel numero 86 di NOVA ASTRONAUTICA (Anno 2000 pag.17) ,davamo notizia in
modo umoristico che l'illogica attrazione elettrodinamica realizzata dai nei
nostri lab. tra circuiti (dipoli) aperti in alta frequenza non poteva essere
spiegata dalla teoria di Maxwell (che prevede solo repulsione), e che quindi
l'unica possibilità era che l'attrazione fosse interpretabile solo
attraverso i raggi traenti dell'astronave Enterprise in STAR TREK (la
documentazione è anche in parte nell'
http://www.mywebpages.com/asps/convergenza.htm )
In data 3 Maggio 2001 ci è sorprendentemente giunta notizia
che altri avevano trovato "apparentemente" qualcosa di analogo a livello
microscopico, nell'interazione tra radiazione e.m. laser e la materia
microscopica
http://www.space.com/businesstechnology/technology/tractor_beam_wg_010504.html.
L'avere solo accennato nei ng italici al fatto che l'Asps avesse la priorità
(Nova Astronautica n.86) di tale evento, ha causato il solito pandemonio
documentato in parte in Nova 88 (Giugno 2001)
http://www.mywebpages.com/asps/na.htm
Una maggiore conoscenza dei dettagli della procedura relativa all'affaire
:"STAR TREK," ONLY SMALLER e la seguente serie di post ( insieme alla
replica e alla Url molto significativa data da G.D. Push) ci porta ad a
escludere qualunque parentela sperimentale con quelle da noi adottate in
ambito Uhf

*************

Oggetto: Re: Momentum violation in laser tractor beam?
Data:01 Jul 2001 11:31:17 -0500
Da:  gdpusch@NO.xnet.SPAM.com (Gordon D. Pusch)
 Società:    XNet Information Systems (Winstar)
                CC:  alibi9@subdimension.com
 Gruppi di discussione:   sci.physics.electromag
     Documentazione:  1 , 2 , 3


serafini <alibi9@subdimension.com> writes:

> Sven Hegewisch ha scritto:
>
>> serafini wrote:
>>
>>> If possible I ask to make clear the following about an incredible
>>> momentum violation in laser tractor beam. The following:
>>>
>>>
http://www.space.com/businesstechnology/technology/tractor_beam_wg_010504.ht
ml
>>>
>>> In fact for the momentum conservation of light (p=E/c) the beam can't be
>>> a ``tractor,'' but it must work as a repulsion beam for momentum
>>> conservation such as light pressure
>>
>> That is third hand information! What did the scientists say ?
>
> First or third hand information the problem of momentum of tractor beam
> is not clear on my opinion in such Url.  It seems to me that EM beams
> can be only repulsive so it is a non-sense they might be attractive

The false description of this effect by the scientifically ignorant media
as a ``tractor beam''  (regrettably apparently encouraged by the
scientist interviewed) are totally misleading --- it is simply a refinement
of the
so-called ``optical tweezers'' effect, which also uses _gradients_ in
the light-pressure field as well as the pressure of the light itself.

If the object being ``grabbed'' has an index of refraction that is
Larger than that of the the surrounding medium, in addition to the
``pressure''
exerted on it by absorbed photons it feels a ``pondermotive force'' that
``attracts'' it toward regions of larger field-strength; i.e., it also
responds to the light-pressure _GRADIENT_. If the object is sufficiently
transparent, this ``gradient'' force can be strong enough to overcome
the momentum transfered to it by the few photons it absorbs, so that
the net effect is that the object appears to be ``attracted'' to the
narrowest point or ``waist'' of a focused beam that converges and
diverges sufficiently rapidly --- creating the *illusion* that the beam is
somehow ``pulling'' on the object if it was initially ``downstream'' of the
``waist.'' See http://www.physics.uq.edu.au/people/nieminen/trapping.html.


-- Gordon D. Pusch

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