Re: Let there be Blah

[blah]

  Blah wrote quite an excellent post. In fact, I've met few physics PhDs
  which would have been able to respond so well. So needless to say, my
  curiosity is peaked concerning who Blah is in the real world. (Tim May,

   Thanks. It's nice to run into physicists and as a physicist, you'll
appreciate the followup to mr. choate's response, since what he suggests
is essentially contrary to special relativity. As for myself, I'm a
nuclear physicist by training (weak interactions - experimental searches
for nucleon substructure in nuclei, parity violation in nuclear
interactions, etc., but no longer in an academic environment.  I read the
archives from time to time to see what's going on, since I have an interest
in the political end of technology.

  I believe, is trained in physicsist, but there's no way someone out of
  school for so long is going to voluntarily remember what's in the last
  chapter of Schiff. Also, they didn't know a lot of this stuff back in the
  horse-and-buggy days when May was in school...)

  Anyway, I DID want to ask ole' Blah what he thought about the following.
  (Now Choate, Shaddup and pay attention: Slap Slap Slap!)

  Since I read through the archives somewhat irregularly, and don't
really try to figure out the personal dynamics, I've often wondered
why mr. choate gets so much abuse, since he's really pretty sane in
comparison to the crackpots that post in the sci.physics.* newsgroups.
However, I think I may have a hint at this point.

As a (fellow) trained physicst, do you actually believe that quantum-
  encrypted signals are truly secure as a byproduct of basic physical law,
  or do even YOU believe that QM is merely a useful calculational tool,
  so that (by inference), Quantum-encrypted signals may one day be 
  interceptable without either Bob nor Alice knowing that a third party 
  is listening?

  I have to split that into several parts. First, I think quantum mechanics
has to be fundamental. I consider that the reason it's a useful calculational
tool, so I take the useful part as a consequence of being correct. It seems
rather bizarre to adopt the view that the universe is classical, and that
quantum mechanics was developed as an an incredibly successful approximation
to the classical model that didn't work. So far, I find all of the attempts
to rationalize quantum mechanics into a pseudo-classical framework (e.g.,
bohmian mechanics), to have serious shortcommings in that those models
pick and choose what they want to explain and ignore what they can't.

  If anything, I'd classify myself as being at the opposite end of the
spectrum than shut up and calculate. The shut up and calculate
approach is ok if what one wants to do is calculate without going out on
a limb, but practically all of the physical intuition comes from knowing
what it means to to have quantities which are unobservable or
indeterminate, so I'd have to say I gave up the idea of any underlying
classical realty.

  Second, the quantum mechanics part of a secure quantum protocol is
only one aspect of a secure quantum protocol. I think richard hughes
at los alamos has already demonstrated that secure quantum encryption
is a reality, if one uses a shared secret to inititialize the session.
On the other hand, I'm rather dubious about a completely secure protocol
which does not require a shared secret.

  Third, the major impediment to implementing such a system would be
not a technical difficulty, but a political one. Administrations like
the current one certainly have no interest in the widespread use of
unbreakable encryption. The general public is lacking both the interest
and technical ability to disinguish between advertising and technical
merit. In fact, the general public doesn't even seem to believe in
punishing outright fraud when it affects them, so I wouldn't hold my
breath for such a system to appear.

  As for myself, I think I've made my bias clear, but I wouldn't call it
  'certainty' by any means.

  I think your safe in your bias. Nature can't be so perverse as to go to
the effort of of creating a classical world and then covering it up with a
convoluted scheme to look like quantum mechanics as some sort of
cruel joke.


As a side note on a different issue. The new scheme for crowd control
utilizing microwaves, should be relatively simple to defeat. Covering
garments made from fine metallic mesh screen, grounded through something
like those little covers with the metallic grounding strips that surgeons
wear ought to do it. Any (fairly good) conductive fabric should work.
Since I have no idea what frequencies are involved, it's hard to say
how corse a mesh one could get away with using. As a comparison,
however, the typical microwave oven generates on the order of 1.5 kW
at 2 GHz or so, and the mesh on the door sheilds the microwaves well
enough to stare at what's inside. Faraday cages in radar labs are
usually made from metallic screen. For that matter, having a line of 
people

Re: Subject: CDR: Re: QM, EPR, A/B

[blah]

From: Jim Choate [EMAIL PROTECTED] wrote:
 On Sat, 4 Jan 2003, blah wrote:
 
  Not from the photons perspective, from a photons perspective there is
  -no- time.

  A photon has no perspective. Anyone that wishes to have the short
version and skip the detailed corrections to misconceptions, they may note
simply that an observer in special relativity compares their results with
other observers through a lorentz transform. There exists no lorentz
transform by which any observer may transform coordinates to a photon,
because the photon has no lorentz frame. Therefore, special relativity
explicitly precludes any perspective which has been suggested as necessary
for a relativistically correct description. Furthermore, since any
observers which differ by a lorentz transform must give equivalent
descriptions which differ by a lorentz transform, for any phenomena,
requiring multiple descriptions for something defeats the entire
reason for the existence of special relativity.

 It is clear from Relativity that as -anything- approaches the speed 
  of light it's mass grows larger (photons have -no- rest mass so 0 can't
  get any bigger than 0) and time -slows to zero-.

   It's called relativity because it assumes no absolute frame against
which speeds must be referenced. Clocks _always_ keep the proper time in
their own rest frame, which means that time dilation, etc., are effects
seen by _other_ observers. However, a photon has _no_ rest frame. You
cannot attach a clock to one. In addition, no modern text would refer to
mass increase. Mass and spin are poincare invariants. An often recommended
text is Spacetime Physics, by Taylor and Wheeler. I recommend making
an investment.

  A signal carries information. You can't use quantum mechanics to
  propagate a signal faster than light.

  Then explain two entangled photons and how they behave.

  OK. And I'll even provide an example which is quite different from the
usual epr cliche at the bottom. Fisrt, however, entangled photons do not
propagate any _information_ faster than than light. In other words, for
puposes of sending information, it's irrelevant what you think happens
faster than light, because no information is propagated between the
observers faster than light. Indeed, the photons are entangled precisely
because the spins are completely indeterminate prior to measurement, so
that there is no information to propagate until each observer measures the
spin of their photon and cannot compare their measurements faster
than light.

  If you want to know how this is applied to quantum cryptography,
look at richard huges site at lanl: http://qso.lanl.gov/qc or
charles bennett's site: http://www.research.ibm.com/quantuminfo

  If you think otherwise, allow me to refer you to the last chapter in
  Quantum Mechanics, L. Schiff, where you will find the commutation
  relations for electromagnetic fields.

   I'm familiar with it,

   Then, you could presumably tell me what the commutation relations are
and what they mean if I were to ask? Or was that merely a lead in to
repeat what what you said earlier without really acknowledging the
objection except as a formality? If not, don't make such claims, since
I won't hesitate to ask when I think I'm being bullshitted.

   however that is taken from the perspective of the
  external observer, not the photon. Now, do the math -from the perspective
  of a the photons-.

  You are confused. Relativistic quantum mechanics is manifestly lorentz
covariant, i.e., it's valid anywhere special relativity applies. Special
relativity tells you that you cannot perform _any_ lorentz transform to a
the frame of reference of a photon, because a photon has no frame in which
it is at rest. If you think otherwise, show me the lorentz transform that
accomplishes what you assert must be done. If you need the lorentz trans-
forms:

ct' =  \gamma(ct - \beta  x)
 x' =  \gamma( x - \beta ct)

or in hyperbolic form:

ct' = ct cosh(A) -  x sinh(A)
 x' =  x cosh(A) - ct sinh(A)

   The fact that you think the physics is frame dependent, means that
you don't even grasp the principle behind relativity, which is that
the physics is frame independent.

  Let me ask you again:

  This would be the _first_ time since you didn't ask _me_ before.

  - How big is the cosmos to a photon?
  - How does time pass to a photon?

  Both of those are meaningless questions which may be attributed to
classical bias in thinking the photon has a well-defined location from
which such a perspective is possible. You can't attach a clock on something
which has no point that defines a location.

Don't be ridiculous. Relativistic quantum mechanics is not even a new
  discipline.

  I am -not- saying that it is -new-. I -am- saying that QM and Relativity
  have -not- been -completely combined- and that until that happens we won't
  and can't understand what is going on.

  As I previously pointed out, special relativity and quantum mechanics

Subject: CDR: Re: QM, EPR, A/B

[blah]

Date: Wed, 1 Jan 2003 00:28:46 -0600 (CST)
Jim Choate wrote:
 Tim May wrote...

 I don't believe, necessarily, in certain forms of the Copenhagen
 Interpretation, especially anything about signals propagating
 instantaneously,

'instantaneously' from -whose- perspective?

  From anyone's perspective. A signal carries information. You can't
use quantum mechanics to propagate a signal faster than light. If
you think otherwise, allow me to refer you to the last chapter in
Quantum Mechanics, L. Schiff, where you will find the commutation
relations for electromagnetic fields.


 Yes, this has been a fashionable set of statements, very smiliar to
 quantum mechanics is merely a useful tool for calclating the outcome
 of experiments.

 Only so long as there are -not- relativistic effects, which -do- happen
 -any- time a photon is involved.

  Don't be ridiculous. Relativistic quantum mechanics is not even a new
discipline. See Bjorken  Drell, Vols. I and II, written circa 1963. The
dirac equation has been around for almost 3/4 of a century and the
klein-gordon equation has been around about 80 years. Had the physicists
of the 1920's been able to interpret the klein-gordon equation at the
time, we would have probably had a relativistic theory before the
non-relativistic theory. The schroedinger equation is a result of needing
an equation that's linear in the time variable, due to not knowing at the
time, how to interpret the quadratic which appears if one substitutes the
quantum operators for the dynamical variables in E^2 = p^2 + m^2 (c==1).

  Your comment about photons is equally ridiculous. I can derive the qed
lagrangian from the dirac equation in about 1 page of arithmetic, just by
requiring the lagrangian to be locally gauge invariant and applying
noether's theorem to obtain the conserved current. What do you think the
A^{u} in the covariant derivative is? Nevermind, I'll tell you. It's the
field of the electron. Sure, relativity is involved. And it's involved in
a very well understood way. Just start with the dirac lagrangian,
L = \Psibar(p/ - m)\Psi and make the substitution \Psi-\Psi\exp(iS),
where S is ann arbitrary function of the spacetime variable, to obtain
the new lagrangian, L'. For the lagrangian to be locally gauge invariant,
the variation, \delta L = L' - L, must vanish to first order.

   General relativity is irrelevant, since (1) we aren't in a strong
gravitational field and the gravitational interaction is about 10^{-32} of
the strength of the EM field, anyway, (2) spacetime is locally flat and
the minimal coupling model in general relativity assumes there is no
curvature coupling, (3) The main difference would end up being that the
photons would propagate along null geodesics that are curved rather than
along null geodesics that are flat. (4) You can replace the ordinary
gauge covariant derivatives with the general relativistically covariant
derivatives. [See for example, Problem Book for General Relativity,
Lighthman, et al, where there is a worked example which includes a
mention of curvature coupling (I think that's the name of the book, but
I don't have it handy, to check it)].

  For relativistic quantum field theory to even work, one must appeal
to the same unobservability of the wavefunction, if one is to obtain
a conserved current. 

***Reality is -observer- dependent***

The major hole in -all- current QM systems is they do not take into
account relativistic effects. Which are required -any time- a photon is
involved.

  There is no major hole. Not even a minor pinprick. You should take a
look at any relativistic quantum mechanics text or any text on quantum
field theory [Gauge Theories of the Strong, Weak and Electromagnetic
Interactions, C. Quigg, is straightforward and physically illuminating].

QED is the most precise theory ever proposed in the entire
history of science. It's a purely relativistic field theory which served
as the prototype for the standard model, which currently explains all
known phenomena except gravity. Incorporating gravity and the standard
model into a single theory is a _technical_ issue not an issue of either
quanum mechanics or general relativity being wrong. Quite the contrary,
both are bviously correct for any purpose that doesn't include black holes
or possibly neutron stars, and even in those cases, one can do quantum
field theory. See Aspects of Quantum Field Theory in Curved Spacetime,
S. Fulling, for an example of quantum field theory in curved spacetime.


 I used to chant this too, but the recent (well, over the last 10 years)
 experimental work in EPR has convinced me that there's really something
 odd going on here.
 Many worlds (first proposed in the 50s and recently revived) is one
  possible explanation for why, for instance, photons in the double slit
 experiment know about the slit they didn't go through. And while I am
 not particularly convinced that this is the explanation (there are other
 basic things about the QM world it