Re: Will Radio Engineering be QM's worst nightmare?


"bz" <bz+sp@xxxxxxxxxxxxxxxxxxxx> wrote in message
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> "Ron Baker, Pluralitas!" <stoshu@xxxxxxxxxxxxxxxx> wrote in
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>
>>
>> "bz" <bz+sp@xxxxxxxxxxxxxxxxxxxx> wrote in message
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>>>>>>>>> "Ron Baker, Pluralitas!" <stoshu@xxxxxxxxxxxxxxxx> wrote in
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>>>>>>>>>
>>>>>>>>>> Is the transition instantaneous at some time between A and B?
>>>>>>>>>
>>>>>>>>> Yes.
>>>>>>>>
>>>>>>>> Why? How do you know?
>>>>>>>
>>>>>>> I don't know. One can never know in science.
>>>>>>> That is, however, my opinion.
>>>>>>
>>>>>> Then you might as well be talking about how many angels
>>>>>> can dance on the head of a pin.
>>>>>
>>>>> Not really. Science is based on evidence. A theory, in order to be
>>>>> accepted, MUST encompass all data. A theory stands until a new
>>>>> [reproduceable verifiable] experiment produces DATA that is contrary
>>>>> to the
>>>>> predictions of the theory.
>>>>
>>>> But all you offered was your opinion.
>>>
>>> And some logic to back it up.
>>
>> Really? Should we go back to the posts and
>> examine it? I'll do that.
>>
>> Can you support your assertions? Can you cite
>> references?
>
>
> http://cacs.usc.edu/education/phys153/lecture_Notes.pdf
> see page 29
> [quote]
> From the excited state, an atom jumps back to a lower energy
> level by emitting a photon.
> How long does it take for an atom to de-excite?
> De-excitation depends on:
> 1) How long the atom stays in the excited state
> 2) The time taken by the atom to jump
> The second step is assumed to be instantaneous.
> [unquote]

You've repeated this in two posts. I'll address it in
the other post.

>
>
>>> I also falsified the 'millions of cycles' model presented in
>>> http://jchemed.chem.wisc.edu/JCEWWW/Articles/DynaPub/DynaPub.html#ref16
>>
>> In your opinion, I'm sure you have. But a funny thing,
>> your soap bubble analogy quite parallels the above
>> article. You just ad hoc'ed an arbitrary pronouncement
>> that photon doesn't exists until the wave detaches from
>> the atom.
>
>
> http://phys.strath.ac.uk/alpha-x/Assets/articles/Reid-time-resolved-
> spectroscopy-2003.pdf
> [quote]
> yielding pulses at around 800 nm at the fundamental, with pulse widths as
> short as 4 -5 fs
> [unquote]
>
> Can we agree that all 800 nm photons are identical in 'size', energy, and
> wavelength? They consist of the same number of EM field cycles?
>
> The period of a 800 nm photon is 2.7 fs. A 4 fs pulse could not contain a
> photon that was much longer than 1 cycle.
>
> Is that sufficient basis for you to accept my statement?

Ditto this. See my next response.

>
>
>>> Some evidence to back up that falsification:
>>>
>>> The reflection of light from a metal surface is thought to be due to
>>> absorbtion and reemission of photons.
>>
>> Support? References?
>
> groups.google.com
> mirror absorption reemission

Burden shifting. You can't put the burden of supporting
your point on me.

>
>>> There does not appear to be any delay
>>> introduced by this event.
>>
>> If there is no delay then how is it said that there
>> is absorbtion/reemission?
>
> There can be delays between the absorption and the reemission. Light
> passing
> through a transparent substance is delayed.

But you brought it up in the case of reflection at
the surface of a metal, presumably to support that
absorbtion and emission are instantaneous.
How is the response pertinent?

>
>>> How do we know the first statement is correct? We can verify it by
>>> using surfaces other than metals. Surfaces that select which photons
>>> they will absorb and reemit. This is left as an exercise for the
>>> reader.
>>
>> What? What is that supposed to mean?
>
> reflection from non metalic surfaces is preferentially polarized. This is
> why
> polaroid sun glasses are useful for reducing glare (refelections) from
> road
> and water surfaces.
>
> Take your laser pointer and bounce the beam off of a wooden desktop at
> about
> a 40 degree angle to the surface of the desk.
>
> Rotate the laser around the axis of emission.
>
> You will notice that the reflected beam has a distinct 'null' in intensity
> as
> the plane of polarization. Adjust the angle of incidence to intensify the
> null. You are at the Brewster angle.

Relevance?

>
>>> How do we know that the second statement is true? We can verify it by
>>> timing light beams that undergo many reflections while passing down a
>>> tunnel made of parallel front surface mirrors. Any delay greater than
>>> that due to the length of the path must be due to time taken by the
>>> transition.
>>
>> References? Or is this a hunch or opinion?
>
> A proposed experiment.

Unsupported speculation.

>
>>> femto second (and below) laser pulses would not be possible if light
>>> emission took longer than the pulse width, nor if the photon wave train
>>> was longer than the pulse width time. Pulse widths are now on the order
>>> of
>>> a single cycle. This pretty clearly indicates that the actual
>>> transition must take place in 1/f time or less.
>>
>> Is that instantaneous? Are you still saying that the transition
>> is instantaneous?
>
> I am setting limit on non-instantanety [if such a word exists]

Sounds like you are redefining 'instantaneous' to spin your
statements to be less incorrect.

>
>> Are you also concluding that if the transition is that quick
>> for a pulsing laser it is also that quick for a CW laser?
>
> Yes.

Noted.

>
> If you have a reason to think that the emission transition takes a
> different
> amount of time in a CW laser than in a pulsed laser, I would love to see
> it.
>
>>> http://hypertextbook.com/facts/2005/LarisaTuchinskaya.shtml
>>>
>>> [quote http://physicsweb.org/articles/world/12/1/8]
>>> According to Heisenberg's uncertainty principle one possible limit is
>>> the switching of electrons from one state to the other. The shortest
>>> theoretical time this can be done is three femtoseconds (3 X 10-15 s).
>>
>> So it can't be instantaneous?
>
> Acccording to that article there is a limit on switching time.

So the transition is not instantaneous.

>
> That doesn't say that the Emission itself doesn't take place
> instantaniously.

And you define emission to occur at the instant the wave
'separates' from the atom?

>
>>> Given that electronic devices are most conveniently made of solid
>>> materials, it can be argued that conventional electronic circuits will
>>> never operate on timescales faster than femtoseconds.
>>>
>>> The femtosecond timescale is also the fundamental limit for many basic
>>> processes in the natural world. Molecular bonds are made or broken on
>>> timescales varying from femtoseconds to picoseconds. The basic
>>> processes of
>>> life, such as photosynthesis, begin on the femtosecond timescale.
>>> [unquote]
>>
>> Could you explain what point you were making with
>> the above?
>
> That the emission could not possibly take as long as
> http://jchemed.chem.wisc.edu/JCEWWW/Articles/DynaPub/DynaPub.html#ref16
> think it takes.

Hmm. Do you like that fs to ps timescale? Because 1 ps
works out to 500 wavelengths at 600 nm.
Hardly instantaneous.

If some molecular bonds are made or broken on
a timescale equivalent to 500 wavelengths then
why can't stimulated emission in a laser take 10^6
wavelengths?

>
> They seem to think the emission takes as long as the average lifetime of
> the
> excited state. They envision photons that are millions of cycles long.
> That
> is clearly WRONG.

Hmm. Capital letters. I must be wrong then.

>
>
> What point have YOU been trying to make?

Transition/emission is not instantaneous.
The EM field/wave function of a 'photon' has
nonzero spacial extent along the direction of motion.
That longitudinal spacial extent or length
can be on the order of 10^6 wavelengths.

--
rb


.

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