Subject: Re: A photon - what is it really ?
From: Klaus Kassner
Date: Fri, 25 Oct 1996 11:13:03 +0200
Peter Diehr wrote:
> magnus.lidgren wrote:
> > Q3. As I understand it, Quantum mechanics states that when a photon makes
> > its way through a glass body, it is absorbed and (a new?) (re?)-emitted a number of
> > times before it passes through. Every time "the photon" actually is a "real" photon it
> > travels at c speed and during "the absorption period" "it" stands still ??
> >
> > Majority opinion was that the photon goes through repeated absorbtions
> > and re-emissions (in the forward direction) thus delaying "its" passage
> > through the glass in correlation with the index of refraction for glass.
> >
>
> This is wrong.
A too strong staatement.
> The photons are not absorbed and re-emitted (you go over some
> of the problems with this later). No, they are scattered.
What is the difference between scattering and absorption and reemission? As far as I
recall, Raman scattering is, for example, described as absorption into a virtual
level and reemission.
> The index of refraction
> is due to "coherent forward scattering". If the scattering is not coherent, then
> the glass is not transparent.
This is correct but compatible with absorption and reemission.
> The net result is a phase shift, which is equivalent to a change of speed for the
> wave front.
>
> question: is a scattered photon the same as the original photon?
> answer: I dunno.
Is this question meaningful?
> > Q4.If a photon is truly absorbed by the media glass, in what way does "it"
> > know (as it then has ceased to exist ?) what direction to take when
> > emitted again and how does it know what frequency to recover?? Is all
> > information, needed to guide the "new" photon to the right path and frequency,
> > delivered from the "old" photon to the glass atoms during absorption and
> > present in the glass atoms while "the photon" is in "absorpted mode".??
> >
> > Majority opinion was that "true" absorption could not have happened, re-emission would
> > then have random direction. Where the information about direction was situated when
> > not carried by the photon was more an open question. Perhaps one photon on its way
> > could guide another while this was emitted , (not quite clear, this issue). Recovering
> > frequency, however, could be possible through the specific amount of energy delivered
> > to electrons, going from one lower shell to a higher and then back again.
A *single* photon will come out at a random direction (although not with uniform distribution).
The information about direction is stored in the wave, i.e., in the many other photons in your
beam. Direction is preserved via interference.
The information about the frequency is stored in the energy difference between the virtual
level to which the absorbed photon excites an electron and the original level of that
electron. Essentially as you said.
> But it only works if the passing photon has the same frequency as the emitted photon,
> which in turn requires that their must be energy levels in the media which correspond
> to that drop in energy.
No there needn't, because the virtual levels can be arbitrarily created for a time interval
permitted by the uncertainty relation.
> > or ( and this is actually the question)
> > 3. propagate the glass in a number of different shapes (still a signal) but slow down
> > to a speed adequate to the media glass, thus substantially gain momentum in ---->
Gain? Lose. (If it came from the left.)
> > direction and as a consequence, in order to conserve momentum, forceing the glass to
> > move in <---- direction as long as the propagation lasts.
The net momentum acquired by the glass will depend on the ratio of intensity that is reflected
to that that goes through. Consider a single photon. If it goes through and has the same
direction (i.e. momentum) on leaving the glass as entering it, it has gained back any losses
of momentum that it may have had during scattering inside the glass. Thus, it does not
transfer any net momentum to the glass (it did so temporarily, while it was inside).
So if you have a beam that goes through and comes out with the same direction as it enters
the glass, the net momentum transfer depends on the number of photons still in that beam
in comparison with that before entering the glass (it also depends on the direction of the
reflected beam). So it is an intensity question.
Subject: Re: Sophistry 103 (was: I know that!)
From: brian artese
Date: Sun, 27 Oct 1996 05:12:53 -0600
Brian:
>... I don't need to answer Bealer and Levin. I've got "Cogito ergo
> >sum" right here; as a premise and a conclusion supposedly derived from
> >that premise, it claims to be self-sustaining. That's why you've got it=
> >in your signature field, right? It's an argument unto itself, and an
> >easily deflatable one at that.
Zeleny: =
> Once again, this approach is inadequate. Descartes explicitly states
> in his replies to the Objections that "when we become aware that we
> are thinking things, this is a primary notion not derived from any
> syllogism" (AT VII 140). Hence to divide the cogito into premisses
> and conclusion is inconsistent with its author's account of its
> nature.
Okay -- let's look at this account: "When we become aware that we are =
thinking things, this is a primary notion not derived from any syllogism." =
=
The discovery takes place at the moment "we become aware that we are thinki=
ng =
things." To keep it in line with the cogito, let's change the plural subje=
ct =
to a singular one: 'when I become aware that I am thinking things'. Well,=
=
look at that! This 'I' that has been disovered 'thinking' has already been=
=
posited as thing that is 'aware'! Again, "X exists, therefore X exists." =
Nifty.
> >I never said that what's laugable about your God is the presumption of h=
is
> >(its) cognition or volition. What's laughable about this "being" is its=
> >supposed ahistoricity and its naive totalizing function. Has there ever=
> >been empirical evidence of any ahistorical thing, or for any
> >ultimate totality? Nope. =
> Has there ever been empirical evidence of mass, or energy, or force,
> or spacetime, or the continuum, or any other ahistorical Platonic
> universal? Certainly there has. =
Uh, no. There has been empirical evidence of Queen Elizabeth and =
trans-continental migration in the Americas, but there has never been =
'evidence' of mass. What would such evidence look like? "This instrument =
reacts to rocks, and we've agreed to call that reaction 'mass' Look, the =
instrument is reacting to *a particular rock*! Therefore, mass exists." A=
re =
you claiming that the rock and the 'mass' have the same existential status?=
=
Are you seriously asking me to believe that particular objects and man-made=
=
categories 'exist' in the same way?
> The manifest success of scientific
> theories that intimately depend on these explanatory concepts is
> evidence enough to sustain the inference of their existence. Can you
> conceive of any empirical evidence to the contrary? I doubt it.
The 'manifest success' of scientific theories depend first and foremost on =
money, material resources and a political establishment sympathetic to the =
science industry. These material products *never* rely on any theory that =
has not already been tested in a material environment. The actual material=
=
result of those tests almost never correspond to the original theory. The =
theory has to then be modified to conform to the material result of the tes=
t. =
The naive assertion that pure abstraction is the 'source' of material =
production is a fiction often perpetrated by scientists. They know very we=
ll =
that the 'material successes' of science depend almost entirely on data =
gleaned from the *results* of actual, material experimentation. Your =
'explanatory concepts' are post facto. And if you look at the history of =
science, there has *never* been a theory that was not based upon some =
previously observed material phenomenon. Your argument, however, requires =
us =
to believe that the abstraction comes *first*, the reality later. This =
fiction is peddled successfully to the children in our grade schools, but =
cannot hold water here.
> As regards the naivety of totalizing, consider applying your epithets at
> home. What have Gorgias or Heidegger or Derrida given us to compare with=
> the legacy of Aristotle and Galileo and Descartes and Einstein? And what=
> could be more naively, corrosively totalizing than consistent skepticism?=
For one thing, they've given us the means to penetrate the snake-oil rhetor=
ic =
of science.
> >>Moreover, Descartes' ontological argument, like his proof of dualism,
> >>can be readily translated into the mathematical formalism of symbolic
> >>logic.
> >Yes, I recognize that mathematics as a man-made abstraction can readily
> >yield 'proofs' of other man-made abstractions. =
> Please explain the process of man-made abstraction. Wherein consists
> the facticity of the number 2? What sort of fabric is it made of,
> and what kind of glue holds it together?
The fabric is the page upon which the number two is written -- but you need=
=
ink to complete the product. Signifiers are real things.
> >I've read Derrida and plenty of his French cronies, and I've never come
> >across any reference to Goedel. I suspect they don't give a shit. I ho=
pe
> >I can come to terms with that... =
> Your suspicion is unfounded in fact. See Deleuze, _La condition postmode=
rne_.
I stand corrected.
> >You seem to think that continental philosophy waits breathlessly for the=
> >next batch of crumpled papers that your favorite mathematicians,
> >symbolists and metaphysicians have handed over upon emerging from their
> >locked rooms. The Frenchies are much more interested in, say, history,
> >philosophy and literature -- and especially in the history *of* these
> >(yes, there is a history of history: a history of how history has been
> >written in different eras) -- all of which are mediated entirely through=
> >*language* (except, of course, when they have to talk about the
> >metaphysicians who ignore any kind of history). Mathematics is,
> >comparatively, of little importance.
> Your trend meter is badly in need of calibration. Strangely enough,
> metahistory no longer enjoys the status it had a decade ago. Blame
> it on the fall of the Evil Empire or on the pernicious influence of
> Hollywood, but academics are churning out narrative history as they
> have not done since the heyday of Michelet and Ranke. To take one
> example, Maurice Lever recently sold his grand biography of Sade to
> the studios for over a million dollars. Does Hayden White stand a
> chance of getting a quarter for the movie rights to the _Tropics of
> Discourse_? Face it -- the writings of your ideological brethren
> exhibit all the vivacity and charisma of Bob Dole on triple Valium.
Very true about the general trend -- although it doesn't really argue again=
st =
my less ambitious comment about contemporary French thought. The French, i=
n =
my opinion, have little aptitude for narration.
> In any event, mathematics is of paramount importance to anyone
> wishing to understand Platonism. And I am told that purporting to
> refute something you cannot understand is an egregious breach of
> etiquette.
I suspect I understand any philosophical movement as well as you do, and I =
certainly don't require your number-crunching for any of it.
> >It's not up to *me* to account for this transcendental 'meaning' that ca=
n
> >never be articulated! If you propose the existence of such a beast, *yo=
u*
> >have to account for it. What we are *given*, in the empirical world, ar=
e
> >signifiers and mute objects that don't have a name until we give them on=
e
> >-- that is, until we assign them a signifier. So where's this signified=
,
> >this 'meaning' that is supposedly in exact correspondence with the
> >signifier, but is not the signifier itself? =
> Nowhere in particular - the same place as mass or charge or number.
Wow -- so tell me where I can find the device to measure meaning or 'the =
signified'. If it's the same as mass and charge, the signified must be a =
constant, and therefore there must be a device that has *revealed it as =
such*, just as there have been devices to reveal the consistency of mass an=
d =
charge.
> >The 'meaning' of the word 'puppy' cannot *be* that puppy I see over ther=
e.
> > That puppy over there is not a 'meaning', not a universal, it's a
> >particular thing, a referent. A particular referent, which is always
> >located in space and time, is not the same thing as a signified or a
> >'meaning.' That particular thing can be said to *partake* of a
> >universal, to partake of a category. Another word for category is
> >'label'; the label we're talking about is entirely represented by -- and=
> >has no existence apart from -- the *word* 'puppy'. There is no signifie=
d,
> >no Platonic form, no third thing in addition to (1) the signifier, and (=
2)
> >that particular referent over there. There is no 'meaning' independent =
of
> >the signifier. =
> Since the child might as well have asked me for a unicorn or a round
> square, the object of his desire is not identifiable with any actual
> or even possible concrete particular. =
Yes... but my argument doesn't claim that a signifier requires an existenti=
al =
correspondent. I brought referents into the picture because Russell wanted=
=
me to account for them.
> To account adequately for the discussion of wants and needs,
> universals are indispensable. =
? I never claimed that universals were dispensable. The extract you quoted=
=
above, in fact, indicated that universals were a huge part of language.
> Note also that mute or unarticulated
> strivings rule out the possibility of reducing these universals to
> their verbal expression and vitiate Derrida's charge that "en
> derni=E8re instance, la diff=E9rence entre le signifi=E9 et le
> signifiant _n'est rien_". =
? Just because a signifier is mute or unarticulated doesn't mean it's =
anything more than a potential signifier.
> Besides, the argument works just as well
> with a proper name of a particular puppy as it does with the common
> name of the young canis familiaris.
Please be more clear about your referents! Which argument are you talking =
about, yours or mine? In either case, I don't see how this distincion =
between a name and a genus argues against what I'm saying.
> Actually, it turns out that if your explanation of signification is
> to incorporate the logical standard of demonstrative reasoning, its
> restriction to signifiers cannot be sustained. The reason for that
> is that any sort of proof theory depends on a criterion of type-
> identity between sign-tokens, which cannot be a particular by
> definition. =
Well, yes -- since 'proof theories' require all objects to be identified wi=
th =
a type, they automatically reject the existential or historical world from =
their domain. But this is no more than saying "In the world of universals,=
=
universals are indispensable." This is similar to your previous claim that=
=
the material products of science arise from abstractions rather than other =
materials.
> If meaning is a signifier[-token] that
> hasn't happened yet, you have posited a thing that doesn't exist.
Yes. But you forget that I said 'If you must use the word "meaning"...' as=
=
an addendum to the comment that you really only need the term 'singifier'. =
I =
just threw that in to mollify those uneasy with discarding the term =
'meaning.'
> That the world could come to an abrupt end after I produce but before
> you interpret this text, does not imply that my production is
> potentially bereft of meaning.
Again: your articulation only has 'meaning' when you or somebody else eith=
er =
paraphrases it ('interprets it', as you say) or re-articulates it. If the =
world ended right after you spoke then it *wouldn't* have any meaning beyon=
d =
your interpretation because there would be nobody around to paraphrase it. =
=
Your use of the term 'potentially' is not helpful because we're trying to =
establish what does happen, not what could happen. And notice your relianc=
e =
on issues about 'the future' when thinking about meaning -- it corresponds =
exactly with what I'm saying about signification necessarily involving =
deferral over time.
=
> >What allows you to talk about "states of mind"? Have you seen them? Or=
> >are, once again, just positing them into existence? =
> Not at all. I am INFERRING their existence from their apparent
> indispensability in psychological explanation. If you want to argue
> that mass is a social construct, the onus is on you to prove that
> mechanical explanation can proceed on the basis of, and reduced to,
> contingent and arbitrary social conventions. Mutatis mutandis, the
> same goes for wants and needs, sights and sounds, affects and
> beliefs, and other cognitive, conative, and perceptual categories.
You're equating mass with 'states of mind'. Need I say more? When a certa=
in =
measuring device 'moves', we say it's measuring mass because the device =
itself has been calibrated to correspond to another device that measures =
mass. But when a third device measures electrical impulses from the brain,=
=
the only inference you can make is that the brain emits electrical impulses=
=2E =
Any babbling about some totality called 'the mind' which hovers over and =
above these impulses is purely a product of your fantasy.
> Besides, you are the one carrying on "what we are *given*, in the
> empirical world." Here is a newsflash: what we are given are not
> "signifiers and mute objects", but the contents of thought and
> perception, from whose deliverances the existence and presence of
> material objects must be inferred.
Ah yes, 'contents *of* thought and perception' -- already positing two =
totalities which encompass these particular 'contents.' What allows you to=
=
posit these totalities *in addition* to the given phenomena that you're =
calling 'contents'? More than that, what allows you to posit this =
metaphysical predicament in which we're encased in a bubble of subjectivity=
=
that always-already separates us from 'material objects'? Are you an Ayn =
Randian?
> We posit any number of entities on the basis of observation. My
> latest practical posit is that of one Brian Artese, a rational animal
> to whom I impute the ability to grasp the meaning of the theses you
> are advancing. Am I jumping to conclusions? You tell me.
Just because you know to attach a particular name to a particular body (in =
this case, a particular cyber-signature), that does not mean that you've =
located a 'mind' or a 'presence'. You've located a body that writes and =
speaks.
> As far as reason is concerned,
> the order of temporal succession makes no difference in the validity
> of an argument. =
? We're not talking about the validity of an argument, we're talking about =
the manifestation of signifiers.
> As far as empirical data goes, there is plenty of
> evidence that the textual units of expressed meaning can be more or
> less arbitrarily expanded or constricted according to the receiver's
> cognitive and perceptual abilities, as happens e.g. during speed
> reading. So neither the order of signifiers nor their succession
> appear to be germane to comprehension.
? I never claimed that a *particular* order or succession was required. I =
only claimed that all signifiers must present themselves in succession, one=
=
after another. Even if you transcribe the last word of this sentence, and =
then the first, and then the ninth, and then the third, and then the fifth =
-- =
you still must do so one after another, in succession.
=
> I do write more carefully; try reading on the same level. I meant the
> faculty of understanding that is not essentially temporal. The key point=
> here is that your implicit presupposition of essential dependence require=
s
> proof, since the logical content of understanding is not so dependent.
?? Wait a minute -- one minute you say that essence and universals are =
indispensable, then you say I need to prove you're relying essentials. I'm=
=
not trying to avoid whatever point you're trying to make here, but I really=
=
don't understand it.
Zeleny:
> >>Like I said, I would not expect the notion of being responsible for
> >>your own beliefs to be areeable to you. Rationalism is a question
> >>of cognitive norms, of which parrhesia is the first and foremost.
Brian: =
> >It's like a religious guy telling someone else that he's incapable of
> >telling the truth because he's not of the faith. (In fact, it *is* a
> >religious guy, and that's exactly what he's telling me!)
Zeleny: =
> I am telling you that your profession of faith is logically inconsistent
> with belief in a standard of truth. If you are incapable of telling the
> difference between logic and religion, so much the worse for you.
> It seems reasonable to assume that material gratification would
> supplant truth-telling in those who implicitly or explicitly reject
> the possibility of aiming at telling the truth. =
What 'profession of faith' have I made? Don't project your essentialism on=
=
me -- I don't need to make a gesture of 'faith' toward some hidden =
everlasting truth in order to validate my sincerity. Such gestures are a =
means by which 'realists' like yourself attempt to make themselves and othe=
rs =
believe that you're shooting for the 'right' target. My truths are =
contextual, as are any honest man's. My criteria for good faith have nothi=
ng =
to do with your theology.
> One of the things
> that came out most clearly in the Sokal controversy is the concern of
> the social constructionists for their shrinking budgets.
Yeah, hopefully everyone will wake up to the truth that humanities =
departments are wallowing in federal grants and corporate handouts, while t=
he =
science industry can hardly scrape together the cash to wash the windows at=
=
Dow Chemical.
What were you saying about honesty?
=
> >>>The cogito is not a logical inference? Then what is that "therefore"
> >>>doing in there? =
> >>Just read the book. It's all explained there in black and white. =
> >I have read it, and I don't remember him explaining how 'ergo' could
> >signify anything other than 'a logical conclusion follows from this
> >premise.' =
> See above.
I have, and I still haven't read anything that explains how 'ergo' does not=
=
imply a logical inference.
=
-- brian